Funded Research Projects

Through the Water Resources Research Act section 104(b) research grants program, Water Resources Research Center (WRRC) has funded approximate 3 – 5 research projects per year since 2000.  Abstract of those funded research projects can be found below.  Projects funded after 2007 also include links to the complete project final reports as downloadable PDFs.
 
Abstracts of 104(b) program funded projects:

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FY 2018

Microplastic Contamination in the Lower Santa Cruz River
Michael Bogan, David Quanrud, Drew Eppehimer

In arid environments, treated wastewater is increasingly recognized as a resource for irrigation, aquifer recharge, and riparian habitat restoration. Water reuse is an important strategy for managing water supply; however, it presents unique challenges in regard to water quality. Microplastics, a type of anthropogenic litter, are an emerging pollutant affecting marine and freshwater systems throughout the globe. Although wastewater treatment removes the majority of microplastics in sewage, wastewater effluent discharge is a significant source of environmental microplastic pollution, and its potential impact on ecological and/or human health is unclear. The lower Santa Cruz River near Tucson, AZ is an effluent-dependent system supported by discharge from Agua Nueva and Tres Rios Water Reclamation Facilities. In a preliminary effort, we have documented the presence of microbeads (a type of microplastic) up to 18 river miles downstream from the Tres Rios effluent outfall. Although we know that microplastics are present in the Santa Cruz, we do not know how abundant they are or what impact they may have on aquatic species. Here, we propose to examine how the density of microplastics varies across space and time in the water column and riverbed sediments of the Santa Cruz River, as well as quantify microplastic consumption rates by resident fish. Work will be conducted along a 2-mi reach downstream from the Agua Nueva and a 22-mi reach downstream from the Tres Rios effluent outfalls. These reaches are separated by ~1.5 miles of dry streambed where rapid infiltration rates limit surface water connectivity to brief periods during flood events. As urban development continues, discharge of effluent into rivers and streams will become more common. This novel study will provide baseline data necessary for water managers, policy makers, and the public to incorporate consideration of these contaminants of emerging concern within effluent management. The project will facilitate education and training of four graduate and three undergraduate students and provide data to support a future larger proposal for federal funding.

Using Fresh Water Algae to Remove Lead from Water
Robert Root and Amanda Minke

Human exposure to lead (Pb) is a global-priority environmental health concern. Lead is a known neurotoxin, and has been linked to diminished IQ and serious health problems, affecting the welfare of millions of people worldwide through natural and anthropogenic contamination of drinking water sources. The recently well-documented case of Pb contamination in municipal drinking water in Flint, Michigan has emphasized the critical need for remediation of contaminant Pb from potable water, but recent findings of Pb in Arizona drinking water have brought this problem much closer to home. Because of its environmental abundance, toxicity, and potential for human exposure, Pb has been designated a priority toxin (#2 after arsenic) by the Agency for Toxic Substance and Disease Registry. This undergraduate-driven project will investigate metal-microbe phytoremediation (removal) of Pb from drinking water using common freshwater algae. Our preliminary data show that wet algae packed on filter paper can remove nearly 100 μg Pb per gram of algal biomass. Removal of lead increased with algal availability, as 1.0 mg Pb in a 1-liter water sample was reduced to Pb = 0.45, 0.30, 0.26 and 0.15 mg l-1 after passing it through 4, 6, 8, 10, and 16 g of algae. Furthermore, a kinetic response was observed for increased reaction durations, indicating that control of Pb sequestration in algae is driven by both diffusion and biochemical interactions. Pb removal by algae showed an inverse relation with free-sulfur, possibly indicating that the mechanism of Pb bioremediation by fresh water algae involves sulfur-functional groups. This proposal will investigate contact time, algal species, and removal mechanisms under expected water chemistry conditions of drinking water to further characterize Pb removal, information that will be critical to the development of cost effective and sustainable bioremediation strategies. This work will not only examine the control of a serious water quality problem using renewable natural resources, it will also support the research of a promising University of Arizona undergraduate.

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FY 2017

Might Recycled Wastewater Solve the Rising Problem of Toxin-Producing Algae?
Kevin Fitzsimmons and Robert Lynch

Cyanobacteria, a phytoplankton phylum found in surface water bodies worldwide, can cause severe aesthetic water quality problems and induce water deoxygenation, leading to fish kills. Furthermore, some cyanobacterial genera, most notably several Microcystis species, are known to produce neurotoxic peptides known as microcystins. Such toxin production is of critical and increasing public health concern, as neurotoxic cyanobacterial algal blooms in freshwater lakes and streams have been implicated in human and animal sickness, and even death, in recent years. Environmental triggers inducing the production of microcystins by algal blooms are poorly understood. Studies have correlated increased toxin production to enhanced temperature, nutrient concentrations, and light intensity, but research results examining microcystin toxin production in response to environmental stimuli have rarely been conclusive outside of the laboratory or over multiple seasons. This has been due, in part, to difficulties inherent in identifying toxin-producing Microcystis bacteria and quantifying potential toxin production. Recent advances in molecular technologies have allowed the development of real-time quantitative PCR assays to detect specific microbial genes in bulk water samples, and this has greatly facilitated the ability to identify and quantify both Cyanobacterial DNA and the toxin synthesase gene (mcyD). This proposal is based on proof-of-concept laboratory work that identified substantial reductions in mcyD genes in recycled municipal wastewater compared to groundwater. We propose to expand this work outside of the lab and into Arizona retention ponds, and to measure specific environmental factors (including temperature, water conductivity, and heavy metal concentrations) that may be reducing toxin synthesis in recycled water retention ponds. This research will result in data that can be utilized in submission of large proposals to Department of Commerce and other funding agencies. Knowledge of the regulation of microcystin toxin biosynthesis would allow implementation of water management strategies to avoid environmental conditions that induce dangerous water quality conditions. In this way, the proposal directly supports WRRA 104b program research priorities of "exploring new ideas that address water problems" and "expanding understanding of…water-related phenomena." In addition, this work will provide summer salary to a master's level student, supporting, "the entry of new research scientists…into water resources fields."

Impact of Projected Climate Changes on Mountain-block Recharge Processes
Thomas Meixner, Jennifer McIntosh, Ravindra Dwivedi and Paul Andrew Ferre

Mountain systems are regionally and locally important areas of recharge for waters that ultimately end up in adjacent alluvial basins, which contain critical groundwater resources for arid and semi-arid regions such as Arizona. For example, in Arizona 66.5% of the state is classified as mountainous and these regions receive a significant amount of precipitation, both rain and snow, compared to nearby low land regions. Yet, little is known about natural recharge processes (e.g. recharge rates, flow paths and residence time) and critical zone services provided by montane regions or their connection to low land regions. Therefore, the main purpose of this study is to improve our current understanding of recharge processes and hydrologic functioning of mountain systems through observational (using multiple tracers) and numerical modeling (using multiple models) approaches. Specifically, our science questions are: (i) What proportion of groundwater discharges into high elevation streams versus infiltrates to subsequently become mountain-block recharge in mountainous catchments? And (ii) Can the optimal set of observations be identified using a multi-model approach to reduce model uncertainty to improve predictions related to total catchment water storage and the water quantity and quality of discharging water downstream? A successful assessment of our science questions will lead to an improved understanding of hydrologic functioning such as recharge processes and how catchments store water and discharge it with time, i.e., streamflow sustainability of high elevation catchments. Our results will further inform water management practices for the state of Arizona by improving our understanding of both groundwater replenishment rates and the susceptibility of these systems to climate change in low-land regions where the major source of groundwater is recharge from local or regional mountain systems. Finally, once successfully tested and applied to the state of Arizona, the findings from our work will be relevant to other fractured-bedrock aquifers in high elevation areas regionally and globally.

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FY 2016

Recycled Water Use for Agriculture: On-farm Demonstration and Evaluation
Channah M. Rock, Natalie Brassill, and Dametreea Carr

Recent drought pressures in California and the West have forced growers to cut water use by 25% through reduced water diversions under their riparian rights, or fallowing of their land (California Water Resources Control Board; 2015). Toward this end, a growing number of industry stakeholders are considering recycled wastewater for crop irrigation. Nontraditional water sources such as recycled water have the advantage of being a constant and reliable water source, and in the United States alone, an estimated 1.7 billion gallons (6.4 million m3) per day of wastewater is reused. Recycled water use on a volume basis is growing at an estimated 15 percent per year, demonstrating its growing acceptance as a clean, safe product.

Understandably, one of the primary concerns with the use of recycled water for agricultural irrigation is the potential for bioaccumulation of emerging contaminants, antibiotics, and AR bacteria. We proposed to engage stakeholders in a 2-year project evaluating perceptions of recycled water quality and its impacts and applicability for produce irrigation. This study includes detailed review of recycled water quality in the literature to identify risk parameters critical for use of recycled water in produce production coupled with stakeholder driven outreach and education in the form of focus groups and needs assessment surveys. Outputs from the project include recommendations for growers interested in utilizing nontraditional water sources.

