Progress 05/01/17 to 04/30/22
Outputs
Target Audience:The target audience was primarily undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV) At UNLD, one PhD student led the greenhouse/hydroponics research and generated plant tissue samples for analysis. At NSC, Co-PD Edmonds developed and delivered curricula specifically focused on hydroponic applications and implications of irrigating with recycled water (urban Agriculture). Several students in the course received field training in hydroponic systems at a local wastewater treatment facility. Three students completed a hydroponics project and presented a poster to NSC faculty, staff and other undergraduates at an on campus research symposium. COVID-related restriction's hindered the team's ability to travel. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One UNLV graduate student, 11 NSC undergraduate students, 1 postdoctoral researcher at the Southern Nevada Water Authority (SNWWA) and 1 research chemist (SNWA) have gained considerable experience in urban agriculture, water reuse principles and or analysis of plant tissue samples for trace organics and antibiotic resistance genes. Of the 11 undergraduate students (10 women, 8 minority) completed research projects, 40 students attended the fall 2021 day trip and 11 different students (10 minority) attended the USDA Southern California research experience in April 2022. How have the results been disseminated to communities of interest?Project specific information was integrated into relevant courses taught by Co-PD Edmonds at NSC. A manuscript was published by the University of Arizona Cooperative Extension, which focused on plant uptake of CEC's in recycled water application, providing important baseline information for growers and other stakeholders. Future dissemination efforts will build on this initial publication and provide project specific data (H. Oswal, D. Gerrity and C. Rock. 2021. Plant Uptake of Contaminants of Emerging Concern During Irrigation with recycled Water, University of Arizona Cooperative Extension). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Q1 Different tomato sample types were processed and analyzed from three different pots irrigated with tap water and five different pots irrigated with UF filtrate. For tap water, all samples were <MRL for the soil and leaves, but there were two detections for sulfamethoxazole in the roots, one detection of trimethoprim in the roots, and one detection of benzotriazole in fruit; resulting average concentrations were all ≤0.3ng/g. Of those compounds, benzotriazole was the only compound with a reportable concentration in tap water, which yields a BCF of 55L/kg for tomato fruit. TOrC uptake was considerably more apparent in tomato plants irrigated with UF filtrate, with nine compounds detected in soil, six in roots, five in leaves, but zero in fruit. Of the compounds detected in multiple sample types, some exhibitedhighest concentrations in roots (triclosan, sulfamethoxazole, benzotriazole), with others exhibiting highest concentrations inleaves (carbamazepine, lidocaine, meprobamate, and sucralose). Sucralose actually increased monotonically between soil (39.7±23.4ng/g), roots (59.8±23.8ng/g), and leaves (162±52.2 For tomato leaves, irrigation with tap water and ozonated UF filtrate resultedin comparable plant tissue concentrations, and although plant tissue concentrations were stillelevated for the various UF filtrates, the concentrations were generally orders of magnitudelower than those observed in the spinach leaves. In fact, with the exception of carbamazepine(1,823L/kg), lidocaine (479L/kg), and TCEP (1,307L/kg), the BCFs were all <100L/kg. For the spinach plants irrigated with ozonated UF filtrate, no compounds were detected above the MRL in the roots or shoots, but sulfamethoxazole, lidocaine, DEET, and sucralose were detected in the spinach leaves in 25-75% of replicate plants. In contrast with some of the elevated data in Phase 2 (soil pots spiked), the concentrations were more similar to those observed in Phase 1 (soil pots), with only sucralose detected frequently and at relatively high concentrations (51.0±12.8ng/g). The tomato plants irrigated with UF filtrate, between four and six of 12 compounds were detected in the various sample types, with only sulfamethoxazole detected in roots, shoots, leaves, and fruit. Concentration profiles also varied by compound, with some compounds detected at highest concentrations in roots (e.g., benzotriazole and sulfamethoxazole), shoots (e.g., triclosan and DEET), or leaves (e.g., carbamazepine, lidocaine, meprobamate, and sucralose). Q2Meprobamate, benzotriazole, DEET, and TCEP were all detected at <10ng/L in wastewater, whereas sucralose was detected at 367ng/L. All target compounds were detected in the UF filtrate, with concentrations ranging from <100ng/L for triclosan and trimethoprim to >10,000 ng/L for benzotriazole and sucralose. The average TOrC concentrationswere