Under flooded conditions, the competition between AsV and P in the rhizosphere deters P uptake and higher concentrations of AsV are absorbed by the plant. Immobilization of As in soils under oxic conditions reduces this competition and P bio availability increases, explaining the higher P concentrations in HS treatments. The nutritional value of rice grain is not typically considered when evaluating the impacts of water management treatments on As uptake, water use, and greenhouse gas emissions. However, potential changes in the grain nutritional content should not be ignored, as rice is a staple food for over half of the world’s population and a critical source of specific nutrients. In this study, in addition to decreasing As grain content, we reveal that II can increase Fe, P, and K levels in rice grain, providing another potential benefit to II management. We confirmed that a single dry down can be a suitable II treatment for minimizing As and Cd concentrations in grain. However, in other rice growing regions different field conditions would exist and II strategies may need to be modified to suit the specific location. To adapt water management regimes to meet specific environmental conditions, a better understanding of the soil and rhizosphere chemistry in rice paddies is crucial. Elucidating the biotic and abiotic changes occurring at the root soil interface and the mechanisms involved in As immobilization and Fe plaque formation, as well as how these are involved in the broader elemental cycling in rice systems,vertical hydroponics can bring us a step closer to defining how we can mitigate the ongoing problem of arsenic in rice while addressing human health concerns for one of the most consumed crops worldwide.

Rice is a staple food for more than half of the world’s population and is particularly susceptible to arsenic accumulation . Elevated As uptake occurs because rice is typically grown under flooded conditions where reduced As predominates and has high mobility and toxicity, leading to accumulation in rice grains and increasing the risk for As consumption by humans . Intermittent irrigation is a water management technique that involves intermittent flooding and draining cycles. Several studies reveal that II is an effective solution for reducing As concentrations in grain, methane gas emissions, and increasing water use efficiency . However, II treatments need additional study to determine their suitability for widespread application in rice paddies. Rice and many other aquatic plants transport oxygen to their roots via aerenchyma, creating an oxidized rhizosphere and resulting in the formation of an iron mineral plaque. This process occurs by oxidation of aqueous FeII present in anoxic soil solution after rice fields are flooded, and the precipitation of iron oxides and hydroxides on the root surface . Iron oxides are extensively studied in numerous disciplines because of their abundance in the environment and high reactivity; they play a vital role in many soil exchange processes. Additionally, Fe plaque formation and composition are affected by environmental factors, such as soil solution composition, pH and redox potential . Fe plaque can account for up to 14% of the dry weight of mature rice roots and can serve as a sink for As . Seyfferth et al., 2017, revealed that Fe and As co occur on the rice root surface. Other studies indicate that rice root iron plaque primarily retains arsenate and someAsIII .

In rice plants grown under continuous flooding, 95% of Fe plaque is composed of ferrihydrite and goethite , and, in lower proportions. lepidocrocite and siderite . The mineral composition of iron plaque is a result of specific biogeochemical factors at the root soil interface, which determine their crystallinity and surface affinity for adsorption of anions and cations . Ferrihydrite is an amorphous mineral that forms via hydrolysis of ferric iron with a large surface area, high adsorptive capacity and a positive charge under most soil conditions, serving as a sink for many oxyanion elements and organic compounds. Ferrihydrite gradually transforms into more thermodynamically stable and more crystalline FeIII oxides, such as goethite, via Ostwald ripening. . Moreover, intermittent irrigation treatments create fluctuating oxic and anoxic conditions in soil, which can alter the speciation of redox active elements at the root soil interface. Iron redox cycling affects the mobility and bio availability of As due to its high affinity for arsenite and arsenate. Oxidizing conditions in the soil can precipitate FeII into FeIII oxides and transform arsenic into AsV , while reducing conditions can lead to the dissolution of iron plaque, resulting in the release of FeII, AsIII and AsV present on root plaque, as well as reduction of AsV . Intermittent irrigation reduces arsenic mobilization by introducing oxic conditions in the soil during the growing season, oxidizing and immobilizing As in soil. Although it is well understood that with redox fluctuations the chemistry of both Fe and As will be affected, we find a gap in understanding how intermittent irrigation treatments of different timing and severity can impact the formation and mineralogy of iron oxides and thus their binding affinity to As. In addition, several authors have studied the sorption of AsIII and AsV on iron oxide surfaces with some evidence for specific binding mechanisms ; however, to our knowledge,hydroponic vertical farming systems a distinction of the binding interactions between AsV and root plaque iron oxides via insitu experiments to evaluate As sorption on the mineral surface have not been conducted.

In Chapter 1, our research demonstrated that II is a suitable strategy to reduce rice As uptake and translocation into the grain, but the chemical changes occurring in the rhizosphere, the mechanisms for As sequestration and the role of Fe plaque remain unclear. The objective of this study is to identify the changes in root plaque chemistry under intermittent irrigation treatments and to understand the binding interactions of synthesized iron oxide minerals present in root plaque with arsenate to facilitate an increased understanding of their impact on rice As uptake.The results from this study demonstrate that the mineralogy of rice root plaque is impacted by water management. Ferrihydrite, goethite, lepidocrocite, and side rite were detected in root plaque samples throughout the growing season, which is consistent with prior studies . In our XRD results, goethite was observed in all plaque samples at the late growth stages . Goethite formation typically follows a mineral ripening process where relatively amorphous and soluble minerals are transformed into a more thermodynamically stable and crystalline phase under oxidizing conditions . Additionally, ferrihydrite was first observed in the XRD spectrum corresponding to the CF treatment, as well as in II treatments at the late growth stages. Several factors can influence the mineralogy of rice root plaque, such as pH and soil solution chemistry. As pH decreases from 7 to 5, ferrihydrite is more likely to form . In the present study, during the 2018 growing season, soil pH increased from 6 to 7.5, making conditions favorable for ferrihydrite formation during the early stages of the growing season. Additionally, this pH range can increase the retention of arsenate by ferrihydrite than goethite . Moreover, Limmer et al., 2018 found that silicon concentrations during the formation of Fe plaque may play a role in its mineralogy. When the ratio of Si/Fe increases, ferrihydrite is more likely to form rather than lepidocrocite . Our SEM results demonstrate that Si and Fe do not co localize in root plaque for all samples. Higher amounts of Si in HS treatment in comparison to CF were found, indicating greater formation of ferrihydrite on roots of II treatments. Under flooded conditions, the transport of oxygen via aerenchyma to the rhizosphere drives the oxidation and precipitation of amorphous iron oxides which are subsequently transformed into goethite. Nevertheless, the identification of ferrihydrite and goethite at different times of the growing season indicates that mineral formation processes are impacted by II, which alters the mineralogy of plaque at different stages of rice growth. Iron plaque formation was studied by Long et al., 2019, revealing that Fe plaque formation occurs progressively; however, it is difficult to identify temporal trends in the mineralogy regarding II treatments when Fe oxide mineral formation begins, during the early stages of rice growth. XRD peak quantification and intensity measurements were limited by the presence of quartz in all samples. Attributed to its highly ordered crystalline structure, absolute intensities of quartz peaks in bulk mineralogy XRD analysis may cause extinction effects and reduce intensities of other mineral peaks, making identification of co existing minerals more challenging .

Additionally, XRD peaks do not often reflect the concentrations of all minerals present in the sample. In some cases, experimental errors or the lattice parameter d= nwill cause the peak positions to vary due to an angle shift. In addition, more crystalline minerals are easier to identify: ferrihydrite being highly amorphous is harder to identify in comparison to a more crystalline mineral such as goethite. For this reason, we focus our discussion on peak identification rather than concentration. Moreover, corresponding XRD peaks from samples collected at the later stages of rice growth, when root plaque mineral composition is less dynamic, are easier to identify in XRD spectra. Furthermore, Liu et al., 2006 found that ferrihydrite and goethite are the iron minerals present in the highest proportion in rice root plaques; therefore, it is critical to understand the binding interactions of these minerals with arsenic. Although the strong adsorption of AsV onto ferrihydrite and goethite has been demonstrated in earlier studies , there is uncertainty about the binding kinetics, and more studies are needed about how the sorption of arsenate compares between these minerals. Thus, insitu ATR FTIR experiments were carried out to elucidate binding mechanisms of AsV to these Fe oxides, which are dominant in the root plaque samples from this study. If specific binding mechanisms can be determined it would improve our understanding of the availability of arsenic for plant uptake under different rice paddy water management. Kinetic analysis results of FTIR spectra for AsV reacted with both goethite and ferrihydrite reveal an increase in peak area as a function of time, indicative of As sorption . These kinetic binding experiments also exhibit a cap on sorption sites of the surface of ferrihydrite based on the peak area change, showing a quick increase of sorption from 15 to 120 minutes. In contrast, for goethite, arsenate sorption increases slower and begins to plateau around 240 minutes. Additionally, we observe a difference in sorption when comparing the delta peak areas of ferrihydrite compared to goethite, being 8 fold higher for ferrihydrite and deducing that it has an increased ability to adsorb arsenate. It is logical to observe that ferrihydrite binds more AsV , as it is a poorly crystalline mineral and its amorphous characteristics are indicative of a greater binding surface and thus can lead to strong affinity for both arsenate and arsenite. These results are in agreement with Huang et al., 2011, which demonstrated higher sorption of iAs for ferrihydrite than goethite, explained by their differences in specific surface area and microporosity. Based on the observed aqueous AsV diagnostic peaks at 907 and 876 cm 1 , we identify distinct peak downshifts in all spectra. When AsV is reacted with goethite IRE coatings, one peak shifts to 871 cm 1 . For AsV reaction with ferrihydrite, a broad peak appears from 883 to 789 cm 1 . A downshift in the location of the FTIR peak for dissolved species upon reaction with a mineral surface is commonly attributed to inner sphere coordination . The reaction of arsenate with iron oxides has been previously studied via H+ /OHrelease stoichiometry titration experiments with strong evidence that arsenate is adsorbed on iron oxide surfaces by forming inner sphere bidentate binuclear complexes . Inner sphere binding, particularly bidentate, is substantially stronger than outer sphere binding and represents a species of Fe that is less bio available. Moreover, prior research has demonstrated that iron and arsenic co occur on the root surface of rice , which is consistent with the positive correlation between Fe and As measured in the DCB extracted plaque for all treatments in the current study .

This research also found that when NRT1.1 was phosphorylated at a low nitrate concentration, it was involved in maintaining the low level primary response; when it was dephosphorylated under a high nitrate concentration, it led to a high level primary response. More recent work has shown that NRT1.1 mediated regulation is quite complex in that it activates distinct signaling mechanisms. Furthermore, a rice homolog of AtNRT1.1has been identified, and variations in this gene in the rice sub species indica have been identified as boosting the absorption of nitrate and the transport of nitrate from roots to shoots, and potentially enhance NUE in rice.Another important nitrate regulator is the transcription factor NLP7, which belongs to the NIN like protein family in Arabidopsis. The NIN protein family was originally found to function in the initiation of nodule development in legume species and these family members are conserved in higher plants and algae. The NIT2 protein is a homologue of the NIN family in Chlamydomonas and can bind to the promoter of the nitrate reductase gene. In Arabidopsis, NLP7 has been demonstrated to be an important positive regulator of primary nitrate response as the induction of the nitrate responsive genes NIA1, NIA2, NRT2.1, and NRT2.2 is inhibited and nitrate assimilation is also impaired in nlp7 mutants. The function of NLP7 in nitrate signaling was further confirmed by the identification of the nlp7 mutant in an effort to explore novel nitrate regulators by using a forward genetics approach. ChIP chip analysis revealed that NLP7 could bind 851 genes including genes involved in N metabolism and nitrate signaling, such as NRT1.1, CIPK8, LBD37/38, and NRT2.1.

A recent study found that NLP7 could regulate the expression of NRT1.1 in the presence of ammonium and bind directly to the promoter of NRT1.1. These findings illustrate that NLP7 works upstream of NRT1.1 directly when ammonium is present. NLP7 can also activate or repress nitrate responsive genes. The Arabidopsis thaliana genome encodes nine NLPs,vertical planters for vegetables all of which contain the conserved RWP RK domain and the PB1 domain. Members of this family can be divided into four subgroups: NLP1 and 2, NLP4 and 5, NLP6 and 7, and NLP8 and 9. Yeast one hybrid screening using four copies of the nitrate response cis element illustrated that all NLPs could bind to the NRE element. In response to nitrate, the transcript levels of NLP genes are not regulated, but examination of an NLP7 green fluorescent protein fusion revealed that localization of NLP7 was modulated by nitrate via a nuclear retention mechanism. Recently, this localization of NLP7 was identified to occur when Ser205 in NLP7 was phosphorylated in vivo in the presence of nitrate. Suppression of the NLP6 function resulted in the down regulation of nitrate responsive genes, indicating that NLP6 is also a master nitrate regulatory gene involved in primary response. Further characterization has shown that the N terminal region of NLP6 is necessary for its activation in response to nitrate signaling. Furthermore, using over expression lines, NLP7 was revealed to significantly improve plant growth under nitrogen poor and rich conditions. Moreover, ZmNLP4 and ZmNLP8, maize homologs of AtNLP7, play essential roles in nitrate signaling and assimilation and promote plant growth and yield under low nitrate conditions, implying that they may be potential candidates for improving the NUE of maize. In addition to NLPs, reverse genetics has identified LBD37/38/39 to be important nitrate regulators. LBD37/38/39 belong to a gene family encoding zinc finger DNA binding transcription factors and are strongly induced by nitrate.

