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Kim H, Voutchkova DD, Johnsen AR, Albers CN, Thorling L, Hansen B. National Assessment of Long-Term Groundwater Response to Pesticide Regulation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14387-14396. [PMID: 36162811 PMCID: PMC9583610 DOI: 10.1021/acs.est.2c02261] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 05/24/2023]
Abstract
Quantitative assessments of long-term, national-scale responses of groundwater quality to pesticide applications are essential to evaluate the effectiveness of pesticide regulations. Retardation time in the unsaturated zone (Ru) was estimated for selected herbicides (atrazine, simazine, and bentazon) and degradation products (desethylatrazine (DEA), desisopropylatrazine (DIA), desethyldesisopropylatrazine (DEIA), and BAM) using a multidecadal time series of groundwater solute chemistry (∼30 years) and herbicide sales (∼60 years). The sampling year was converted to recharge year using groundwater age. Then, Ru was estimated using a cross-correlation analysis of the sales and the frequencies of detection and exceedance of the drinking water standard (0.1 μg/L) of each selected compound. The results showed no retardation of the highly polar, thus mobile, parent compounds (i.e., bentazon), while Ru of the moderately polar compounds (i.e., simazine) was about a decade, and their degradation products showed even longer Ru. The temporal trends of the degradation products did not mirror those of the sale data, which were attributed to the various sale periods of the parent compounds, sorption of the parent compounds, and complex degradation pathways. The longer Ru in clayey/organic sediments than in sandy sediments further confirmed the role of soil-specific retardation as an important factor to consider in groundwater protection.
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Affiliation(s)
- Hyojin Kim
- Department
of Quaternary and Groundwater Mapping, Geological
Survey of Denmark and Greenland (GEUS), Universitetsbyen 81, Building 1782, 8000 Aarhus, Denmark
| | - Denitza D. Voutchkova
- Department
of Quaternary and Groundwater Mapping, Geological
Survey of Denmark and Greenland (GEUS), Universitetsbyen 81, Building 1782, 8000 Aarhus, Denmark
| | - Anders Risbjerg Johnsen
- Department
of Geochemistry, Geological Survey of Denmark
and Greenland (GEUS), Øster Voldgade 10, 1350, Copenhagen, Denmark
| | - Christian Nyrop Albers
- Department
of Geochemistry, Geological Survey of Denmark
and Greenland (GEUS), Øster Voldgade 10, 1350, Copenhagen, Denmark
| | - Lærke Thorling
- Department
of Quaternary and Groundwater Mapping, Geological
Survey of Denmark and Greenland (GEUS), Universitetsbyen 81, Building 1782, 8000 Aarhus, Denmark
| | - Birgitte Hansen
- Department
of Quaternary and Groundwater Mapping, Geological
Survey of Denmark and Greenland (GEUS), Universitetsbyen 81, Building 1782, 8000 Aarhus, Denmark
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2
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Richards LA, Kumari R, Parashar N, Kumar A, Lu C, Wilson G, Lapworth D, Niasar VJ, Ghosh A, Chakravorty B, Krause S, Polya DA, Gooddy DC. Environmental tracers and groundwater residence time indicators reveal controls of arsenic accumulation rates beneath a rapidly developing urban area in Patna, India. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 249:104043. [PMID: 35767908 DOI: 10.1016/j.jconhyd.2022.104043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
Groundwater security is a pressing environmental and societal issue, particularly due to significantly increasing stressors on water resources, including rapid urbanization and climate change. Groundwater arsenic is a major water security and public health challenge impacting millions of people in the Gangetic Basin of India and elsewhere globally. In the rapidly developing city of Patna (Bihar) in northern India, we have studied the evolution of groundwater chemistry under the city following a three-dimensional sampling framework of multi-depth wells spanning the central urban zone in close proximity to the River Ganges (Ganga) and transition into peri-urban and rural areas outside city boundaries and further away from the river. Using inorganic geochemical tracers (including arsenic, iron, manganese, nitrate, nitrite, ammonium, sulfate, sulfide and others) and residence time indicators (CFCs and SF6), we have evaluated the dominant hydrogeochemical processes occurring and spatial patterns in redox conditions across the study area. The distribution of arsenic and other redox-sensitive parameters is spatially heterogenous, and elevated arsenic in some locations is consistent with arsenic mobilization via reductive dissolution of iron hydroxides. Residence time indicators evidence modern (<~60-70 years) groundwater and suggest important vertical and lateral flow controls across the study area, including an apparent seasonal reversal in flow regimes near the urban center. An overall arsenic accumulation rate is estimated to be ~0.003 ± 0.003 μM.yr-1 (equivalent to ~0.3 ± 0.2 μg.yr-1), based on an average of CFC-11, CFC-12 and SF6-derived models, with the highest rates of arsenic accumulation observed in shallow, near-river groundwaters also exhibiting elevated concentrations of nutrients including ammonium. Our findings have implications on groundwater management in Patna and other rapidly developing cities, including potential future increased groundwater vulnerability associated with surface-derived ingress from large-scale urban abstraction or in higher permeability zones of river-groundwater connectivity.
