INCENTIVIZING AND DEVELOPING BEST PRACTICES TO ENHANCE GROUNDWATER SUPPLY AND QUALITY WITH MANAGED RECHARGE OF NON-TRADITIONAL WATER SOURCES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1025094
• Grant No.: 2021-67019-33595
• Cumulative Award Amt.: $499,840.00
• Proposal No.: 2020-05545
• Project Start Date: Dec 1, 2020
• Project End Date: Nov 30, 2024
• Grant Year: 2021
• Program Code: [A1411]- Foundational Program: Agricultural Water Science

Recipient Organization
UNIVERSITY OF CALIFORNIA AT SANTA CRUZ
1156 HIGH STREET
SANTA CRUZ,CA 950641077

Performing Department
Earth & Planetary Sciences

Non Technical Summary
Agricultural activity in many regions is limited by the availability and quality of fresh water. Groundwater pumped from wells is particularly important in many parts of the United States. In some areas, much or most agricultural activity depends on groundwater. Unfortunately, groundwater supplies are being depleted in many places because of increased use, changing land use, and shifts in climate. The last two of these factors tend to limit the inflow of surface water into aquifers (subsurface formations that can store and transmit water in usable quantities), also known as "recharge." Groundwater depletion also leads to a lowering of water quality, as salts, nutrients, and other contaminants can increase overtime. Managed recharge is a set of methods and tools that can be used to increase the supply and quality of groundwater. Thus there is a need to improve strategies to increase groundwater recharge, and to improve water quality in the process. This project seeks to enhance groundwater supplies and quality by helping with managed recharge using stormwater runoff, excess surface flows that occur during and after intense rain events. We are particularly interested in determining how best to reduce the content of "nitrate," a common contaminant in runoff in agriculturally active regions, during managed recharge. The primary approach we will use is the addition of a carbon source to shallow soil where water flows into underlying aquifers, for example wood chips, mulch, alfalfa, and/or almond shells. These soil amendments should help to stimulate the activity of natural microbes that live in the soil and can help to remove nitrate. We are also exploring how removal of nitrate might be accompanied by higher concentrations of metals in infiltrating water. This will be done with a mixture of field and laboratory experiments, including work at an active managed recharge site using stormwater. In the field region, the research team is helping to run a program that pays pumping-fee rebates to regional stakeholders who host recharge projects on their property. This novel incentive program may help to encourage others to help build and operate recharge systems, for the benefit of groundwater supply and quality. This project is a collaboration between university personnel, Resource Conservation District staff, a regional water agency, and agricultural stakeholders.

Animal Health Component

10%

Research Effort Categories

Basic

50%

Applied

10%

Developmental

40%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
112	0210	2050	50%
112	0210	2000	30%
102	4099	1103	20%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 112 - Watershed Protection and Management;

Subject Of Investigation
4099 - Microorganisms, general/other; 0210 - Water resources;

Field Of Science
1103 - Other microbiology; 2050 - Hydrology; 2000 - Chemistry;

Keywords

water quality

best practice

ecosystem services

groundwater

nutrient cycling

sustainable

Goals / Objectives
We propose to conduct linked field and laboratory studies, using a new managed aquifer recharge (MAR) site that applies a nontraditional water source and uses carbon-rich soil amendments, to improve groundwater quality through enhanced removal of nitrate, aided by native soil microbes. The project site is being operated as part of a novel incentive program that compensates stakeholders for improvements they make to local and regional water resources, an approach that has potential to be developed more broadly across the U.S. as a management practice. Proposed work includes field-scale preparation, operation, and validation of the field MAR system; laboratory experiments and analyses of soil, fluid, and microbial samples, to assess nitrate removal efficiency and potential mobilization of soil metals; and synthesis of existing and new data to provide a holistic assessment of improvements to water quality and supply associated with incentivizing MAR. This project is a collaboration between university personnel, Resource Conservation District staff, a regional water agency, and agricultural stakeholders, and may be a template for broader application of methods and management goals.Project goals and objectives are:(1) Test for improvements in water quality during infiltration for MAR at a field scale as a result of adding bioavailable carbon to shallow soil. a. Instrument an active field site being used for MAR, to collect data and samples while infiltration and recharge are occurring. b. Measure inflowing and outflowing concentrations of key nitrogen species and compare differences between native soil and amended locations. (2) Determine whether conditions that help to reduce nutrient loads may also result in mobilization of naturally occurring soil metals, and if these metals may be readsorbed to subsurface soils during transport through the vadose zone. a. Assess metals concentrations in samples collected as part of Goal 1 b. Conduct laboratory batch experiments to assess the extent of trace metal leaching and reabsorption under conditions encountered during infiltration for MAR(3) Measure whether application of carbon-rich soil amendments cause shifts in the subsurface microbiology towards taxa capable of denitrification and hydrocarbon degradation. a. Analyze 16S rRNA gene from DNA of materials extracted from soil samples, before and after infiltration for MAR, in native soil and below soil augmented with bioavailable carbon. b. Conduct genomic analyses examining both specific taxa and the metagenome of soil samples, to quantify whether shifts in microbial ecology occurred.(4) Assess water quality benefits that result from soil carbon amendments as part of a novel incentive program called "Recharge Net Metering." a. Complete analysis of the quantity and quality of water that infiltrated into the ground at a field site as part of a Recharge Net Metering pilot program, which provides a financial incentive to landowners to offset loss of land use and operation/maintenance of infiltration systems. b. Report results to a regional water agency as the basis for issuing a pumping fee rebate, and assess if there continues to be interest in participation in the pilot program.