Further characterization revealed that over expression of LBD37/38/39 can repress the expression of nitrate responsive genes including NRT2.1, NRT2.2, NIA1, and NIA2, indicating that the three LBD members function as negative regulators in nitrate signaling. Recently, following advances in bio informatics and global sequencing analysis, systems biology approaches have been developed and successfully applied to plant nitrogen research. The transcription factors SPL9, TGA1, and TGA4 have been sequentially identified by systems approaches. SPL9 was predicted to be a potential regulatory hub and may target sentinel primary nitrate responsive genes. Research has demonstrated that miR156 can target SPL9 and a mutation in the miR156 caused over expression of SPL9. Accordingly, miR156 resistant SPL9 transgenic plants were investigated and it was revealed that the transcript levels of NRT1.1, NIA2, and NIR significantly increased in response to nitrate, demonstrating that SPL9 plays a negative role in the primary nitrate response. TGA1 and TGA4 belong to the bZIP transcription factor family and are induced by nitrate in roots. Interestingly, induction of TGA1 and TGA4 is inhibited in chl15 and chl19 mutants after nitrate treatment, implying that the regulation of TGA1 and TGA4 by nitrate is affected by nitrate transport, but not the signaling function of NRT1.1. Transcriptome analysis of the roots of tga1 tga4 double mutant plants revealed that most of the genes differentially expressed in the double mutant were regulated by nitrate. Among these target genes of TGA1 and TGA4, induction of NRT2.1 and NRT2.2 was substantially reduced in the double mutants. Further analysis demonstrated that TGA1 could bind to NRT2.1 and NRT2.2 promoters to positively regulate their expression . These results all serve to suggest that TGA1 and TGA4 play important roles in the primary nitrate response.Recently, Shuichi’s lab found that nitrate inducible GARP type transcriptional repressor1 proteins act as central regulators in nitrate signaling.

Co transfection assays revealed that NIGT1 clade genes including NIGT1.1/HHO3, NIGT1.2/HHO2, NIGT1.3/HHO1, and NIGT1.4/HRS1 were all induced by nitrate and were redundant in repressing the nitrate dependent activation of NRT2.1. EMSA and chromatin immunoprecipitation–quantitative PCR analysis further showed that NIGT1.1 could directly bind to the promoter of NRT2.1. Transcriptome and co transfection analysis also illustrated that the expression of NIGT1s was auto regulated and controlled by NLPs. In addition, NIGT1.1 can suppress the activation of NRT2.1 by NLP7. Further investigation suggested that the regulation of NRT2.1 by NIGT1.1 and NLP7 is independent due to their distinct binding sites. A genome wide survey discovered the potential target genes that might be regulated by both NLP mediated activation and NLP NIGT1 transcriptional cascade mediated repression or the NLP NIGT1 cascade alone. Furthermore, phosphate starvation response 1 , the master regulator of P starvation response, also directly enhanced the expression of NIGT1 clade genes,vertical farming technology serving to reduce nitrate uptake. CIPK8 and CIPK23 are calcineurin B like interacting protein kinases. CIPK8 is induced rapidly by nitrate and down regulated in the chl15 mutant. Analysis of two independent T DNA insertion lines showed that induction of NRT1.1, NRT2.1, NIA1, NIA2, and NiR by nitrate was reduced in cipk8 mutants indicating that CIPK8 works as a positive regulator in the primary nitrate response. Further investigation revealed that CIPK8 regulated the nitrate induced expression of NRT1.1 and NRT2.1 under higher but not lower nitrate conditions , suggesting that CIPK8 functions as a positive regulator when nitrate is replete. CIPK23 can be induced by nitrate and downregulated in the chl15 mutant like CIPK8. Expression of the nitrate responsive gene NRT2.1 was upregulated in the cipk23 mutants after nitrate treatment, indicating that CIPK23 plays a negative role in primary nitrate response . This gene is essential for the affinity switch of NRT1.1: it interacts with NRT1.1 and phosphorylates NRT1.1 at T101 under low nitrate concentrations to enable NRT1.1 to operate as a high affinity nitrate transporter, while it dephosphorylates NRT1.1 when nitrate is replete so that NRT1.1 functions as a low affinity nitrate transporter. CPK10, CPK30, and CPK32 are subgroup III Ca2+ sensor protein kinases .They have all been identified as master regulators that orchestrate primary nitrate responses. Analysis of the single cpk10, cpk30, and cpk32 mutants has shown that they only trivially affect nitrate responsive genes. However, in the double mutants cpk10 cpk30, cpk30 cpk32, and cpk10 cpk32 and the triple mutant cpk10 cpk30 cpk32, nitrate responsive marker genes were reduced. Transcriptomic analysis showed that CPK10, CPK30, and CPK32 modulated various key cellular and metabolic functions immediately activated by nitrate. Furthermore, CPK10, CPK30, and CPK32 can phosphorylate NLP7 at Ser205 in vivo in the presence of nitrate, and trigger the nitrate CPK NLP signaling network. Recently, three other nitrate regulatory genes NRG2, CPSF30L, and FIP1 were identified using a forward genetics method. Two independent NRG2 T DNA insertion lines showed reduced induction for nitrate responsive sentinel genes , indicating that NRG2 plays an essential role in nitrate signaling.

At the physiological level, NRG2 affects accumulation of nitrate in plants. Further investigation revealed that it regulates nitrate uptake by roots and the translocation of nitrate within plants. These effects might be achieved through modulating NRT1.1 and NRT1.8 as the expression of both genes was altered in the mutants. Genetic and molecular data suggest that NRG2 can regulate the expression and work upstream of NRT1.1, but function independently, with NLP7 in regulating nitrate signaling. In addition, transcriptomic analysis showed that four clusters in the differentially expressed genes in nrg2 mutant were involved in the regulation of nitrate transport and response, confirming that NRG2 plays essential roles in nitrate regulation. Interestingly, NRG2 can directly interact with NLP7 in vitro and in vivo, as revealed by yeast two hybrid and BiFC experiments. All these results demonstrate that NRG2 is an important nitrate regulator. In addition, the Arabidopsis genome harbors 15 members that are homologous with the NRG2 protein. All members of the NRG2 family contain two unknown conserved domains: DUF630 and DUF632. Whether and which other members of the NRG2 family are involved in nitrate signaling and what functions the two domains play are interesting and pertinent directions for future research. The CPSF30 gene encodes 28 kD and 65 kD proteins. The 28 kD protein was identified as a cleavage and polyadenylation specificity factor; the protein contains three characteristic CCCH zinc finger motifs and functions as both an endonuclease and an RNA binding protein. An additional YTH domain, along with the three zinc finger motifs, are contained in the 65 kD protein. A mutant allele of CPSF30, cpsf302 with a G to A mutation in the first exon of gene CPSF30, was identified by genetic screening and used to explore the functions of CPSF30. The expression of nitrate responsive genes can be down regulated in response to nitrate in cpsf302 compared to wild type and restored to wild type levels in a complemented CPSF30L/cpsf302 line, indicating that CPSF30L is involved in nitrate signaling. CPSF30L can regulate nitrate accumulation and assimilation at the physiological level. Transcriptomic analysis showed that genes involved in six nitrogen related clusters, including nitrate transport and assimilation, were differentially expressed in the cpsf302 mutant. Further study revealed that CPSF30 could work upstream of NRT1.1 and independently of NLP7. CPSF30 can also affect NRT1.1 mRNA 30 UTR alternative polyadenylation. All these results demonstrate that CPSF30 plays an important role in the primary nitrate response. FIP1, a factor interacting with poly polymerase 1, was identified as a positive nitrate regulatory gene using the fifip1 mutant and a FIP1/fifip1 line. Nitrate induced expression of NIA1, NiR, and NRT2.1 is repressed in the fifip1 mutant and can be restored to the wild type in the FIP1/fifip1 line. Furthermore, FIP1 can affect nitrate accumulation through regulating the expression of NRT1.8 and nitrate assimilation genes. Further research found that FIP1 could interact with CPSF30 and both genes can regulate the expression of CIPK8 and CIPK23. In addition, FIP1 can affect the 3 0 UTR polyadenylation of NRT1.1, a similar function to CPSF30. CPSF30, FIP1, and some other components such as CPSF100 can form a complex involved in poly processing. Together, these findings suggest that the complex composed by CPSF30 and FIP1 may play important roles in nitrate signaling. In the extant literature, key molecular components involved in primary nitrate responses, covering nitrate sensors, transcription factors, protein kinases, and polyadenylation specificity factors, have been identified. Methodologically, this has been achieved by using forward and reverse genetics as well as systems biology approaches . In summary, in the presence of both ammonium and nitrate , NRT1.1 functions as a sensor. NLP7, NRG2, and CPSF30 have been revealed to work upstream of NRT1.

There was a general pattern that suggested increasing salinity led to decreasing tissue water potential. However, only E. californica, F. salina, and J. carnosa showed a significant change in water potential as salinity increased. The observed change was likely due to increased solute concentration in the tissue to compensate for higher solute concentration in the soil . As soil solute concentrations increase, it becomes more difficult for plants to take up water. In response, plants can concentrate solutes in their tissue, creating a hypertonic state that allows continued passive uptake of water . Lack of response to increasing salinity for some species may have resulted from insufficiently stringent treatments. Our highest salinity treatment was 60% seawater, whereas plants in the low ecotone can experience inundation with full strength seawater. The average low marsh soil has a salinity concentration of 43.9 ppt , while seawater averages about 34.9 ppt, indicating that some species can survive 125.79% seawater. Because our plants only received 60% seawater, or roughly half the concentration plants can experience in the field, it would be useful to repeat this greenhouse experiment with higher salinity treatments. Drought effects can be similar to salinity effects, causing plants to become hypertonic to increase water uptake . Drought significantly affected all species, causing a decrease in water potential when compared to the saturation treatment. It should be noted that although our drought treatment had a significant effect, it is unlikely to replicate true field conditions. To avoid mortality in the greenhouse, plants received water every three to four days, which differs greatly from natural rainfall patterns, even in the wet season. During the dry season, soil moisture is often between 30%  80% of sample weight for marsh and low ecotone soil cores in the high ecotone and upland locations, soil moisture accounts for 0%  30% of sample weight.

We have no data showing whether we achieved similar conditions with potting soil in the greenhouse, and regardless,hydroponic vertical farm we would expect more rapid drying in pots than for in situ field soil. Thus, as for all greenhouse studies, results presented here should be used with caution when predicting performance in the field. To expand on these results, the greenhouse experiment should be repeated using native marsh soil as the substrate and including higher salinity treatments . Response to treatment in marsh soil should provide a more accurate prediction of response to field conditions. Surprisingly, measured differences in water potential did not translate to plant performance. Neither growth nor survival were visibly affected by watering treatment, even in potentially stressful low volume / high salinity treatments. Existing literature suggests that halophytes concentrate solutes to generate low tissue water potential, allowing continued passive uptake of water. In this case, low tissue water potential is not detrimental, since it prevents or reduces water deficits that can impair growth. Another possible reason for the lack of effect on growth was timing of the experiment. We began the experiment in June, when most individuals were beginning to reproduce. Beyond this point, energy is less likely to be allocated to vegetative growth and more likely to be allocated towards reproduction or survival strategies, like salt management . In contrast, younger plants allocate the majority of their energy to vegetative growth . Adaptations, such as salt glands or specialized vacuoles, areenergy expensive and require energy normally allocated to growth . Additionally, decreasing water potential has been shown to inhibit cell expansion , which would disproportionately affect young plants, since the rate of cell expansion in mature plants is reduced. Therefore, by better aligning the experimental period with the natural growth period, and focusing on young plants, treatment effects on growth might become more apparent. D. spicata displayed the greatest variability in tissue water potential, and this variability may have been influenced by factors other than watering treatment. D. spicata was grown in shallower, wider pots in a sandier potting medium. In both volume treatments, water would drain quickly through the pots, leading to uneven soil saturation that likely affected treatment efficacy and making it difficult to draw definitive conclusions regarding the large range in water potential.