Sunlight Driven Reactive Oxygen Species Production for Natural Attenuation of Wastewater Trace Organic Compounds
Robert Arnold and David Quanrud

Observations of the Santa Cruz River downstream from Tucson's wastewater treatment plants indicate that a number of important trace organic compounds (TOrCs) are gradually attenuated with distance while others tend to persist. Mechanisms responsible for transformation of TOrCs in the aquatic environment are seldom known with certainty. Sunlight (photolysis) can play an important role in observed transformations-via direct and indirect photolysis. In direct photolysis, the energy of the photon is directly responsible for the conversion of the target compound to product(s). In indirect photolysis, light energy activates an intermediate compound(s), such as singlet oxygen, which then either reacts with the target or with an another compound to produce an intermediate capable of reacting with the target. This project aimed to establish the roles of singlet oxygen, and other intermediates in attenuating target TOrCs in artificial sunlight (UVA-340); to construct and validate a mechanistic model of the process; and develop next experimental steps leading toward valid simulation of indirect photolysis of TOrCs involving reaction with singlet oxygen. In wide range of experimental conditions, agreement was obtained between observed and predicted values for target contaminant transformations, which suggests that the project's modeling techniques will be useful for studying more complex physical-chemical situations. This is an important step in the eventual development of mathematical representation of these transformations under conditions relevant to water and wastewater treatment.

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FY 2015

Water Sources Over Time for a Semi-Arid River - Implications for Water Resources and Groundwater Modeling
Thomas Meixner, Steve Leavitt, and Kiyomi Morino

Recent results for several semi-arid rivers indicate that semi-arid rivers can derive their sustained baseflow waters from a variety of water sources including snowmelt floods, summer monsoon thunderstorm floods and mountain front recharge sources. The source of water to these semi-arid rivers has important implications for ecosystems that derive their sustained baseflows in the semi-arid regions of the world. The recent studies have demonstrated that traditional conceptions of semi-arid river baseflow being sustained by basin groundwater derived from Mountain System processes are not entirely true. It is an open question however whether the identified flood versus basin groundwater sources are due to a continuing natural process and recharge mechanism or whether the importance of floodwater sources is evidence of hydrologic stress on these rivers due to human land and water management practices or to climate change and variability. A way to assess what these water sources have been over time is to observe the water sources that vegetation has used over time to assess the changes in water source over the last 30-60 years. We propose to investigate the variability of water in the San Pedro River and asssociated groundwater system using Populis Fremontis (Cottonwood) tree rings. Using this approach as well as using available data from modern day sampling of water isotopes in the precipitation, streams and groundwaters of the San Pedro basin, we will assess how water sources have changed in the San Pedro basin over time. Additionally we will use a simple surface groundwater model to assess what the potential changes in river flows were that explain the observed water isotopes in trees. Critically we view this project as a proof of concept which if successful could lead to the use of paleohydrologic methods in assessing processes, mechanisms and management in semi-arid rivers in the southwest and around the world.

Impact of Upgraded Wastewater Reclamation Facilities on Chemicals of Emerging Concern in the Effluent-Dependent Lower Santa Cruz River
David Matson Quanrud and Shane Snyder

The reliability of water supply to communities in Arizona and in other southwestern states is threatened by population growth and climate change. In future years, these communities will need to rely on water resources of impaired initial quality to balance supply and demand. Potable reuse of reclaimed water is an almost certainty in the future. Conventionally treated municipal wastewater contains an assortment of pharmaceuticals and personal care products along with a myriad of other contaminants of emerging concern (CEC) at sub-part-per-billion levels that are sometimes poorly attenuated during wastewater treatment. Pima County recently improved their two main municipal wastewater reclamation facilities (WRFs) that discharge treated effluent to the effluent-dependent Lower Santa Cruz River (SCR). Due to improved effluent quality, the river hydraulics have changed, with higher infiltration rates into the riverbed and a shortened wetted reach of the Lower SCR. Resultant impacts of these changes on CEC loading rates to the SCR watershed, as well as impact on natural attenuation processes during surface transport are unknown. This project will begin to fill that void by examining the presence and fate of a large suite of CECs along the entire wetted reach of the Lower SCR. The impact of the upgraded WRFs on CECs in the Lower SCR will be evaluated by comparison of project generated data with results from previous investigations by the PIs on the Lower SCR. Project results will support larger grant requests from e.g. the NIWR 104g program to fully evaluate fate of CECs in all phases of concern including impacts to local groundwater quality and riverbed sediment sorption/desorption phenomena.

Characterization of Uranium and Arsenic in Unregulated Water Sources on the Navajo and Hopi Reservations
Jani C. Ingram

The overall goal of the proposed research is to determine levels of uranium and arsenic in unregulated water sources in the western region of the Navajo Reservation as well as parts of the Hopi Reservation in northeastern Arizona. The purpose of this study is to collect information that will assist tribal leaders in understanding the extent of contamination on their lands. Currently there is minimal published information concerning uranium and arsenic in unregulated water sources on these Native American lands. However, preliminary work by our lab has shown elevated levels of uranium and arsenic in some of the unregulated water sources as well as variations in the basic water chemistry, even for wells in close proximity. An important next step in this research is to confirm the preliminary results as well as disseminating the information to the tribal leaders as well as the rest of the scientific community. The long-term research objective in the Ingram laboratory is to explore the relationship between health issues facing the Navajo Nation and chronic exposure to environmental uranium. Recently, the Ingram lab has been approached by Hopi community members to investigate contamination of their water sources by arsenic. Thus, the Ingram research has begun investigating both uranium and arsenic from water sources on both the Navajo and Hopi Reservations. Uranium and arsenic are issues to the Navajo and Hopi as they both geologically and anthropologically (through mining) affect their lands since they are both located on the Colorado Plateau. It is estimated that 30% of the Navajo people living on the Reservation rely on water hauled from unregulated wells for their consumption, household, and livestock needs. The proposed approach for this research will involve collection of new water samples as well as resampling wells previously investigated and characterizing these samples for uranium and arsenic. Additionally, general water chemistry will be characterized for samples with high levels of uranium and arsenic. Analytical methodology for these analyses has been utilized by the Ingram laboratory for past projects which will aide in the work proposed here. The project will involve Navajo undergraduate students in the Ingram laboratory. The results of this work will be used to further the understanding of environmental uranium and arsenic present in the water sources on the Navajo and Hopi Reservations. The outcome of this project will provide the information as to the extent of uranium and arsenic contamination on these Native American lands which is critical to establishing the relationship between chronic exposure to environmental uranium and arsenic, and health effects.

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FY 2014

Improving Integrated Surface Water and Groundwater Management in the United States:  Case Studies of Innovative Groundwater Governance Approaches
Sharon B. Megdal, Andrea Gerlak and Robert Varady

The proposed project investigates groundwater governance practices of the U.S. states in order to (1) assess the performance of these practices and (2) examine how they contribute to integrated surface/groundwater management.

Groundwater is a critical component of the water supplies for agriculture, cities, industry, and ecosystems around the world. In the U.S., groundwater represents much of our potential future water supply. Water management is largely decentralized in the U.S., with each state maintaining significant authority and autonomy when addressing groundwater regulation and governance. As population growth,k economic development, changing land-use patterns, and climate change stress existing water supplies, it is essential to identify ways to improve the ways we govern and manage groundwater.

Better groundwater governance will indeed improve water management and enhance the nation's water supply. Yet despite the importance of groundwater for all of the water using sectors in the U.S., there is currently no comprehensive compendium of information on groundwater governance in the U.s., and, consequently, no assessment and analysis of these practices.

This project will build upon a pilot survey the project team has recently completed. The "Initial U.S. Groundwater Governance Survey" (Initial Survey) collected baseline, descriptive information on groundwater governance from nearly all states and the District of Columbia. The Initial Survey collected information from a state agency official for each state and has yielded important baseline information on groundwater governance across the U.S.

The project will further analyze and map the results of the Initial Survey. It will also pursue in depth investigation of the laws and practices of three case studiess characterized by innovative groundwater governance strategies that contribute to integrated surface/groundwater management to enable identification of best practices. The case study analysis will consider: groundwater governance practices, approaches, trends, and innovations; catalysts of and impediments to integration of groundwater and surface water management; outcomes associated with integrated surface/groundwater management; and obstacles and barriers to integration, as well as opportunities that could facilitate it.

Development of Antibiotic Resistance during Wastewater Treatment
Jean McLain

As communities throughout the U.S. and the world move towards increases in water reclamation to augment surface and groundwater supplies, the potential for the release of antibiotic-resistant bacteria into the environment grows in concern. However, despite the potential for AR proliferation in wastewater treatment, few studies have attempted to identify processes or operational conditions contributing to the selection of resistant bacteria or those that are capable of reducing the level of resistance in wastewater. Such information is critical in quantifying the environmental burden of wastewater treatment plants with respect to antibiotic resistance and developing the most effective treatment strategies to mitigate any concerns. The proposed study will quantify the impact of treatment optimization on the development of resistance in bacteria using bacterial cultivation methods. Bacterial isolates will be exposed to four antibiotics to assess the level of resistance using laboratory methods developed by the PI. This work will be part of a larger study (with cooperators from University of Nevada, Las Vegas) that will also quantify the presence of resistance genes and trace levels of antibiotics in wastewater samples at several full-scale treatment plants. This work will also serve to train a promising pre-medical undergraduate at the University of Arizona in laboratory methodologies. By characterizing the long-term impacts of AR in the environment, this study will provide additional knowledge and tools for treatment process optimization, resistance mitigation, and future risk communication efforts.