then compared against the selected spiking concentrations for Phase 2 (low=10/500 μg/L and high 50/2,500μg/L) to determine the corresponding concentration ratios for each target compound, ranged from ~10-600x for the low spike and 50-3,000x for the high spike. For the Phase 1 experiments, TOrC uptake was evaluated for spinach with unspiked UF filtrate as irrigation water and for tomato plants with tap water and UF filtrate. Sucralose was the only compound detected above the MRL in any spinach leaf samples, with concentrations ranging from <26 to <44ng/g for the censored samples and 61-140 ng/g the samples with reportable concentrations (average=67.5±52.0ng/g). For Phase 2, fewer sample types were evaluated, but pots were irrigated with a wide variety of irrigation waters, including tap water, ozonated UF filtrate, unspiked UF filtrate, low/high spike UF filtrate, and sequential irrigation with high spike UF filtrate followed by tap water (tomato plants only). In contrast with Phase 1, which only sucralose was detected in spinach leaves with UF filtrate irrigation, nearly all compounds were detected in spinach leaves during Phase 2, regardless of irrigation water. In order to bound at least 70% of the BCFs on the basis of sample type, the following groupings (log10) were established: tomato roots=0 to 2 (86% of allBCFs), tomato shoots = 0 to 2 (71% of all BCFs), tomato leaves= -1 to 3 (90% of all BCFs), tomato fruit= -2 to 2 (72% of all BCFs), and spinach leaves = 1 to 4 (71% of all BCFs). For spinach leaves, all of the BCFs that exceeded 4 log10 were the result of irrigation with unspiked UF filtrate during the Phase 2 experiments, which were potentially impacted by methanol addition. The corresponding log10 averages were as follows: tomato roots= 0.89±0.78, tomato shoots= 1.09±0.82, tomato leaves= 0.92±1.22, tomato fruit= 0.16±1.70, and spinach leaves= 2.58±1.35 (all values) and 2.21±1.07 (excluding values >4 log10). The tomato fruit BCFs were considerably lower on average, which would suggest reduced uptake into the edible portion of the plant, but BCFs were actually statistically similar across all tomato sample types (p>0.05). In contrast, the BCFs for the spinach leaves were significantly greater than those of the tomato plants, regardless of sample type (p<0.01), suggesting that spinach plants are capable of accumulating higher TOrC concentrations and thus may lead to greater human exposure to these compounds. Q3 There were no noticeable differences in TOrC uptake in the soil pots vs. the hydroponic system. Q4Since the same pots were used for multiple growth phases, it is possible that TOrC accumulation led to increased uptake during Phase 2 (spiked, particularly for tap water irrigation, but this was not confirmed in our study. ?Q5Average 16S rRNA gene concentrations decreased from almost 10 log10 gc/L in full-scale secondary effluent, to 9.5 log10 gc/L in ozonated secondary effluent, to 7.2 log10 gc/L in the UF filtrate. The individual log10 reduction values (LRVs) were 0.40 for ozonation and 2.77 for ultrafiltration. The ampC and vanA genes were <LoQ in all samples, while the tet and sul ARGs were detected in the secondary effluent and ozonated secondary effluent. The concentrations of both sul ARGs were approximately two orders of magnitude higher than the tet ARGs. Only sulI was detected in the UF filtrate, resulting in ultrafiltration LRVs ranging from >1.22 to >3.17 for all targets. For Phase 2, 16S rRNA and chloroplast gene targets were detected for nearly all irrigation conditions for the spinach leaves, tomato leaves (excluding ozonated UF filtrate)and tomato fruit. The tomato plants irrigated with ozonated UF filtrate, leaves from two plants were <LoQ for the 16S rRNA gene (V5-V6) and chloroplast assays. The 16S V4 assay was positive in both plants, but the average concentration was approximately one order of magnitude lower than other samples. The ampC target failed the melt curve QA/QC criterion for several spinach leaf samples and all tomato leaf samples, but it showed proper melt curve characteristics in nearly every tomato fruit sample. When ampC was quantifiable in the spinach leaves, the concentrations were approximately 10-fold higher than tomato fruit. The vanA target was detected in every spinach and tomato leaf sample at concentrations of ~4 log10 gc/g. The tetO target was not detected in any sample during Phase 2, while tetW was detected in at least one replicate plant for spinach leaves, tomato leaves, and tomato fruit regardless of irrigation water quality. The tetO and tetW targets were detected in secondary and ozonated secondary effluent but not after ultrafiltration, so similar to ampC and vanA. Finally,sulI--the only ARG detected in recycled water after ultrafiltration--was detected under all conditions unless the melt curve indicated non-specific amplification, with concentrations in spinach and tomato leaves of ~3-4 log10 gc/g and ~3 log10 gc/g in tomato fruit.