Project Methods
We will quantify impacts of managed aquifer recharge (MAR) on water quality by combining mass balance and point infiltration measurements with measured differences in nutrient and trace metal concentrations and loads, comparing flow through native soil to that through a carbon-rich permeable reactive barrier (PRB). We will extend field-scale (operational) data with results of plot-scale and laboratory experiments; the most important interpretation will be the extent of water quality improvement and nutrient load reduction during infiltration for MAR. We will also assess overall effort and project costs, relative to the cost of water and alternative schemes for increasing supply and or reducing demand, to better understand the efficacy of applying the ReNeM approach, and soil carbon treatment during MAR more broadly, in other settings. The volume of water that infiltrates as part of a MAR system will be determined by mass balance: I = Qin + P - Ev - ?S, where I = gross infiltration, Qin = infiltration basin inflow, P = precipitation on the basin area, Ev = evaporation from the infiltration basin, and ?S = observed change in storage. Basing the net metering program on I instead of groundwater recharge, which is notoriously difficult to measure, places the incentive program on firm hydrologic footing, recognizes hydrologic system services provided by infiltration, and focuses on the region where most rapid nutrient processing occurs. P will be measured on site with a tipping bucket rain gauge. Ev is estimated conservatively as reference evapotranspiration from the nearby stations. Qin will be measured by continuous monitoring of inflow stage and application of the Manning equation for open channels and pipes. ?S values will be determined differences in water elevation and infiltration basin geometry.Point measurements of infiltration, linking fluid flow rates to nutrient cycling, will be determined using thermal probes designed and built in-house, using heat as a tracer. Probes are built using autonomous temperature loggers, placed inside PVC tubing, and installed in holes that are backfilled with silica slurry to prevent annular flow and assure a good thermal contact with the shallow soil. Soil samples used for grain size analysis will be digested, freeze dried, and analyzed in a Beckman Coulter LS13320 Particle Size Analyzer. Analysis for total organic carbon and total nitrogen will be completed with a Thermo Fisher Flash 2000 after multiple stages of oven drying and vapor acidification. Certified soil reference materials indicate errors <3%. Fluids will be sampled from inflowing water and within the upper ~1 m of saturated soil at the base of the infiltration basin using hand-built piezometers (6 mm OD) made from polycarbonate tubing with drilled perforations and wrapped in a nylon screen. Nests of piezometers will be installed at multiple depths in hand-augered holes that are roughened (to remove a skin left by the auger bucket), then backfilled with 1-2 mm (10-20 mesh), well-rounded silica sand. A bentonite seal will be installed between piezometer depths, to avoid cross-contamination, and nylon tubing will be run up the basin slope to an access road, then tied off and capped. Researchers will visit the site during active infiltration and connect a peristaltic pump to the sample tubing, slowly drawing fluid up from depth and into pre-labeled and acid-washed polyethylene and glass bottles. Samples will be placed on ice in a cooler and returned to the lab, where they will be processed using 0.22 µm or 0.45 µm filters (depending on analyses), then frozen at -20 °C until analyzed. Nitrogen species (NO3-, NO2-, NH4+) will be determined by colorimetric flow injection analysis on a Lachat Instrument QuickChem 800. Dissolved organic carbon will be measured by combustion catalytic oxidation using a Shimadzu TOC-VCSH total organic carbon analyzer. Regular analyses of sample splits, blanks, and laboratory standards indicate accuracy for both instruments of ~3%. Concentrations of chloride, sulfate, bromide, and phosphate will be analyzed using a Dionex ICS 2100, with frequent commercial and internal (check) standards. Metal concentrations and speciation will be assessed in both liquid and solid phase samples to assess the temporal changes. Total concentration of metals including Mn, Fe, and As in 0.22 μm filtered and acidified liquid samples will be determined using ICP-OES or ICP-MS. Aqueous Mn(II), Fe(II), and As(III) will be quantified in anoxically collected liquid samples using formaldoxime, phenanthroline, 1,5-diphenylcarbazide (DPC) colorimetric methods. Aqueous As(III) will be determined using a modified hydride-generation ICP-MS method. Preparation of anoxic samples for colorimetry and MS will be done in an anaerobic glove bag (COY chamber) with 95% N2:5% H2 atmosphere. All aqueous samples will be analyzed in triplicate. Soil solid phase analysis will include total elemental composition and metal and metalloid speciation associated with the solids to determine how As, Fe, and Mn concentrations differ and how speciation and association with soil matrix changes over time. Bulk soils will be sampled in triplicate (each replicate will be a composite of multiple bulk samples) within each carbon treatment area at the start and end of the water year. Total solid phase elemental composition will be measured on dried, sieved, then ground samples using X-ray fluorescence (Spectro XEPOS XE). The N2-BET method will be used to determine bulk soil surface area from each C treatment plot. XRD will be performed on soil samples to provide a general mineralogical composition, particularly for more crystalline components including primary minerals and secondary clay minerals. Soil microbiomes will be characterized using established approaches for 16S rRNA amplicon sequencing. Soil samples will be subsampled into sterile Whirl-Pak bags (~50 g) and flash frozen in a liquid nitrogen dewar, followed by storage at -80?C until processing. Total DNA will be extracted using the Qiagen PowerSoil DNA extract kit, and nucleic acids are purified from the soil matrix by centrifugation and DNA affinity column purification. DNA is quantified by fluorescence using a Qubit instrument. The DNA is used as a template to PCR amplify the partial 16S rRNA gene using primers that target variable regions of the gene. Unique DNA sequencing "bar-codes" are added by another PCR step. After purification and normalizing the DNA concentration, the samples are pooled in one tube and sequenced by Illumina MiSeq platform (paired end 300). Data are processed via a bioinformatic pipeline including removing primer sequences and low quality sequencing data; taxonomic classification, diversity assessment (alpha and beta diversity metrics), and conducting various multivariate statistical analyses.