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FY 2013

Discrimination-Inference to Reduce Expected Cost Technique (DIRECT): A new framework for water management and stakeholder negotiation
Paul Ferre

Water scarcity in the Southwestern United States has led to water resource disputes among stakeholders.  Two factors confound resolution of disputes.  First, there exists imperfect understanding of groundwater responses to anthropogenic and natural stresses, largely owing to insufficient existing hydrogeologic data.  Second, market and non-market values of water are difficult to quantify.  These factors are closely linked and there is a real opportunity for maximizing the value of water resources while minimizing conflict through the development of an integrated framework that jointly considers hydrologic science, data collection, and economic valuation.

The project continues development and testing of a novel approach referred to as Discrimination-Inference to Reduce Expected Cost Technique (DIRECT). DIRECT uses multiple models to quantify uncertainty in future hydrologic conditions and economic cost models to quantify the risk associated with water resource scarcity. DIRECT uses measurement optimization techniques to select hydrologic data best suited to reduce uncertainty with the express purpose of reducing expected costs.  The project involves ongoing collaborative work with the Desert Rivers Initiative (DRI) of the Arizona Land and Water Trust (ALWT).

The project includes three components: (1) describe market and non-market valuation techniques to quantify the economic effects of hydrologic changes in the basins where ALWT is currently pursuing water conservation agreements; (2) develop a set of computer-based tools to link multiple hydrologic models with economic cost models and provide easy-to-interpret visualizations; and (3) apply DIRECT at an existing ALWT site, identifying hydrologic data needed to reduce prediction uncertainty and economic data needed to formulate site-specific cost functions.  Findings will be communicated in collaboration with the ALWT in educational outreach and stakeholder negotiations.

Do Simple Carbon Additions Reduce Resistance to Antibiotics in Environmental Bacteria?
Jean McLain and Channah Rock

Antibiotics are released daily into the natural environment in treated recycled water and application of municipal biosolids onto agricultural fields, leading to increasing concerns regarding their contribution to the presence and persistence ofantibiotic resistance in environmental microbes.  This is of special concern in the state of Arizona, where applications of recycled water and biosolids to agricultural and riparian areas are increasing each year.  While conducting a multi-year study examining the effects of long-term (20+ years) application of recycled municipal wastewater and biosolids on the development of antibiotic resistance in soils, an intriguing pattern emerged.  Though no increase in antibiotic resistance in environmental bacteria has been observed to date, isolates at both locations show a marked decrease in multiple-antibiotic resistance in sites receiving long-term applications of recycled water and biosolids.  We hypothesize that the long-term application of recycled water and biosolids has increased soil organic carbon reserves and this has, in turn, decreased bacterial competition for organic molecules and decreased the necessity for bacterial antibiotic production.  The proposed study will examine this hypothesis in a laboratory setting.  A detailed assessment of the potential for abatement of multiple-antibiotic resistance may help to alleviate environmental and public health concerns regarding the use of recycled water and biosolids to augment water and soil carbon supplies in Arizona.

Sequential Advanced Oxidation and Soil-Aquifer Treatment for Management of Trace Organics in Treated Wastewater
Eduardo Saez and David Quanrud

The reliability of water supply to communities in Arizona and in other southwestern states is threatened by population growth and climate change.  In future years, these communities will need to rely on water resources of impaired initial quality to balance supply and demand.  Potable reuse of reclaimed water is an almost certainty in the future.  Wastewater contains an assortment of pharmaceuticals and personal care products along with a myriad of other trace organic contaminants (TOrCs) at sub-part-per-billion levels that are sometimes poorly attenuated during conventional wastewater treatment.  There has, however, been relatively little research to evaluate interactions between specific engineered processes and natural attenuation mechanisms in terms of overall reduction to either specific TOrCs or the biochemical properties of treatment residuals.  This project will begin to fill that void by examining potential synergy between advanced oxidation (UV/peroxide) and simulated soil-aquifer treatment (SAT) for removal of a representative suite of TOrCs that routinely survive conventional wastewater treatment.  Advanced oxidation includes a variety of engineered processes that have in common the ability to generate hydroxyl radicals that indiscriminately oxidize reduced chemical targets, including the vast majority of TOrCs in treated wastewater.  SAT encompasses processes such as sorption and biochemical transformation that result in contaminant attenuation during the infiltration and underground storage/transport of treated wastewater.  It is anticipated that advanced oxidation will transform a number of otherwise persistent contaminants into forms that are more readily attacked by processes that contribute to SAT.  Furthermore, the combination of engineered and natural processes is likely to provide water quality benefits for protection of human and environmental health at a cost that is much lower than engineered processes along. 

Extraction Methods for Engineered Nanoparticles from Aqueous Environmental Samples
Paul Westerhoff and Yu Yang

Increasing use of engineered nanomaterials (NMs) in industry, commerce, food, pharmaceutical, residential and agricultural applications have begun and likely will lead to their release to the environment.  Nanoparticles are one important category of NMs, and are operationally defined as having at least one dimension less than 100 nm.  Metallic NPs, including those based upon silver, zinc, titanium, exhibit acute and chronic toxicity; although it should be noted that consistent nomenclature and dosemetrics for these endpoints are not documented in the literature, nor is a single mechanisms of toxicity.  Managing the risk from engineering NPs required exposure data to accompany toxicity date.  Like other trace pollutants, extraction and separation methodologies from complex aqueous matrices (wastewater, surface water, etc.) allow increased sensitivity and quantification.  For metallic NPs extraction methods would facilitate differentiation of ionic versus nano or particulate forms.   The objective of this research is to compare recovery efficiencies of several metallic nanoparticles by various LLE and SPE methodologies.  Well characterized silver NPs, nano ZnP, and nano TiO2 will be used for extraction test because of their wide application and risk concern in the environment.  Liquid- liquid extraction (LLE) and solid-phase extraction (SPE) will be evaluated in terms of NP transfer efficiency and effect.  Experiments will assess recovery efficiency as a function of initial concentration and water matrix conditions (ultrapure water, Colorado River water, raw and treated wastewater).

In the shorter-term, extraction will enhance our ability to separate NPs from complex matrices, aiding in more detailed characterization (microscopy).  In the longer-term, these straight-forward extraction procedures could be coupled with inexpensive photonic based detection (UV/VIS or fluorescence) that leverage the surface plasmon properties of metallic NPs yielding robust methods to answer a question: are nanoparticles present in my water?  Coupled with other methodologies developed around single particle ICP-MS, the researchers expect to have the means to assess size and number of particles.

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FY 2012

Fate of Emerging Nanoparticle Contaminants during Aquifer Recharge with Treated Wastewater
Reyes Sierra and James Field (Link here for final report)

The growing application of engineered nanomaterials (particles less than 100 nm) in industrial processes and consumer products is leading to increasing emissions of nanoparticles (NPs) into the environment. Engineered NPs are contaminants of emerging concern. Studies conducted over the past 10 years have provided compelling evidence that a variety of engineered NPs can cause toxic effects to mammalian cells and other ecologically-important species. Effluent discharges from municipal and industrial wastewater treatment plants are important sources of NP emissions into the environment. In Arizona and other locations where artificial aquifer recharge with treated sewage is practiced, NPs carried by the wastewater could potentially be transported to groundwater used for drinking water supply. The purpose of this study is to determine the extent to which NPs in treated wastewater are attenuated by soil-aquifer treatment.

Does Increasing Solids Retention Time in the Wastewater Treatment Process Affect the Persistence of Antibiotic Resistance Genes?
Channah Rock and Leif Abrell (Link here for final report)

The conventional activated sludge (CAS) process exposes bacteria to both ideal growth conditions and relatively high concentrations of trace chemical pollutants. Though increased solids retention time (SRT) has been correlated with reductions in trace antibiotics, higher SRTs also provide prolonged exposure of bacteria to influent antibiotic levels, potentially increasing the development of antibiotic resistance (AR). The proposed study will assess the effects of varying SRT in full-scale activated sludge processes on the degradation of trace antibiotics and microbial selection for AR. A detailed assessment of rates in AR development and identification of bacterial processes contributing to AR will aid in technological advances to decrease the prevalence of AR in recycled water, alleviating environmental and public health concerns.

The proposed study will expand upon our preliminary results to provide a comprehensive evaluation of temporal variability in loadings of antibiotic concentrations, genes conferring AR to bacteria, and relative proportion of AR E. coli (Gram negative) and Enterococcus (Gram positive) in raw wastewater, activated sludge solids, and finished effluent.