Publications
- Type:
Other
Status:
Published
Year Published:
2021
Citation:
H. Oswal, D. Gerrity and C. Rock. 2021. Plant Uptake of Contaminants of Emerging Concern During Irrigation with recycled Water, University of Arizona Cooperative Extension
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Progress 05/01/20 to 04/30/21
Outputs
Target Audience: The target audience has primarily been undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). At UNLV, one PhD studentled the greenhouse/hydroponics research and generatedplant tissue samples for analysis. At NSC, Co-PD Edmonds developed and delivered curricula specifically focused on hydroponics applications and the implications of irrigating with recycled water (Urban Agriculture). Several students in the course received field training in hydroponics systems at a local wastewater treatment facility. Three students completed a hydroponics project and presented a poster to NSC faculty, staff, and other undergraduates at an on-campus research symposium. Eight students completed projects on urban agriculture in general.A majority of the year was dedicated to restarting the experimental components of the project following extended COVID-related disruptionsso outreach and research dissemination were limited. COVID-related restrictions also hindered the team's ability to travel andparticipate in research conferences. Changes/Problems: The COVID-19 pandemic continued to limit progress on the research early in the reporting period, but the team was able to restart the final hydroponics growth phase, generate plant tissue samples, and submit them for processing and analysis. Those samples remained archived for a period of time due to work-from-home requirements and subsequentstaffing shortages at the partner institution (Southern Nevada Water Authority). However, those samples are now being analyzed, and all results are expected to be available by the end of October 2021. In late 2021 and early 2022, the project team will focus on final data analysis and research dissemination. What opportunities for training and professional development has the project provided? 1 UNLV graduate student, 11 NSC undergraduate students, 1 postdoctoral researcher at theSouthern Nevada Water Authority (SNWA), and 1 research chemist (SNWA) have gained considerable experience in urban agriculture, water reuse principles, and/or analysis of plant tissue samples for trace organics and antibiotic resistance genes. How have the results been disseminated to communities of interest? Project-specific information was integrated into relevant courses taught by Co-PD Edmonds at NSC. A manuscript previously submitted to the University ofArizonaCooperative Extension, which wasfocused on plant uptake of CECs in recycled water applications, was accepted and is now in press. Once published, that article will provide important baseline information for growers and other stakeholders. Future dissemination efforts will build on this initial publication and provide project-specific data. What do you plan to do during the next reporting period to accomplish the goals? The project team completed all growth phases of the project and expects to complete the analytical components of the project by the end of October 2021.At that point, the PhD student will focus on data analysis, reporting (publication and dissertation), and other forms of research dissemination by the overall project team (e.g., industry conferences).?
Impacts
What was accomplished under these goals?
