Identifying the Presence of AMD-Derived Soil CO 2 in Field Investigations Using Isotope Ratios

摘要

Recent incidents of hazardous accumulations of CO 2 in homes on or adjacent to reclaimed mine land have been shown to be linked to neutralization reactions between acidic mine drainage and carbonate material. An efficient and economic method is necessary to identify the presence of acid mine drainage- (AMD-) derived CO 2 on reclaimed mine land, prior to construction. One approach to identify the presence of AMD-derived CO 2 is to characterize stable carbon isotope ratios of soil CO 2 . To do so, a viable method is necessary to acquire soil gas samples for isotope ratio analysis. This paper presents preliminary investigations of the effectiveness of two methods of acquiring gas samples (sampling during soil flux measurements and using slam bar) for isotope analysis. The results indicate that direct soil gas sampling is cheaper and provides better results. Neither method is adequate without accounting for temporal effects due to changing gas transport mechanisms. These results have significant implications for safe post-mining land uses and future investigations of leakages from geologic carbon sequestration sites.