Progress 12/01/20 to 11/30/24

Outputs
Target Audience:Target audiences for this project included multiple groups: - Staff of the Pajaro Valley Water Management Agency (PVWMA), who are partners in the recharge net metering (ReNeM) program and issue groundwater pumping fee rebates on the basis of data provided by the team. - California regulatory agency staff (State Water Resources Control Board, Central Coast Regional Water Quality Control Board) - Project stakeholders - landowners and growers at Kelly Thompson Ranch, who host the managed recharge project, and other ReNeM project participants who want to know how these projects perform and what challenges may be encountered. - Members of the public within the Pajaro Valley, who look to the agency for leadership in water resource management, and may be considering participation in the ReNeM program - Other technical (scientific, engineering) professionals who are involved in water resource management efforts around the state and around the U.S., who look at this work in terms of how similar projects might be developed and operated in their basins and regions. - Undergraduate students in courses that were offered at project institutions: Introduction to Soil Sciences, Environmental Soil Chemistry, and the Latinxs & The Environment seminar series (UCR) Groundwater and Environmental Sciences Capstone Seminar (UCSC) The topics of focus in these classes included: groundwater resources, managed recharge, and how shifts in redox conditions can lead to denitrification and potentially metals mobilization. Funded summer research fellowships were offered through the Latinxs & the Environment program, which is intended to increase participation of Latinx/e students in environmental research with particular emphasis on processes that can affect the health of historically marginalized groups. Changes/Problems:The Covid pandemic presented numerous challenges, including limiting access to laboratory and field facilities, requiring that personnel be transported in separate vehicles, and limiting opportunities for team meetings. We also had some restrictions in access to key instrumentation for sample analyses, causing significant delays. Nevertheless, we completed work as proposed and generated novel and actionable results. What opportunities for training and professional development has the project provided?This project provided significant opportunities for training of students and junior technical staff in three laboratory groups at UCSC (hydrogeology, environmental microbiology) and UCR (soil chemistry). To date we have had participation on this project by eight graduate students, 11 undergraduate students, and three junior technical support staff. These personnel trained in interdisciplinary research as well as presenting research at conferences. For example, students who work in the microbiology area have learned techniques in geochemistry such as performing various water chemistry measures (e.g. DOC, nitrate, nitrite), ICP-MS analyses for metals, and learning how to organize, plan, and conduct a field research project focused on hydrologic data and sample collection. Similarly, students who work mostly in geochemistry have learned bioinformatics and how to analyze microbiome/sequencing data. Graduate students had the opportunity to visit the Stanford Synchrotron Radiation Lightsource for X-ray absorption spectroscopic analysis for samples collected from redox transition reactors. This cross-disciplinary work is invaluable profession development. We also trained personnel with the Resource Conservation District of Santa Cruz County and the Pajaro Valley Water Management Agency, who are helping to operate and support the ReNeM program. How have the results been disseminated to communities of interest?Project results have been presented at public meetings, small meetings of stakeholders, and at technical and scientific meetings. Five peer-reviewed papers were published during the award period, another is in review, and three more papers are in preparation, as part of three additional Ph.D. theses. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We completed numerous activities in support of goals and objectives (1), (2) and (3), as listed above. - We instrumented the Kelly Thompson (KT) field site in advance of water years 21-24 (each water year begins 10/1 of the previous calendar year), installing pressure gauges to monitor water levels in sedimentation and infiltration basins, fluid sampling piezometers at multiple depths in the shallow subsurface and in the same X-Y locations to collect bottom water, and thermal probes to determine vertical flow rates using heat as a tracer. - We collected sediment samples from multiple locations around the basins to assess soil texture, C/N content, total elemental concentrations, and soil microbiology prior to infiltration. - We visited the KT field site multiple times during each water year when the system was operating, to verify functioning of the instrumentation and service those instruments (replacing desiccant packs and batteries, checking security, etc) and to collect water samples from the surface and subsurface. - On the basis of data and samples collected, we prepared annual system reports for 2021-23; the report for WY24 is in progress. These reports are used by the water agency as the basis for issuing a pumping fee rebate to KT project stakeholders. - We analyzed water samples collected during WY20-23 for water quality parameters, and compiled this information with other data to assess performance, including cycling of nutrients and metals. These results were presented at numerous technical and public meetings, and are shown in a peer-reviewed publication that is currently in review (Serrano et al., 2024 - in review). - Tests were run using six (6) intact soil cores, 1 m in length, from the base of the KT infiltration basin, for laboratory experiments using different carbon amendments to assess impacts on water quality during infiltration. Thousands of samples were analyzed for dissolved carbon, nutrients, and metals. This work formed the basis for E. Kam's M.S. thesis, completed in Summer 2023, and we are currently working on a paper describing these results. - An additional set of six (6) intact 1 m soil cores were tested to examine the impact of wet-dry cycling on carbon, nitrogen, and metals cycling with and without woodchip amendments. Wet-dry cycling simulated intermittent rain events. Hundreds of water and soil samples were analyzed for carbon, nitrogen, and metals concentrations and metals transformations during redox cycling. -Redox cycling was imposed on soils from the field site using a batch reactor design that allowed for high temporal resolution tracking of metals, carbon, and nitrogen dynamics in the soil solids and aqueous phase. Our findings show that woodchip addition enhances manganese and arsenic release through increasing dissolve organic carbon concentrations during anoxic periods, but both metals are re-adsorbed or precipitated (immobilized) during oxic periods. Overall, arsenic and manganese dissolution was less impactful with each successive redox cycle. In contrast, total chromium release was enhanced during oxic periods and immobilized likely as Cr hydroxides during anoxic periods. The presence of nitrate also acted as a redox buffer, helping to maintain the redox status at a more oxidizing level which prevented some arsenic and manganese release from soil solids. Taken together, the results demonstrate that woodchip addition and saturated anoxic conditions can mobilize manganese and arsenic, but when oxic conditions ensue during the dry season, both metals are likely immobilized through precipitation or re-adsorption mechanisms. Results have been presented at national and international scientific conferences and a manuscript draft has been prepared. The work was led by a PhD candidate and contributed to goals 2C and 2D. - To investigate the roles of subsurface clay lenses in nitrogen and metals cycling, flow-through chambers were designed and used in collaboration with researchers and scientists at Stanford Synchrotron Radiation Lightsource (SSRL) where high-energy X-rays were used to observe how metals cycling was influenced by both woodchips and carbon-rich clay lenses during intermittent wetting (rain) events. Preliminary results demonstrated that clayey lenses in soils may be important in situ sources of organic carbon that drive subsurface metals release. The work was led by a PhD candidate and contributes to goals 2C and 2D. - Hundreds of batch adsorption experiments were performed to assess metals adsorption on soils of varying texture from 0 to 2 m depth. Synchrotron X-ray absorption analysis was applied to determine how metals were adsorbed (retained) on soil minerals.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Ying, S.C., Maki, B., Aiken, M.L., Thorpe, L., Fisher, A. Water quality trade-off considerations for agricultural managed aquifer recharge. Goldschmidt Conference, Chicago, IL. 08/07/24, oral presentation (invited).
• Type: Peer Reviewed Journal Articles Status: Published Year Published: 2023 Citation: Bruce, M., L. Sherman, E. Bruno, A. T. Fisher, and M. Kiparsky (2023), Recharge net metering (ReNeM) is a novel, cost-effective management strategy to incentivize groundwater recharge, Nature Water, 1(10), 855-863, doi:10.1038/s44221-023-00141-1.
• Type: Other Status: Published Year Published: 2024 Citation: Fisher, A. T., Enhancing groundwater recharge to sustain communities and aquatic systems: opportunities through net metering and levee setbacks, Chancellor's Journey to Learning, UCSC Institute for Arts and Sciences, 29 October 2024 (invited).
• Type: Other Status: Published Year Published: 2024 Citation: Fisher, A. T., Using managed recharge in with stormwater, improving water quality during infiltration, and recharge as a hydrologic system service, Turlock Irrigation District's Idle Lands Recharge Demonstration and On Farm Recharge Field Day, Ceres, CA, 6/26/24, oral presentations (invited).
• Type: Other Status: Published Year Published: 2024 Citation: Fisher, A. T., Gorski, G., Weathers, T., Saltikov, C., Schmidt, C., Camara, K., Lockwood, B., Lurie, L., McCarthy, E., Harmon, R., Groundwater Recharge: A Critical Surface-subsurface Connection for California's Central Coast, California Naturalist Program, Santa Cruz, CA, 4/25/24, oral presentation (invited).
• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Ying, S.C., Maki, B., Smock, D., Serrano, A., Edwards, N., Webb, S., Fisher, A. Metal mobilization during managed aquifer recharge on agricultural lands. American Chemical Society Annual Meeting, (Spring), New Orleans, LA., 03/20/24 oral presentation (invited)
• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Ying, S.C., Maki, B., Aiken, M.L., Hope, M.J., Edwards, N., Webb, S., Fisher, A. Safe water for all: from geochemistry to community engaged research. ASA-CSSA-SSSA Annual Meeting, San Antonio, TX; 11/10/24, oral presentation (invited)