1) Antibiotic resistance genes (ARGs) were successfully analyzed in all plant tissue samples generated in earlier phases of the project. There appear to be significant differences in concentration as a function of ARG, plant type,and plant structure. Those analyses/statistics will be finalized in late fall 2021. 2) The PhD student completedPhase 3 of the research (i.e., the hydroponics growth phase) once the UNLV labs were reopened. This phase consisted oftwo parallel, nutrient film technique (NFT)hydroponics systems irrigating with eitherultrafiltration effluent or ozonated ultrafiltration effluent. Fifty-six (56) plant tissue samples consisting of eitherroots, leaves, or fruit were generated from spinach and tomato plantsharvested inJune2021. Samples were then submitted to the Southern Nevada Water Authority (SNWA) for analysis. Water quality and plant characteristics were assessed over the entire growth period.All sampleswerecryo-milled to prep for microwave-assisted extraction, solid phase extraction, and LC-MS/MS analysis. Additional samples were submitted and will be processed for nucleic acid extraction and antibiotic resistance gene quantification.The trace organic and ARG data are all expected to beavailable in October 2021, at which point the graduate student can start generating research deliverables (publication, dissertation, conference presentations). 3) One finding from the hydroponics phase of the research was ultrafiltration effluent hindered growth of thespinach plants specifically, while ozonated ultrafiltration effluent was successfully used as an irrigation water. We hypothesize that infectious pepper mild mottle virus (PMMoV)may have been present in the wastewater and may have infected the spinach plants; ozone presumably inactivated the PMMoVand allowed for successful growth of the spinach plants. The team started a short-term experiment with ultrafiltration effluent and autoclaved ultrafiltration effluent to test this hypothesis. The team will evaluate plant quality and yield and will also evaluate plant uptake of PMMoV at the end of the growth cycle.
Publications
- Type:
Other
Status:
Awaiting Publication
Year Published:
2021
Citation:
Oswal, H., Gerrity, D., Rock, C. Plant uptake of contaminants of emerging concern during irrigation with recycled water. Arizona Cooperative Extension. In press.
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Progress 05/01/19 to 04/30/20
Outputs
Target Audience: For the first three years of the research, the target audience has primarily been undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). At UNLV, 3 undergraduate students, 3 graduate students, and 2 postdoctoral researchers have been assisting with the research. At NSC, Co-PD Edmonds has developed and delivered curricula specifically focused on hydroponics applications and the implications of irrigating with recycled water. Students in those courses have received field training in hydroponics systems at a local wastewater treatment facility.A majority of year 3 was dedicated to completing theexperimental components of the research so outreach and research dissemination were limited. Changes/Problems:There were two major issues that hindered progress on the grant in year 3. First, the primary Ph.D. student working on the grant terminated his program on short notice in order to return to his home country for personal reasons. We were able to replace him quickly with a new Ph.D. student, but that student still needed to be trained on the various water quality methods, irrigation water collection procedures, and plant maintenance efforts. Second, the COVID-19 pandemic required the project team to terminate all research activities in mid-March. Phase 3 of the research (hydroponics growth phase) was already underway, but the plants had to be abandoned on short notice. We will restart phase 3 once we are approved to return to the laboratory/greenhouse and are able to access the local wastewater treatment plant for irrigation water collection. COVID-19 also resulted in cancellation of multiple conferences where we planned to present data related to this project. We plan to resubmit related abstracts for future conferences once they are rescheduled. What opportunities for training and professional development has the project provided? Similar tothe first two years of the research, 3 UNLV undergraduate students, 3 UNLV graduate students, and 2 postdoctoral researchers (UNLV and DRI)have been assisting with the research. Approximately 25 undergraduate students at NSC enrolled in a course (instructed by Co-PD Edmonds) that focused on the use of recycled water in hydroponics systems for food crop production. How have the results been disseminated to communities of interest? Project-specific information was integrated into relevant courses taught by the Co-PDs, including one course at NSC that was entirely devoted to the topic of this USDA research. In collaboration with one of the Ph.D. students working on the grant,PD Gerrity submitted a manuscript to the Arizona Cooperative Extension focused on plant uptake of CECs in recycled water applications. That manuscript is currently under review. What do you plan to do during the next reporting period to accomplish the goals?The project team expects to complete all experimental portions of the research within the next reporting period. A number of personnel issues, compounded bythe COVID-19 pandemic, severely hindered progress on the grant during year 3. However, once personnel are authorized to return to their respective institutions, we expect to be able to complete the research within the no-cost extenstion timeframe.
