Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark
Nitrogen impact on the aquatic environment, including coastal areas, is too high in many countries worldwide, particularly in areas with intensive agriculture. Efficient mitigation initiatives demand that important pathways and the fate of nitrate in the hydrological cycle are known. In this study,...
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| Format: | Article |
| Jezik: | English |
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Geological Survey of Denmark and Greenland
2023-11-01
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| Serija: | GEUS Bulletin |
| Teme: | |
| Online dostop: | https://geusbulletin.org/index.php/geusb/article/view/8351/14410 |
| _version_ | 1827630754965749760 |
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| author | Peter B.E. Sandersen Hyojin Kim Rasmus Jacobsen Jesper B. Pedersen Birgitte Hansen |
| author_facet | Peter B.E. Sandersen Hyojin Kim Rasmus Jacobsen Jesper B. Pedersen Birgitte Hansen |
| author_sort | Peter B.E. Sandersen |
| collection | DOAJ |
| description | Nitrogen impact on the aquatic environment, including coastal areas, is too high in many countries worldwide, particularly in areas with intensive agriculture. Efficient mitigation initiatives demand that important pathways and the fate of nitrate in the hydrological cycle are known. In this study, we focus on groundwater nitrate contamination in two near-shore catchment areas in north-west Denmark. Groundwater in the area is mainly located in buried tunnel valleys, which are subsurface structures eroded by meltwater during Pleistocene glaciations in former glaciated areas. Groundwater samples from the aquifers inside the buried valleys reveal the presence of up to 120 mg/l nitrate down to 10 m below sea level and about 1 km down from the stream outlet towards the coast. We interpret the complex tunnel-valley infill to be responsible for the spatial heterogeneity of the groundwater geochemistry, where sandy geological windows create localised hydraulic pathways and complex redox structures. Groundwater and stream water chemistry in the study area clearly demonstrate the role of groundwater in nitrate transport within the catchment as well as the direct pathway to the coast bypassing the stream and riverine systems. Our results show that the buried tunnel valleys potentially contribute to submarine groundwater discharge and therefore could be responsible for a hitherto unaccounted input of nitrogen to the marine environment. |
| first_indexed | 2024-03-09T14:11:13Z |
| format | Article |
| id | doaj.art-cfbbf07caaf24f3e9941802c4446414f |
| institution | Directory Open Access Journal |
| issn | 2597-2154 |
| language | English |
| last_indexed | 2024-03-09T14:11:13Z |
| publishDate | 2023-11-01 |
| publisher | Geological Survey of Denmark and Greenland |
| record_format | Article |
| series | GEUS Bulletin |
| spelling | doaj.art-cfbbf07caaf24f3e9941802c4446414f2023-11-29T10:12:08ZengGeological Survey of Denmark and GreenlandGEUS Bulletin2597-21542023-11-015311410.34194/geusb.v53.83518351Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, DenmarkPeter B.E. Sandersen0Hyojin Kim1Rasmus Jacobsen2Jesper B. Pedersen3Birgitte Hansen4Department of Near-Surface Land and Marine Geology, Geological Survey of Denmark and Greenland, Aarhus, DenmarkDepartment of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen, DenmarkDepartment of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen, DenmarkHydroGeophysics Group, Department of Geoscience, Aarhus University, Aarhus, DenmarkDepartment of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen, DenmarkNitrogen impact on the aquatic environment, including coastal areas, is too high in many countries worldwide, particularly in areas with intensive agriculture. Efficient mitigation initiatives demand that important pathways and the fate of nitrate in the hydrological cycle are known. In this study, we focus on groundwater nitrate contamination in two near-shore catchment areas in north-west Denmark. Groundwater in the area is mainly located in buried tunnel valleys, which are subsurface structures eroded by meltwater during Pleistocene glaciations in former glaciated areas. Groundwater samples from the aquifers inside the buried valleys reveal the presence of up to 120 mg/l nitrate down to 10 m below sea level and about 1 km down from the stream outlet towards the coast. We interpret the complex tunnel-valley infill to be responsible for the spatial heterogeneity of the groundwater geochemistry, where sandy geological windows create localised hydraulic pathways and complex redox structures. Groundwater and stream water chemistry in the study area clearly demonstrate the role of groundwater in nitrate transport within the catchment as well as the direct pathway to the coast bypassing the stream and riverine systems. Our results show that the buried tunnel valleys potentially contribute to submarine groundwater discharge and therefore could be responsible for a hitherto unaccounted input of nitrogen to the marine environment.https://geusbulletin.org/index.php/geusb/article/view/8351/14410submarine groundwater dischargeredox modellingburied tunnel valleysnitrate in groundwaternitrogen flux to the marine environment |
| spellingShingle | Peter B.E. Sandersen Hyojin Kim Rasmus Jacobsen Jesper B. Pedersen Birgitte Hansen Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark GEUS Bulletin submarine groundwater discharge redox modelling buried tunnel valleys nitrate in groundwater nitrogen flux to the marine environment |
| title | Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark |
| title_full | Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark |
| title_fullStr | Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark |
| title_full_unstemmed | Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark |
| title_short | Transport of nitrate-containing groundwater to coastal areas through buried tunnel valleys, Denmark |
| title_sort | transport of nitrate containing groundwater to coastal areas through buried tunnel valleys denmark |
| topic | submarine groundwater discharge redox modelling buried tunnel valleys nitrate in groundwater nitrogen flux to the marine environment |
| url | https://geusbulletin.org/index.php/geusb/article/view/8351/14410 |
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