Progress 12/01/22 to 11/30/23

Outputs
Target Audience:Target audiences for this project included multiple groups: - Staff of the Pajaro Valley Water Management Agency (PVWMA), who are partners in the recharge net metering (ReNeM program) and issue groundwater pumping fee rebates on the basis of our studies. - California regulatory agency staff (State Water Resources Control Board, Central Coast Regional Water Quality Control Board) - Project stakeholders - landowners and growers at Kelly Thompson Ranch, who host the managed recharge project, and other ReNeM project participants who want to know how these projects perform and what challenges may be encountered. - Members of the public within the PVWMA, who look to the agency for leadership in water resource management, and may be considering participation in the ReNeM program - Other technical (scientific, engineering) professionals who are involved in water resource management efforts around the state and around the U.S., who look at this work in terms of how similar projects might be developed and operated in their basins and regions. - Undergraduate students in three courses being offered at project institutions: Introduction to Soil Sciences (100 students) and Environmental Soil Chemistry (40 students) (UCR) and Environmental Sciences Capstone Seminar (UCSC), engaging >150 students/year. Foci for these classes include groundwater resources, managed recharge, and how shifts in redox conditions can lead to denitrification and potentially metals mobilization. Changes/Problems:We have mostly recovered from COVID restrictions, but are still being careful during transportation to/from field sites and during lab work. From Dec 2022 to Sept 2023 the Stanford Synchrotron Radiation Light source was closed due to flooding during a rainstorm in Dec 2022 that caused a transformer to be damaged beyond repair. The synchrotron was completely inoperable until Sept 2023, when the UCR team received the first set of beamtime that was requested in Nov of 2022. Our solid phase metals analyses has been significantly delayed due to this accident. We have coordinated with SSRL beamline scientists and should receive additional beamtime by Spring 2024. What opportunities for training and professional development has the project provided?This project has provided and continues to provide significant opportunities for training of students and junior technical staff in three lab groups at UCSC (hydrogeology, environmental microbiology) and UCR (soil chemistry). To date we have had participation on this project by seven graduate students, nine undergraduate students, and two junior technical support staff. These personnel have trained in interdisciplinary research as well as presenting research at conferences. For example, students who work in the microbiology area have learned techniques in geochemistry such as performing various water chemistry measures (e.g. DOC, nitrate, nitrite), ICP-MS analyses for metals, and learning how to organize, plan, and conduct a field research project focused on hydrologic data and sample collection. Similarly, students who work mostly in geochemistry are learning bioinformatics and how to analyze microbiome/sequencing data. Graduate students had the opportunity to visit the Stanford Synchrotron Radiation Lightsource for X-ray absorption spectroscopic analysis for samples collected from redox transition reactors. This cross-disciplinary work is invaluable profession development. We are also training personnel with the Resource Conservation District of Santa Cruz County and the Pajaro Valley Water Management Agency, who are helping to operate and support the ReNeM program. How have the results been disseminated to communities of interest?Project results have been presented at public meetings, small meetings of stakeholders, and at technical and scientific meetings. Two papers were published during the review period in peer-reviewed journals, and we are preparing additional studies for publication. What do you plan to do during the next reporting period to accomplish the goals?We re-instrumented the main field site prior to start of WY-23. We are prepared for more field sampling and analysis when hydrologic conditions permit. We will also continue lab work to analyze samples collected in the third project year, including hydrologic, geochemical, and microbial analyses (comparing samples from before and after infiltration). We will use the newly designed and fabricated X-ray ready flow-through chambers to perform redox oscillation experiments in the lab prior to deploying at the synchrotron. We plan to complete in-lab redox oscillation experiments by March 2024 in time for X-ray mapping time in Spring 2024. We will also repeat batch redox oscillation experiments with a higher oxic:anoxic ratio (6:1) to simulate the long dry and shorter wet conditions within KT basin soils. We plan to submit the first 1:1 batch reactor experiment results for publication in early 2024.

Impacts
What was accomplished under these goals? During the reporting period, we completed numerous activities in support of goals and objectives (1), (2) and (3), as listed above. - We instrumented the Kelly Thompson (KT) field site in advance of water year 2023 (WY-23, began 10/1/22), installing pressure gauges to monitor water levels in sedimentation and infiltration basins, fluid sampling piezometers at multiple depths in the shallow subsurface and in the same X-Y locations to collect bottom water, and thermal probes to determine vertical flow rates using heat as a tracer. - We collected sediment samples from multiple locations around the basins to assess soil texture, C/N content, total elemental concentrations, and soil microbiology prior to the WY-22 infiltration season. - We visited the KT field site multiple times during WY-23 to verify functioning of the instrumentation and service those instruments (replacing desiccant packs and batteries, checking security, etc) and to collect water samples from the surface and subsurface. - On the basis of data and samples collected, we prepared an annual system report in Fall 2022 that will be used by the PVWMA as the basis for issuing a pumping fee rebate to KT project stakeholders. - We analyzed water samples collected during WY-23 for water quality parameters, and are compiling this information with other data to assess cycling of nutrients and other improvements. - Tests were completed using six (6) in-tact soil cores, 1 m in length, from the base of the KT infiltration basin, for laboratory experiments using different carbon amendments to assess impacts on water quality during infiltration. Thousands of samples were analyzed for dissolved carbon, nutrients, and metals. This work formed the basis for E. Kam's M.S. thesis, completed in Summer 2023. - We have completed sediment reaction experiments that allowed us to impose redox transitions on project soils with and without nitrate and carbon amendments to evaluate the role of seasonal shifts on the effectiveness of carbon addition using wood mulch and almond shells on denitrification and metals mobilization. We completed determining adsorption isotherms to determine whether subsurface sediments can indeed inhibit further transport of metals into aquifer through adsorption mechanisms. We will continue to use this project's objectives as materials for coursework at UCSC and UCR, and will give presentations at conferences in 2024. - 16S rRNA gene amplicon sequencing of soil samples was completed to assess changes in abundance of taxa associated with infiltration for managed recharge. We have established a protocol for quantifying biodegradable dissolved organic carbon (BDOC), which is being used in laboratory microcosm studies. Here we are testing how different carbon amendments used at the field site impacts the rate microbial reduction of nitrate. The protocol assesses how much BDOC is produced from the different carbon amendments. - We completed batch reactor experiments with KT basin soils that underwent multiple redox oscillations at a 1 oxic:1 anoxic temporal ratio (2 weeks oxic, 2 weeks anoxic per cycle) with and without wood mulch addition and nitrate. Results show that iron, arsenic, manganese, and chromium release correlated with redox conditions and the presence of nitrate buffered the release of manganese with and without carbon additions. Dissolved organic carbon concentrations increased during anoxic periods and decreased during oxic periods demonstrating rapid carbon respiration by aerobes when oxygen was available and slowed respiration by anaerobes during anoxic periods. Soil and water samples were collected over the course of 3 cycles (6 weeks) and analyzed for metals concentration, dissolved metals speciation (i.e., Fe(II), As(III), and As(V), and solid phase metals speciation using X-ray absorption spectroscopy at Stanford Synchrotron Radiation Light Source. - Arsenic and manganese adsorption isotherms were completed to assess arsenic adsorption on MAR soils in basin regions that did not have carbon added at five depths from surface to 2 m below surface of the bottom of the basin ranging from loamy sand to silt texture. All soils after adsorption isotherms are completed will be analyzed using X-ray absorption spectroscopy to assess changes in solids-associated Mn and As speciation due to mineral surface catalyzed oxidation or reduction. - Cutting-edge flow-through chambers that allow real-time μ-XRF total elemental mapping were designed in collaboration with Dr. Nick Edwards and Dr. Sam Webb, beamline scientists at the Stanford Synchrotron Radiation Lightsource (SSRL). The chamber will be filled with KT basin sandy soils surrounding a clayey segment to simulate KT basin soil texture heterogeneity. Stormwater can then be added to the chamber and effluent collected with a fraction collector inside the X-ray hutch while XRF mapping occurs. We have submitted a beamtime request for BL 7-2 at SSRL and should receive the first beamtime for mapping by Spring 2024.