Many investigators have recognized that wastewater treatment plants (WWTPs) are the principal recipients of enteric bacteria with multiple AR. However, few studies have examined the effects of different WWT strategies, including SRT optimization, on the prevalence of AR bacteria and/or AR genes in treated effluent.  Researchers have examined antibiotic degradation through WWT processes and have reported fairly high effluent concentrations in the μg L-1 range. Thus, though increasing SRTs will increase microbial diversity and achieve more extensive degradation of antibiotics, the combination of rapid bacterial growth and high antibiotic concentrations may provide ideal conditions for the development of AR. Additional processes (e.g., secondary clarification and tertiary filtration) may further increase the proportion of AR bacteria in effluent water.

Though the related work indicates the potential for development of AR with increasing SRT, to date this phenomenon has not been studied in controlled experiments. A mass balance of AR bacteria, genes coding resistance, and the total microbial population is necessary to determine relative changes during WWT processes. There is also a need to identify factors (e.g., antibiotic concentrations, SRT, disinfection processes) most significantly impacting levels of AR genes leaving WWTPs. To date, no standard methods for evaluation of AR genes have been established for wastewater. Preliminary work performed by our research team has focused on the development of statistically robust and reproducible laboratory methods proposed for this study.

By monitoring several locations within the WWT train, this study will allow the project team to characterize the impact of WWT on AR prevalence and the downstream impacts on end-users and the environment.  Ultimately, this study will provide utilities with new knowledge and tools for treatment process optimization and AR mitigation.

Toxicity of Emerging Contaminants in an Effluent Dependent Stream: the Role of Suspended Solids and Sediments
David Quanrud, Robert Arnold, Eduardo Saez and Shane Snyder (Link here for final report)

This project will evaluate the toxicity and endocrine disruption activity due to trace organic contaminants (TOrCs) associated with solid phase sources and sinks in an effluent dependent stream near Tucson, Arizona. The work builds on a recent study by the PIs that examined the transport and fate of a suite of TOrCs along a 22-mile reach of the Lower Santa Cruz River (SCR) extending downstream from two municipal wastewater treatment facilities in Pima County, Arizona. Project results will provide the first information concerning toxicity, including estrogenic, androgenic, and cytotoxicity measurements derived from solid-phase associated TOrCs in sources and sinks in the Lower SCR. Proposed work is motivated by the need to assess the transport and fate of TOrCs toxicity contribution provided by the solid-phase in an effluent dependent stream, along with the need to establish baseline data in the Santa Cruz River prior to the 2015 completion of upgraded treatment processes at the two Pima County municipal wastewater treatment facilities that will substantially improve effluent quality and river health.

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FY 2011

Characterization of Chelating Agents in Non-regulated Water Sources on Navajo Lands
Jani C. Ingram (Link here for final report)

The long-term research objective is to explore the relationship between health issues facing the Navajo Nation and chronic exposure to environmental uranium.  Uranium is an issue to the Navajo as over half of the uranium deposits in the United States are thought to be located in the Colorado Plateau region that includes the Navajo Lands.  Mine sites in the Cameron, Arizona area (southwestern area of the Navajo Reservation) are located close to the groundwater, making this an area of particular concern with regards to environmental uranium exposure.  Many homes on Navajo Lands have no electricity or running water.  It is estimated that 30-40% of the people living there rely on water hauled from unregulated wells for their consumption, household, and livestock needs.  A study by the Army Corps of Engineers, conducted in the late 1990s indicates that a number of these wells have uranium concentrations exceeding the Environmental Protection Agency’s drinking water standards.  This study will collect information to determine chelating agents present in unregulated water sources in the southwestern region of the Navajo Reservation that will lead to an understanding of the specific uranium species present in these waters.  Determination of the chemical species of uranium present, as it is the specific uranium species that dictates bioavailability.  Preliminary work has shown elevated levels of uranium in some of the unregulated water sources as well as variations in the basic water chremistry, even for wells in close proximity. The proposed approach for this research will involve collection of new water samples from wells near Cameron and Leupp, Arizona and characterize these samples for chelating agents.  Both inorganic anionic species as well as organic acid and amine compounds will be investigated.  The outcome of the project will provide the basis for determining bioavailability of uranium species which is critical to establishing the relationship between chronic exposure to environmental uranium and health effects.

Iodinated Disinfection By-product Formation from Water Reuse Practices
Shane Snyder (Link here for final report)

Expanding water demands in Arizona have put increasing pressure on city officials and scientists to develop innovative ideas to conserve dwindling water supplies.  Reclaimed water is a viable option. However, because of the high iodide concentration in wastewater, there are concerns that iodide wil not be removed during infiltration processes of groundwater recharge. The formation of iodinated disinfection by-products (DBPs) is a concern as iodinated DBPs are more toxic than their chlorinated or brominated analogues. While utilities emphasize water treatment for harmful biological entities, they sometimes inadvertently neglect changes in the natural organic matter (NOM) as a result of advanced treatment, disinfectant addition, and percolation through an aquifer.  When ozone, chlorine, or monochloramine are utilized to treat the water pumped from the aquifer, harmful disinfection by-products may form from reaction with NOM.  The purpose of this study is to determine if iodinated DBP formation will be more problematic during indirect water reuse due to advanced treatment.

Hydrology Versus Ecology: The Effectiveness of Constructed Wetlands for Wastewater Treatment in a Semi-arid Climate
Laura Turnbull, Daniel L. Childers and Benjamin P. Warner

Urbanization is a major driver of land-use change world-wide, including semi-arid areas of the southwestern USA, such as Phoenix, and is associated with an increase in the volume f municipal wastewater that is tied to the growing human population in the city.  Increasingly, wetlands are being constructed for tertiary wastewater treatment (i.e., nutrient removal from effluent). The use of constructed wetlands to improve the quality of wastewater effluent is relatively uncommon in arid ecosystems, however, and lessons learned from their use in more mesic settings may not translate well to dryland settings. The project addresses two pertinent questions about these aridland wetland treatment ecosystems: 1) Is wetland uptake and transformation of bioactive solutes [by plants and soil microbes] sufficient to counteract the effects of evapoconcentration to yield a net improvement in the quality of wastewater? 2) What are the relative effects of surface water evapoconcentration and soil evapoconcentration on the short and long-term ability of constructed wetlands to improve wastewater quality?

In semi-arid climates, high evaporation rates will concentrate solutes in the water column while high evapotranspiration rates (by wetland plants) will concentrate solutes in the soils of constructed wetlands.  The concentration of bioactive and non-bioactive solutes via these processes may exceed the ability of wetland biological processes to transform and remove bioactive solutes, thus reducing he treatment efficacy of the wetland.  These same processes will also concentrate solutes that are not biogeochemically active, particularly in soils, perhaps to the point that wetland plant function and thus treatment efficacy are adversely affected.  The extent to which evaporation and evapotranspiration concentrate solutes in wetland soils and water will vary based on factors that include the volume of wastewater discharge into the wetland, water residence time in the wetland, and time of the year.

The research is guided by four primary objectives: 1) to derive the hydrological budget for the Tres Rios constructed wetland ecosystem in Phoenix, AZ; 2) to derive solute budgets for the Tres Rios constructed wetland ecosystem, for bioactive and non-bioactive solutes; 3) to quantify the relative difference between evapoconcentration and wetland-assimilation of solutes; and 4) to quantify wetland ecosystem/biogeochemical function. The primary outcome of this research will be improved understanding of the efficacy of semi-arid constructed wetlands to improve water quality given the potentially confounding effects of evapoconcentration.  This improved understand will be of direct benefit to municipalities, which are required to meet water quality regulations set by the EPA.

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FY 2010

Perflouronated Compounds in Arizona Groundwater: Sources of Contamination, $10,061
David M. Quanrud, Leif M. Abrell, Robert G. Arnold and A. Eduardo Sáez, University of Arizona (Link here for final report)

This project is motivated by recent (2009) recognition that the trace organic contaminant perfluorooctane sulfonate (PFOS) is present in potable Arizona groundwater sources.  The Tucson Water Department detected PFOS in four groundwater production wells tested at concentrations ranging from 3.9 to 65 ng/L.  The Environmental Protection Agency (EPA) placed a health-based advisory guideline of 200 ng/L for PFOS, and added it to the Safe Drinking Water Act Contaminant Candidate List 3 in 2009.  PFOS and a related compound, perfluorooctanoic acid (PFOA), are persistent anthropogenic chemicals and suspected human carcinogens with half lives in the human body of 4-10 years. 

The project team will identify major sources of PFOS (and possibly PFOA) in groundwater in the Tucson Basin.  The project will support development of a broader effort to investigate the causes and means for preventing PFOS/PFOA contamination of groundwater in southwestern urban areas.  Measurements will yield data that informs the public about potable water quality characteristics and establishes whether these chemicals are attenuated during infiltration/percolation for groundwater replenishment.  The project represents an initial step toward a PFOS/PFOA management strategy serving all communities that rely heavily on groundwater to satisfy their potable water requirements.

