University of California

Presentations 2016

Detailed Report by Session Themes : Emerging Contaminants

Burow, Karen

Presentation Title
Decadal-scale changes in uranium and bicarbonate concentrations in groundwater in the U.S.: Effects of irrigation on the mobilization of uranium
Institution
U.S. Geological Survey
Presentation
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Abstract
Uranium has been shown to be mobilized by downward-moving irrigation water in the eastern San Joaquin Valley (SJV) of California (Jurgens and others, 2010). Development of the landscape for crop production has caused increased bicarbonate concentrations in shallow groundwater, and increased rates of recharge. The downward moving, bicarbonate-enriched groundwater mobilizes naturally-occurring uranium in the sediments. Consequently, uranium concentrations at depth are increasing with time, and are affecting wells used for drinking water. It is hypothesized that the process observed in the SJV will be operative in other arid and semi-arid areas of the U.S., but not in humid areas. Water-quality data from 1,105 wells from across the U.S. were compiled from the U.S. Geological Survey National Water-Quality Assessment project. Most of the wells were first sampled during 1993-2002 and then subsequently sampled during 2001-2012. Some wells used in the analysis were sampled in 2001-2005 and subsequently sampled during 2012-2014. Uranium concentrations in groundwater were highest in the arid to semi-arid climate zones in the western U.S, where uranium in surficial sediments and rocks are abundant. Sixty-four wells (6 percent) sampled in the second decade were above the U.S. EPA MCL of 30 ug/L; all but one are in the arid west. Areas with low uranium concentrations in surficial rocks and sediments such as the Coastal Plain in the southeastern U.S., the upper Midwest, and northeast parts of Oregon and Washington generally have low concentrations of uranium in groundwater. Large uranium and bicarbonate increases (differences are greater than the uncertainty in concentrations) occur in 109 wells between decade 1 and decade 2. Similarly, large uranium and bicarbonate decreases occur in 76 wells between decade 1 and decade 2. Significantly more wells are concordant (uranium and bicarbonate are both going the same direction) than discordant (uranium and bicarbonate are going opposite directions) (p<0.001; Chi-square test). The largest percent difference in uranium concentrations occur in wells where uranium is increasing and bicarbonate is also increasing, These large differences occur mostly in the arid to semi-arid western U.S., consistent with the process of the mobilization of uranium by the increasing bicarbonate concentrations in irrigated areas. Uranium was not detected in either decade in 53 percent of the wells in the dataset. Ninety percent of these wells with no detections occur in the humid or dry sub-humid climate zones of the eastern U.S. Speciation calculations on water from wells with a detection in at least one decade indicate that the uranium in groundwater occurs predominantly in the form of ternary complexes of uranyl carbonate with calcium (94 percent of samples). The concordant change in uranium and bicarbonate concentrations and the dominantly neutral pH ranges (6-8) are consistent with the speciation calculations, and consistent with the processes found by Jurgens and others (2010). References: Jurgens, B.C., Fram, M.S., Belitz, Kenneth, Burow, K.R., and Landon, M.K., 2010, Effects of groundwater development on uranium: Central Valley, California, USA: Ground Water, v. 48, no. 6, pp. 913-928

Chaves, Henrique

Presentation Title
An Index for Evaluating the Risk of Water Contamination by Pesticides: Development and Validation
Institution
EFL - University of Brasilia
Presentation
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chaves2
Abstract
Since the surface and groundwater are strategic and vulnerable environmental compartments, their contamination by pesticides could cause significant damage to man and the ecosystems. The objective of this study was to develop a simple and robust index (ARCA) to estimate the risk of water contamination by pesticides, in different agronomic and environmental settings, and to validate it at the field level. The risk of contamination (R) in the ARCA index is the product of the environmental vulnerability of the site (V) and the contamination potential of the pesticides (Pc). The vulnerability is the product of the clay content of the soil, the distance to the nearest stream, and the type of soil management. The contamination potential is given by the product of the pesticide mobility, persistence, and its toxicity to man and fish. An experiment was carried in a soybean field in Brasilia, Brazil, to validate the model. In that field study, the glyphosate concentration on the slope runoff and in the leachate were compared with the pesticide behavior predicted by the index. Furthermore, the glyphosate concentrations in the river downstream were compared with the risk calculated by the index. In both cases, the ARCA index correctly predicted the values and trends obtained in the field study. However, considering the limited scope of the field experiment, it is recommended that additional studies be carried, to better assess the validity of the ARCA index.