However, low water potential values are not uncommon for D. spicata. Other authors have observed sustained, highly negative water potential used to compensate for soil salinity . The highest D. spicata mortality in our experiment occurred in the drought treatments, with three out of four deaths in the 60% seawater drought treatment. Nonetheless, increased drainage and evaporation rates likely contributed to mortality for this species. E. californica was affected by both the drought and salinity treatments, causing lower water potential and a slight negative effect on growth. Interestingly, our results contrast with those from another study. Jong measured E. californica net dry weight when irrigated with a saline Hoagland solution in sandy soil, using artificial sea salt instead of seawater. The water potential of their maximum salinity treatment was similar to our 60% seawater treatment, but the authors found that dry weight of E. californica decreased significantly as salinity increased. This experiment used young E. californica seedlings  the first tissue harvest occurred when seedlings were one month old and continued every 8 days until all plants were harvested, with the authors noting a difference in dry weight between treatments . Since we did not observe a difference in above ground biomass, the contrasting results may be due to the misalignment of experiment start time with the natural growth period. F. salina did not show an effect of salinity and drought stress on total plant growth, since biomass was maintained across treatments. In contrast, Barbour’s and Davis’s results showed a decrease in F. salina’s growth as salinity increased, with total mortality at approximately 89% seawater Hoagland solution . Plants in their non saline control showed the most growth, measured by the length of the main and lateral shoots . The majority of our plants remained constant in size.

The high mortality rate across treatments was driven by aphid infestation, despite attempts to control aphids with Botanigard . The highest mortality occurred in the drought, 60% seawater treatment,vertical farm suggesting that stringent growing conditions may have made plants more susceptible to aphid induced mortality. J. carnosa was the only species that added biomass between the first and final surveys. However, growth did not differ across treatments . One study found that J. carnosa grew best in non saline or minimal saline environments , using recently germinated individuals with stalks that extended 1 10cm above the growing substrate . In contrast, two other studies found that J. carnosa can tolerate salinities twice as concentrated as seawater, but moderate salinity conditions were ideal . St. Omer and Schlesinger used Hoagland solution in a greenhouse experiment to determine that maximum J. carnosa growth, measured by total dry weight, occurred at about 30%  60% NaCl, with growth decreasing above 60% salinity. They did not record plant age . The age of the plants likely impacted the differences in growth among studies due to the difference of energy allocation between mature and immature plants, which would have been exacerbated with higher salinity. Barbour and Davis used younger plants, which may have been more sensitive to treatment effects compared to the St. Omer and Schlesinger experiment , and the results reported here. Our experimental results align more closely with those of St. Omer and Schlesinger , even though our experimental design was more similar to Barbour and Davis . The experiment should also be repeated with younger plants to determine if age has any effect on salinity and drought tolerance. Other experiments that used younger plants observed a decrease in growth or total biomass as salinity levels increased, contrasting with our finding that plants are largely unaffected by salinity. Seedlings are more desirable to use in revegetation operations due to the reduced propagation cost and transplant effort, so it is important to determine the range of conditions young plants can tolerate. Our experiment addressed a knowledge gap regarding halophyte salinity and drought tolerance that could inform the design of future restoration projects and experiments in Pacific coast salt marshes. Revegetation efforts often have low success rates due to the stringent abiotic conditions within the ecotone, which disproportionally affect seedlings . Furthermore, the different natural distributions of halophytes within the ecotone suggest that salinity and drought tolerance could vary among species. In our experiment, treatments had negligible effects on growth or survival – only water potential was affected. These results imply that these five species could survive anywhere within the ecotone, by employing different physiological adaptations – such as succulence, salt glands – to withstand stressful conditions.

However, our results are likely not representative of plant performance in the field due to a variety of factors. The timing of our experiment did not align with the natural growth period of the plants, causing us to use mature plants rather than young seedlings. Additionally, our use of 60% seawater is not representative of the tidal inundation that some of the species may experience in the field. Therefore, future experiments will examine how these factors influence outcomes, using lessons learned during this effort. Taken together, findings from this set of experiments will allow us to 1) identify zones within the ecotone maximizing survival and establishment on a by species basis, or 2) demonstrate that species are flexible enough to compensate for conditions across the ecotone, making careful placement of species unnecessary. In either case, these experiments will provide valuable insight to restoration practitioners. Ultimately, we hope that this work will support rapid and robust strategies to recreate thriving salt marsh systems. Plant growth and yield in natural environments depend on a plethora of interactions with bacteria and fungi. The microbial community associated with roots was proposed to be assembled in two steps: first, the rhizosphere is colonized by a subset of the bulk soil community and, second, the rhizoplane and the endosphere are colonized by a subset of the rhizosphere community. Intriguingly, a set of recurring plant associated microbes has emerged. This review focuses on how plants shape their rhizobiome. On the one hand, common factors among plants likely lead to the assembly of the core microbiome. On the other hand, factors specific to certain plants result in an association with microbes that are not members of the core microbiome. Here, we discuss evidence that plant genetic factors, specifically root morphology and root exudation, shape rhizobiomes. Initial evidence for an influence of plant genotype on rhizobiome composition was that similar rhizobiomes assembled in association with arabidopsis and barley grown in the same experimental conditions, although they displayed different relative abundances and some specific taxonomic groups. A correlation between phylogenetic host distance and rhizobiome clustering was described for Poaceae species, distant relatives of arabidopsis, rice varieties, and maize lines, but not for closely related arabidopsis species and ecotypes. Distinct rhizobiomes were also described for domesticated plants, such as barley, maize, agave , beet , and lettuce , compared with their respective wild relatives. Interestingly, not all plants have a rhizobiome distinct from bulk soil: some species, such as maize and lotus, have assembled a distinct rhizobiome, whereas other species, such as arabidopsis and rice, assembled a rhizobiome similar to bulk soil. The former species display a strong, and the latter a weak rhizosphere effect . The cause of this phenomenon is currently unknown. The strength of the rhizosphere effect varies with the developmental stage of the plant. Similarly, root exudation and microbial communities were found to change with the age of the plant. Furthermore, distinct rhizobiomes were associated with different developmental stages of arabidopsis, rice, and Avena fatua grown during two consecutive seasons. Pioneering studies demonstrated the ability of microbes to alter plant development. Overall, it appears evident that host genotype, domestication, and plant development influence the composition of rhizobiomes. As an alternative to plant developmental stage, residence time of plants in soil was discussed as a hypothesis for successive microbiomes. These contrasting results might be partially explained by differing environmental influences, host plants, or soils, and additional work is needed to resolve these questions. In this review, we discuss root morphology and root exudates as two genetic factors shaping plant–microbiome interactions, and we examine the following aspects: how root morphology and border cells affect rhizobiomes; how plant exudates shape the rhizobiome; and possible plant transport proteins involved in exudation. Figure 1 provides a general overview of exometabolite networks in the rhizosphere, and Box 1 illustrates the interplay between root exudates, border cells, and rhizobiomes in phytoremediation.

Some complex interrelationships and dependencies between species comprising ecosystems have been described.However, focused research could rationally identify species for routine evaluations; likewise, the scientific rationale behind test species should be reported.Thus, research should define an optimal suite of test species and end points to determine the ecosystem response to a given ENM. In general, biological receptors should be chosen for expected exposures stemming from realistic exposure scenarios. For example, relatively insoluble ENMs may, depending on their density, size and agglomeration state, rapidly settle out of suspension and associate with aquatic sediments. In that case, initial hazard assessment could focus on benthic, rather than pelagic, receptor organisms.Conversely, for ENMs that rapidly dissolve under environmental exposure conditions, conventional ecotoxicological exposure scenarios may be applied and receptors chosen to assess dissolution product toxicity. However, ENM dissolution rates vary, and pelagic organisms can be more sensitive than benthic organisms.Thus, both ENM compartmentalization and form must be accounted for when choosing receptors.Multiple effects measurements should be applied to answer research questions. Rapid screening assessments should be prioritized within a testing strategy . Mechanistically understanding overt toxicity is needed, which may require measuring more omics end points and choosing variables for developing mathematical models to predict toxicity at untested concentrations or conditions.Omics technologies can also identify potential modes of action that are conserved among different species. However,roll bench different scientific communities will have varying preferences in defining needs for omics level investigations.

Effects interpretation requires understanding the effective toxicant dose or other basis of impacts.For ENMs, the mass concentration basis of dosing may relate only partially to the effective applied dose, since biological effects often originate from surface interactions with receptors.Furthermore, ENMs are more complex than conventional chemicals because ENM shape, aggregation state and surface area may influence toxicity.Thus, surface area applied has been suggested as a supplemental dosing metric.However, ENM surface area in suspension/solid media is not a straightforward assessment given that ENMs may aggregate with a size distribution that is affected by the medium in which they are dispersed. In addition, coatings, either on pristine ENMs or acquired in the test media or environment, may alter toxicity.ENM amounts and forms effecting biological impacts should be understood and related to the administered dose to inform environmental risk assessment.This is the essence of dosimetry in ENM ecotoxicology. As with other exposure concerns related to hazard assessment, appropriate dose measurement depends on receptor and ENM characteristics, which are scenario dependent. For example, mammalian cells are harmed by ENMs that become internalized, yet uptake pathways depend on ENM characteristics.Then again, bacterial receptors that affect ecosystem level processes may be impacted by externally associated ENMs at the cell membrane, or even in the surrounding environment. In those cases, dosimetry relies on understanding ENM behavior in the complex media in which bacteria reside , which is scenario driven. End point observations of ENM damage will also depend on ENM processing in cells. During hazard assessments, understanding the history of biological interactions with internalized, or otherwise associated ENMs may not be feasible. Yet efforts should be made to measure and spatially associate ENM bio burden within biological receptors, and to examine the relationships of applied ENMs to apparent effective dose and to effects.Overall, it is not recommended to categorically exclude select conditions, environmental compartments, protocols, receptors, or end points, since any may be environmentally relevant.

Rather, careful experimental designs around well conceived, plausible exposure scenarios should be emphasized; also, ENM characteristics that influence biological responses under the dynamic conditions that occur in the environment and in biota should be characterized and quantified. One could imagine identifying key material environment system determinants that could be systematically varied to provide test results across relevant determinant ranges. Such ideas are not specific to ENM ecotoxicology, but could establish defensible practices for making progress in hazard assessment while the ENM industry rapidly advances.Mesocosms are “enclosed experimental systems [that] are intended to serve as miniaturized worlds for studying ecological processes.” While the distinctions between mesocosms and other experimental systems are not well delineated, mesocosms are generally larger experimental units and inherently more complex than benchtop microcosms or more simplified laboratory experiments.Mesocosms for ENM ecotoxicology are intended to increase the complexity of experimental systems, such that more realistic ENM physical compartmentalization, speciation,and uptake into biota can be achieved alongside biotic effects.Also, the intent is to realistically characterize ENM fates and interactions with environmental system components, and to reveal fluxes among compartments of the ecosystems responsive to internal system influences that are unconstrained by investigator interventions.Mesocosms have been used for testing relative biotic effects of ENM variants,and discerning ENM effects separately from effects of dissolution products .Mesocosm testing may occur following individual organism and microcosm studies . For example, to study how ENMs impact crops, one could first establish the potential for hydroponic plant population impacts,use soil microcosms to understand ENM bio availability via observing soil microbial community shifts,and then scale up to greenhouse mesocosms of soil grown crops. This sequence could provide an understanding of plant−microbe interactions,ENM transformation and uptake in plants,commercial greenhouse supplies and effects on food nutritional quality.

Still, there are relatively few published studies using mesocosms to assess ENM ecological hazards,and the design and operating variables of existing mesocosm studies are wide ranging.By contrast, wastewater associated ENMs,and their transformations,effects, and fates in wastewater treatment plants ,along with the potential for ENMs to impact WWTP processes,have been more extensively studied. Since sewage contains ENMs, WWTPs are inherent forms of mesocosms.Studies at entire WWTP scales elucidate ENM fates during wastewater treatment, including significant association with biological treatment biomass that becomes bio solids.However, only 50% of bio solids produced in the U.S. are land applied, and these bio solids are used on less than 1% of agricultural land in the U.S. . Bio solids are land applied even less in the European Union.Thus, knowledge of ENM fates in WWTPs and how final residues are disposed regionally are needed to develop plausible exposure scenarios. Concerns with mesocosms include factors that can be difficult to control and that mesocosms may respond to artifacts including “wall” or “bottle” effects.Further, mesocosms can conflate direct and indirect toxicant effects, typically do not have a full complement of control conditions, and deliver inconclusive results . Biological communities in mesocosms also lack realistic ecological interconnections, interactions, and energy flows. Nevertheless, outcomes can be improved by using carefully designed mesocosms and associated experiments.For example, combined with analyzing mesocosm samples, performing practical “functional assays” such as for heteroaggregation,allows for anticipating phenomena and later interpreting ENM transformation and compartmentalization in mesocosms.Similarly, batch physical association experiments if conducted using realistic components, and over time frames that allow for quantifiable mass transfer can assess ENM biomass association and readily suggest ENM fates in WWTPs.Still, hydrodynamic conditions are different in simplified tests versus mesocosms, which are different from those in the natural environment. Hydrodynamic conditions will impact ENM fate and transport and thus exposure concentrations at receptor boundaries. The inability to capturereal environmental hydrodynamic conditions in any experimental scale is a general shortcoming for both ecotoxicology and transport studies.Although mesocosms do not fully simulate real environments,mesocosms are useful and should be employed, albeit judiciously due to their resource intensity, within a strategy . Recommendations regarding using mesocosms for assessing ENM environmental hazards are provided in Table 2.Mesocosm studies must be designed and conducted around well conceived questions related to plausible exposure scenarios; they should use select end points, potentially including sensitive omics measurements,to answer questions or test hypotheses.Internal process and constituent characterization should be thorough and equally responsive to well conceived, realistic scenarios. Functional assays, that is, “intermediary, semi empirical measures of processes or functions within a specified system that bridge the gap between nanomaterial properties and potential outcomes in complex systems”,should precede mesocosm designs and experiments, and aid interpreting mesocosm results . Mesocosm artifacts are avoidable by following best practices for design and operation, although possible interferences of particulate material testing with assays must be evaluated.As for other hazard assessments, ENMs should be tested across the product life cycle, within a motivating exposure scenario. Similarly, suitable material controls should be used to test hypotheses regarding ENM specific effects .