Publications

• Type: Theses/Dissertations Status: Accepted Year Published: 2023 Citation: E. Kam, Influence of soil carbon amendments on denitrification in linked field and laboratory studies of managed aquifer recharge, Master of Science in Earth Science, University of California, Santa Cruz, September 2023.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Maki B., Aiken, M., Chung, T., Thorpe, S., Serrano A., Schrad, N., Saltikov C., Fisher, A., and Ying, S. Impact of redox fluctuations on trace metal mobilization during managed aquifer recharge (MAR). Environmental Geochemistry and GeoSciences (EGGS) Group Seminar. Stanford Synchrotron Radiation Light source. December 1st, 2022. Oral Presentation, invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Hails, E., E. Kam, R. J. Hess, E. Rojas, A. T. Fisher, Understanding N and C Dynamics Using Budgets and Isotopes in Managed Aquifer Recharge Systems Enhanced with Bioavailable Carbon, Eos Trans. Am. Geophys. Union, Fall Meeting, H55J-0702, Chicago, IL, 16 December 2022, poster presentation, https://agu.confex.com/agu/fm22/meetingapp.cgi/Paper/1189449.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Pensky, J., A. T. Fisher, G. Gorski, N. Schrad, V. Bautista, and C. Saltikov (2023), Linking nitrate removal, carbon cycling, and mobilization of geogenic trace metals during infiltration for managed recharge, Water Research, 239, 120045, https://doi.org/10.1016/j.watres.2023.120045.
• Type: Theses/Dissertations Status: Accepted Year Published: 2023 Citation: E. Hails, The Effects of a Carbon Amendment on Carbon and Nitrogen Cycling During Infiltration for Managed Aquifer Recharge, Bachelor of Science in Environmental Sciences, University of California, Santa Cruz, June 2023.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Bruce, M., L. Sherman, E. Bruno, A. T. Fisher, and M. Kiparsky (2023), Recharge net metering (ReNeM) is a novel, cost-effective management strategy to incentivize groundwater recharge, Nature Water, 1(10), 855-863, doi:10.1038/s44221-023-00141-1.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kam, E., E. Hails, R. J. Hess, E. Rojas, A. T. Fisher, Influence of soil carbon amendments on denitrification in linked field and laboratory managed aquifer recharge systems, Eos Trans. Am. Geophys. Union, Fall Meeting, H55J-0701, Chicago, IL, 16 December 2022, poster presentation, https://agu.confex.com/agu/fm22/meetingapp.cgi/Paper/1194458.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Pensky, J. L., A. T. Fisher, G. Gorski, V. Bautista, L. Serafin, A. Calderwood, H. E. Dahlke, Assessing the Impact of Soil Carbon Amendments on Water Quality and the Potential to Address Legacy Contaminants during Flood-Managed Aquifer Recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, H55D-04, Chicago, IL, 16 December 2022, oral presentation, https://agu.confex.com/agu/fm22/meetingapp.cgi/Paper/1081733.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Thorpe, L., Rodrigues, M., Vega, M., Pinelo, J., Maki, B., Fisher, A. T., Ying, S. C., Assessing Nitrous Oxide Emissions from Managed Aquifer Recharge Basins Undergoing Wet-Dry Cycling Column Simulations, Goldschmidt Conference, 10 July 2023, Lyon, France, poster presentation, https://conf.goldschmidt.info/goldschmidt/2023/meetingapp.cgi/Paper/17026.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Serrano, A., V. Bautista, A. T. Fisher,, Assessing biogeochemical processes influencing redox-sensitive elements: Batch and flow-through experiments with implications for managed recharge, Goldschmidt Conference, 10 July 2023, Lyon, France, oral presentation, https://conf.goldschmidt.info/goldschmidt/2023/meetingapp.cgi/Paper/14239.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Ying, S.C., Maki, B., Gonzalez, D., Edwards, N., Webb, S., Fisher, A. We got rid of the nitrate, now whats up with the metals? Stanford Synchrotron Radiation Lightsource Users Meeting September 25, 2023, Stanford, CA. Oral Presentation, invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Serrano, A., V. Bautista, A. T. Fisher,, Assessing biogeochemical processes influencing redox-sensitive elements: Batch and flow-through experiments with implications for managed recharge, Goldschmidt Conference, 21 October 2023, Latinxs & the Environment Conference, Riverside, CA oral presentation.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Fisher, A. T., Beganskas, S., Gorski, G., K. Camara, A. Serrano, V. Bautista, K. Miller, M. Kiparsky, M. Bruce, J. Pensky, E. Kam, L. Lurie, E. McCarthy, H. Dailey, L. Sherman, Recharge Net Metering (ReNeM): A Novel Approach for Improving Groundwater Supply and Quality, Coastal Resilience Laboratory, Center for Ocean Health, UCSC, 6 December 2022, invited.
• Type: Other Status: Published Year Published: 2023 Citation: Seminar: Ying, S.C., Aiken, M.L., Maki, B., Saltikov, C., Fisher, A.T. Naturally occurring metals in groundwater cause disparity in safe drinking water access. Department of Environmental Health Sciences, School of Public Health, UCLA. 8 November 2023, invited.
• Type: Other Status: Published Year Published: 2023 Citation: Seminar: Fisher, A. T., L. Lurie, D. Hermstad, K. Camara, Recharge Net Metering (ReNeM): A Novel Approach for Improving Groundwater Supply and Quality, Greater Monterey County, Regional Water Management Meeting, 15 February 2023, invited.
• Type: Other Status: Published Year Published: 2023 Citation: Seminar: Fisher, A. T., Groundwater, water supplies, water quality, managed recharge, Environmental Science 10, Cabrillo College, 24 April 2023, invited.
• Type: Other Status: Published Year Published: 2023 Citation: Seminar: Fisher, A. T., Beganskas, S., Gorski, G., Weathers, T., Saltikov, Schmidt, C., Young, K., Weir, W., Lozano, S., Camara, K., Lockwood, B., Lurie, L., McCarthy, E., Harmon, R., Groundwater Recharge: A Critical Surface-subsurface Connection for California's Central Coast, California Naturalist Program, UCSC Arboretum, 25 May 2023, invited.
• Type: Other Status: Published Year Published: 2023 Citation: Seminar: Ying, S.C., Maki, B., Thorpe, L., Saltikov, C., Fisher, A.T. From microbes to humans: How soil microbes contribute to metals contamination of drinking water. Department of Entomology, UC Riverside, 26 October, 2023, invited.

Progress 12/01/21 to 11/30/22

Outputs
Target Audience:Target audiences for this project included several distinct groups: - Staff of the Pajaro Valley Water Management Agency (PVWMA), who are partners in the recharge net metering (ReNeM0 program and issue groundwater pumping fee rebates on the basis of our measurements. - California regulatory agency staff (State Water Resources Control Board, Central Coast Regional Water Quality Control Board) - Project stakeholders - landowners and growers at Kelly Thompson Ranch, who host the managed recharge project, and other ReNeM project participants who want to know how these projects perform and what challenges may be encountered. - Members of the public within the PVWMA, who look to the agency for leadership in water resource management, and may be considering participation in the ReNeM program - Other technical (scientific, engineering) professionals who are involved in water resource management efforts around the state and around the U.S., who look at this work in terms of how similar projects might be developed and operated in their basins and regions. - Undergraduate students in two courses being offered at project institutions: Introduction to Soil Sciences (UCR) and Environmental Sciences Capstone Seminar (UCSC), engaging >100 students. Foci for these classes include groundwater resources, managed recharge, and how shifts in redox conditions can lead to denitrification and potentially metals mobilization. Changes/Problems:COVID requirements and limitations greatly restricted (slowed and, in some cases, prevented) lab work and field work during the first part of the second project year, causing significant delays in experiments and analysis of samples, but lab and field access had mostly returned as of Summer 2022. That said, we continue to struggle with supply chain disruption, and this has slowed experimental work. Also because of COVID, synchrotron facilities were shut down, and it took over a year to be allocated analysis time to examine metals speciation in our samples. What opportunities for training and professional development has the project provided?This project has provided and continues to provide significant opportunities for training of students and junior technical staff in three lab groups at UCSC (hydrogeology, environmental microbiology) and UCR (soil chemistry). To date we have had participation on this project by seven graduate students, nine undergraduate students, and two junior technical support staff. These personnel have trained in interdisciplinary research as well as presenting research at conferences. For example, students who work in the microbiology area have learned techniques in geochemistry such as performing various water chemistry measures (e.g. DOC, nitrate, nitrite), ICP-MS analyses for metals, and learning how to organize, plan, and conduct a field research project focused on hydrologic data and sample collection. Similarly, students who work mostly in geochemistry are learning bioinformatics and how to analyze microbiome/sequencing data. Graduate students had the opportunity to visit the Stanford Synchrotron Radiation Lightsource for X-ray absorption spectroscopic analysis for samples collected from redox transition reactors. This cross-disciplinary work is invaluable profession development. We are also training personnel with the Resource Conservation District of Santa Cruz County and the Pajaro Valley Water Management Agency, who are helping to operate and support the ReNeM program. How have the results been disseminated to communities of interest?Project results have been presented at public meetings, small meetings of stakeholders, and at technical and scientific meetings. Three papers were published during the review period in peer-reviewed journals, and we are preparing additional studies for publication. What do you plan to do during the next reporting period to accomplish the goals?We reinstrumented and sampled the main field site prior to start of WY23, have conducted one synoptic sampling campaign (during the only rainfall event to have occurred this year to date). We are prepared for more field sampling and analysis when hydrologic conditions permit. We will also continue lab work to analyze samples collected in the second project year, including hydrologic, geochemical, and microbial analyses (comparing samples from before and after infiltration). We have continued to design and run sediment reaction experiments that allow us to impose redox transitions on project soils with and without nitrate and carbon amendments to evaluate the role of seasonal shifts on the effectiveness of carbon addition using wood mulch and almond shells on denitrification and metals mobilization. We will complete the on-going adsorption isotherms to determine whether subsurface sediments can indeed inhibit further transport of metals into aquifer through adsorption mechanisms. We will continue to use this project's objectives as materials for coursework at UCSC and UCR, and will give presentations at national and international conferences in 2023.

