Heidelberg 1999 – scientific programme

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UP: Umweltphysik

UP 5: Hydrologie

UP 5.6: Talk

Thursday, March 18, 1999, 11:30–11:45, KO

Pore-scale modelling of diffusion limited contaminant release — •Helmut Geistlinger and Detlef Lazik — UFZ; Theodor-Lieser-Str. 4; 06129 Halle

In the Bitterfeld lignite seam aquitard we have observed asymmetric Gaussian-like concentration profiles of organic contaminants. Similar concentration profiles were observed in a clayey groundwater aquitard at Dover Air Force Base, Delaware. For a diffusion-based interpretation of these concentration profiles Ball et al. (1997) have derived an analytical solution for the two- aquitard diffusion problem. Applying this general solution, we derived for the first time an analytical expression for the contaminant release function (Geistlinger et al. (1998)). The knowledge of this function is necessary both for forensic modelling of the case history and for predictive modelling of the future contaminant release of the aquitard (see Ball et al., 1997).

First results show that the theoretical concentration profiles exhibit the same characteristic features like the experimental ones: asymmetry, Kd-dependent maxima and maxima positions in the meter range (Geistlinger et al. (1998)). An interesting feature is that due to the presence of the interface the isotropic diffusion phenomena is able to describe the maxima migration through the aquitard; e.g. for = 10, and t = 10 and 50 a the maximum positions are 1.5 and 2.4m, respectively. In this paper we present the best fits for different concentration profiles of drilling cores.