The recommendations made regarding exposure conditions in assessing ENM hazard potentials for model organisms should be followed for mesocosm studies . Additionally, mesocosm designs should incorporate exposure durations, which should be sufficiently long to address population growth, reproduction, bio accumulation, trophic transfer, and possibly transgenerational effects. Sufficient measurements of ENM concentrations and time dependent properties must be made for clear interpretations. Key to successfully interpreting mesocosm studies is using validated methods for measuring ENMs in complex media. Measurements should include the size distribution, concentration and chemical composition of ENMs in the test system, including biological tissues,over time.In some cases, transformation products are inventoried thoroughly during long term field relevant exposures.Detection schemes require sample preparation to assess in situ exposures before quantitative analyses, or drying and embedding before visual confirmation by electron microscopy. The potential for artifact introduction should be recognized. Recovery methods continually develop, such as cloud point extraction for concentrating ENMs from aqueous matrices.Depending on the exposure scenario, in situ aging may be a study objective. However, it is important to define what “aging” really means and the specific application domain, since “aging” is a wide ranging term and can be used in different contexts, making comparisons impossible. At least, studies should be undertaken over sufficiently long time frames , which may include repeated ENM applications,such that appropriate aging, that is, time dependent transformation under realistic conditions, could occur. Alternatively, preaged ENMs could be used. However, preaging protocols are not yet standardized and, while some convention could allow for comparing across studies, the appropriate aging protocol would depend on the envisioned exposure scenario. Cocontaminants should be considered and potentially introduced into mesocosms, since some ENMs sorb, concentrate, and increase exposure to other contaminants.Select end points should account for ENMs as chemosensitizers.Also, mesocosm study designs should anticipate and plan for measuring secondary effects . In summary, while few mesocosms have been used in assessing ENM ecotoxicity and are also rare for conventional chemical testing, such systems potentially offer greater realism. Still, mesocosm exposure and design considerations should derive from immediate environmental applicability. The value of mesocosms to ENM ecotoxicology can increase by following recommendations including: addressing context dependent questions while using relevant end points; considering and minimizing artifacts; using realistic exposure durations; quantifying ENMs and their products; and considering ENM aging, cocontaminants, and secondary biological effects . Further, it should be acknowledged that mesocosms do not fully recreate natural environmental complexity. For example, aquatic mesocosms do not recreate actual environmental hydrodynamic, or temperature cycling, conditions. Hydrodynamics can significantly impact ENM aggregation or heteroaggregation, and fate and transport . Therefore, potential impacts on the resulting concentrations at the receptor boundaries should be considered.ENM environmental exposure conditions herein refer to where, how much, and in what forms ENMs may occur in the environment. These are central issues for ecotoxicology of ENMs because they suggest test exposure scenarios in which ENMs could impact biological receptors within environmental compartments influenced by various factors . These issues also influence outcomes of key regulatory concern: persistence, bio accumulation, and toxicity.Discharges underpin exposure scenarios,are initiated by situational contaminant releases , and are referred to as source terms. Mass balance based multimedia simulations mathematically account for released contaminants as they are transported and exchanged between environmental media, where contaminants may be transformed and may ultimately concentrate, potentially with altered compositions and structures . Far field exposure modeling approaches vary by question, the modeling purpose , the required spatial resolution , the temporal conditions , and the predictive accuracy required.Material Flow Analysis , which is a type of life cycle inventory analysis, has been advanced to track ENM flows through various use patterns into volumes released into broad environmental compartments,scaled to regional ENM concentrations that release via WWTPs to water, air, landfills, and soil.Such models estimate exposure concentrations in part via engineering assumptions and in part via heuristics.Also, such material flow analysis models depend on the underlying data which are not readily available, making it difficult to validate model results and potentially leading to inaccurate estimates.

Certainly the only reason any Iquiteño Jewish migrant goes to Israel is because of Israel’s recruiting of Jews from the diaspora, rhetoric backed up with citizenship and financial assistance. On the other hand, Israel does so because it is important for it to be seen as a homeland for all Jews, and Iquiteño Jews across borders of time, gender, and age strongly identify as Jews who want a homeland. Furthermore, gaining their citizenship in Israel is, like citizenship anywhere else, a long, arduous, confusing, and sometimes humiliating process. As a reminder, an Iquiteño who wishes to move to Israel must register with the Iquitos synagogue as someone who has Jewish ancestry or someone who does not , take multiple years of classes in conversational Hebrew, Jewish liturgy and ritual, Israeli culture, and successfully perform their learning over a period of more years to a series of community leaders, rabbis, and semi-official migration bureaucrats before “converting,” a process which may feel hurtful to those who already identified as Jewish, all before even considering taking the first practical steps towards movement. The main difference seems to be that for Iquiteño Jews, this process occurs largely before the actual movement takes place. Furthermore, once Iquiteño Jewish migrants are in Perú, their citizenship is revealed to be partial. Because conversions in Iquitos are performed according to Conservative/Masorti standards, not Orthodox ones,round plastic pots Iquiteño Jewish migrants are still barred from institutions such as marriage as a result of their ambiguous halakhic status.

They will also face less ambiguous racism and xenophobia. They are in arguably within the privileged tier in the Israeli Jewish/Palestinian binary, and their citizenship is hard-won and partial compared to other European-Jewish migrants and native Israeli Jews. These difficulties often appear in the ways in which the familial patterns of Iquiteño Jewish migrants differ from those of non-Jewish Peruvian migrants. The gender pattern is different: while in previous major 21st century waves of Peruvian migration, women have overwhelmingly formed the vanguard and later brought their male relatives with them , in Iquitos the pattern is that whole families migrate at once, leaving behind only scattered adult or near-adult children and siblings. Is this a factor only of guaranteed citizenship and Israel’s financial assistance, which removes barriers that separate other families? The household strategy approach to migration suggests that sending individual members of a family helps diversify that family’s options and adding to their overall economic security. The “absorption basket” governmental aid to new citizens from the ends after twelve months from arrival, meaning new migrants cannot rely on the Israeli state for long.Similarly, Iquiteño Jewish migrants to Israel buck another common demographic trend in Peruvian migration: they take their children with them rather than leaving them to finish their educations in Peru, as can be assumed to be usual by the low proportion of Peruvian migrants under age 20. The children of Iquitos’ Jews go to good schools and expect to go to university, whether in Iquitos or, more prestigiously, in Lima. Those good schools, however, are private Catholic schools, a situation that perturbs parents who want their children to be educated in environments that value and promote Jewishness, not simply educated.

This concern for children’s Jewish education was, as discussed in the previous chapter, by far the most commonly listed reason for migration. For many parents, a Jewish education that they feel will help make their children more Jewish is worth disrupting education in an absolute sense. Education is not a neutral driver in this case, or even a blunt-force promise of opportunity; questions of identity visibly trump questions of practicality and pedagogy. From a neoclassical economics standpoint that privileges economic self-interest as the main driver of human motion, one might expect that the differences in standard of living and wages between Israel and Perú would encourage migrants to stay in Israel, rather than Iquitos. Peruvian migration in general does indeed lend some support to this thinking: return migration is relatively uncommon for Peruvians specifically and non-Jewish Latin American migration to Israel conforms to this pattern. However, Iquiteño Jews do not necessarily expect a better life in Israel in economic terms, although the shift seems clear on the surface. The majority of Iquitos’ Jewish community is lower-middle to middle class —shopkeepers, professionals, clerical and medical workers—and usually moves down the economic ladder when they move to Israel. In my 2019 interview group, nineteen of my adult subjects expressed anxiety about their work prospects in Israel, and were particularly nervous about the difficulties of learning Hebrew as adults to the level necessary to do their present jobs. One young woman, a math teacher, told me about her older sister, a family medicine doctor who, after seven years in Israel, had been able to recertify herself as a nurse. As for herself, she thought, perhaps there would be some posts for tutoring the children of other Spanish-speaking migrants until she could learn enough to earn an Israeli teaching credential.

On the Ramla Tinos Facebook page, which circulates death notices, flyers for secondhand refrigerators,hydroponic bucket and the periodic Jewish meme in Spanish to the approximately 1,800 Latin American olim who make up its followers, a typical job ad is for domestic labor in private homes or factory jobs. This is not the kind of work the majority of Iquiteño Jews do in Iquitos, and combined with the testimony of my interview subjects, suggests that life will in many ways be economically harder in Israel than in Perú, and many Iquiteños know it. It seems implausible, therefore, that neoclassical-style economic thinking, easy citizenship, or the promise of a wealthier life could explain why Iquiteño-Jewish migration follows a riskier and more permanent pattern than is usual among 21st century migrants generally and even Latin American migrants to Israel specifically. Life for recent olim from Latin America, who face racial, religious, linguistic, and legal barriers to full citizenship and economic success, is arguably more difficult in Israel than it was at home, something of which prospective migrants are aware, at least in part. I do not wish to ignore the fact that migration dynamics often become self-sustaining as time goes by. Ethnic enclaves like those that my subjects and their Israel-dwelling relatives tell me have sprung up around the central bus station in Tel Aviv, in Ramla, and in Beersheba represent social capital that softens arrivals for new migrants and provides information and formal and informal labor opportunities. Transnational social fields develop institutional frameworks and pulls of their own, and become self-sustaining. All this is true and demonstrably affects the ways in which Iquiteño Jews migrate: as discussed in the previous chapter, by the time of writing, almost everyone left in the Iquitos community has friends and family living in Israel with whom they desire to reconnect. Even so, transnational social fields can become self-sustainingly circular , so it still matters why this social field has become self sustainingly unidirectional. Moreover, it is not simply coincidental that these Jews ended up in and stayed in Israel, and treating this group as if it were not engaged in behavior that conforms to a certain set of expectations about the reciprocal roles of diaspora and homeland in favor of simplistic economic arguments is shortsighted. Discussions with Iquiteño Jews laid out in the previous chapter made clear that the majority of these potential migrants feel an intense affinity for Israel that out times outweighs their expressed love for Perú. I also described how the revitalization of Jewish life in Iquitos has from the start been shaped by individuals and organizations with a desire to see the Jewish diaspora support Israel in multiple ways up to and including permanent migration as religiously inflected olim, not simply any other migrant. The educational materials and conversion processes made available to the Jews of Iquitos suggest the similarity of the Biblical Holy Land and the modern State of Israel and reinforce the primacy of Israel for diaspora Jewish identity. They seem to have successfully created a now self-sustaining model of Jewish identity in which migration to Israel to live a “more Jewish” or “better Jewish” life is key to proving belonging and status in the community and in a perceived global community of Jews. Although this might seem a natural equivalency, it is in no way a given that the modern state of Israel should be the locus of current Jewish transnational activity.

Over the course of thousands of years of Jewish diaspora, Jewish self-rule developed in countries far from the Holy Land, belying the assumption that owning the territory of the erstwhile Kingdom of Israel was necessary. In the modern era, diaspora nationalism, which for Jews indicates not the support of the home country in the diaspora but the assertion of real, valid, solid identities as Jews in the diaspora had an enormous influence on Jewish arts and letters and political activity, including proposals for alternate Jewish homelands in places as diverse as eastern Russia and the Niagara River, New York. As Lesser and Rein argue so forcefully, hyphenated Jewish identities can and often do focus as strongly on the host national segment as on the Jewish one. As Roniger argues, the usefulness of acknowledging and acting upon transnational ties is perpetually in flux. It is not natural and obvious that the Jews of Iquitos, simply for being Jews, should have decided to engage in transnational activity with Israel specifically. If a purely economic analysis suggests that transnational activity was inevitable in a globalized world, precluding a durable community in Iquitos, it was not inevitable that Iquitos’ Jewish community should decide to focus its transnational activities to such an extent on Israel. It is possible to imagine stronger links with Argentina’s Jewish population that did not lead back to Israel, just as it is possible to imagine connections with communities in the United States that were not tied solely to migration. It is even possible to imagine a resurgence of interest in Morocco, from whence the ancestors of most of Iquitos’ Jewish population hail, far more recently than any connection to the land of Israel. It has only been made to seem as though Israel was the choice so obvious it could not be passed up through precisely the utilization of diaspora discussed at the beginning of this chapter. When respected religious officials like Rabbi Guillermo Bronstein, long-term guests like Ariel Segal, and philanthropic organizations like the Jewish Agency for Israel and the Federación Sionista del Perú all push a specific narrative of the inadequacy of diaspora and the illegitimacy of diasporic identities in which dedication to Jewish life and possession of a valid Jewish identity is shown through attachment to the state of Israel, the rhetoric combines with the economic. Iquitos’ Jewish community is a clear example of transnational practices, from commerce to migration, being guided by rhetoric that takes strict Safran-style interpretations of diaspora for its guide. Apart from simply steering migrants towards a particular destination, this blending of diaspora with transnational practice also produces different outcomes from groups in similar situations who are engaged in transnational activity without belonging to a diasporic people. Transnational social fields occur thanks to economic and practical principles; this transnational social field occurred thanks to economics and the conscious deployment by activists, states, and organizations of diaspora as more than a myth. If this situation is true for the Jews of Iquitos, it can be true for other diasporic peoples, whether they more closely resemble a Safranesque diaspora or a Berns-McGown-like one. If, as Roniger states, Jews in the diaspora can choose when and where to direct their transnational efforts after absorbing changing messages about their own and their ties’ legitimacy, so can other diaspora groups, whether or not that identity is conventionally considered strong. Homelands can shape a narrative in which being part of the diaspora makes an individual less than both a person living in the homeland and a person native to the host country, where recall and return are not only necessary performances of identity but can be acted upon in practical ways, whether through voting abroad, sending back money, or moving back home.