Impacts
What was accomplished under these goals? During the reporting period, we completed numerous activities in support of goals and objectives (1), (2) and (3), as listed above. - We instrumented the Kelly Thompson (KT) field site in advance of water year 2022 (WY22, began 10/1/21), installing pressure gauges to monitor water levels in sedimentation and infiltration basins, fluid sampling piezometers at multiple depths in the shallow subsurface and in the same X-Y locations to collect bottom water, and thermal probes to determine vertical flow rates using heat as a tracer. - We collected sediment samples from multiple locations around the basins to assess soil texture, C/N content, and soil microbiology prior to the WY22 infiltration season. - We visited the KT field site multiple times during WY22 to verify functioning of the instrumentation and service those instruments (replacing desiccant packs and batteries, checking security, etc) and to collect water samples from the surface and subsurface. - On the basis of data and samples collected, we prepared an annual system report in Fall 2022 that will be used by the PVWMA as the basis for issuing a pumping fee rebate to KT project stakeholders. - We analyzed water samples collected during WY22 for water quality parameters, and are compiling this information with other data to assess cycling of nutrients and other improvements. - We used six (6) in-tact soil cores, 1 m in length, collected in the base of the KT infiltration basin, to run laboratory experiments using different carbon amendments to assess impacts on water quality during infiltration. Three of these cores have been tested, and tests on the remaining three cores will be done in the next 3-4 weeks. Hundreds of samples are to be analyzed for dissolved carbon, nutrients, and metals. - 16S rRNA gene amplicon sequencing of soil samples was completed to assess changes in abundance of taxa associated with infiltration for managed recharge. We have established a protocol for quantifying biodegradable dissolved organic carbon (BDOC), which is being used in laboratory microcosm studies. Here we are testing how different carbon amendments used at the field site impacts the rate microbial reduction of nitrate. The protocol assesses how much BDOC is produced from the different carbon amendments. - We performed batch reactor experiments with KT basin soils that underwent multiple redox oscillations (2 weeks oxic, 2 weeks anoxic per cycle) with and without wood mulch addition and nitrate. Results show that iron, arsenic, manganese, and chromium release correlated with redox conditions and the presence of nitrate buffered the release of manganese with and without carbon additions. Dissolved organic carbon concentrations increased during anoxic periods and decreased during oxic periods, demonstrating rapid carbon respiration by aerobes when oxygen was available and slowed respiration by anaerobes during anoxic periods. Soil and water samples were collected over three cycles (six weeks) and analyzed for metals concentration, dissolved metals speciation (i.e., Fe(II), As(III), and As(V), and solid phase metals speciation using X-ray absorption spectroscopy at Stanford Synchrotron Radiation Light Source. - Arsenic adsorption isotherms were completed to assess arsenic adsorption on MAR soils in basin regions that did not have carbon added at five depths from surface to 2 m below surface of the bottom of the basin, with textures ranging from loamy sand to silt texture. Manganese adsorption isotherms are currently underway on the same basin soils. All soils after adsorption isotherms are completed will be analyzed using X-ray absorption spectroscopy to assess the strength of Mn and As association (binding) to soil particles to assess their mobility.