Lapen, David

Presentation Title
Veterinary antibiotic, pathogen, and antibiotic resistance genes in tile effluent and shallow groundwater following manure application: Influence of controlled tile drainage
Institution
Agriculture and Agri-Food Canada, Ottawa
Presentation
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lapen1
Abstract
Chlortetracycline, tylosin, and tetracycline (plus transformation products), and DNA-based Campylobacter spp. and tetracycline antibiotic resistant gene (tet(O)) in tile drainage and shallow (1.2 to 2m depth) groundwater were examined following a autumn liquid swine manure application on clay loam plots under controlled (CD) and free (FD) tile drainage. The chlorotetracyline transformation product iso-chlortetracycline was the most persistent veterinary antibiotic (VA) analyte in water. Rhodamine WT (RWT) tracer was mixed with manure and monitored in tile and groundwater. RWT and VA concentrations were strongly correlated in water. While CD reduced tile discharge and eliminated application-induced VA movement to tile drains, total VA mass loading from tile was not affected significantly by CD. At CD and FD test plots, the biggest ‘flush’ of VA mass and highest VA concentrations occurred in response to precipitation received 2d after application, which strongly influenced the flow abatement capacity of CD on account of highly elevated water levels in field initiating overflow drainage for CD systems (when water level <0.3m below surface). VA concentrations in tile and groundwater became very low within 10 d following application. Both Campylobacter spp. and tet(O) genes were present in groundwater and soil prior to application, and increased thereafter. Unlike the VA compounds, Campylobacter spp. and tet(O) gene loads in tile drainage were reduced by CD, in relation to FD; which was consistent with how CD mitigated loading of fecal indicator bacteria over the study period.

Mas-Pla, Josep

Presentation Title
Exploring the origin and migration of antibiotics in aquifers to evaluate their impact on groundwater resources quality
Institution
Catalan Institute for Water Research & University of Girona
Presentation
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maspa2
Abstract
Emergent organic contaminants (EOCs), especially veterinary antibiotics related to farming activities, are of great concern on groundwater quality. They presence affect microbial communities inhabiting aquifers, shaping their composition and stimulating the spread of antibiotic resistance among community members.This study focuses on the behavior of antibiotics in groundwater in an agricultural area. Nevertheless, aquifer interaction with stream recharge, fertilization and infiltration of treated wastewater creates a mixture of both domestic and veterinary antibiotics. As reactive compounds, their migration is controlled by soil processes, mainly adsorption. Their origin and fate in the subsurface are key factors for designing mitigation and prevention strategies; not only in terms of water quality, but also in relation to the spread of antibiotic resistance in groundwater microbiota.A field study is being conducted in a fluvio-deltaic aquifer (Fluvià River, NE Catalonia). Samples collected during spring 2015 consist of 47 groundwater, 7 surface water, and 2 wastewater treatment plant effluents. We measured their hydrochemistry, including isotopic data for water and nitrate molecules. Antibiotics were pre-concentrated by solid phase extraction and quantified using an optimized protocol based on liquid chromatography tandem mass spectrometry (UHPLC–QqLIT). The phylogenetic composition of groundwater bacterial communities was analyzed by high throughput sequencing. Concentration of antibiotic resistance genes (ARGs) were determined using qPCR and specific primers for target genes (qnrS, ermB, tetW, sul-I and blaTEM). Also, copy numbers of the Class I integron integrase gene (intl1) was analyzed as a proxy for anthropogenic pollution. Copy numbers of bacterial 16S rRNA gene were also determined to estimate bacterial abundance and to normalize ARG data. Seasonal campaigns are being conducted in 8 representative wells.Average nitrate concentration in groundwater and surface water was 42.4 mg/L and 7.3 mg/L. Up to 21% of the groundwater samples had nitrate concentrations above 50 mg/L. Antibiotics found in groundwater were fluoroquinolones (Ciprofloxacin, Danofloxacin, Enrofloxacin, Norfloxacin, Ofloxacin, and Orbifloxacin), macrolides (Azithromycin), quinolones (Flumequine, Oxolinic Acid, and Pipemidic Acid) and sulfonamides (Sulfamethoxazole). Sulfamethoxazole was detected in 80% of the samples with a mean concentration of 6.1 ng/L, with a highest concentration of 28.6 ng/L. Ciprofloxacin was measured in 45% of the samples, with mean concentration of 77.2 ng/L and highest concentration of 298.3 ng/L. In turn, only fluoroquinolones (Ciprofloxacin, Enrofloxacin, Norfloxacin and Orbifloxacin) and sulfonamides (Sulfamethoxazole) were detected in surface water samples. Most detected antibiotics were Sulfamethoxazole and Ciprofloxacin (mean concentrations of 8.5 and 211.8 ng/L; highest concentrations of 211.8 and 287.7 ng/L, respectively), similarly to the results obtained for groundwater. Enrofloxacin was also quantified in 2 samples with relatively high concentration (290 ng/L). Results showed presence of all analyzed ARGs, and allowed to distinguish the origin of the antibiotics, whether veterinary or clinical. In particular, sul-I and intI1 were the most abundant ARGs in all samples (averages of 1.10x105 and 1.63x104, respectively). In summary, despite the widespread occurrence of veterinary antibiotics detected in the Baix Fluvià aquifer, the stream influence may also contribute to the groundwater antibiotic load with antibiotics used in human health. Despite the diffuse origin of most veterinary, no continuous spatial concentration trend has been observed in the aquifer. This suggests that soil adsorption and dilution may locally alter the antibiotic composition of groundwater. Some wells showed a high relative abundance of several ARGs highlighting that antibiotic pollution maintain a reservoir of resistance in groundwater that may eventually pose a risk for human health. This field study points out the multifaceted aspects of antibiotic pollution that finally control the impact on groundwater quality and its management.Acknowledgements: This study is part of the PERSIST project funded by the EU Water JPI (JPIW2013-118).