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Affiliation(s)
- Laura A Richards
- Department of Earth and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK.
| | - Rupa Kumari
- Mahavir Cancer Sansthan and Research Center, Phulwarisharif, Patna 801505, Bihar, India
| | - Neha Parashar
- Mahavir Cancer Sansthan and Research Center, Phulwarisharif, Patna 801505, Bihar, India; now at Indian Institute of Technology Patna, Patna 801106, Bihar, India
| | - Arun Kumar
- Mahavir Cancer Sansthan and Research Center, Phulwarisharif, Patna 801505, Bihar, India
| | - Chuanhe Lu
- Department of Earth and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK
| | - George Wilson
- Department of Earth and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK
| | - Dan Lapworth
- British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK
| | - Vahid J Niasar
- Department of Chemical Engineering, The University of Manchester, Manchester M13 9PL, UK
| | - Ashok Ghosh
- Mahavir Cancer Sansthan and Research Center, Phulwarisharif, Patna 801505, Bihar, India
| | | | - Stefan Krause
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - David A Polya
- Department of Earth and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK
| | - Daren C Gooddy
- British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK
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3
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Wang J, Cao Y, Wang J. Land-atmosphere fluxes and concentrations of CFC-11 and CFC-12 based on in situ observations from a coastal salt marsh in eastern China: Implications for CFC remediation. MARINE POLLUTION BULLETIN 2021; 172:112848. [PMID: 34403926 DOI: 10.1016/j.marpolbul.2021.112848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/07/2021] [Accepted: 08/08/2021] [Indexed: 06/13/2023]
Abstract
Regional- and national-scale emissions of chlorofluorocarbons (CFCs), especially in Eastern China, are of great concern to environmentalists and policy makers. To determine the source-sink dynamics of coastal salt marshes for CFC-11 and CFC-12 in the local atmosphere, we studied a coastal salt marsh in Northern Jiangsu Province, taking measurements of the atmospheric concentrations and fluxes of CFC-11 and CFC-12 using static flux chambers in August (growing season) and December (non-growing season) of 2013, and along both creek-side and vegetated transects. We observed unexpectedly high concentrations of CFC-11 (676.5 × 10-12) and CFC-12 (794.6 × 10-12) in the salt marsh in 2013, with predominantly non-local emissions. Overall, the study salt marsh acted as a net sink for CFC-11 and CFC-12, with the average flux ranging from -11.4 μg m-2 h-1 to 5.0 μg m-2 h-1 for CFC-11 and from -7.4 μg m-2 h-1 to 0.7 μg m-2 h-1 for CFC-12. This clearly indicates that the high concentrations of CFC-11 and CFC-12 measured in the atmosphere were not caused by local emissions; terrigenous sources most likely act as the main exogenous input pathway. Our study suggests that salt marsh ecosystems may be worthy of attention as sinks for CFC-11 and CFC-12; as such, the ecological restoration of salt marshes is critical to better offset increasing CFC-11 and CFC-12 emissions.
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Affiliation(s)
- Jinshu Wang
- School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221009, China
| | - Yingjia Cao
- School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221009, China
| | - Jinxin Wang
- School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221009, China.