Impacts
What was accomplished under these goals?
The project team completed most of its phase 2 research focusing on the differential accumulation of contaminants of emerging concern (CECs) in plant structures as a function of water quality, specifically based onpretreatment (ultrafiltration vs. ultrafiltration+ozonation)and CEC concentration (ambient vs. spiked CECs). All plant tissue samples were processed and analyzed for CEC concentrations. The soil samples from phase 2 will be analyzed during the no-cost extension, along with completion of the phase 3 hydroponics research.Antibiotic resistance gene (ARG) assays will be completed for phases 2 and 3 (hydroponics) over the next year.
Publications
- Type:
Other
Status:
Under Review
Year Published:
2020
Citation:
Oswal, H., Gerrity, D., Rock, C. Plant uptake of contaminants of emerging concern during irrigation with recycled water. Arizona Cooperative Extension. Under review.
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Progress 05/01/18 to 04/30/19
Outputs
Target Audience: For the first two years of the research, the target audience has primarily been undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). At UNLV, 3 undergraduate students, 3 graduate students, and 2 postdoctoral researchers have been assisting with the research. One Ph.D. student made an oral presentation at the International Ozone Association (IOA) meeting in Las Vegas in August 2018. That presentation reached approximately 30 industry professionals with experience/interest in ozone applications for water and wastewater treatment. Waterreuse in agricultureis a rapidly growing area so this is an important audience for this research. Approximately 25 undergraduate students at NSC enrolled in a course(instructed by Co-PD Edmonds) that focused on the use of recycled water in hydroponics systems for food crop production. These students (10 of whom self-identify as minority status)also assisted with the field research at a local water reclamation facility. One student also presented her research at the Ecological Society of America meeting in New Orleans in August 2018. That same research was presented as part of 2 poster presentations at NSC. The project team also developed a collaborative relationship with a new hydroponics company in Las Vegas (Oasis Biotech). The project team discussed the goals of the research with representatives from Oasis Biotech and will also be using the company's hydroponics technology as part of the year 3 research. Changes/Problems:Phase 2 testing involved agreenhouse comparison of water quality using recycled water treated with (1)ultrafiltration and (2) ultrafiltration + ozonation. Toward the end of the initial round of phase 2 testing, the greenhouse suffered an infestation of white flies, which adversely impacted plant health. Because of the potential confounding effects of the infestation, we decided to repeat the entire growth cycle/experiment, but we still harvested a subset of the tomatoes to generate preliminary data. There were no major changes to the experimental approach--just a delay in research progression because of the need to repeat the growth cycle. What opportunities for training and professional development has the project provided?For the first two years of the research, the target audience has primarily been undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). At UNLV, 3 undergraduate students, 3 graduate students, and 2 postdoctoral researchers have been assisting with the research. Approximately 25 undergraduate students at NSC enrolled in a course(instructed by Co-PD Edmonds) that focused on the use of recycled water in hydroponics systems for food crop production. These students (10 of whom self-identify as minority status)also assisted with the field research at a local water reclamation facility. The vast majority of these students had never previouslybeen exposed to research/practice in agroecosystems. The project team also offered its time and expertise to assist Oasis Biotech with water quality concerns. How have the results been disseminated to communities of interest?