Improved Darcian streambed measurements to quantify flux and mass discharge of volatile organic compounds from a contaminated aquifer to an urban stream

Quantifying VOC transport from contaminated groundwater to streams is challenging and important for understanding off-site migration of VOCs, cross-media contamination (groundwater to surface water and eventually air), and potential impacts on downstream ecosystems and human populations. A streambed point sampling approach was used to quantify fluxes of water and 14 VOCs from groundwater to an urban stream in North Carolina, USA, during summer (June 2015) and winter (January 2016). The approach is unique in coupling measurements of vertical hydraulic conductivity, vertical hydraulic head gradient, and groundwater VOC concentration at each individual sampling point, reducing or eliminating some potential concerns with other Darcian methods for quantifying VOC inputs to streams.