A contaminant plume is conceptually the result of the relative balance between the mass discharge of the contaminant from the source and the rate at which the contaminant is attenuated in the down gradient environment (i.e., natural attenuation capacity). Consequently, contaminant risk can be managed through the favorable alteration of the source mass discharge, the rate of attenuation in the plume, or both. In this context, the source is broadly defined as any mass stored in the subsurface with sufficient capacity to sustain a contaminant plume and may include, for example, nonaqueous phase liquid or dissolved and sorbed contaminant mass in low hydraulic conductivity media. Past research efforts have focused on the impact of aggressive remediation technologies on dense nonaqueous phase liquid (DNAPL) source zones, and the relationship between DNAPL mass reduction and changes in source mass discharge. DNAPL impacted sites continue to be a focus area and research is in progress to understand the uncertainty of mass discharge measurements from sources zones, how to predict long-term mass discharge behavior, and the response of the contaminant plume to changes in source mass discharge at field sites. Research is also being conducted to understand how contaminated, low-conductivity regions within aquifers act as secondary contaminant sources and the long-term behavior of mass discharge from these regions. Field and laboratory based experimentation are being conducted with the support of numerical modeling studies.

 

Reference

Brooks MC, et al: Journal of Contaminant Hydrology 102(1-2): 140, 2008

 

key words

Aquifers; Groundwater contamination; Groundwater remediation; Source zones; Mass flux; Mass discharge; Back diffusion;

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