Is Israel engaged in constructing a machine in which “problematic,” marginal, questionable Jews are found, processed, and shaped into ideal settlers? Although this process is unwieldy, multipart, historical, inefficient, and only partially successful, in this chapter I argue that this immigration process does succeed in its primary goal of convincing diasporic Jews to identify with Israel, migrate, and solidify Israeli racial hierarchies. Regardless of the personal meaning of conversions to Iquiteños, they are a powerful tool for the education and selection of potential Israelis. Since some Mizrahi and Sephardi communities wield significant power within Israel, and Israel’s secular courts have loosened restrictions on the kinds of conversions that turn potential olim into viable proto-Israelis, why do Iquiteños nonetheless convert in Orthodox Ashkenazi modes3? The obvious answer is that affiliating themselves with relatively disadvantaged groups is unwise. Forward-thinking action towards assuming a more privileged position in Israel seems like a rational step to take, but how is that position of privilege communicated to Iquiteños, and what parts of the social position are received as most attractive? How is the sincere potential religiosity of conversion tied to expectations of more material gains in a way that Iquiteños understand and respond to? The overlap of personal choice and state-level manipulation may reveal much about how the diaspora relates to a modern state claiming centrality and authenticity, and vice-versa.

The second chapter takes a closer look at the transnational frameworks introduced in the first,strawberry gutter system expanding its scope to Latin American Jewry writ large, and then to the global Jewish diaspora. It argues that Jewish discourse continually constructs the meaning of diaspora internal to its community, even as sociological discourse constructs a different meaning that is more closely related to the concept of transnationalism. Each definition ignores the ways in which the modern international arena of nation states can actively use these definitions to influence behavior: using the rhetoric of diaspora to encourage transnational activities and using transnational activities to curate and control who belongs to the diaspora. This expansion to the global, theoretical level comes before the exploration of the state level because it is vital to contextualize transnationalism and diasporic rhetoric before jumping into case-by-case examples. Latin American Jews are immensely diverse and their communities and relationships within the region and within the global Diaspora are complex and long-standing. The literature that uses transnationalism to better understand the identities of Jews in Latin America tends to position them on a spectrum with a national identity and a Jewish identity at opposite ends. At one end are scholars like Judit Bokser-Liwerant , who see Jews in Latin America as Jews foremost. From this point of view, a sense of pan-Jewish ethno-religious identity unites Jews across national borders, often to the exclusion of meaningful national identities. In this understanding, Jewishness is the most important tile in Jewish individuals’ mosaics of identity,and lends itself naturally to transnational behavior. This presumed behavior and presumed identification with other Jews across and irrespective of national borders is also assumed to have something to do with the fact of being a diasporic people. On the other end of the spectrum are Jeffrey Lesser and Raanan Rein , who have both rejected what they deem the “essentializing” pan-Jewishness of a stance like Bokser Liwerant’s in favor of seeing Jews in Latin America as national citizens first. Jews are expected to look to the host nation first when assessing their own identities, rather than emphasizing their Jewishness to the exclusion of their national identity.

This results in a range of hyphenations, such as Jewish-Argentinian, Jewish-Peruvian, etc. While transnational behavior may occur, the Jewish identity is usually considered to be one of the less prominent identities that an individual counts towards their identity mosaics. Lesser and Rein’s concern with the differences in Jewish life, treatment, and identification between countries is important to remember, particularly when examining shifts in local conditions that may lead Jews to consider migration. Nevertheless, it can be essentializing as well in its focus on discrete and identifiable national identities and can minimize important regional similarities or historical ties between communities. By being able to see this distinction, it also becomes possible to see how a sense of belonging to a diaspora can influence transnational behaviors. In fact, diasporic history and transnational behavior are often actively conflated to achieve political and/or economic aims, especially pan-Jewish and Zionist activism, religious philanthropy, and Jewish education. Jewish philanthropy that calls on a diasporic identity to solicit transnational donations has a long history, which includes transnational emissaries in the early modern period when nations were first developing. Iquitos experiences its own version of this border-crossing Jewish philanthropy, and has done since the turn of the century. Frequent intra diaspora migration for professional purposes has a similarly long history: traders, clergy, and activists maintain personal, business, and religious connections across national borders, alternately using the diaspora and transnationalism to justify each other..4 Often, the existence of a diaspora sets the stage for many kinds of transnational activities, which may or may not symbolically call upon the diaspora to achieve their goals. At the same time, transnational activity may make a sense of diasporic pan-Jewishness stronger and a more active part of individuals’ self-identification. Participating or not in transnational activity between nodes of the diaspora also comes into play when gauging Jewish authenticity.

The third and final chapter returns to a single country-level case study, this time in Israel through a structural examination of the great contradiction of Israeli immigration policy. Israel’s view of immigrants and potential immigrants is torn between religious and secular interests,hydroponic fodder system which prioritize Jewish purity and Jewish numbers, respectively. On the one hand, secular Zionist immigration policy requires more and more Jewish bodies in Israel to make the state more secure and overwhelm Palestinians still living there through sheer numbers and new settlements. In light of this need for numerical superiority, politicians on this side of the ideological divide are willing to expand ideas of authentic Jewishness. On the other hand, ultra-Orthodox religious factions wish to keep the answer to the question of “who is a Jew?” very narrow, because a narrow definition allows them to maintain certain special privileges above and beyond those granted to all Israeli citizens. Furthermore, the current citizenship regime and their status as European-descended Ashkenazim grants these groups the structural privilege to effectively lobby for such restrictive definitions. Both sides need each other to form an effective governing coalition, and as such, the immigration of “problematic” Jews is not halted completely. Rather, the two sides compromise such that the secular bureaus in charge of immigration and Diaspora relations will attempt to create a machine of policy and outreach that produces more desirable Jews from an Ashkenazi-normative religious perspective, that is, to make “inauthentic” Jews “authentic.” Furthermore, the fact that most Iquiteño migrants are settled in the mixed city of Ramla indicates that they serve the Israeli state in constructing a racial hierarchy. Demographic warfare is not general, but is in fact quite tactical and specific. In this case, the absorption of Iquiteño Jews into an Ashkenazi mold is not only an indicator of intra-Jewish hierarchy, it is a way of reinforcing, even creating, an Israeli racial project in which even the most “undesirable” Jews can be wielded against Palestinians. In this way, Iquiteño Jews are literally and metaphorically placed definitively apart from pale-skinned Ashkenazi, but above Palestinians. The way in which Iquiteños are asked to shape themselves also includes shaping themselves as an ethnic group against a racialized Arab Other. Driven by many transnational forces, including powerful movements within global Jewries, the Jews of Iquitos have dramatically changed their religious practices, self identifications, and migration plans, mostly with the goal of migrating to Israel for reasons that combine the practical and the spiritual. Although the Jewish community of Iquitos is very small, and grows smaller yearly due to emigration, its marginal position within Jewish hierarchies of ethnicity, religion, and nation helps reveal the messy, contested borders of contemporary Jewishness and how Jews actively change what it means to be authentically Jewish. Human identities are always a mosaic of multiple facets of greater or lesser saliency, and Jewish identities that cross or complicate those boundaries are possible and common. Iquiteño Jews fall across many of those borders.

As they do so, they bring into focus the intersections of symbolic diaspora and practical transnationalism, the historical mutability of Jewish authenticity, and the active use of these intersections and the Diaspora at large by the Israeli state as it seeks to solidify and stabilize its contemporary centrality to modern Judaism. By seeing and seeking to understand these often-ignored or hidden points of difference and conversion, scholars and activists can examine the ways in which they define their own religious and ethnic identities, make their discussions of religion and migration more respectful and nuanced, and take control of the narratives that predicate rights and safety on authenticity. And, finally, understanding the differences between transnational communities and diasporic peoples will reveal the usefulness of diasporic rhetoric to actors seeking to influence groups’ transnational activities, and therefore the changes in migration patterns, racial and ethnic formations, and self-identifications of diasporic peoples. For the Jews of Iquitos, migration to Israel is seen as a step in the pathway to becoming an authentic Jew that is as necessary as a conversion process. This blending of Israeli and Jewish identity stems from institutional influence in the early days of Iquitos’ community renaissance, but has since become self-sustaining thanks to global-level economics and individual-level transnational affective bonds. Iquiteño Jews do not see their conversions as solely an instrumentalist tool to gain a more economically privileged life in Israel, nor do they see their conversions as completely individual pursuits of spiritual fulfillment. Rather, they are motivated by both practical and spiritual concerns, which are made to converge at key points thanks to diasporic influence on transnational actions. This phenomenon challenges common narratives in the sociology of conversion that require total separation of the practical and the spiritual. It is often useful, even necessary, to make such a separation, but insisting on its essentialness makes it difficult to study cases where the two converge. These points of convergence are often important in understanding the justifications, motivations, and identifications of individuals as well as the influence of organizations and states with religious aims. Choosing to interpret these convergences as only blinkered fantasies hiding self-interested, rational motivations, quite aside from being condescending, also hides the very real power of religious belief to motivate action. In this case, the decisions made by Iquiteños occur at the crux of individual belief and global political dynamics, so recognizing both dynamics as important is key to understanding their joint influence. In the case of global Jewry and other diasporic peoples with strong religious identities, this convergence helps make the rhetoricization of diaspora an effective tool to encourage and guide transnational activity.It is a value-added process model, recognizing that while conversion is often portrayed within Christian or Christian-secular contexts like the Western university as a blinding flash of inspiration that transforms its individual subject in an instant, as in the Confessions of Saint Augustine or Kierkegaard’s The Sickness Unto Death , in most cases, conversion is a long and social process. Their model has also been heavily critiqued. Critics find that it leaves little room for converts’ own perceptions of their experience, while at the same time relying on individuals’ reportage of their “turning points” and their “seeking” behaviors. Furthermore, it is flawed in its insistence on the presence of each and every one of its purported prerequisites for conversion, in particular because each of these prerequisites are characterized purely as the answer to some inner, individual spiritual lack, leaving aside the many other tools converts have at their disposal, and which they may use alongside or indistinguishable from religious responses. That said, I feel this model accurately emphasizes the importance of affective bonding and community ritual to conversion. Phillips and Snow emphasize the importance of that affective bonding and intensive interaction, and add the important note that it is those two activities that help potential converts choose between many possible options when they convert.

In general, fully senesced leaves have as much as 75% reduced protein content compared with green leaves, primarily from the dismantling of chloroplasts, and though yellow, senescing leaves still have live cells with active mitochondria, leaves that have turned brown as a result of drying no longer contain biologically active cells . Therefore, green, senescing and fully senesced bay leaves are substrates that likely vary in their suitability for colonization by P. ramorum and stream-resident clade 6 Phytophthora species, taxa that commonly occur at high inoculum levels in northern California coastal forest streams. We have shown that there is a difference in trophic specialization between the saprotrophically competent, clade 6 Phytophthora species, such as P. gonapodyides, and P. ramorum, an aggressive pathogen on many plant species. In that study, green California bay leaves were rapidly colonized by P. ramorum in streams but were succeeded nearly completely within three weeks by clade 6 Phytophthora species. It remains uncertain, however, whether P. ramorum was displaced by more competent saprotrophs or receded from an inability to persist in tissues that it had colonized as they progressively decomposed. Additionally, as most leaf litter consists of senesced leaves, it is important to know how these differently adapted taxa can compete for and persist on biologically inactive leaf tissue. Finally, though stream resident Phytophthora species are assumed to contribute to leaf decay given their regular recovery from streams and frequent association with decomposing vegetation, experimental evidence for the kind and extent of this contribution is lacking.