Use of Fish as Integrative Samplers of Uranium and Lead Isotopes in the Colorado River, $9,900
Charles A. Sanchez, John T. Chesley and Peter N. Reinthal, University of Arizona

The Colorado River is contaminated with low levels of uranium and other metals.  Uranium is a health concern as a potential carcinogen and as a causal agent of kidney dysfunction. Renewed emphasis on alternative energy sources has revived interest in uranium mining on the Colorado Plateau. The Colorado River transects and drains the plateau, and is an important source of drinking and irrigation water.  This project will evaluate fish tissue as an integrative sampler of uranium, lead, and other metal contaminants in the Lower Colorado River region.

The project team will utilize high-precision analyses of radiogenic isotopes (lead, uranium, and strontium) to identify probable sources of these elements and, by proxy, other potential contaminants.  The data will be critical in the identification of the sources and pathways of these potential toxins in the food web—necessary information before any possible efforts can be made to reduce human exposure to these toxic elements.  The measurements will also provide a baseline should future exploration and mining activity enhance contamination or accidental release occurs.

Biochar soil amendments to increase the water holding capacity of sandy, arid soils, $10,000
Janick F. Artiola, Craig Rasmussen and Robert J. Freitas, University of Arizona (Link here for final report)

Arizona is entering into the second decade of a statewide drought, creating a critical need for water conservation efforts.  Agriculture in Arizona accounts for about 70% of the total state water use.  In addition, flood and furrow irrigation, known to have poor irrigation efficiencies (less than 50%), are the primary methods of water delivery to Arizona crops.  Arizona’s arid and semi-arid sandy soils do not retain water efficiently and require more irrigation than loamy soils to maintain adequate water supplies to crops. 
The primary goal of this project is to evaluate the water-related impacts of biochar applications on semi-arid irrigated soils common in the western U.S.  The project team will characterize the properties of biochar generated from the pyrolysis of crops, and evaluate changes in the physical properties of soils amended with biochar.   They hypothesize that biochar amendments, by improving the soil water-holding capacity, will at least initially improve irrigation efficiency, and increase plant growth and soil fertility.  In addition to the expected water conservation benefits, biochar applications also capture and store carbon from agricultural wastes that would otherwise contribute to carbon dioxide in the atmosphere.

Bioremediation of Uranium Plumes with Nano-Scale Zero Valent Iron, $10,977
James A. Field and Reyes Sierra, University of Arizona (Link here for final report)

Uranium is an important environmental contaminant impacting groundwater supplies in Arizona. The main sources are from uranium mine tailings, former uranium processing plants, and high natural background levels in areas of granite bedrock. In the environment, uranium generally occurs as hexavalent uranium (U6+) or tetravalent uranium (U4+). While U6+ is soluble and mobile, U4+ is highly insoluble and immobile. Therefore, reductive precipitation is an attractive approach to remove soluble uranium and remediate contaminated groundwater. Reduction of soluble U6+ can be catalyzed by chemical and microbial processes involving anaerobic bacteria. Typically organic substrates are utilized as the electron donors to drive biological uranium reduction.

Preliminary work by the project team has led to the enrichment of a novel uranium-reducing bacterial culture that is capable of utilizing zero-valent iron (ZVI) as an electron donor. The microbial culture greatly accelerates uranium reduction rates with ZVI by more than 20-fold in a sustained fashion. ZVI has some important advantages over alternative bioremediation strategies relying on organic electron donors. The ZVI could provide a long-term reservoir of slow-release electron equivalents as well as buffer against uranium re-oxidation.  
The project team will investigate the use of nano-sized ZVI as an electron donor for uranium-reducing microorganisms. Stabilized dispersions of nano-sized ZVI can be transported through porous media to facilitate in situ bioremediation of uranium-contaminated groundwater. This project is expected to lead to the development of a low-cost and low-maintenance method for in situ bioremediation that will generate insoluble uranium minerals that are stable against re-oxidation over prolonged time periods. Application of this technique could be expanded to the treatment of other toxic contaminants amenable to microbial reductive processes.

Sources and transport of nitrogen from sky-island ecosystems to groundwater basins, $10,000
Jennifer C. McIntosh, Armin Sorooshian and Kathleen Ann Lohse, University of Arizona (Link here for final report)

Atmospheric deposition of nitrogen (N) is a significant source of nutrients and contaminants to the land surface that can impact water quality, biodiversity, and ecosystem function.  Some of the highest rates of N deposition (primarily from anthropogenic activities) in the Western United States have been reported in semi-arid high elevation catchments adjacent to urban areas.  These mountain systems are important sources of recharge to adjacent alluvial groundwater basins.  Despite this, relatively little is known about the importance and magnitude of N inputs to sky-island systems and the transport of this atmospheric N through mountain catchments to groundwater basins. 

The project team will investigate the dominant sources of N input to the Santa Catalina Mountains, and evaluate the impact of climate and bedrock type on N reaction and transport.  They will measure the N-species composition (NO3, NO2, NH4, amines, organic-N) and stable isotopes (δ15N, δ18O, Δ17O) of atmospheric deposition, soil pore waters, and surface waters at multiple elevations in the Santa Catalina Mountains underlain by different bedrock types.  Results from this study will provide an increased understanding of the sources and amounts of nitrogen being deposited to sky-island ecosystems, and how nitrate is retained and/or transported from mountain catchments to adjacent groundwater basins. 

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FY 2009

Mercury Source Fingerprinting in Arid Lands Aquatic Ecosystems, $10,585
Paul T. Gremillion and Michael Ketterer, Northern Arizona University  (Link here for final report)

Mercury (Hg) is well known as a global pollutant; its main source is coal combustion, and deposition of Hg into aquatic systems and landscapes produces subtle neurotoxic effects in vertebrates at low concentrations.  Identifying Hg sources and unraveling their relative contribution to the Hg inventories in water, soil, sediment and biota remains an elusive problem despite four decades of environmental studies of Hg.  Recent research, however, indicates that Hg exhibits small variance in its stable isotope compositions; this variance is source-related and can potentially be used to understand sources, transport, and biogeochemical cycling of Hg.
This project is developing the capability of measuring small difference in mercury isotope compositions using an instrument available at NAU, known as a multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS).  The project team is applying developed Hg isotope measurement capabilities in a “proof of principle” fashion to two Arizona lakes exhibiting large recent increases in Hg deposition: Upper Lake Mary and Carnero Lake.

Transport and fate of Mercury and Other Metals in Tucson’s Urban Metropolitan Area: Role of watershed sources versus atmospheric deposition, $10,000
Kathleen A. Lohse, Paul D. Brooks and Jennifer McIntosh, University of Arizona  (Link here for final report)

In arid and semi-arid environmental, such as Arizona, runoff from urban areas is often actively managed as a part of storm water management but also as active and/or focused recharge to groundwater.  These activities result in a modified hydrologic template in which to understand water quality issues and raise concerns and questions about the tradeoffs between urban storm recharge and water quality.  There is growing attention on the adverse effects of mercury and other metals in the environment.  In particular, mercury is a persistent bioaccumulative toxin; it persists in the environment for long periods by cycling between the air, water and soil, and bioaccumulates in animal and plant tissues.  Preliminary data from a study conducted in the Tucson Basin shows high concentration of mercury (Hg) in the urban runoff across different urban sites, suggesting high deposition of Hg to the Tucson Basin.  However, questions remain about whether these samples are representative of storm events and seasonal loads and whether they are biased toward peak concentrations because they were a small subset of samples screened for Hg. 

This project is examining the impacts of urbanization on storm runoff and transport and fate of Hg and other metals in soils and to surface and ground waters.  Specifically, the project team is analyzing runoff and soil samples for Hg and other metals to verify patterns in runoff and explore the fate of Hg and other metals in soils.  The research results will be used to inform water managers about best management practices for storm water and the potential tradeoffs of enhanced recharge and increased loads of metals, particularly Hg, in the environment, surface waters and possibly ground waters

The Ecohydrology and Management of Pinus Ponderosa Forests in the Southwest, $9,986
Georg Koch and Lucy P. Mullins, Northern Arizona University  (Link here for final report)

Management initiatives and a changing climate present new challenges to understanding the role of southwestern forests in regional hydrology.  The headwaters of many watersheds in the Southwest consist of ponderosa pine-dominated forest uplands.  These uplands supply 70-90% of the annual streamflow in the region and therefore are an important link in watershed-atmosphere interactions.  Fire exclusion, heavy grazing, and high seedling recruitment over the last century have produced a forest structure characterized by high tree density and decreased herbaceous vegetation that is vulnerable to stand-replacing fires and subsequent soil erosion.  Thinning of ponderosa pine forests to reduce fire risk and restore ecological health is a major management initiative in the Southwest.  As current treatments around communities expand to larger scales, it becomes important to understand their effects on the components of the forest water balance.  

The project is examining how restoration thinning of ponderosa pine forests alters the components of evapotranspiration and sources of plant-transpired water.  The research addresses two major questions.

