Upscaling dissolved phase mass flux for complex DNAPL source zones

The NAPL phase in the Dense Non-Aqueous Phase Liquid (DNAPL) contaminated site are dissolved in the flowing groundwater sustainably, thus a downstream contaminant plume is created, and a threat is posed to human health. It is important to accurately estimate the downstream contaminant mass flux from the DNAPL source zone. Due to the geological heterogeneity, the mass flux of dissolved phase is changed periodically. The dual-domain upscaling model developed by Christ et al. was often used to calculate the mass flux, however, it was only applicable to the DNAPL source zone with weak heterogeneity. Many numerical examples were used for complex DNAPL source zones with strong heterogeneity, to modify the empirical formula for deriving the source zone depletion index in the dual-domain model, thus the application scope of the dual-domain upscaling model were extended to strong heterogeneity. The applicability and accuracy of the modified model was validated based on Monte Carlo synthetical cases and two two-dimensional sandbox experiments. The comparison results showed that the modified model could be widely applied to complex DNAPL source zones with different structures. Compared with the previous, the accuracy of the mass flux calculated by the modified model was increased by about 35%. © 2022, Editorial Board of China Environmental Science. All right reserved.