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Phillips E, Gilevska T, Horst A, Manna J, Seger E, Lutz EJ, Norcross S, Morgan SA, West KA, Mack EE, Dworatzek S, Webb J, Lollar BS. Transformation of Chlorofluorocarbons Investigated via Stable Carbon Compound-Specific Isotope Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:870-878. [PMID: 31789027 DOI: 10.1021/acs.est.9b05746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Compound-specific isotope analysis (CSIA) is a valuable tool in contaminant remediation studies. Chlorofluorocarbons (CFCs) are ozone-depleting substances previously thought to be persistent in groundwater under most geochemical conditions but more recently have been found to (bio)transform in some laboratory experiments. To date, limited applications of CSIA to CFCs have been undertaken. Here, biotransformation-associated carbon isotope enrichment factors, εC,bulk for CFC-113 (εC,bulk = -8.5 ± 0.4‰) and CFC-11 (εC,bulk = -14.5 ± 1.9‰), were determined. δ13C signatures of pure-phase CFCs and hydrochlorofluorocarbons were measured to establish source signatures. These findings were applied to investigate potential in situ CFC transformation in groundwater at a field site, where carbon isotope fractionation of CFC-11 suggests naturally occurring biotransformation by indigenous microorganisms. The maximum extent of CFC-11 transformation is estimated to be up to 86% by an approximate calculation using the Rayleigh concept. CFC-113 δ13C values in contrast were not resolvably different from pure-phase sources measured to date, demonstrating that CSIA can aid in identifying which compounds may, or may not, be undergoing reactive processes at field sites. Science and public attention remains focused on CFCs, as unexplained source inputs to the atmosphere have been recently reported, and the potential for CFC biotransformation in surface and groundwaters remains unclear. This study proposes δ13C CSIA as a novel application to study the fate of CFCs in groundwater.
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Affiliation(s)
- Elizabeth Phillips
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | - Tetyana Gilevska
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | - Axel Horst
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | - Jesse Manna
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | - Edward Seger
- The Chemours Company , Wilmington , Delaware 19899 , United States
| | - Edward J Lutz
- The Chemours Company , Wilmington , Delaware 19899 , United States
| | | | | | | | - E Erin Mack
- Corporate Remediation Group , E. I. DuPont de Nemours and Company , Wilmington , Delaware 19805 , United States
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5
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Yang Z, Tang C, Li X, Zhang H, Cai Y. Dynamics of dissolved greenhouse gas response to seasonal water mixing in subtropical reservoirs. ENVIRONMENTAL MONITORING AND ASSESSMENT 2019; 191:639. [PMID: 31529378 DOI: 10.1007/s10661-019-7772-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Although indispensable, significant uncertainty still exists in the underlying processes of the formation, dynamics, and emission of greenhouse gases (GHGs), the critical elements needed for the accurate estimation of greenhouse gas fluxes in inland lakes and reservoirs. Seasonal changes in water thermal stratification and turbulence strongly influence the concentration and emission of dissolved GHGs in water columns. Here, we studied the stratification and overturn processes of water column in the subtropical Lianhe Reservoir during different seasons and determined the dynamics of dissolved CO2, CH4, and N2O in the reservoir. Observation of temperature and analysis of chlorofluorocarbons (CFCs) clearly suggested that stratification of water column occurred in summer, but not in winter. The results showed that while dissolved oxygen (DO) was high in the top 5-m layer (the upper epilimnion layer), it dropped considerably especially below 10 m, resulting in an increase in concentration of CO2 and CH4. The high concentrations of dissolved N2O and CH4 were related to the decomposition of organic matter in the hypolimnion layer under anaerobic conditions after stratification. In winter overturn period, vertical circulants of water not only homogenized the concentration of DO in the water column, but also potentially moved CO2, CH4, and N2O from the bottom to the surface of the reservoir. The estimated GHG flux from the reservoir was - 7.13 mmol m-2 day-1 in summer and 2.14 mmol m-2 day-1 in winter. There was the potential that CO2 fluxes from subtropical lakes and reservoirs are overestimated by traditional geochemical models.