  • How are total evapotranspiration and its components altered by forest thinning treatments?  An eddy covariance system is measuring stand-level evapotranspiration at a control site and a thinned site.  Transpiration of individual trees of different size classes is determined separately using sapflow systems.  A combination of root trenching and soil lysimeters is used to estimate understory transpiration and surface evaporation.  The research hypothesis is that stand-level evapotranspiration will be greater in the thinned site due to increased water availability stimulating overstory tree transpiration, increased throughfall precipitation increasing herbaceous understory transpiration, and higher soil irradiation increasing soil evaporation.
  • How does stand density influence reliance on winter versus summer precipitation?  The project team is using hydrogen and oxygen stable isotope analysis of water to determine the local isotopic signatures of winter and summer precipitation inputs.  Because winter and summer precipitation events in the Southwest are dominated by different major air circulation systems, these two inputs have distinct isotopic signatures.  By measuring the isotopic signature of xylem sap in trees in control and thinned plots throughout the year, the project team will determine the relative reliance on water inputs received as winter snows versus summer rains.  The research hypothesis is that deeper soil waters are largely derived from winter precipitation, that winter soil water recharge is greatest in thinned stands, and that these water sources are primarily used by large trees. Thinned stands are hypothesized to be more reliant on winter precipitation due to less crown interception of snow inputs in combination with greater soil surface evaporation and herbaceous transpiration of ephemeral summer inputs.

Research results will be useful to water managers as insight into the impacts of an increasingly widespread management practice—restoration thinning—on ecosystem-scale water use and potential water yield of southwestern ponderosa pine forests.  In addition, information on the relative contributions of winter and summer precipitation inputs to tree transpiration will provide better understanding of how changing precipitation patterns might influence the productivity and water balance of these watersheds.

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FY 2008

Database Creation: Transboundary San Pedro Valley Aquifer, $10,000
Christopher A. Scott and Prescott Vandervoet, The University of Arizona  (Link here for final report)

Transboundary aquifers have been recognized by the U.S. Congress as a topic of interest as demonstrated by the passage of the Transboundary Aquifer Assessment Act of 2006. There exists no formal agreement for transboundary groundwater management between the U.S. and Mexico, yet communities from both nations depend on groundwater resources along the international border.
  
This project is compiling references and an annotated bibliography in database format for studies and other relevant information on the U.S.-Mexico transboundary San Pedro Aquifer.  The research team is undertaking comprehensive review using electronic searchable resources in an effort to compile all available materials for database inclusion. Governmental and non-governmental agencies in Arizona and Sonora were contacted and visited in an effort to collect all publicly available documents related to the transboundary San Pedro aquifer. The database will be easily accessible in electronic format to interested parties, agencies and organizations. 

Meta-Analysis of Rangeland Water-Yield Experiments for the Southwestern U.S., $10,000
Ed de Steiguer, The University of Arizona

An understanding of the effects of rangeland management activities on water yield is needed to assist in alleviating future water supply problems in Arizona.  Such understanding is possible through quantitative synthesis of existing rangeland water-yield research.  This project is applying statistical meta-analysis techniques that have been successful in other scientific disciplines to data from a large number (100 or more) watershed and rangeland water yield studies.  For the meta-analysis, the project team is creating a database that encodes these studies in terms of water yield and other resource outputs, experimental treatments, site-related variables and factors related to experimental design. The research is expected to provide technical coefficients that may be used in the development of decision support systems, optimization models and other tools for managers of semi-arid rangelands.

Lessons Learned: Extending the student/staff/faculty collaborative work model to the K-12 environment, $11,475
James Riley, The University of Arizona

Aridity is a fact of life in Arizona, yet current architectural design and landscape planning practices do not often account for water scarcity.  Rainwater is a dramatically underutilized resource, often seen as a nuisance because of a lack of knowledge about rainwater harvesting.
   
This project built on previous work teaching and demonstrating the techniques and benefits of rainwater harvesting on the campus of The University of Arizona, and extended the work into the community.  The collaborative approach that proved successful on the campus was used to involve the students, parents, faculty and staff at Brichta Elementary School in a rainwater harvesting project. In addition, the project team designed and implemented a rainwater harvesting system at Cochise Residence Hall to alleviate flooding problems on the grounds and adjacent neighborhood streets during heavy rains.  University students with experience on previous projects took leadership roles and gained useful practical experience. 

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FY 2007

Riparian Vegetation Response to Cessation of Groundwater Pumping, Lower San Pedro River, Arizona, $11,990
Julie Stromberg, Arizona State University

Hundreds of millions of dollars are being spent on the restoration of riparian ecosystems throughout the Southwest, often without sufficient scientific background to inform the efforts and ensure success. A novel restoration approach has been pioneered along the lower San Pedro River by the Nature Conservancy of Arizona and other collaborating groups. The lower San Pedro River Basin constitutes an important conservation landscape in southeastern Arizona, but, on some reaches, groundwater and surface water have declined below threshold levels needed to sustain cottonwood-willow forests and emergent wetlands. In some areas, tamarisk shrublands now dominate the floodplain, and the stream channels are wide and dry. The restoration approach involved purchase of farms that pumped large quantities of alluvial groundwater for crop irrigation, and subsequent reduction of pumping rates to negligible levels. The assumption is that the biotic components of the riparian ecosystems will establish on their own accord, following restoration of the hydrologic regime, thereby obviating the need for restoration plantings. There is a need to document the results of this hydrologic restoration strategy to assess its effectiveness on the San Pedro River as well as its applicability to other settings. In 2002 and 2003, the PI initiated baseline monitoring at seven restoration research sites and five reference sites on the Lower San Pedro. The PI is using research funds to allow for another year of data collection and for data analysis and synthesis. Data will be collected on metrics that should change rapidly in response to hydrologic restoration (herbaceous vegetation composition and diversity along the low-flow channel; annual growth increments of Fremont cottonwood and Goodding willow trees; woody tree seedling densities) and those that will change over a longer time span (woody vegetation density, composition, and age structure; floodplain patch structure; stream geomorphology). Results will provide managers with feedback about the effectiveness and time-span of this restoration approach. Another important benefit relates to informing approaches to the management of tamarisk, considered by some to be a problematic species. The PI expects that the hydrologic changes at the Lower San Pedro restoration sites will drive shifts in woody riparian plant composition from tamarisk to cottonwood/willow; if so, this study will provide a demonstration of an alternate approach to traditional invasive species management.

Compound Specific Isotope Determination of Biodegradative Activity in a Chlorinated Solvent Contaminated Aquifer System, $10,000
Mark Brusseau, University of Arizona

The sustainability of potable water supplies is a critical issue in Arizona, given the recent and ongoing population increase, economic expansion, and arid climate. A major component of water-resources sustainability is the contamination of vital groundwater supplies by hazardous chemicals. In Arizona, chlorinated solvents, including tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC), are the primary contaminant at 43 of 48 State and Federal Superfund sites. In aggregate, these sites comprise billions of liters of contaminated groundwater. Accordingly, these chlorinated-solvent contaminated sites pose a significant and long-term risk to the sustainability of potable groundwater in Arizona. Remediation of polluted soil and groundwater at chlorinated-solvent contaminated sites is therefore of immediate importance in protecting groundwater resources in the state of Arizona. Recently, monitored natural attenuation (MNA) has garnered increasing interest as a low cost, effective solution for remediation of contaminated groundwater. The successful application of MNA has the potential to save millions of dollars in remediation costs, as well as protecting the quality of critical groundwater resources. The goal of this project is to provide a simple and broadly applicable method to assess the feasibility of using MNA at chlorinated-solvent contaminated sites in Arizona. The availability of such a method would greatly enhance the ability to quickly and effectively evaluate sites, thereby providing valuable information for site owners and regulators. One potential low-cost, rapid method for directly identifying the presence of biological natural attenuation processes is Compound Specific Isotope (CSI) analysis. This method takes advantage of the natural fractionation of carbon isotopes during biological transformation. The specific objective of this project is the development of CSI analysis methods that will permit rapid and accurate screening of the suitability of Arizona sites for MNA.