Publications

• Type: Journal Articles Status: Published Year Published: 2022 Citation: Gorski, G., A. T. Fisher, H. Dailey, S. Beganskas, and C. Schmidt (2022), The potential for nitrate removal during infiltration: mapping with machine learning informed by field and laboratory experiments, Hydrol. Proc., 14750, https://doi.org/10.1002/hyp.14750.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Schrad, N., J. Pensky, G. Gorski, S. Beganskas, A. T. Fisher, and C. Saltikov (2022), Soil characteristics and redox properties of infiltrating water are determinants of microbial communities at managed aquifer recharge sites, FEMS Microbiol. Ecol., https://doi.org/10.1093/femsec/fiac130.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Fisher, A. T., K. Camara, A. Serrano, S. Beganskas, M. Kiparsky, B. Lockwood, G. Gorski, J. Pensky, E. McCarthy, L. Sherman, L. Lurie, Recharge Net Metering to Enhance Water Supplies, Water Quality, and Hydrologic System Services, and Incentivize Stakeholder Engagement, Eos Trans. Am. Geophys. Union, Fall Meeting, SY35A-09, New Orleans, LA, 15 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Serafin, L., J. Pensky, A. T. Fisher, B. Gooch, L. Foglia, A. Calderwood, H. Dahlke, V. Bautista, G. Gorski, The Addition of Carbon Amendments during Managed Aquifer Recharge and their Impacts on Water Quality and Enhancement of Denitrification, Eos Trans. Am. Geophys. Union, Fall Meeting, H35P-1227, New Orleans, LA, 15 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Serrano, A., V. Bautista, A. T. Fisher, Biogeochemical transformations linked to varying carbon amendments during infiltration for managed recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, H35P-1216, New Orleans, LA, 15 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Pensky, J. L., Fisher, A. T., Bautista, V., Gorski, G., Faraola, S., Gooch, B., Foglia, L., Linking Physical Infiltration Processes to Changes in Water Quality and the Potential to Address Legacy Contaminants during Flood-Managed Aquifer Recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, H12G-01, New Orleans, LA, 13 December 2021, poster presenation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Kam, E., J. Pensky, M. McCarthy, A. T. Fisher, Shifts in soil chemistry during infiltration through soils amended with bioavailable carbon, Eos Trans. Am. Geophys. Union, Fall Meeting, EP15C-1345, New Orleans, LA, 13 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Hess R. J., J. Pensky, A. T. Fisher, Using Sediment Texture to Estimate Infiltration Rates at a Managed Aquifer Recharge Site, Eos Trans. Am. Geophys. Union, Fall Meeting, ED35A-0608, New Orleans, LA, 15 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Bautista, V., Serrano, A. Fisher, A. T., Bosworth-Ahmet, E., Quantifying Spatial and Temporal Variations in Infiltration During Managed Aquifer Recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, H35P-1223, New Orleans, LA, 15 December 2021, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Maki, B., Aiken, M., Chung, T., Thorpe, S., and Ying, S. Trace metal mobilization during managed aquifer recharge (MAR): A batch reactor approach assessing the influence of alternating oxic-anoxic cycling on metal release and transformation during MAR. American Chemical Society, Spring 2022 Meeting, 20-25 March 2022, San Diego, California. Oral presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Fisher, A. T., K. Camara, G. Gorski, A. Serrano, J. Pensky, S. Beganskas, E. McCarthy, M. Kiparsky, L. Sherman, B. S. Lockwood, and L. Lurie, Five years of Recharge Net Metering (ReNeM) to improve water supplies and water quality, 11th International Symposium on Managed Aquifer Recharge, Long Beach CA, 13 April 2022, oral presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Maki, B., Aiken, M., Chung, T., Thorpe, S., Schrad, N., Saltikov C., Fisher, A., and Ying, S. Could replenishing Californias aquifers lead to metals contamination of groundwater? UC Global Health Day, 7 May 2022. University of California Santa Cruz, Santa Cruz, California. Poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Maki, B., Aiken, M., Chung, T., Thorpe, S., and Ying, S. Impact of redox fluctuations on trace metal mobilization during managed aquifer recharge (MAR). Annual Symposium for the Environmental Toxicology Graduate Program, University of California Riverside, Riverside, CA. 13 June 2022. Oral presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Maki, B., Aiken, M., Chung, T., Thorpe, S., and Ying, S. Trace metal mobilization during managed aquifer recharge (MAR): A batch reactor approach assessing the influence of alternating oxic-anoxic cycling on metal release and transformation during MAR. Goldschmidt International Conference on Geochemistry and Related Subjects, 10-15 July 2022. Honolulu, HI. Oral Presentation.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Fisher, A. T., Incentives for Groundwater Recharge in California, Water Education for Latino Leaders (WELL) UnTapped Fellowship Program, online seminar and discussion, 17 February 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Fisher, A. T., Beganskas, S., Gorski, G., Weathers, T., Saltikov, C., oung, K., Weir, W., Lozano, S., Camara, K., Lockwood, B., Schmidt, C., Coburn, C., and Harmon, R., Groundwater Recharge: A Critical Surface-subsurface Connection for California's Central Coast, California Naturalist Program, UCSC Arboretum, 12 May 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Ying, S.C., Aiken, M.L., Maki, B., Saltikov, C., Fisher, A.T. From molecular geochemistry to policy: How manganese contributes to water contamination. Department of Soil Science, University of S�o Paulo, 5 September 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Ying, S.C., Aiken, M.L., Maki, B., Saltikov, C., Fisher, A.T. From molecular geochemistry to policy: How manganese contributes to water contamination. Center for Nanotechnology and Agriculture (CENA), University of S�o Paulo, 23 September 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Maki B., Aiken, M., Chung, T., Thorpe, S., Serrano A., Schrad, N., Saltikov C., Fisher, A., and Ying, S. Impact of redox fluctuations on trace metal mobilization during managed aquifer recharge (MAR). Redox Anomalies in Soil and Sediment Group Seminar, Stanford Synchrotron Radiation Light source. 3 November 2022. Oral Presentation, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Ying, S.C., Aiken, M.L., Maki, B., Saltikov, C., Fisher, A.T. From molecular geochemistry to policy: How manganese contributes to water contamination. Brazilian Synchrotron Light Source (LNLS) Seminar Series, 17 November 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Fisher, A. T., Beganskas, S., Pensky, J., K. Camara, A. Serrano, V. Bautista, E. Kam, E. McCarthy, L. Lurie, B. Lockwood, Mapping, Modeling, Measuring, and Monetizing Enhanced Groundwater Recharge with Stormwater, University of New Mexico, Albequerque, NM, 17 February 2022, invited.
• Type: Other Status: Published Year Published: 2022 Citation: Seminar: Fisher, A. T., The Water Cycle, Water Use, and Groundwater Recharge in California, ES10: Environmental Science, Cabrillo Community College 17 April 2022, invited.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Pensky, J., A. T. Fisher, G. Gorski, N. Schrad, H. Dailey, S. Beganskas, and C. Saltikov (2022), Enhanced cycling of nitrogen and metals during rapid infiltration: Implications for managed recharge, Sci. Total Environ., 838, 156439, https://doi.org /10.1016/j.scitotenv.2022.156439.

Progress 12/01/20 to 11/30/21

Outputs
Target Audience:- Staff of the Pajaro Valley Water Management Agency (PVWMA), who are partners in the recharge net metering (ReNeM0 program and issue groundwater pumping fee rebates on the basis of our measurements. - California regulatory agency staff (State Water Resources Control Board, Central Coast Regional Water Quality Control Board) - Project stakeholders - landowners and growers at Kelly Thompson Ranch, who host the managed recharge project, and other ReNeM project participants who want to know how these projects perform and what challenges may be encountered. - Members of the public within the PVWMA, who look to the agency for leadership in water resource management, and may be considering participation in the ReNeM program - Other technical (scientific, engineering) professionals who are involved in water resource management efforts around the state and around the U.S., who look at this work in terms of how similar projects might be developed and operated in their basins and regions. - Undergraduate students in two courses being offered at project institutions: Introduction to Soil Sciences (UCR) and Environmental Sciences Capstone Seminar (UCSC), engaging >100 students. Foci for these classes include groundwater resources, managed recharge, and how shifts in redox conditions can lead to denitrification and potentially metals mobilization. Changes/Problems:COVID requirements and limitations greatly restricted (slowed and, in some cases, prevented) lab work and field work during the first project year, causing significant delays in experiments and analysis of samples. In addition, shipments have been slow due to national and international supply chain issues; this remains an ongoing problem. As a result, we expect experimental work to require additional time. Also because of COVID, synchrotron facilities were shut down, and it took over a year to be allocated analysis time to examine metals speciation in our samples. Unfortunately, the information acquired from the synchrotron cannot be reproduced through another method because of the relatively low concentrations of metals in our samples (natural soils). Conditions have been relatively dry at the field site, and that provides limited opportunities for field sampling during infiltration system operation. However, we also have an extensive laboratory experiment and analytical program, so that provides additional opportunities to achieve project goals, even if field conditions are not ideal. What opportunities for training and professional development has the project provided?This project is providing a significant opportunity for training of students and junior technical staff in three lab groups at UCSC (hydrogeology, environmental microbiology) and UCR (soil chemistry). To date we have had participation on this project by seven graduate students, five undergraduate students, and two junior technical support staff. These personnel have trained in interdisciplinary research as well as presenting research at conferences. For example, students who work in the microbiology area have learned techniques in geochemistry such as performing various water chemistry measures (e.g. DOC, nitrate, nitrite), ICP-MS analyses for metals, and learning how to organize, plan, and conduct a field research project focused on hydrologic data and sample collection. Similarly, students who work mostly in geochemistry are learning bioinformatics and how to analyze microbiome/sequencing data. Graduate students had the opportunity to visit the Stanford Synchrotron for X-ray absorption spectroscopic analysis for samples collected from redox transition reactors. This cross-disciplinary work is invaluable profession development. We are also training personnel with the Resource Conservation District of Santa Cruz County and the Pajaro Valley Water Management Agency, who are helping to operate and support the ReNeM program. How have the results been disseminated to communities of interest?Project results have been presented at public meetings, small meetings of stakeholders, and at technical and scientific meetings. One overview journal paper has been published, and we are preparing additional studies for peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?We reinstrumented and sampled the main field site prior to start of WY-22, have conducted one synoptic sampling campaign (during the only rainfall event to have occurred this year to date), and have collected cores that will undergo laboratory testing. We are standing by for more field sampling and analysis when hydrologic conditions permit. We will also continue lab work to analyze samples collected in the first project year, including hydrologic, geochemical, and microbial analyses (comparing samples from before and after infiltration). We have continued to design and run sediment reaction experiments that allow us to impose redox transitions on project soils with and without nitrate and carbon amendments to evaluate the role of seasonal shifts on the effectiveness of wood mulch addition on denitrification and metals mobilization. We plan to test other carbon amendments include alfalfa which we hypothesize will hasten denitrification, but also enhance naturally-occurring metals release from the sediment. We will also finish developing adsorption isotherms to determine whether subsurface sediments can indeed inhibit further transport of metals into aquifer through adsorption mechanisms. We plan to have multiple manuscripts produced in the next reporting period. We will continue to use this project's objectives as materials for coursework at UCSC and UCR, and will give presentations at national and international conferences in 2022.

