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Original article (peer-reviewed)

Journal Science of The Total Environment
Volume (Issue) 722
Page(s) 137749 - 137749
Title of proceedings Science of The Total Environment
DOI 10.1016/j.scitotenv.2020.137749

Open Access

URL http://doi.org/10.1016/j.scitotenv.2020.137749
Type of Open Access Green OA Embargo (Freely available via Repository after an embargo)

Abstract

The persistence of groundwater contaminants is influenced by several interacting processes. Physical, physico-chemical, and (bio-)chemical processes all influence the transport of contaminants in the subsurface. However, for a given hydrogeological system, it is generally unclear to which degree each of these phenomena acts as a control on plume behaviour. Here, we present a comprehensive investigation of these processes and their influences on plume behaviour and persistence in layered sedimentary systems. We investigate different scenarios that represent fundamental configurations of common contaminant situations. A confined aquifer over- and underlain by aquitard layers is investigated in a source-removal scenario and a constant-source equilibrium scenario. Additionally, an aquitard overlain and underlain by high permeability units is investigated in a source-removal scenario. In these investigations, we vary layer thickness, as well as parameters governing advection, (back-)diffusion, sorption, and degradation. Extensive analysis of these results enables quantification of the influence of these parameters on maximum down-gradient concentration, plume persistence duration, and plume spatial extent. Finally, parameter space dimensionality reduction is used to establish trends and regimes in which certain processes dominate as controls. A lower limit to plume extent as a function of a novel constructed parameter is also determined. These results provide valuable quantitative information for the assessment of the fate of groundwater contaminants and are applicable to a wide range of aqueous-phase solutes.
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