Sources of Nitrate in Groundwaters of the Tucson Basin, $9,121
Thomas Meixner, University of Arizona

While it is generally assumed that high nitrate levels in groundwater are associated with human activities (irrigation, fertilizer use, feed lots, septic tanks and municipal sewage), in arid states like Arizona this is not always the case. Often times elevated nitrate in groundwater can be due purely to natural processes, a combination of natural and human processes, or neglected human impacts on the environment (e.g. atmospheric nitrogen deposition). Since understanding the mechanism of contamination is the first step to understanding how to solve any contamination problem, significant efforts have been expended in the past to understand the sources and mechanisms of nitrate contamination in groundwater. This project will utilize two differing flow path transects within the Tucson basin to investigate the sources of nitrate to groundwater in the Tucson basin. The research has three objectives 1) Use geochemical and isotopic techniques to quantify groundwater sources. 2) Quantify nitrate isotopes to connect groundwater nitrate to various nitrate sources and sinks. 3) Develop conceptual model of nitrate sources and processes along the two flowpaths using results of first two objectives and existing nitrate and groundwater geochemical data. To achieve these objectives we will collect water along two flowpath using Tucson Water wells. The first transect will traverse the Tanque Verde and Rillito creek drainages and look at an increase in nitrate along this transect. The second Set of wells will be across the Santa Cruz river in the neighborhood of the Sweetwater recharge facility where there are high nitrate concentrations near the river and lower nitrate concentrations farther from the river. The first transect allows us to focus on the sources of water and nitrate in the groundwater system while the second transect allows us to investigate the relative importance of denitrification or mixing around the sewage recharge facility. Samples from each transect will be analyzed for major geochemical composition and sulfur, water and nitrate isotopes. These suites of geochemical and isotopic analyses should allow us to partition the reasons for nitrate variability in Tucson groundwater between water sources, biogeochemical sinks and mixing.

Geospatial Analysis of Urban Thermal Gradients: Application to Tucson Arizona's Projected Water Demand, $12,000
Christopher Scott, University of Arizona

The water budgets of urban and urbanizing areas are hypothetically affected in a significant manner by rising regional temperatures, which have been demonstrated to result from urban heat island effects and broader warming across the Southwest. Both urban and regional warming are projected to increase even further with city growth and climate change. It is therefore important to understand the relation between urban water demand and spatial and temporal temperature trends in urban [-izing] areas. This project proposes to conduct geospatial analysis of Landsat TM thermal infrared data (x, y, t) and DEM (z), thereby generating surfaces of heat source-sink gradients, signatures of the persistence of thermal threshold exceedances, and identifying features or episodes of thermal reset, e.g., [micro-] topographic cooling corridors, vegetation buffers, or precipitation events. For the Tucson Arizona basin, thermal gradients will be mapped over the period 1984 to the present and spatially correlated to urban growth, urban heat island effects, and water supply. Indoor vs. outdoor water use will be estimated from supply data using temporal disaggregation techniques. Results will be assessed with reference to the growth and water demand scenarios in the Tucson Water Plan 2000-2050. The resulting thermal surfaces and persistence datasets are also expected to be of utility to planners, urban landscape ecologists, and the research community. The project will a) produce a manuscript for submission to a peer-reviewed journal, b) result in multiple proposals for continued investigation targeted particularly at EPAs Science to Achieve Results (STAR) and NSF's Coupled Natural-Human Systems (CNH) programs, and c) support the teams efforts to strengthen the University of Arizona's capability and expertise in the area of human-environmental feedbacks in the rapidly urbanizing Sonoran Desert Ecoregion.

Modification of Conventional Wastewater Treatment Processes for Estrogen Removal, $11,454
David Quanrud, University of Arizona

Meeting regional water demands without long-term reliance on groundwater mining will depend on wastewater renovation and reuse. By 2025, it will be necessary to reclaim and reuse approximately 100,000 AFY of wastewater in the Tucson Active Management Area. Acceptable uses and use-dependent treatment requirements remain to be established. That is, growth cannot be sustained without considering water resources of lower water quality. Municipal wastewater is the only resource of that kind that is present in abundance in every high-growth region including Tucson or, if magnified, the Tucson/Phoenix corridor. Observations during the last decade or so related to residual trace organics in conventionally treated wastewater suggest that advanced treatments are requisite to the kinds of reuse applications that are now being considered. Among the myriad trace organic contaminants in wastewater effluent, hormones and hormone mimics may be of greatest concern to human and environmental health. Estrogen and estrogen mimics are among the most relevant sources of concern in waters destined for reuse. Wastewater reclamation and reuse will be a major part of both water supply and wastewater treatment planning. The fate of trace organics during wastewater treatment or, from another perspective, facilities design/operation for control of trace organics should be an important factor in facilities planning. The project is designed to provide data in that critical area. The project is a full-scale investigation of wastewater treatment processes that are likely to reduce significantly the activities of estrogenic and androgenic compounds in wastewater. The processes of interest are (i) membrane biological treatment and (ii) activated sludge treatment.

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FY 2006

Student Training, Research, and Participation in Water Harvesting Design and Implementation, $11,624 
J. Riley, University of Arizona

This project will develop the means to apply water harvesting techniques at the University of Arizona and educate university students about water harvesting while addressing significant surface water flow concerns on the university campus. The project will work initially with the Surface Water Working Group in solving a flooding problem near the McKale Memorial Center sports complex by incorporating appropriate water harvesting interventions. Students will work closely with principal investigators, consultants, and university staff to study existing problems and design and implement innovative water harvesting solutions, possibly including infiltration basins, swale and berm contouring, mulches, walk way redesign, and native plant landscaping.

Perfluorinated Chemicals in Municipal Wastewater Treatment Plants in Arizona, $11995
R. Sierra, University of Arizona

There is presently no data on the occurrence of PFCs in wastewater treatment plants in Arizona, yet PFCs are extensively used in the growing semiconductor industry sector in the State and in a wide variety of other industrial, commercial and consumer applications. This study will develop novel methods (F-NMR, HPLC/MS/MS) to detect and quantify PFCs in municipal wastewater and in sewage sludge, and then apply these methods to conduct a preliminary evaluation of PFCs in selected municipal wastewater treatment plants in Arizona. Partitioning of PFCs into biosolids will also be investigated under well-defined laboratory conditions.

An Investigation in the Upper Santa Cruz River 2005 Riparian Vegetation Die-off, $11,940
B. Orr, University of Arizona

Since approximately March of 2005, a significant fraction of the riparian trees and upland mesquite bosques along a 10-mile stretch of the Upper Santa Cruz River have been dying for unknown reasons. The die-off is an indication that the balance of the ecosystem has recently shifted, and the future direction of water management will need to incorporate this shift into decision-making processes. As a preliminary step in this direction, this project will integrate geospatial and temporal analysis of historical photography and satellite imagery, basic water quality analysis and tree pathology testing to understand the historical context and potential causal factors which may provide insight into this sudden mortality.

Advanced Biotechnology for Recycling Dairy Wastewater, $12,600 
Q. Hu, Arizona State University

The goal of this proposed research project is to develop an advanced microalgal biotechnology that can be integrated into existing nutrient management practices to treat dairy wastewater and to bring it to below USEPA limits for reuse on the farm. The biological principle behind this technology is that photosynthetic microalgae use solar energy to rapidly assimilate nitrogen and phosphorous. A cost-effective photobioreactor will further enhance this biological process and make it economically feasible and environmentally sound. The major objectives of the proposed research are to: 1) evaluate maximum sustainable nutrient uptake potential by isolated microalgal strains growing in dairy wastewater; and 2) construct a novel large-scale column photobioreactor and demonstrate its effectiveness in removing nutrients from wastewater so that the treated water can be recycled. 

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FY 2005

Salt River Riparian Ecosystem Restoration, $8,869 
J. Stromberg, Arizona State University

This study will monitor the vegetation and surface water in several reaches of the Salt River in the Phoenix metropolitan area prior to implementation of several large-scale restoration actions. The monitoring will provide valuable pre-restoration information to restoration designers, as well as early-stage input on success or failure of the restoration measures.

Big ChinoBasin 3-D Digital Hydrogeologic Framework Model, $9,000 
A. Springer, Northern Arizona University

This study will construct a Digital Hydrogeologic Framework Model (DHFM) to characterize the subsurface geology of Big Chino Basin, located at the headwaters of the Verde River. The DHFM will serve as a tool for understanding and conveying the complex subsurface hydrology of the region to water managers and others. The model will also be utilized by the USGS Water Division in Tucson to construct a Groundwater Flow Model for the region.

Preliminary Evaluation of Perchlorate Contamination of Ground Water in The Lower Colorado River Region, $11,949
C. Sanchez, University of Arizona

This study will evaluate groundwater in the Yuma area of the lower Colorado River region for perchlorate contamination. Little information presently exists on the extent that seepage from surface water conveyance systems and irrigation drainage has contaminated groundwater sources in the Yuma area.

An Outdoor Multi-Stage, Continuous-Flow Photobioreator for Bioremediation of Nitrate Contaminated Groundwater, $11,740
Q. Hu, and M. Sommerfield, Arizona State University

This study will design, fabricate and operate a Multiple-stage, Continuous-Flow Photobioreactor (MCP) to remove nitrate from groundwater in a cost-effective and environmentally-friendly way. The photobioreactor will utilize a microalgal species that can thrive in groundwater and take up nitrate at high rates. The algal biomass produced as a by-product from the photobioreactor can be used as an organic fertilizer or animal feed.

Treatment of Nitrate in Groundwater with Autotrophic Bioreactors, $10,000
R. Sierra and J. Field, University of Arizona

The goal of this project is to evaluate the feasibility of a low cost, low maintenance packed-bed bioreactor utilizing insoluble sulfur as the electron donor for denitrification. Additionally, the project investigates the role of naturally occurring groundwater alkalinity in fulfilling neutralization and inorganic carbon requirements of the process. The outcome of the project will be a simple design concept that can be utilized by small water utilities for the affordable and reliable treatment of nitrate in groundwater.

