Distinguishing Geogenic Load and Anthropogenic Contribution to Soil Contamination in Mineralised Mountain Landscape of Ore Mountains (Czech Republic) Using Cumulative Distribution Functions

Abstract

In ore regions impacted by mining and metal smelting emissions, distinguishing between geogenic anomalies and anthropogenic contamination poses a significant challenge. In a study from two areas with different mining histories in the Ore Mountains, Czech Republic, we demonstrate that sampling of topsoils and subsoils respecting local geology and correct soil data treatment respecting soil textural variability effects are indispensable to the correct construction and interpretation of geochemical maps and identification of anthropogenic contamination by As, Cu, Pb, and Zn. The list of analysed elements must include both potentially toxic and lithogenic elements, otherwise natural controls of soil composition cannot be deciphered. By using empirical cumulative distribution functions, we found that local backgrounds for As/Fe and Pb/Ti are naturally elevated (5.7 to 9.8 times and 2.1 to 2.7 times higher, respectively) compared to the global averages. We constructed geochemical maps with topsoil minus subsoil concentrations to show the main directions of spreading anthropogenic contamination. The anthropogenic diffuse contamination contribution was calculated and expressed as an enrichment relative to the local background (16% and 12% for As/Fe and 17% and 14% for Pb/Ti, respectively). This corresponds to topsoil enrichment by ca. 15 and 14 mg kg−1 for As and ca. 35 and 42 mg kg−1 for Pb in the two study areas. The obtained estimates were comparable to the results from the local peat archives. The approach we used is efficient in deciphering natural and anthropogenic controls of PTEs in geochemically complicated areas.