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Affiliation(s)
- Zhenglun Yang
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, 271-8510, Japan
| | - Changyuan Tang
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, 271-8510, Japan.
| | - Xing Li
- School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, No. 206 Guanggu 1st road, Wuhan, 430205, China.
| | - Han Zhang
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, 271-8510, Japan
| | - Yangyang Cai
- School of Environmental Science and Engineering, Sun Yat-sen University, 135 Xingang Xi Road, Guangzhou, 510275, China
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6
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Richards LA, Magnone D, Sültenfuß J, Chambers L, Bryant C, Boyce AJ, van Dongen BE, Ballentine CJ, Sovann C, Uhlemann S, Kuras O, Gooddy DC, Polya DA. Dual in-aquifer and near surface processes drive arsenic mobilization in Cambodian groundwaters. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 659:699-714. [PMID: 31096400 DOI: 10.1016/j.scitotenv.2018.12.437] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
Millions of people globally, and particularly in South and Southeast Asia, face chronic exposure to arsenic from reducing groundwaters in which. Arsenic release to is widely attributed largely to reductive dissolution of arsenic-bearing iron minerals, driven by metal reducing bacteria using bioavailable organic matter as an electron donor. However, the nature of the organic matter implicated in arsenic mobilization, and the location within the subsurface where these processes occur, remains debated. In a high resolution study of a largely pristine, shallow aquifer in Kandal Province, Cambodia, we have used a complementary suite of geochemical tracers (including 14C, 3H, 3He, 4He, Ne, δ18O, δD, CFCs and SF6) to study the evolution in arsenic-prone shallow reducing groundwaters along dominant flow paths. The observation of widespread apparent 3H-3He ages of <55years fundamentally challenges some previous models which concluded that groundwater residence times were on the order of hundreds of years. Surface-derived organic matter is transported to depths of >30m, and the relationships between age-related tracers and arsenic suggest that this surface-derived organic matter is likely to contribute to in-aquifer arsenic mobilization. A strong relationship between 3H-3He age and depth suggests the dominance of a vertical hydrological control with an overall vertical flow velocity of ~0.4±0.1m·yr-1 across the field area. A calculated overall groundwater arsenic accumulation rate of ~0.08±0.03μM·yr-1 is broadly comparable to previous estimates from other researchers for similar reducing aquifers in Bangladesh. Although apparent arsenic groundwater accumulation rates varied significantly with site (e.g. between sand versus clay dominated sequences), rates are generally highest near the surface, perhaps reflecting the proximity to the redox cline and/or depth-dependent characteristics of the OM pool, and confounded by localized processes such as continued in-aquifer mobilization, sorption/desorption, and methanogenesis.
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Affiliation(s)
- Laura A Richards
- School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK.
| | - Daniel Magnone
- School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK
| | - Jürgen Sültenfuß
- Institute of Environmental Physics, University of Bremen, Bremen 28359, Germany
| | - Lee Chambers
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Charlotte Bryant
- NERC Radiocarbon Facility, Scottish Enterprise Technology Park, East Kilbride G75 0QF, UK
| | - Adrian J Boyce
- Scottish Universities Environmental Research Centre, East Kilbride G75 0QF, UK
| | - Bart E van Dongen
- School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK
| | - Christopher J Ballentine
- School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK
| | - Chansopheaktra Sovann
- Department of Environmental Science, Royal University of Phnom Penh, Phnom Penh, Cambodia
| | - Sebastian Uhlemann
- British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG, UK
| | - Oliver Kuras
- British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG, UK
| | - Daren C Gooddy
- British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK
| | - David A Polya
- School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK.
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7
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Lapworth DJ, Das P, Shaw A, Mukherjee A, Civil W, Petersen JO, Gooddy DC, Wakefield O, Finlayson A, Krishan G, Sengupta P, MacDonald AM. Deep urban groundwater vulnerability in India revealed through the use of emerging organic contaminants and residence time tracers. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 240:938-949. [PMID: 29949845 DOI: 10.1016/j.envpol.2018.04.053] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/10/2018] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
Abstract
Demand for groundwater in urban centres across Asia continues to rise with ever deeper wells being drilled to avoid shallow contamination. The vulnerability of deep alluvial aquifers to contaminant migration is assessed in the ancient city of Varanasi, India, using a novel combination of emerging organic contaminants (EOCs) and groundwater residence time tracers (CFC and SF6). Both shallow and intermediate depth private sources (<100 m) and deep (>100 m) municipal groundwater supplies were found to be contaminated with a range of EOCs including pharmaceuticals (e.g. sulfamethoxazole, 77% detection frequency, range <0.0001-0.034 μg L-1), perfluoroalkyl substances (e.g. PFOS, range <0.0001-0.033 μg L-1) as well as a number of pesticides (e.g. phenoxyacetic acid, range <0.02-0.21 μg L-1). The profile of EOCs found in groundwater mirror those found in surface waters, albeit at lower concentrations, and reflect common waste water sources with attenuation in the subsurface. Mean groundwater residence times were found to be comparable between some deep groundwater and shallow groundwater sources with residence times ranging from >70 to 30 years. Local variations in aquifer geology influence the extent of modern recharge at depth. Both tracers provide compelling evidence of significant inputs of younger groundwater to depth >100 m within the aquifer system.