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FY 2004

Controlling Salt Accumulation to Enhance Sustainability of Subsurface Drip Irrigation, $11,993
T. Thompson, A. Warrick (UA)

This project provides a framework for evaluating the effects of Subsurface Drip Irrigation (SDI) system architecture, soil characteristics, and environmental conditions on the accumulation of salts in soils irrigated by DSI. Results from the project will be used to calibrate a model to be used to predict salt accumulation with SDI, allowing the optimization of management practices to prevent excessive salt accumulation.

Measurement of Estrogenic Activity in Sludges and Biosolids, $12,305
D. Quarund, W. Ella, R. Arnold, J. Chorover (UA)

The study provides data on (1) procedures for recovery of sorbed hydrophobic estrogenic compounds in soil or biosolids, and (2) total estrogenic activity derived from wastewater treatment and changes in estrogenic activity during anaerobic digestion, dewatering and composting. The project offers method development for extraction of estrogenic activity from solids and baseline information regarding their presence in sludges and biosolids. Project results provide utilities and government agencies with a basis for rational decisions relative to the need for and design of follow-on investigations in this area of inquiry.

Permeable Reactive Biobarriers For The Containment and Remediation of Acid Mine Drainage, $11,678
J. Field, R. Sierra (UA)

This project examines the potential of permeable reactive biobarriers (PRBs) to prevent the spread of acidity, sulfates, and metals from acid mine drainage (AMD) to surface or groundwater. In this project, the activity of sulfate reducing bacteria is promoted in order to convert sulfate to sulfide, which will precipitate a wide spectrum of metal and metalloid contaminants as sulfide minerals. The research specifically examines the applicability of utilizing slow-release electron donating substrates to support microbial activity over extended periods of time. The project will result in the development of a concept for the low-cost containment of AMD. Successful application of this technology will benefit rural citizens living in mining-impacted areas by protecting precious water resources.

Estimation Of Acute Upper Lethal Water Temperature Tolerances Of Native Arizona Fishes, $8,100
S. Bonar (UA)

This research provides the upper temperature tolerances of spikedace Meda fulgida, loachminnow Tiaroga cobitis, longfin dace Agosia chrysogaster, speckled dace Rhinichthys osculus , Gila topminnow Poeciliopsis occidentalis occidentalis, Gila chub Gila intermedia, roundtail chub Gila robusta, Yaqui topminnow Poeciliopsis occidentalis sonoriensis, Sonoran sucker Catostomus insignis, and desert sucker Catostomus clarki. . Basic data on the temperature tolerances of a suite of Arizona fishes will be valuable to fisheries managers, hydrologists, and biologists. Hydrologic modeling and other information can often predict what effect a particular land use practice, such as riparian cover removal or water withdrawal will have on the water temperatures of a river. This information is useful for aquatic biologists and managers to help predict how changes in water temperatures might affect the availability of habitat for the existing native fish community of a river.

Impact Of Drought On Management Of Salt Sensitive Plants With Reclaimed Water, $7,000
U. Schuch (UA)

This study develops management strategies on how to manage irrigation of salt sensitive plants with reclaimed water and subjected to frequent drought stress while maintaining functional and aesthetic value of the plants. Six species were grown for 12 weeks with reclaimed or potable water outdoors to expose plants to maximum evaporative demand and heat stress. At the end of the growing period, plants were subjected to increasing levels of water stress alleviated by periods of leaching to determine their response.

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FY 2003

Attenuation of Estrogenic Activity in Reclaimed Water and Stormwater During Impoundment in Natural Systems, $12,214
M. Karpisack, W. Ella, D. Quanrud, C. Gerba, R. Arnold, K. Lansey (UA)

This work examines the efficacy of constructed wetlands as a polishing technique for removal of estrogenic activity in wastewater effluent and stormwater runoff. The project provides data on

Site-specific data relevant to the fate of human estrogen and estrogen mimics during effluent polishing operations at the Sweetwater wetlands and Kino wetlands; data on fate of estrogenic activity as function of wetland detention time; Information leading to consensus regarding use-dependent treatment requirements for water reuse application; and, site-specific data on fate of estrogenic activity in stormwater during wetland treatment at the Kino wetlands.

Impacts of Conservation Measures and Alternative Water Supplies on Groundwater, $9,677
A. Springer (NAU)

This project provides a better understanding of the impacts of various conservation measures and alternative water supplies on the recharge to aquifers and volumes of water stored in aquifers. The study developed generic groundwater models to understand the impacts of: different conservation measures on groundwater budgets; different alternative water supplies on groundwater budgets; conservation measures on a calibrated groundwater flow model of a specific aquifer, and; alternative water supplies on a calibrated groundwater flow model of a specific aquifer.

Selection of High Performance Microalgae for Bioremediation of Nitrate-Contaminated Groundwater, $10,550
Q. Hu (ASU)

This project is a step in the development a large-scale engineered microalgal nitrate-striping system for groundwater nitrate removal. Nitrate can be effectively taken up by photosynthetic cyanobacteria and microalgae, which require mostly nitrate, inorganic carbon, and light for growth, t he use of photosynthetic organisms minimizes the need of chemicals and energy from fossil fuels for nitrate removal. An engineered microalgal bioreactor may sustain continuous cultures of a high cell density of desirable organisms, large quantities of raw water can be stripped of nitrate within a short period of time. An engineered microalgal nitrate-striping biotechnology could be a long-term, environmentally safe, and cost-effective approach for large-scale nitrate removal from contaminated groundwater in Arizona . This project specifically isolates and screens a large number of microalgal species collected from major water bodies in the metro Phoenix area, focused on identifying desirable strains that can rapidly assimilate nitrate from groundwater efficiently and effectively.

Integrating Research and Education to Assist Watershed Initiatives: A Survey of Three Arizona Watershed Organizations, $12,451
R. Varady, J. de Steiguer, D. Young, A. Browning-Aiken, R. Meredith (UA)

This study of watershed organizations concludes that collaboration is a process that requires gaining trust among members, agreeing on the nature of the problem(s), having the capacity to bring resources (technology, science, funding, political and economic support) to the table, and a basic knowledge about basin hydrology and water laws. Much of this process revolves around obtaining "collaborative know-how" or learning how to "cooperate and work with organizations that have different values, procedures and processes." The research objective of "Integrating Research and Education to Assist Watershed Initiatives" was to create a pilot survey instrument to assess watershed organizations in Arizona and to test that instrument in the three watersheds. The three Arizona watersheds tested were the Upper San Pedro, Verde, and Santa Cruz River Basins.

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FY 2002

Microbial Mediated Mobilization of Arsenic from Drinking Water Treatment Residuals in Landfills, $11,996
J. A. Field, A. J. Gandolfi, R. Sierra-Alvarez (UA)

Impacts of Ungulates on Vegetation in Proximity to Water Catchments, $11,325
P. R. Krausman and J. P. Marshal. (UA)

Evaluating the Irrigation Efficiencies and Turf/Landscape Maintenance Practices on the Campus of Northern Arizona University, $12,000
D. Slack, P. Waller, R. Bowen. (UA)

The Effect of Mycorrhizae on Competitive Ability and Drought Tolerance of Cottonwood (Populus fremontii) and Saltcedar (Tamarix ramosissima), $9,017
J. Stromberg, J. Stutz, V. Beauchamp. (ASU)

Regional Aquifers Characterization Through Spring Discharge Analysis, $11,865
A. Springer, S. Flora. (NAU)

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FY 2001

Salt Tolerance of Southwestern Perennial Ornamentals, $12,000
U. K. Schuch. (UA)

Develop Arid West Bioassay Capability for Modification of Water Quality Criteria & Effluent Testing, $11,276
D. J. Baumgartner, K.M. Fitszimmons, S.G. Nelson. (UA)

New Approaches To Addressing Tribal Water Rights, $12,000
B. G. Colby. (UA)

Measurement of Estrogenic Activity and Volume Contribution of Treated Wastewater In Water From Wells Along The Santa Cruz River, $12,700
M. M. Karpiscak, R. G. Arnold, C. P. Gerba, K. E. Lansey, W. P. Ela. (UA)

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FY 2000

Ponderosa Pine Water Balance at Hart Prairie: Role of Herbaceous Transpiration, $10,375
Abe Springer and Tom Kolb. (NAU)

Field Studies of Virus Transport Through Unsaturated alluvium and Fractured Rock, $11,858
W. J. Blanford; M. L. Brusseau; C. P. Gerba; T. C. Jim Yeh. (UA)

Multiobjective Optimization of a Public Supply Wellfield Using an Artificial Neural Network and Non-Linear Programming, $8,000
D. Davis, F. Szidarovszky, E. A. Coppola Jr. (UA)

Using Ground Water Penetrating Radar and Tensiometry to Estimate Recharge from the Rillito Creek, $12,000
P. Ferre (UA)

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