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Nitrate vulnerability assessment of aquifers

Hansen, Birgitte, Sonnenborg, Torben O., Møller, Ingelise, Bernth, Jens Demant, Høyer, Anne-Sophie, Rasmussen, Per, Sandersen, Peter B.E., Jørgensen, Flemming
Environmental earth sciences 2016 v.75 no.12 pp. 999
aquifers, drinking water, geophysics, groundwater, groundwater flow, landscapes, nitrate reduction, nitrates, water supply, Denmark
Protection of groundwater against nitrate has a high priority in a country like Denmark with intensive agricultural production and with drinking water production based on groundwater. This paper presents a Site-specific Concept for Aquifer Nitrate Vulnerability Assessment (SCANVA) aimed at protecting groundwater resources. SCANVA is a qualitative dynamic concept adjusted to the specific study area depending on the hydrogeological and geochemical conditions. It comprises a synthesis of very detailed site-specific geological, geophysical, hydrogeological and chemical data, and a definition of nitrate vulnerability founded on redox conditions in the ground. Data are used to interpret the geological architecture of the subsurface, the groundwater flow and the geochemical groundwater conditions. These interpretations are integrated to assess nitrate vulnerability of the aquifers in three dimensions and identifying nitrate-vulnerable zones. The paper demonstrates the practical use of the concept in a Danish intensive agricultural area with a glacially formed landscape. Glaciotectonic has led to a high geological heterogeneity and very complex composition of thrusted and folded layers, which to a large extent affect the nitrate vulnerability of the aquifers. SCANVA can be directly applied to specific hydrogeological conditions anywhere with intensive N loss from agriculture, a groundwater-based drinking water supply, nitrate reduction in the ground and glacially dominated landscapes and deposits. Potentially, the concept might also be adapted to other specific substances, dominating geochemical processes, and geological settings.