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Affiliation(s)
- D J Lapworth
- British Geological Survey, Maclean Building, Wallingford, OX10 8BB, UK.
| | - P Das
- Department of Geology and Geophysics, IIT-Kharagpur, Kharagpur, 721302, West Bengal, India
| | - A Shaw
- Department of Geology and Geophysics, IIT-Kharagpur, Kharagpur, 721302, West Bengal, India
| | - A Mukherjee
- Department of Geology and Geophysics, IIT-Kharagpur, Kharagpur, 721302, West Bengal, India.
| | - W Civil
- National Laboratory Service, Star Cross, Exeter, EX6 8FD, UK
| | - J O Petersen
- British Geological Survey, Maclean Building, Wallingford, OX10 8BB, UK
| | - D C Gooddy
- British Geological Survey, Maclean Building, Wallingford, OX10 8BB, UK
| | - O Wakefield
- British Geological Survey, Environmental Science Centre, Keyworth, NG12 5GG, UK
| | - A Finlayson
- British Geological Survey, Lyell Centre, Edinburgh, EH14 4AP, UK
| | - G Krishan
- National Institute of Hydrology, Roorkee, 247667, Uttarakhand, India
| | - P Sengupta
- Department of Geology and Geophysics, IIT-Kharagpur, Kharagpur, 721302, West Bengal, India
| | - A M MacDonald
- British Geological Survey, Lyell Centre, Edinburgh, EH14 4AP, UK
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Sorensen JPR, Lapworth DJ, Nkhuwa DCW, Stuart ME, Gooddy DC, Bell RA, Chirwa M, Kabika J, Liemisa M, Chibesa M, Pedley S. Emerging contaminants in urban groundwater sources in Africa. WATER RESEARCH 2015; 72:51-63. [PMID: 25172215 DOI: 10.1016/j.watres.2014.08.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/11/2014] [Accepted: 08/01/2014] [Indexed: 05/05/2023]
Abstract
The occurrence of emerging organic contaminants within the aquatic environment in Africa is currently unknown. This study provides early insights by characterising a broad range of emerging organic contaminants (n > 1000) in groundwater sources in Kabwe, Zambia. Groundwater samples were obtained during both the dry and wet seasons from a selection of deep boreholes and shallow wells completed within the bedrock and overlying superficial aquifers, respectively. Groundwater sources were distributed across the city to encompass peri-urban, lower cost housing, higher cost housing, and industrial land uses. The insect repellent DEET was ubiquitous within groundwater at concentrations up to 1.8 μg/L. Other compounds (n = 26) were detected in less than 15% of the sources and included the bactericide triclosan (up to 0.03 μg/L), chlorination by-products - trihalomethanes (up to 50 μg/L), and the surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (up to 0.6 μg/L). Emerging contaminants were most prevalent in shallow wells sited in low cost housing areas. This is attributed to localised vulnerability associated with inadequate well protection, sanitation, and household waste disposal. The five-fold increase in median DEET concentration following the onset of the seasonal rains highlights that more mobile compounds can rapidly migrate from the surface to the aquifer suggesting the aquifer is more vulnerable than previously considered. Furthermore it suggests DEET is potentially useful as a wastewater tracer in Africa. There was a general absence of personal care products, life-style compounds, and pharmaceuticals which are commonly detected in the aquatic environment in the developed world. This perhaps reflects some degree of attenuation within the subsurface, but could also be a result of the current limited use of products containing emerging contaminants by locals due to unaffordability and unavailability. As development and population increases in Africa, it is likely a wider-range of emerging contaminants will be released into the environment.