Impacts
What was accomplished under these goals? During the reporting period, we completed numerous activities in support of goals and objectives (1), (2) and (3), as listed above. - We instrumented the Kelly Thompson (KT) field site in advance of water year 2021 (WY-21, began 10/1/20), installing numerous pressure gauges to monitor water levels in the sedimentation and infiltration basins, fluid sampling piezometers at multiple depths in the shallow subsurface and in the same X-Y locations to collect bottom water, and thermal probes to determine vertical flow rates using heat as a tracer. - We collected sediment samples from multiple locations around the basins to assess soil texture, C/N content, and soil microbiology prior to the WY-21 infiltration season. - We visited the KT field site multiple times during WY-21 to verify functioning of the instrumentation and service those instruments (replacing desiccant packs and batteries, checking security, etc) and to collect water samples from the surface and subsurface. - On the basis of data and samples collected, we prepared an annual system report in Summer 2021 that was used by the PVWMA as the basis for issuing a pumping fee rebate to KT project stakeholders. - We analyzed water samples collected during WY-21 for water quality parameters, and are compiling this information with other data to assess cycling of nutrients and other improvements. - We are in the process of analyzing soil samples to assess bulk chemistry and assess C/N concentrations. - We collected six (6) in-tact soil cores, 1 m in length, and are preparing to run laboratory experiments using different carbon amendments to assess impacts on water quality during infiltration. - We are in the process of conducting 16S rRNA gene amplicon sequencing of soil samples, to assess changes in abundance of taxa associated with infiltration for managed recharge. We have established a protocol for quantifying biodegradable dissolved organic carbon (BDOC), which is being used in laboratory microcosm studies. Here we are testing how different carbon amendments used at the field site impacts the rate microbial reduction of nitrate. The protocol assesses how much BDOC is produced from the different carbon amendments.

Publications

• Type: Journal Articles Status: Published Year Published: 2021 Citation: Miller, K., A. T. Fisher, and M. Kiparsky (2021), Incentivizing groundwater recharge in the Pajaro Valley through recharge net metering, Case Studies in the Environment, (5)1: 10.1525/cse.2021.1222393.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Schrad, N., J. Pensky, G. Gorski, S. Beganskas, A. T. Fisher, C. Saltikov Impacts of Stormwater Infiltration on the Microbial Community during Managed Aquifer Recharge, Goldschmidt 2021 Virtual Conference, 8 July 2021, Theme 11: Metals and Nutrients in Terrestrial and Freshwater Systems
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Fisher, A. T., Beganskas, S., Gorski, G., Weathers, T., Saltikov, C., Schmidt, C., Teo, E., Young, K., Weir, W., Lozano, S., Camara, K., Lockwood, B., Lurie, L., McCarthy, E., Harmon, R., Groundwater Recharge: A Critical Surface-subsurface Connection for California's Central Coast, California Naturalist Program, UCSC Arboretum, 20 May 2021, invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Fisher, A. T., Mapping, Modeling, Measuring, and Monetizing Enhanced Groundwater Recharge with Stormwater, California Irrigation Institute, 59th Annual Conference, Virtual by teleconference, 1 February 2021, oral presentation, invited.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Ying, S. C., Aiken, M. L., Fisher, A. T., Serrano, A., and Saltikov, C. Managed aquifer recharge and its potential effects on water quality in Californias Central Coast. Health Disparities Research Center Annual Symposium. UC Riverside, California, USA. February, 2021.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Bautista, V., Pensky, J., Fisher, A. T., Gooch, B., Foglia, L., Soil Properties Below a Flood-Managed Aquifer Recharge Site on the Flood Plain of the Cosumnes River, Elk Grove, CA, Eos Trans. Am. Geophys. Union, Fall Meeting, H112-0009, Virtual by teleconference, 11 December 2020, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Flores, J. Pensky, J., Fisher, A. T., Soil Properties and Analysis of Sediment samples from a Site to be Used for Flood Managed Aquifer Recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, ED037-0020, Virtual by teleconference, 14 December 2020, poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Gorski, G., Fisher, A. T., Dailey, H. M., Beganskas, S., Schmidt, C., Mapping Denitrification Potential During Infiltration with Machine Learning Informed by Field and Laboratory Information, Eos Trans. Am. Geophys. Union, Fall Meeting, H071-05, Virtual by teleconference, 9 December 2020, oral presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Pensky, J. L., Fisher, A. T., Bautista, V., Gorski, G., Faraola, S., Gooch, B., Foglia, L., Linking Physical Infiltration Processes to Changes in Water Quality and the Potential to Address Legacy Contaminants during Flood-Managed Aquifer Recharge, Eos Trans. Am. Geophys. Union, Fall Meeting, H11L-1664, Virtual by teleconference, 9 December 2020, oral presentation, invited.
• Type: Other Status: Published Year Published: 2021 Citation: Fisher, A. T., Camara, K., Serrano, A., McCarthy, E., Lurie, L., Water year 2021 report on performance of the infiltration system at Kelly Thompson Ranch, as part of the recharge net metering program, Annual report to the Pajaro Valley Water Management Agency, 21 p.
• Type: Other Status: Published Year Published: 2021 Citation: Fisher, A. T., Camara, K., McCarthy, E., Lurie, L., Bautista, V., Gorski, G., Serrano, A., Pensky, J., Beganskas, S., An Update on Recharge Net Metering, with Distributed Stormwater Collection linked to Managed Aquifer Recharge (DSC-MAR), Meeting of the Board of Directors, Pajaro Valley Water Management Agency, Virtual by teleconference, 22 September 2021, oral presentation, invited.
• Type: Other Status: Published Year Published: 2021 Citation: Fisher, A. T., Camara, K., McCarthy, E., Lurie, L., Bautista, V., Gorski, G., Serrano, A., Pensky, J., Beganskas, S., Continuation of the Recharge Net Metering program in the Pajao Valley, Meeting of the Projects Committee, Pajaro Valley Water Management Agency, Virtual by teleconference, 28 April 2021, oral presentation, invited.