SEMINAR: Soil and Water Seminar Series 2010 (SEE), Weds28Jul:

Soil and Water Seminar to be given by Dr. Henning Prommer - All welcome!

TITLE: "Incorporating isotope fractionation processes into reactive transport models: From lab to field-scale"

ABSTRACT: Quantification of natural attenuation processes at contaminated field sites normally relies on the documentation of contaminant concentration changes downstream of source zones and the interpretation of concentration changes of additional geochemical indicators. However, whether the reduction of contaminant concentrations is a result of true contaminant destruction or of other attenuation processes, in particular dispersion/dilution, can not always be established easily and conclusively. As a result, compound specific isotope analysis (CSIA) has become an increasingly accepted field method to quantify the extent of degradation for a range of organic compounds, especially for chlorinated hydrocarbons. CSIA-based quantification typically relies on the use of the Rayleigh equation. Its applicability is, however, mostly limited to parent compounds since the analysis of reaction intermediates and final products may be compromised, especially for complex, parallel reaction pathways. These limitations can be overcome by incorporating isotopic fractionation processes into reactive transport models. The presentation will provide a brief overview on model approaches and discuss both successfully completed and ongoing model applications for various contaminants (PCE, TCE, 1,2 DCA, VC BTEX/PAHs) that range from controlled laboratory experiments over a well-instrumented research site to physically and chemically highly heterogeneous aquifers.