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Affiliation(s)
- J P R Sorensen
- British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK.
| | - D J Lapworth
- British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK
| | - D C W Nkhuwa
- University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia
| | - M E Stuart
- British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK
| | - D C Gooddy
- British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK
| | - R A Bell
- British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK
| | - M Chirwa
- University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia
| | - J Kabika
- University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia
| | - M Liemisa
- Lukanga Water and Sewerage Company Limited, P.O. Box 81745, Kabwe, Zambia
| | - M Chibesa
- Lukanga Water and Sewerage Company Limited, P.O. Box 81745, Kabwe, Zambia
| | - S Pedley
- Robens Centre for Public and Environmental Health, University of Surrey, Guildford GU2 7XH, UK
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9
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Cao Y, Tang C, Song X, Liu C, Zhang Y. Characteristics of nitrate in major rivers and aquifers of the Sanjiang Plain, China. ACTA ACUST UNITED AC 2012; 14:2624-33. [DOI: 10.1039/c2em30032j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Newman BD, Osenbrück K, Aeschbach-Hertig W, Solomon DK, Cook P, Rózański K, Kipfer R. Dating of 'young' groundwaters using environmental tracers: advantages, applications, and research needs. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2010; 46:259-78. [PMID: 20845177 DOI: 10.1080/10256016.2010.514339] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Many problems related to groundwater supply and quality, as well as groundwater-dependent ecosystems require some understanding of the timescales of flow and transport. For example, increased concern about the vulnerabilities of 'young' groundwaters (less than ~1000 years) to overexploitation, contamination, and land use/climate change effects are driving the need to understand flow and transport processes that occur over decadal, annual, or shorter timescales. Over the last few decades, a powerful suite of environmental tracers has emerged that can be used to interrogate a wide variety of young groundwater systems and provide information about groundwater ages/residence times appropriate to the timescales over which these systems respond. These tracer methods have distinct advantages over traditional approaches providing information about groundwater systems that would likely not be obtainable otherwise. The objective of this paper is to discuss how environmental tracers are used to characterise young groundwater systems so that more researchers, water managers, and policy-makers are aware of the value of environmental tracer approaches and can apply them in appropriate ways. We also discuss areas where additional research is required to improve ease of use and extend quantitative interpretations of tracer results.
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Affiliation(s)
- Brent D Newman
- Water Resources Programme, International Atomic Energy Agency, Vienna International Centre, Vienna, Austria.
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11
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Gourcy L, Baran N, Vittecoq B. Improving the knowledge of pesticide and nitrate transfer processes using age-dating tools (CFC, SF6, 3H) in a volcanic island (Martinique, French West Indies). JOURNAL OF CONTAMINANT HYDROLOGY 2009; 108:107-17. [PMID: 19631404 DOI: 10.1016/j.jconhyd.2009.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 06/24/2009] [Accepted: 06/25/2009] [Indexed: 05/14/2023]
Abstract
Numerous successful examples of CFC and SF(6) groundwater dating applications were recently published. However the proposed CFC/SF(6) method needs various hydrodynamic parameters that are not always available. In order to predict groundwater-quality trends in areas where the hydrogeological context is poorly known, a dating method using tritium, CFC and SF(6) was successfully implemented in Martinique. Hydrogeological understanding is limited in this volcanic island where groundwater contamination by pesticides and nitrate has been recently proven in various areas. A negative correlation was observed between nitrate concentrations and groundwater ages while pesticide contamination showed a more complex schema. Consequently the presence of old groundwater clearly explained the absence or low pesticide and nitrate concentrations in some areas. However a possible degradation of the water quality is to be feared in the future. In view of the relatively long transfer times and the complexity of the remobilization processes of solutes, the expected effects of any modifications in the use of fertilizers, or of changes in pesticide-use legislation, would take a long time to become apparent.
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Affiliation(s)
- Laurence Gourcy
- BRGM, Water Division, Avenue C Guillemin, BP 6009, F-45060 Orléans Cedex, France.
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