Confirming observations examine the reliability of a conceptual site model

Abstract:

Improvements in environmental management could be made if nitrate sources, were reliably determined using conceptual site models. To examine reliability, hence the predictive capability of a conceptual subsurface model, we combine the results of geophysics- and direct push-based measurements with an assessment of hydrogeochemistry and dual nitrate isotopes at the Wurmlingen site (near Tübingen), southwest Germany. On the basis of resistivity method of geophysics and direct push-based electrical conductivity logging, we detected a channel-like low resistivity structure at the base of the aquifer. This structure was not immediately evident from inspection of the area's relatively flat surface topography. Dual nitrate isotopes inferred soil organic nitrogen and animal manure and septic wastes as nitrate sources. Observations suggest that the imaged low resistivity structure with higher nitrate concentrations and enriched nitrate isotopic signatures could be a preferential flow path with consequences for further understanding of the occurrence of geochemical and microbiological processes.