Date of this Version
American Geophysical Union, Vol. 85, No. 44, pp. 449, 455, November 4, 2004.
In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology, petroleum extraction, carbon sequestration, etc.), scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.
In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency,Department of Energy,Nuclear Regulatory Commission, Department of Agriculture,and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically, the goals of the WG are to (1) evaluate the state of the art in conceptual model development and parameterization for RTM,as applied to soil, vadose zone, and groundwater systems, and (2) prioritize research directions that would enhance the practical utility of RTM.
The WG is addressing issues related to the fate of reactive solutes in complex field systems, where spatially and temporally subsurface properties directly influence not only the physical processes of flow and transport,but also the rates and extent of biogeochemical reactions. Of particular interest is the interplay between physical and reaction processes,and how this coupling could be efficiently and realistically accounted for in RTM.The WG has focused on the evaluation of conceptual models; improvement of numerical approaches and comparison of computer codes are outside the scope of WG activities.
The activities of the WG to date have included a literature review, internal meetings,and sponsorship of a workshop (see:www.iscmem.org for the full membership and background of the WG, and information on other interagency environmental modeling groups). The workshop included agency representatives and federal and academic specialists in model development, geochemistry,hydrology,and microbiology. This article summarizes findings of the WG to date with respect to the status of RTM for inorganic contaminants.