Sutton, Nora

Presentation Title
LINKING MICROBIAL COMMUNITY COMPOSITION TO IN SITU NATURAL ATTENUATION OF EMERGING CONTAMINANTS
Institution
Wageningen University
Presentation
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Abstract
The presence of low concentrations of hydrophilic, organic emerging contaminants pose a threat to the quality of groundwater resources utilized for drinking water purposes. While extensive monitoring of the chemical composition of groundwater has revealed the presence of a variety of organic contaminants, relatively little is known about the natural attenuation of these compounds in situ. Biodegradation has been shown to be an effective transformation processes for a wide variety of emerging contaminants. However, it remains difficult to translate these results to in situ degradation in (usually) oxygen-depleted, oligotrophic groundwater with heterogeneous distribution and low emerging contaminant concentrations. Research was performed to gain insight on biodegradation of emerging contaminants in groundwater by examining microbial community composition and geochemistry. Groundwater samples collected at discreet depths ranging from 12 to 55 m in two monitoring wells were chemically analyzed to determine groundwater chemistry and contaminant distribution. Additionally, samples were analysyed for microbial community composition by sequencing of a PCR-amplified fragment of the 16SrRNA gene. Results indicate a distinct difference in both groundwater composition and microbial community diversity between wells and in depth. The groundwater profiles demonstrate the heterogeneity of subsurface geochemistry, highlighting the fact that contaminated water travels through a variety of environments between its source and extraction for drinking water. Differences in the abundance of electron acceptors, concentration of nutrients, and presence of electron donors, such as DOC, in addition to emerging contaminants play an important role in microbial community composition and in situ biodegradation. Redundancy analysis of groundwater geochemical characteristics, emerging contaminant concentrations, and microbial community diversity indicates a negative correlation between the availability of electron acceptors (nitrate and sulfate) and the presence of contaminants. In contrast, dissolved organic carbon correlated with the presence of organic contaminants. Overall, the results presented here are a first step towards better understanding the geochemical and microbiological factors affecting in situ emerging contaminant biodegradation.

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