(1) Presentations were made at the annual meetings of the Ecological Society of America and the International Ozone Association. (2) Poster presentations were made at local scientific meetings targeting a wider range of students from Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). (3) Project-specific information was integrated into relevant courses taught by the Co-PDs, including one course at NSC that was entirely devoted to the topic of this USDA research. (4) A collaboration was developed with Oasis Biotech (a hydroponics company in Las Vegas)to share knowledge, technologies, and resources. What do you plan to do during the next reporting period to accomplish the goals?The next reporting period will include four major components: (1) Analyze all phase 2 samples for the target trace organic compounds. All water, soil, and plant tissue samples were collected at the end of phase 2, which focused on a greenhouse comparison of irrigation water quality with respect to the uptake/fate of contaminants of emerging concern. Thosesamples are currently being processed by the analytical laboratory (Southern Nevada Water Authority). (2) Perform all molecular analysesto quantify antibiotic resistance genes and characterize microbial community structure.DNA has been extracted from soil and plant tissue samplesand is awaiting analysis by qPCR and 16S rRNA gene sequencing. (3) Complete the hydroponics phase of the research. Two hydroponics units were acquired from Oasis Biotech during year 2. Those units will be irrigated with recycled water treated with (1)ultrafiltration and (2) ultrafiltration + ozonation. Plant tissue samples will then be analyzed for the target trace organic compounds and antibiotic resistance genes. (4) Once the data collection phase is completed, we plan to collaborate with Dr. Channah Rock at the University of Arizona to prepare a Cooperative Extension article to disseminate the results from our research and similar studies in the literature. The article will address plant uptake of contaminants of emerging concern during irrigation with recycled water.
Impacts
What was accomplished under these goals?
The research team completed its phase 2 greenhouse experiments studying the impact of water quality on the uptake/fate of contaminants of emerging concern (CECs)in spinach and tomato plants irrigated with recycled water. Separate plants were irrigated with two different recycled water qualities: (1) ultrafiltration effluent and (2) ozonated ultrafiltration effluent. The primary objective of this research phase was to determine whether advanced treatment with ozonation reduced CEC uptake into edible portions of food crops. The phase 2 samples are currently being analyzed, but preliminary data suggest the following: (1) Recycled water is a viable water source for food crop irrigation, although there are several potential water quality concerns such as elevated levels of total dissolved solids and potential CEC uptake. At this time, it is still unclear whether the additional costs and complexity of ozonation are warranted with respect to CEC uptake and overall plant health. (2) Initial results indicate that the uptake of CECs into plant leaves is higher in hydroponics systems for many--but not all--target compounds. Uptake is also crop-dependent, with lower levels detected in spinach vs. tomato plants. (3) CECs accumulate in soil and roots, some reach plant leaves, and few CECs (if any) are detected in plant fruit when irrigated with water containing environmentally relevant CEC concentrations. Initial results indicate that CECs were only detected in tomato fruit when the irrigation water was spiked at orders of magnitude higher concentrations than what is typically observed in practice. Sequential irrigation with spiked recycled water prior to fruiting and then unspiked tap water appeared to reduce CEC accumulation in tomato fruit. (4) By studying the abundance of a gene linked to plant stress, there did not appear to be any statistically significant difference in plants irrigated with tap water vs. plants irrigated with recycled water in an aeroponics system.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Oswal, H., Gerrity, D., 2018. Role of ozone in agricultural water reuse applications. International Ozone Association (IOA) Annual Pan American Group Conference and Exhibition (Las Vegas, NV). Oral Presentation.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2019
Citation:
Kujat, K., 2019. Ultrafiltered wastewater as a medium for growing cherry tomatoes in an aeroponic unit. Thesis. Nevada State College.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2019
Citation:
Edmonds JW, Sackett JD, Lomprey H, Hudson HL, Moser DP. The aeroponic rhizosphere microbiome: Community dynamics in early succession suggest strong selectional forces. Antonie van Leeuwenhoek Journal of Microbiology.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Edmonds, J., Kujat, K. 2018. Microbial rhizosphere interactions in plants grown with treated wastewater using aeroponic technology. Ecological Society of America Meeting. New Orleans, LA.
