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Buss J, Achten C. Spatiotemporal variations of surface water quality in a medium-sized river catchment (Northwestern Germany) with agricultural and urban land use over a five-year period with extremely dry summers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 818:151730. [PMID: 34800458 DOI: 10.1016/j.scitotenv.2021.151730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
Medium-sized rivers, which are used for intensive agriculture and urban infrastructure, are subject to manifold hydrochemical stressors. Identifying and monitoring these stressors is important for river basin management and a functioning ecosystem. To understand the spatiotemporal variation of surface water quality in a highly modified lowland river, the Münstersche Aa River (Northwestern Germany) with 62% of land used for agriculture and 26% urban/residential area, was exemplarily studied. A total of 519 samples were collected using two automated high-frequency samplers and five catchment-wide sampling campaigns. They covered the five-year period 2015-2020 and included two extremely dry summers. The Münstersche Aa catchment is dominated by low permeable strata resulting in surface water runoff (Baseflow Index: 0.41) which leads to a high amplitude of discharge variation (mean discharge: 0.7 m3/s) with high flow conditions in winter/spring, and low discharge during summer/fall. In wintertime, maximum nitrate concentrations (up to 73 mg NO3/L) and loads (up to 1300 t NO3/a; up to 98% in winter) correlate with high-flow conditions. δ18O and δ15N isotopic analysis indicated manure from farmland as the major source of nitrate whereas the impact of municipal wastewater treatment plants was neglectable. Increased nitrate concentrations are linked to the higher proportion of farmland in the upper catchment (77%) compared with the lower catchment (47%). In summertime, at extremely low flow conditions, surface water consisted of up to 100% of treated wastewater, resulting in the highest measured chloride, sodium and potassium concentrations. The river is impacted by strongly seasonal and different stressors, which can be expected to intensify with ongoing climate change. Results from this study may help to adapt monitoring schemes for the Münstersche Aa but also for other lowland streams with comparable land-use targeting the goals of the Water Framework Directive.
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Affiliation(s)
- Johanna Buss
- Institute of Geology and Palaeontology - Applied Geology, University of Münster, Corrensstrasse 24, 48149 Münster, Germany
| | - Christine Achten
- Institute of Geology and Palaeontology - Applied Geology, University of Münster, Corrensstrasse 24, 48149 Münster, Germany.
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Nitrate sources and mixing in the Danube watershed: implications for transboundary river basin monitoring and management. Sci Rep 2022; 12:2150. [PMID: 35140301 PMCID: PMC8828721 DOI: 10.1038/s41598-022-06224-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/18/2022] [Indexed: 11/10/2022] Open
Abstract
Dispersed and unknown pollution sources complicate water management in large transboundary watersheds. We applied stable isotopes of water and nitrate together with contaminants of emerging concern (CECs: carbamazepine, caffeine, sulfamethoxazole, perfluorooctanoic acid and 2,4-dinitrophenol) to evaluate mixing and inputs of water and contaminants from tributaries into the mainstem of the transboundary Danube River. Stable isotope (δ18O, δ2H) variations from low values (− 13.3 ‰, − 95.1 ‰) in the Upper Danube after the Inn River confluence to high values (− 9.9 ‰, − 69.7 ‰) at the Danube River mouth revealed snowmelt dominated tributary mixing (~ 70%) in the mainstem. Stable isotopes of nitrate (δ15N-NO3) in the Danube River varied from lower values (+ 6.7 ‰) in the Upper Danube to higher values after the mixing with Morava River (+ 10.5 ‰) and showed that cold snowmelt can reduce biological activity and controls nitrate biotransformation processes in the mainstem up to 1000 km downstream. Data on emerging contaminants affirmed the low biodegradation potential of organic compounds transferred into the mainstem by tributaries. We found pollutant source tracing in large rivers is complicated by mixing of multiple sources with overlapping isotopic signatures, but additional tracers such as CECs improve the interpretation of hydrological processes (e.g., water transit time) and support tracing of nitrate pollution sources, and biogeochemical processes. Our approach can be applied to other watersheds to improve the understanding of dilution and mixing processes. Moreover, it provides directions for improving national and transboundary water quality monitoring networks.
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Tian L, Gao Y, Yang G, Schwartz B, Cai B, Lei G, Shi G, Ray C, Sok S, Martinez E, Li Y, Wu H. The evolution of hydrochemical and isotopic signatures from precipitation, surface water to groundwater in a typical karst watershed, Central Texas, USA. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2021; 57:492-515. [PMID: 34269607 DOI: 10.1080/10256016.2021.1948410] [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: 01/23/2021] [Accepted: 05/28/2021] [Indexed: 06/13/2023]
Abstract
The Upper Cibolo Creek (UCC) karst watershed in Central Texas, USA, represents a portion of the drainage area that supplies water to the recharge zone for the Edwards Aquifer. However, the surface water-groundwater interactions along the UCC are not well quantified, and the hydraulic interactions are important for water budget and water quality of the aquifer. In this study, we investigated the evolution of hydrochemical and isotopic signatures (δ18O, δ2H and d-excess) from precipitation, surface water to groundwater in the UCC watershed from 2017 to 2019, and investigated surface water-groundwater interactions using samples from 14 creeks/spring sites. Factor analysis for the observed parameters demonstrates that changes in water hydrochemistry are primarily controlled by human activity, precipitation input, and water-rock interaction. Hierarchical clustering analysis of temporal isotope variations confirms that significant surface water-groundwater interactions occur in the UCC watershed. We identified relationships between nitrate concentrations at creek/spring sites and land-use conditions, and nitrate input sources were determined utilizing the dual-isotope analyses (δ15N and δ18O) of nitrate. This study provides capacity for a more precise assessment of water resources and water quality in Central Texas.
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Affiliation(s)
- Lijun Tian
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | - Yongli Gao
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | - Guang Yang
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
- College of Water and Architectural Engineering, Shihezi University, Shihezi, People's Republic of China
| | - Benjamin Schwartz
- Edwards Aquifer Research and Data Center, Texas State University, San Marcos, TX, USA
| | - Binggui Cai
- School of Geographical Sciences, Fujian Normal University, Fuzhou, People's Republic of China
| | - Guoliang Lei
- School of Geographical Sciences, Fujian Normal University, Fuzhou, People's Republic of China
| | - Guitao Shi
- School of Geographic Sciences and State Key Lab of Estuarine and Coastal Research, East China Normal University, Shanghai, People's Republic of China
| | - Christopher Ray
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | - Soeuth Sok
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | - Erica Martinez
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | - Yunxia Li
- Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX, USA
- College of Resources and Environmental Sciences, Hunan Normal University, Changsha, People's Republic of China
| | - Haibin Wu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, People's Republic of China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, People's Republic of China
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