Moreover, it is unknown how the introduction of an exotic and plant pathogenic species, like P. ramorum, strawberrry gutter system into a stream ecosystem might affect the decomposition of leaf litter by other organisms, such as resident Phytophthora species. Therefore we undertook a laboratory study to determine: How well P. ramorum and P. gonapodyides could use senesced leaves as a substrate in comparison to green, live leaves, whether colonization by and persistence of P. ramorum on leaves was affected by competition with P. gonapodyides, and how much each of these Phytophthora species contribute to the decay of each leaf type. To test the capacity of P. ramorum and P. gonapodyides to colonize green and senesced bay leaves, we conducted controlled environment experiments exposing leaves to an inoculum of each species alone and in combination in microcosms designed to simulate an aquatic environment. The experiment consisted of a randomized complete block design with treatments representing a complete factorial of bay leaf type , stream water addition , and Phytophthora inoculation. These 16 treatment combinations were replicated in five blocks arranged in three growth chambers. The experimental unit was a mesh packet of five leaves which were sampled at intervals over 16 weeks from microcosms. One treatment packet per sampling served for decomposition as percent biomass loss and another for colonization based on isolations on a selective medium. We repeated the experiment once, with leaf types maintained in the same microcosm in the first and in separate microcosms in the second experiment.

We conducted a separate experiment with yellow, senescing leaves collected while still attached to trees and with the cuticle intact, with P. ramorum-only and combined P. ramorum/ P. gonapodyides treatments as well as non-inoculated controls, in a completely randomized design with four reps in a single growth chamber. We collected leaves from two sites where our previous field experiments were conducted. One was a canyon through which Graham creek runs at Jack London State Park which consists of redwood forest with California bay as a dominant riparian tree, along with redwood , Douglas fir , tanoak , bigleaf maple , and less frequently, madrone. The second included canyons around Copeland Creek at Sonoma State University’s Fairfield Osborn Preserve which is characterized by mixed evergreen forest with a prevalence of California bay, white alder , big leaf maple, and occasionally, tanoak, madrone and coast live oak. At each site, we collected green, symptom-free bay leaves with a mature cuticle from trees and brown, recently shed bay leaves from beneath trees in the manner of Wood et al.. Brown leaves were collected from both sites in September 2014, allowed to air dry in the laboratory, and then stored in sealed plastic bags at room temperature until used in experiments. Green leaves were collected on 12 December 2014 from the redwood forest site and on 5 August 2015 from the mixed evergreen forest site. Yellow leaves were collected directly from trees at the mixed evergreen forest site on 7 September 2015. Green leaves were stored at 4 ◦C for up to three weeks prior to use in experiments and yellow leaves were likewise stored but deployed in experiments within one week of collection. We collected leaves primarily from riparian areas around the described creeks, though, at the mixed evergreen forest site,grow strawberry in containers we had to seek symptomless leaves to some extent from plateaus above the canyons.

Leaf treatments were in the same microcosm for the first experiment using leaves from the redwood forest and separate in the second experiment with leaves from the mixed evergreen forest. Yellow leaves were collected from the mixed evergreen forest site only. We tested a sub-sample of 50 of each leaf type for both sites—through isolations attempted on a selective medium as described below—to verify that there were no pre-existing Phytophthora infections. Brown leaves were soaked in sterile deionized water at 4 ◦C for two days prior to these test isolations. Leaf packets were prepared for each leaf type by packing five leaves into a flat envelope of 1 mm plastic mesh approximately 20 × 20 cm so that the leaf surfaces were in minimal contact with one another and each packet was sealed by folding over the open lip and securing it with two common metal staples. We assembled microcosms simulating an aquatic decomposition environment similar to the approach described by Medeiros et al.. White plastic buckets were used in the first and yellow leaf experiments and opaque plastic containers in the second experiment. Each container was aerated through a tube terminating in an aeration stone fed by an air pump that was turned on for 30 minutes twice daily using an electric timer. Aeration intensity was moderated with the addition of adjustable valves inserted in the tubing. A dilute nutrient solution was used as the base for the water mixtures in microcosms in order to avoid osmotic stress on spores. This was achieved by adding Hoagland’s #2 salts to autoclaved Millipore®filtered water for a final concentration of 0.01× the standard concentration. To test for any effect of natural stream microbiota on Phytophthora colonization or leaf decomposition, we included an addition of auto-claved or non-sterilized stream water as a treatment factor. The final composition of water in microcosms consisted of 4 L nutrient solution and 2 L stream water in the first experiment, and 4 L nutrient solution and 1 L stream water in the second. We collected water from streams in a bucket, pouring it through several layers of cotton mesh into 4 L plastic bladders that we consolidated into larger plastic containers or used directly to transport water out of the field. Once brought to the laboratory, stream water was stored in plastic containers in a growth chamber at 12 ◦C and 12 h photoperiod for 20 and 23 days prior to deployment in the first and second experiments, respectively. After storing the water for seven days, we submerged symptomless California bay leaves collected at each site as baits in each container for two days to confirm that Phytophthora zoospores were not present.

We tested baits for infection using the isolation technique described below. No Phytophthora infections were detected from baits at this point. In the experiment with yellow leaves, we used only 4 L of a nutrient solution without stream water addition. We measured stream pH, electrical conductivity and temperature on site at the time of stream water collection and subsequently in each microcosm throughout the experiments with a portable sensor. Stream pH, EC, and water temperature were 8.55, 208 µS/cm, and 13.5 ◦C, respectively, for the redwood forest stream on the 9 December 2014 collection date, and 8.08, 363 µS/cm, and 17.7 ◦C, respectively, for the mixed evergreen forest stream on the 5 Aug 2015 collection date. To approximate natural stream pH in microcosms, we amended the mix of dilute nutrient solution and stream water in each microcosm with potassium carbonate buffer at approximately 10 mg/L and adjusted it with KOH and HCl for a target of pH 8.3. The average pH measured in microcosms periodically over the course of experiments was 7.99 , 8.33 and 8.24 in the first, second and yellow leaf experiments, respectively. The average EC was 208 , 141 , and 98 in the first, second, and yellow leaf experiments, respectivelyTo determine the rate of decomposition measured as leaf biomass loss, we weighed leaves to the hundredth decimal of a gram with an analytical balance prior to packing and we labeled the packets with aluminum tree tags secured with a plastic tie for future identification. We estimated the original dry mass of both leaf types from the average dry weight of a sub-sample of 50 fresh or air dried leaves. The average percent dry weight for green and brown leaves, respectively, was 40.9 and 94.3 for the first experiment and 53.5 and 92.6 for the second experiment. The average percent dry weight for yellow leaves was 55.0. The average estimated weight in grams for five green leaves was 0.84 and 1.13 , and that for five brown leaves, 0.91 and 0.85 for the first and second experiments, respectively. For five yellow leaves, the estimated average weight in grams was 0.98. At each sampling, leaves were retrieved from tagged leaf packets, rinsed gently with deionized tap water to remove adhering debris, oven-dried in a paper envelope or an open aluminum foil envelope at 55–60 ◦C for 48 h, and weighed as described above. The fraction of original biomass was calculated for all leaves in a packet by dividing the weight at the time of sampling by the estimated original dry biomass. To determine the level of Phytophthora colonization of leaves, at each sampling we collected a packet for each leaf type from each container to evaluate by culturing on Phytophthora-selective PARP-H medium 50 ppm and hymexazol 25 ppm. Upon retrieval, leaves were submerged and gently rubbed free of biofilm in 1% household bleach solution , surface sterilized in fresh bleach solution for three to seven minutes, rinsed with deionized tap water, and then laid out on paper towels and the excess water allowed to evaporate. Finally, leaves were wrapped in a paper towel and stored at 4 ◦C until isolations by culturing could be performed. Isolations were attempted from all leaves belonging to treatment using a ‘mosaic’ sampling approach whereby the leaf discs are removed from the petiole, midrib and flanking lobes of the leaf at approximately 1 cm distance from one another in order to collect a representative sample from the entire leaf. For experiments with green and brown leaves, isolations were initiated immediately after collection, with most samples processed within 29 days. All isolations were completed by 46 days after collection. Storage period did not alter results when included as a covariate in models for these experiments and was excluded from the final analyses. Isolations from leaves of the yellow leaf experiment were completed within nine days after collection, and all isolations from a single collection week were completed in one day. The presence of P. ramorum and P. gonapodyides was determined by microscopic examination of isolate morphologies directly from the isolation plates after four to five days and checked again periodically for three weeks. To test for active sporulation from colonized leaves in the microcosms, periodically a California bay leaf disc was floated as bait—either naked or in a roughly 35 mm2 mesh envelope—on the surface of the water in each microcosm for three to seven days, after which it was surface sterilized and isolations attempted from it on selective PARP-H medium. We conducted these tests of sporulation four times during the first and yellow leaf experiments, and three times during the second experiment. Additionally, we tested for sporulation periodically for up to eight weeks after all leaves had been removed from microcosms to determine if Phytophthora spores could persist in the absence of a substrate.

The data presented clearly demonstrate the efficacy of CWs for treatment of water containing current pollutants that either resist treatment in WWTPs or are directly discharged into surface water via runoff. There are several types and variations of CWs that have been utilized to facilitate treatment of a wide array of contaminants in an abundance of applications. The two major types of treatment wetlands are surface flow CWs and subsurface flow CWs. An example of a surface flow CW is shown in Figure 1.3. Surface flow CWs may contain floating plants, submerged plants, emergent plants, or some combination of the three, and possess areas of open water. Subsurface flow CWs may employ horizontal flow or vertical flow; the former usually consists of a vegetated gravel bed with water flowing horizontally below the bed surface from inlet to outlet while the latter involves water treatment as it percolates through the plant root zone of a vegetated sand or gravel bed. Hybrid CWs are typically composed of a surface flow CW and subsurface flow CW operated in series. Recently, unit process CWs have been implemented in an effort to isolate the ideal conditions necessary to treat particular pollutants in independent ponds, with the goal being to operate distinct ponds in series to treat multiple contaminant classes within the same treatment chain. Examples of unit process CWs are open water cells, macrophyte-dominated wetland cells, and bivalve filtration wetland cells. An example of a unit process open water CW is depicted in Figure 1.4. CW treatment is usually the result of a combination of abiotic degradation,flood tray microbial degradation, sorption, and phytoremediation, depending on the specific contaminant and the design of the CW cell. 

There has been some research focused on the treatment of fiproles and pyrethroids by CWs in urban and agricultural settings. A recent study of a treatment wetland receiving treated effluent from a WWTP found that the CW removed 44% of fipronil and 47% of total fiproles. Another study of an agricultural drainage wetland observed removal rates of 52-94% for pyrethroids. It is clear that CWs have the potential to remove urban insecticides such as fiproles and pyrethroids from surface water, but the precise mechanisms and ideal conditions for their treatment remain unclear. Wetlands are among the most biologically productive ecosystems onEarth, allowing them to transform many ubiquitous pollutants at relatively low cost. For these reasons, CWs present an ideal option for the treatment of fiproles and pyrethroids in surface water. Stormwater and wastewater effluent are contaminating urban streams with toxicologically relevant concentrations of urban-use insecticides. It is essential to study novel water treatment strategies to improve the quality of surface water that has been polluted by storm water and wastewater discharge. Alternatively, identifying sources of urban insecticides and modifying their application practices may serve to reduce the mass loadings of these compounds in surface runoff. If water quality is not improved, sensitive aquatic organisms will continue to encounter adverse effects, potentially causing detrimental effects on ecosystem services and local food webs. Furthermore, water reuse initiatives may uncover as-yet-unknown human health consequences presented by use of recycled water containing insecticides. More information is needed to develop strategies to reduce insecticide concentrations being deposited into surface water via storm water and wastewater treatment.

It is imperative to understand the urban sources of insecticide contamination to reduce runoff transport of these contaminants by altering application practices. Furthermore, CWs hold a great deal of promise for reducing urban insecticide concentrations in storm water, wastewater, and surface water. It is vital to assess the removal efficacy of fiproles and pyrethroids passing through CW treatment systems. Pursuing these goals will assist in the development of improved mitigation and treatment practices for water contaminated with urban pollutants. Urban-use insecticides are primarily applied to eliminate structural pests such as ants, termites, roaches, and spiders. Extensive outdoor urban pesticide use is a cause for concern since surface runoff of these biologically active compounds into urban waterways following rainfall or irrigation has the potential to exert adverse effects in non-target aquatic organisms. The high incidence of impervious surfaces in urban environments, which may account for 50-90% of residential and commercial surface areas, prevents infiltration of water into soil and facilitates runoff and offsite transport of pollutants such as pesticide residues to urban streams. Perpetual urban expansion is projected to triple the global urban land area between the early 2000s and 2030 , exacerbating the issue of urban pesticide runoff and contamination to surface water. Fipronil is a moderately hydrophobic phenylpyrazole insecticide applied for a multitude of urban pest control purposes by licensed applicators. Applications include perimeter and underground injection treatments to manage ants and termites, veterinary flea and tick treatments, insect control baits, and landscape maintenance. After application, fipronil degrades primarily into fipronil desulfinyl, fipronil sulfide, and fipronil sulfone following photolysis, reduction, and oxidation, respectively. According to the Pesticide Use Reporting database, over 24,000 kg a.i. of fipronil were applied in 2016 in California, where use is confined to urban areas. Consequently, fipronil and its degradation products are frequently detected in surface water, such as in regions like California.