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Progress 05/01/17 to 04/30/18
Outputs
Target Audience:At this early state of the research, the target audience has primarily been undergraduate and graduate students enrolled at Nevada State College (NSC) and the University of Nevada Las Vegas (UNLV). Approximately 30 undergraduate students at NSC enrolled in courses (instructed by Co-PD Edmonds) that focused on the use of recycled water in hydroponics systems for food crop production. Undergraduate (3) and graduate students (1) at UNLV were directly involved in the formal research activities. The project team also gave a presentation to operators and managers at the study site (a local wastewater treatment facility) to convey the importance of the research,to foster personnel 'buy-in', and to communicate issues that might compromise the integrity of the research (e.g., unexpected facility shutdowns). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?As part of theundergraduate curriculum at Nevada State College, approximately 30 undergraduate students have been exposed to concepts in water reuse andhydroponics. In addition, operators and managers at the local wastewater treatment facility have been introduced to those same concepts as part of an effort to foster buy-in from the facility personnel. What do you plan to do during the next reporting period to accomplish the goals?In the second year of the research, the team will be studying the role of advanced wastewater treatment in mitigating the accumulation of contaminants of emerging concern in agroecosystems irrigated with recycled water. Specifically, the research team will irrigate spinach and tomato plants with the same wastewater quality used in year 1, ozonated wastewater, and wastewater spiked with ~25x and ~100x ambient concentrations of the target compounds. These experiments will aid in determining whether plant uptake depends on the concentration of the target compounds and whether advanced treatment with ozonation is effective in reducing human exposure to contaminants of emerging concern. The research team will also begin collecting data related to microbial community structure and antibiotic resistance gene occurrence in these systems using the methods validated in year 1. Toward the end of the second year, the research team will begin the third phase of the research, which involves a comparison of plant uptake of contaminants of emerging concern in soil-based vs. hydroponics systems. Design and construction of the hydroponics system will begin in the summer of 2018. The research team will also presentpreliminary data at the annual conference of the International Ozone Association in August of 2018. The research team will also prepare a more mechanistic summary of the existing data to aid in future dissemination efforts (i.e., peer-reviewed publications and conference presentations).
Impacts
What was accomplished under these goals?
Due to widespread water scarcity issues,alternative water supplies such as treated wastewater (or recycled water) are increasingly being usedfor agricultural applications. However, treated wastewater is known to contain a wide variety of contaminants of emerging concern, including over-the-counter medications, antibioticsand other prescription drugs, flame retardants, antibiotic resistance genes, etc. This research isquantifying the uptake of these contaminants into food crops irrigated with recycled water to characterize the potential public health implications. If the research demonstratesde minimis risks associated with this practice, thisfunding may enablebroader implementation of nonpotable water reuse. However, it is currently too early to draw any definitive conclusions or cite any concrete impacts from the research. In thisfirst year, the researchers studied the uptake of 13 different contaminants of emerging concern by spinach and tomato plants irrigated with recycled water from a local wastewater treatment facility. All 13 chemical compounds wereconsistentlydetectedin the recycled water at concentrations ranging from 22 parts-per-trillion for the antimicrobial compound triclosan to nearly 50 parts-per-billion for the artifical sweetener sucralose. However,only sucralose was detected in the spinach leaves, although thesoil and roots of the spinach plants werenot tested.Multiple compounds were detected in the soil, roots, and leaves of the tomato plants, but none were detected in the tomato fruit fromplants irrigated with recycled water. This indicates that uptake depends on the plant, plant structure,and also on the chemical properties of the target compounds, but moreimportantly, these preliminary data indicate that human consumption of these food crops would pose de minimis public healthrisks, potentially providing support for the practice of irrigating food crops with recycled water. The researchers also successfully validated the molecular methods that will be used to evaluate the fate of antibiotic resistance genes when irrigating food crops with recycled water. Specifically, the research team tested several DNA extraction/purification methods and also validated the primers and assays that will be used to quantify the antibiotic resistance genes. These methods will be implemented during the next phase of the research.
Publications
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