Spatial Variation of Selenium in Appalachian Coal Seams

The potential environmental impacts from coal extraction have led to many investigations of the geochemistry of coal. Previous studies have shown that selenium (Se) is an environmental contaminant due to its mutagenic effects on sensitive macro-organisms as a result of bioaccumulation in affected waters. Some regulatory authorities have responded by requiring the sampling of coal seams and adjacent rock for Se prior to authorizing a given coal mining permit. In at least one case, a single continuous rock core was sampled for Se to determine the threshold of Se across a 2.2 square kilometer proposed surface coal mine. To examine the adequacy of such an approach, we investigated the spatial variability and correlation of a West Virginia Geological and Economic Survey (WVGES) dataset of Se concentrations from coal seams collected within Appalachia (1088 samples). We conducted semi-variogram and Kriging cross-validation analyses on six coal seams from the dataset. Our findings suggest no significant spatial correlation of Se within a given coal seam.