In a study of runoff discharge collected from residential storm drain outfalls in Southern and Northern California, median total fiprole concentrations were found to be 204-441 ng L-1 and 13.8-20.4 ng L-1, respectively, and 90th percentile total fiprole concentrations were 338-1169 ng L-1 and 62.6-65.3 ng L-1, respectively. In a recent study surveying urban creeks, rivers, and storm drain outfalls, fipronil sulfide, fipronil sulfone, fipronil desulfinyl,ebb and flow tray and fipronil were detected in 8%, 63%, 65%, and 75% of samples, respectively. The presence of fiproles in surface water is significant, since these compounds have been shown to exert toxic effects in a variety of non-target aquatic organisms with an LC50 of 140-320 ng L-1 for Palaemonetes pugio, Neomysis americana, and Simulium vittutum, and an EC50 of 32.5 ng L-1 and 7-10 ng L-1 for Chironomus dilutus. Therefore, in regions such as California, fiproles are ubiquitously present at toxicologically relevant levels in urban surface water ecosystems. However, little is presently known about the principal sources of fiproles in urban surface runoff, which hampers watershed-scale risk assessment as well as the development of effective strategies for mitigation. In the context of this study, runoff sources are defined as environmental matrices that contribute fiprole residues to surface runoff following known pesticide application. Primary objectives of this study were to characterize the affinity of fiproles for common urban matrices, to investigate persistence of fiproles in urban compartments, and to identify potential sources of fiproles in urban runoff. Bench sorption experiments were conducted for fiproles in urban dust, soil, and concrete. In addition, runoff water, urban dust, soil, and concrete wipe samples were collected from multiple fipronil-treated homes in Southern California from July-December 2016. This study represents the first systematic investigation of potential runoff sources of fiproles in urban residential environments. Results may be used to direct mitigation efforts of these compounds and to guide future pollution prevention initiatives for similar contaminants in urban watersheds. Fipronil , fipronil desulfinyl , fipronil sulfide , and fipronil sulfone were obtained from the United States Environmental Protection Agency’s National Pesticide Standard Repository.Isotopically labeled fipronil was purchased from Cambridge Isotope Laboratories. Solvents and other chemicals were of pesticide or GC-MS grade.

Small concrete cubes used in the sorption isotherm experiment were made in the laboratory via a process described elsewhere. Sorption isotherms were constructed over a period of five days by mixing concrete cube, urban dust, or the sandy loam soil samples in aqueous solutions simultaneously spiked with all four fiproles at 5, 20, 50, 100, 200, or 500 μg L-1. NaN3 was amended at 200 mg L-1 in the solution to suppress microbial activity and CaCl2 was added at 100 mg L-1 to adjust the solution’s ionic strength. Samples were prepared by adding 10 mL of the solution to a 40 mL amber glass vial containing one concrete cube, 2 g of dust , or 2 g of soil and mixing on a horizontal shaker at 120 rpm for 5 d. No statistically significant fiprole losses occurred over the course of the incubation. Sample vials were centrifuged at 1500 rpm for 30 min to separate the aqueous and solid phases. Aqueous phases were collected and extracted with 10 mL hexane by mixing on a horizontal shaker at 200 rpm for 30 min a total of two times. Solid phase samples were mixed with 1 g NaCl and 4 g anhydrous Na2SO4 and then extracted with 10 mL of 8:2 acetone:hexane by mixing at 200 rpm for 30 min a total of two times. The solvent extract of the aqueous or solid phases was evaporated to dryness under a gentle stream of nitrogen at 40 °C, and the condensed extracts from solid phase samples were subject to clean up using Florisil cartridges according to the procedure listed in the supporting information. Cleaned extracts were evaporated to dryness at 40 °C under a stream of nitrogen, and all extracts were reconstituted in 1.0 mL hexane before analysis. Five homes in Riverside, CA, received standard perimeter spray treatments of a professional fipronil formulation diluted from a suspension concentrate per the label instructions in July 2016, and the treatment was similar to the conventional treatment described in Greenberg et al.. Pre-treatment runoff concentrations of fiproles revealed low-level background contamination of all four compounds. However, these concentrations were two to three orders of magnitude lower than 1 d runoff concentrations and were similar to 153 d runoff concentrations. Therefore, this background contamination likely did not impact the conclusions presented in this study. Fiproles in runoff, soil, urban dust, and concrete were monitored at five time points during July-December 2016. Weather during this period was very warm and dry until light rainfall occurred in December prior to the collection of the final set of samples. The results reported herein were likely not impacted by this rainfall since the final samples still contained fiproles at concentrations similar to those measured at the previous time point. Runoff samples, one from each home at each time point , were collected by building a temporary water berm approximately 6 m away from the home’s garage door. Berm dimensions and composition were described in detail in Greenberg et al.. Each driveway was rinsed with a hose to generate a volume of runoff sufficient for the collection of a 1 L water sample in an amber glass bottle. Sample bottles were transported to the laboratory on ice within 3 h and stored at 4 °C until extraction. Extraction of runoff water samples was adapted from the methods in Gan et al.. Briefly, water samples were combined with 30 mL NaCl and liquid-liquid extraction was performed with 60 mL dichloromethane a total of three times. Extracts were then evaporated using a Büchi RE121 Rotovapor , solvent exchanged into 9:1 hexane:acetone , and cleaned up by loading into a Florisil cartridge preconditioned with hexane and eluting with 9:1 hexane:acetone. Cleaned extracts were evaporated to dryness under a gentle stream of nitrogen at 40 °C and reconstituted in 1.0 mL hexane. At each house and sampling time point, the following urban solid samples were simultaneously collected: one soil sample from the home perimeter, two dust samples from paved surfaces, and two concrete wipe samples from concrete walkways near the driveway. Soil samples from the 0-3 cm depth were collected into 40 mL amber glass vials. Total organic carbon content for the home soil samples was determined to be 3.80% using the aforementioned method. Urban dust samples were collected using a method similar to Richards et al.. Briefly, dust was sampled using a handheld vacuum fitted with a metal housing and mesh containing a Whatman GF/A glass fiber filter paper. The area to be vacuumed was marked off using a 0.5 m2 frame. If additional dust was needed to obtain a sufficiently large sample, the frame was moved to an adjacent region of the concrete surface for vacuuming. Filter papers were subsequently removed from the vacuum and stored in 40 mL amber glass vials. The total organic carbon content of the urban dust samples was measured to be 6.54% utilizing the previously described method. 

The LACER study used a two-tiered framework to investigate total employment, with tier one industries being directly related to water industry, and tier two being industries that are impacted by water, such as landscaping, architects, or wholesale chemicals. To understand an industry’s regional intensity, economic geographers often use locational quotients of sectoral employment. Various government agencies compile economic data and use the North American Industry Classification System to classify business establishments according to sector, or type of economic activity. An industry locational quotient compares the number of people employed in an industry in a region with the national employment average. A location quotient of “one” will mean that a region has exactly the same number of people as the nation as a whole. A high location quotient means that the region has many more people employed than the national average. For example, Hollywood is Southern California’s most famous industry cluster as the nations employment in the motion picture and video production industry—NAICS code 51211—generates a location quotient of a 12.8, meaning that the region has 12.8 times the national average for employment in the industry . In 2010 nationally, there were 197,627 employed in the motion picture and video production center. The Los Angeles MSA alone had 101,439 employed in the local MSA . An MSA is a Metropolitan Statistical Area, which is in this case spans from Santa Ana to Los Angeles. In comparison to motion pictures,blueberry grow pot the highest concentration in water related fields is 2.5 in electronics manufacturing, and plastics materials wholesaling respectively.

Neither of those are very central to the water industry, although electronics manufacturing does include control instruments used in the water industry . Even the next highest, fluid power and hose fitting, is only tangentially related to water as most manufactured parts are used in motor assembly. The region does, however, have a very strong presence in sewage treatment facilities, and plastics product manufacturing, which are both important to water technologies. My investigation of the Los Angeles CSA excludes the San Diego Region, where presumably the industry is just as strong, if not stronger. For example, an estimated 3,000 people work for companies in the San Diego area supplying equipment or logistical support just for desalination plants alone . The San Diego desalination industry earns an estimated $350 million in annual revenues . The global water reuse industry really took off around the year 2000, with global capacity nearly quadrupling by the year 2010. The industry analyst group, Global Water Intelligence, forecasts that reuse capacity will double again by 2016 and grow nearly 20% annually . Globally, half of all reused water is used for outdoor purposes: agriculture , landscaping , and environmental restoration . Industry follows with 20% of reused water, followed by various non potable uses . Less than 3% is used for drinking water . In sheer volume, the United States is the global leader, reusing 14% of its wastewater. Followed by China who also reuses roughly 14%, but only half the quantity. However in percentage of use, Kuwait and Israel dwarf the world, reusing 91% and 85% respectively. They are followed by Singapore , Egypt , Australia . Like the water industry itself, the water reuse industry is a difficult one to narrowly define. Obviously, the industry has a very close overlap with the wastewater treatment industry.

In addition to the water and wastewater utilities, there are the various service providers and the miscellaneous material suppliers , and also the speciality suppliers of specific physical and biological wastewater treatment equipment. In today’s world where many utilities are often privately run, there are also firms that operate the treatment plants, such as Berlinwasser International, CH2M Hill OMI, Metito, Suez Environment, United Utilities and Veolia Water. In this investigation of the innovation systems I have chosen to focus on the engineering firms involved in the building wastewater treatment complexes and the specific manufactures and suppliers of the advanced wastewater treatment systems necessary for urban water reuse. For it is these firms that are at the forefront of water reuse innovation.Here I wish to discuss the most important ones which take place in the advanced processes of the tertiary and quaternary treatment stages which are necessary for water reuse. These are the heart of the water purification process and the firms which manufacture these materials will be global winners as the industry grows. In order to identify these firms, I have loosely classified them under the following three categories: advanced membrane manufacturers, advanced disinfection manufacturers, and advanced wastewater supply firms . The major technologies involved in advanced membranes are Microfiltration, Reverse Osmosis, Nanofiltration, and Ultrafiltration. Microfiltration is a separation process that uses polypropylene hollow fibers—essentially tiny straws—to filter the water. Reverse Osmosis membranes are made of semi-permeable plastic polymer and water is forced through under high pressure. Nanofiltiration is similar in that it relies on osmosis but uses even smaller filters than microfiltration. Electrodialysis is an electrically-driven technique that can be used at the tertiary stage and is often employed in desalination plants.

Disinfection tools, such as high-intensity ultraviolet light, and chemical methods, like hydrogen peroxide, disinfect and destroy any trace organic compounds that may have passed through the reverse osmosis membranes. Engineers who may read this report will likely be disappointed at these gross simplifications, and omissions of other important technologies relevant to the water reuse process. They might also note that there are many more exciting emerging technologies currently being researched at labs throughout the world. It is highly likely that some of these emerging technologies will revolutionize the industry, but I am interested in the odds that those technologies might be developed here in California. The following table identifies the leading global water reuse technology manufacturers and suppliers. As one might expect in a highly urbanized dry region with large endowments of physical and human capital, Southern California has a fairly vibrant water technology industry. Over half of the 30 leading reuse technology suppliers,hydroponic bucket have a direct local presence in the state and many more have formed partnerships with local firms or distributors. Industry analysts have estimated that there are over 3,000 people working in the southern California region that supply or support water reuse or desalination equipment. The industry brings in over $350 million in annual revenues . At least six of the major firms—Siemens Water Technologies , Trajan Ultraviolet , Hydronautics, and Xylem, Pall Corporation, and Koch Membranes—have facilities within the state. Interestingly though, Hydronautics, is the only major firm with headquarters in the state, located in Oceanside. Advanced disinfection technology leader, Trajan Technologies, also operates the local Aquafine Corporation. Trojan purchased local US Peroxide, LLC of Laguna Niguel, California in 2003 . The ITT corporation spinoff, Xylem—named for the plant tissue water transport system—specializes in fluid technologies and also operates multiple facilities in Southern California. Most notably, the global behemoth Siemens Water Technologies was actually a local firm until relatively recently. The company that became US Filter was founded in El Monte, California in 1953 . US Filter was one of the first major water industry conglomerates, acquiring over 60 companies before being purchased by French giant Vivendi. In 1997, US Filter became the United States’ first billion-dollar firm specialized in water and wastewater treatment systems . At the time, Fortune magazine ranked USF among the 100 fastest-growing companies in the world, with compound annual revenue growth of 66% between 1991-96. In turn, it was sold to Siemens in 2004 . The headquarters was then moved to Pennsylvania. The company still has major operations in California, but it is noteworthy that the firm’s major new global water research and development facility is being developed in Singapore, rather than California . Many of the largest global technology conglomerates—including Siemens Water Technologies, but also GE Water, Veolia, and most obviously the new $3.2 Billion water focused firm Xylem, have made water reuse central to their business future. The name Xylem literally means the part of the plant that draws water from the ground. Some analysts speculate that trusted global brands like GE or Siemens will reassure the public that water reuse is a safe technology . These firms will also likely lower the cost of water reuse technologies which will further accelerate the growth of the market. Several engineering firms, notably CDM and MWH Global, have also focused their operations on becoming the market niche leaders. Both firms were involved in the construction of GWRS. The international market is highly fragmented with many speciality contractor/consultants in addition to large numbers of local firms. Most large service firms rely on armies of local subcontractors to actually do most of the construction . There are a relatively small number of global leading firms which tend to dominate the large, or particularly complicated infrastructure projects, such as England’s Chunnel, or Boston’s Big Dig.

These market leading firms—and their employment base—tend to be concentrated in North America and Europe. However, with the rapid rise of the rest of the world, one can expect to see a growing diversity with more competition coming from abroad. Indeed, local firms in East Asia, the Middle East, and Latin America are already taking the largest share of their domestic projects, and are beginning to compete for projects in the US and Europe as well. California in particular, has a very high concentration of engineering firms. It would be an interesting scholarly investigation to document the creation agglomeration. It likely reflects the region’s early strength in major construction projects in mining, water, and petroleum industries. And of course, the region was an early home to major transportation networks such as railroads, ports, and the world famous freeway networks. The explosion of the defense industry in California coincided with the rise of the US global military domination—and California firms accompanied the military abroad to build major infrastructure projects. Of the five American firms that dominate the list, all have a strong history in California. For example, CH2M Hill became famous for its work on a Lake Tahoe wastewater project , and Fluor Corporation was founded in California before moving to Texas along with the oil industry . Interesting, neither of California’s largest global firms, Bechtel or URS Corporation are strong in water infrastructure projects, with Bechtel claiming zero revenue from either water supply or wastewater projects, and URS claiming less than $90 million in water related revenue—a far cry from the firm that made its name building the Hoover Dam . When looking at the largest water supply and infrastructure firms in the world, one may find that California continues to play a huge role. Seven of the top ten firms in water infrastructure have a presence in California, and nine of the largest wastewater infrastructure firms have offices in the state. In fact, the two largest wastewater firms, Los Angeles-based AECOM and Colorado’s MWH Global, have major offices in the state. MWH Global is a firm that has dedicated itself to the water infrastructure industry, with water and wastewater projects making up 43% and 41% of all revenue, respectively—over 80% of all firm work. This is very notable as MWH Global has a major water testing laboratory facility, MWH Laboratories, based in Monrovia in Southern California. The facility employs over 100 people and is the largest potable and recycled water focused laboratory in the country . Of particular importance to water reuse plant construction are AECOM, Arcadis, Black & Veatch, CDM, CH2M Hill, TetraTech, and MWH . AECOM and Tetra Tech are both based in Southern California while CDM, CH2M Hill, Black & Veatch, and MWH all have strong representation in the state. MWH Global has a major water testing laboratory in the state . Additionally, many slightly smaller local firms such as Brown and Caldwell or Parsons Corporation are still very important players in the water engineering market . Globally, water reuse projects are generally contracted and built using a design-build model where the project is owned and operated by the municipality . However, innovative financing agreements and Build-Own Operate , and Design-Build-Operate where the building firm own the facility, are growing in popularity . This will have implications for the engineering market as it would favor large multinationals that have operations expertise, such as Suez or United Utilities.

Many water special districts receive property taxes in order to support their operations, while others are funded primarily through user fees. Some special districts can also issue local general obligation bonds backed by property tax levies in order to fund capital investments . In some areas of California, there are also private utilities that provide these services. Private water companies are closely regulated by the Public Utilities Commission to ensure responsible behavior . For example, strict requirements of justification must be met before they are allowed to raise their prices . The sheer number of water policy authorities greatly complicates the state’s recent efforts at integrated water management. In recent decades CADWR has made strides in moving to regional water management. Today much of the water resource management is divided among 9 sub regions which are defined by the natural geography rather then political borders . In 2002, the legislature created the Integrated Regional Water Management Program to promote inter agency cooperation . Under IRWM, local agencies together submit to the state a regional water management plan that comprehensively addresses water issues—including water supply reliability, water use efficiency, storm water, groundwater, flood control, etc. These projects then become eligible for funds from water bonds. IRWM is jointly managed by the Department of Water Resources and the State Water Resources Control Board . Many IRWM projects have been funded by the successive water bonds approved since 2002.

Although the program has been hailed as a step towards integrated water management,hydroponic gutter my interviews indicated that agencies have found its implementation to be difficult. One project manager complained about its complexity and the uncertainty of funding. Regardless, people agreed that it has led to some improvement in inter agency cooperation . In the Western United States, water agencies have historically been the central agents in water management. The journalist Robert Gottlieb and geographer Margaret Fitzsimmons, have together written a history of California agencies arguing that the relatively undemocratic water agencies have often served as a “hidden government” directing the growth of the state from behind the scenes . Gottlieb and Fitzsimmons focus on the Metropolitan Water District of Southern California , the regional water wholesaler that is responsible for more than half the regions water supply. MWD is a special district regional wholesaler that delivers water to 26 member public water agencies—14 cities, 11 municipal water districts and one county water authority. These agencies in turn serve more than 300 cities and numerous unincorporated communities in the six counties of Los Angeles, Orange, Riverside, San Bernardino, San Diego and Ventura . MWD was established by an act of the California legislature in 1927 and incorporated in 1928 . MWD’s stated mission is to: “provide its service area with adequate and reliable supplies of high quality water to meet present and future needs in an environmentally and economically responsible way” . In a region with world famous water agencies such as the Los Angeles city owned Department of Water and Power , MWD is the major water agency of Southern California.

The district imports water from the Colorado River and Northern California—through contract with the State’s DWR—to supplement local supplies. MWD’s 2013 annual budget is projected to be $1.78 billion . It owns and operates an extensive system of water infrastructure including 16 hydroelectric facilities, nine reservoirs, five water treatment plants—four of which are among the 10 largest plants worldwide— and nearly 1,000 miles of large diameter pipes . MWD contracts with thousands of firms to build, manage, and supply this vast infrastructure . Metropolitan is governed by a 37-member board of directors representing the 26 member agencies. The board operates under a weighted voting system, with voting share determined by assessed property valuation . MWD’s existence has allowed growth throughout the region regardless of local water conditions. New developments simply have to hook up to the MWD system and purchase water imported from the Colorado River or northern California. The MWD’s model has been remarkably successful in procuring water and promoting regional growth. Since MWD’s founding, its service area has exploded from 625 square miles to approximately 5,100 square miles . However, it is not without significant challenges. In particular, late comers to the MWD cooperative, such as San Diego County Water Authority , have grave concerns about their water security, as they are last in line should significant shortages ever occur. San Diego received as much as 95% of its total water supply from MWD as late as the early 1990s . To alleviate this risk SDCWA has recently bypassed MWD to purchase water directly from Imperial valley farmers in order to diversify its water supplies. However, SDCWA must use MWD’s infrastructure in order to “wheel”, or move, the water, and MWD charges for this separately—at a price that SDCWA objects. This has led to several clashes between MWD and SDCWA in the past and is a major source of simmering tension today. In fact, in April of 2012, SDCWA filed a lawsuit to stop the MWD from raising its water rates, arguing that San Diego is being unfairly penalized by the increase. SDCWA not only claims discrimination, but claims it is being conspired against by other agencies . SDCWA has begun a very loud public campaign against MWD.

The water economist, David Zetland, wrote his dissertation on the earlier 1995 dispute between SDCWA and MWD’s other member agencies. Zetland points out that MWD’s cooperative structure is not conducive to settling disputes among members, since conflicts over policies are determined by median votes which are heavily weighed towards early members . Zetland argues that MWD’s structure was much more effective in its early history when water was abundant and costs were subsidized for most members,hydroponic nft channel but today as the region faces potentially declining supply, it is no longer effective as water is growing more expensive and therefore should be priced to reflect its true current costs. Furthermore, Zetland found that despite MWD’s great successes in promoting regional growth it has been remarkably inefficient in its allocation of water . MWD charges the same price for delivery anywhere, regardless of delivery costs. It mixes fixed and variable costs into one price, and sets that price a year ahead of time without knowledge of the future water supply conditions. This inevitably leads to some inefficiencies as some regions get water for bargain rates compared to the costs of extracting it, while others pay much more dearly. However, this cooperative structure has also succeeded in promoting regional growth, as developers were ensured of a guaranteed water supply at a stable price regardless of conditions. In recent decades, MWD has begun revising its role from strictly procuring additional supplies to also helping member agencies develop increased local water resources through water conservation, recycling, and water storage. In addition to management expertise, it provides financial incentives to its member agencies for local investments in water management projects and programs. MWD has also established groundwater banking partnerships and water transfer arrangements in order to secure additional supplies . Through a partnership with the Bureau of Reclamation, the MWD administers an Innovation Conservation Program . ICP has annual research grants for technologies and innovative management approaches that promote water conservation . Additionally, MWD has several business outreach programs designed to educate businesses about contracting and supply opportunities . Recently, after recommendations from the Blue Ribbon Committee, MWD has slightly expanded its role to include fostering local regional economic development and spur technological innovation through the introduction of a “Managing Your Innovation” program. The program has several goals, to research and promote innovative solutions to water issues, to help innovators commercialize their products, and to build regional networks in order to promote knowledge spillovers . Managing Your Innovation hosts quarterly events, bringing inventors together with entrepreneurs, financial experts, and government agencies. The program is a much smaller version of other successful innovation initiates that have worked elsewhere to promote innovation, such as Singapore’s SWA. However, the tiny scale of these programs—simply a few annual meetings in thecase of Managing Your Innovation—demonstrates that local business development is not a major priority of local water agencies.

My interviews strongly collaborated this finding, despite the laments of MWD employees who were actively working to improve the local business climate. They agreed that it was not a primary goal of the organization. One entrepreneur with a lauded efficiency product who was interviewed complained of the difficulty reaching the right people They pointed to the sheer number of local agencies and the task of tracking down the appropriate people to speak with, and that many were unwilling to take chances on newer products, or really any chances at all. They also noted the dated websites of MWD and other regional agencies . There are several additional points one should take away from this brief discussion of California’s water governance. First, water prices are often subsidized. For example, water end-users in Southern California often do not pay for the Federal or State agencies that are working to procure their water, nor do they regularly pay for the infrastructure that moves the water—although maintenance costs and new infrastructure are generally covered. Even projects where local agencies built and financed the initial infrastructure, such as LADWP’s Los Angeles Aqueduct, those capital costs were paid long ago, resulting in current prices that are far below replacement costs. This is a major dampener to developing new sources, or new technologies to more efficiently use our current supplies. Next, even with regional cooperative organizations such as MWD and state efforts to coordinate diverse entities such as the IRWM program, the incredibly complicated water market leads to a multitude of water pricing regimes. Some water districts have a protected groundwater supply that is cheap to pump, and thus, might charge very cheap prices. Others might not have groundwater at all, or groundwater which is heavily polluted, and they are under court order to clean the water resulting in very high local prices. This results in vastly divergent water prices which makes it difficult for entrepreneurs to make return on investment decisions, and thus, limited potential investment in new technology . Some local agencies have implemented effective tiered pricing regimes that effectively promote conservation and efficiency, while many others have not. Agencies in politically progressive areas tended to be the most advanced in this regard . An additional point needs to be made about water agencies in general, and that is that they are paid by volume of water produced. Therefore, they have little incentive to invest in conservation measures, or in new technology which may make them more efficient, since every reduction in water use will result in a reduction of revenue. During the energy crisis of the 1970’s, the State of California recognized the perverse incentives that these “irony of conservations” gave energy firms. Therefore, the state began the process of “decoupling” natural gas and energy revenues from volume of sales in order to increase investment in conservation and efficiency . This has widely been credited with spurring California’s renewable energy and clean technology industries. . Numerous critics, such as Ingram and Fraser , have argued that water agencies are intrinsically path dependent on heavy infrastructural solutions at the cost of ignoring other viable solutions. Path dependency refers to the limiting of options that naturally occur as a result of previous decisions. Today, our water agencies already have invested in water infrastructure and are staffed by professional engineers trained to support the infrastructure. They are managed by leaders who are both straddled with the long term repayment of capital costs and under pressure by current vested interests in continuing business as usual. Therefore, it is not surprising that water agency leaders are most likely to make new decisions that utilize that infrastructure rather than promote innovative solutions. There is a large volume of critical literature that chronicles the process of institutionalizing the paths that serve to benefit the long term interests of certain participants. For example, the aforementioned Gottlieb and Fitzsimmons collaboration that pointed to political benefits for land developers. In practice, this often results in the adoption of technological solutions, usually heavy water infrastructures, over alternatives.