Spatial distribution of soil enrichment in As in the vicinities of historical mines – a case study of mining sites in the Sudetes, SW Poland

Spatial distribution of As in a surface soil layer was determined in three historical mining sites in the Sudetes where As ores were exploited and processed over the centuries: in Złoty Stok (formerly: Reichenstein), Radzimowice (Altes Berg) and Czarnów (Evelinensgluck). Of those sites, Złoty Stok that operated until 1962, is the largest one. Thirteen patches of land situated in all those sites (6, 4, and 3, respectively) were chosen for analysis, each with an area of 2-5 hectares. They differed in terms of sources of soil enrichment in As, land topography and various types of land use or habitats. Both soils that developed on waste rock dumps and tailings, as well as those in their surroundings were examined. Simplified maps of As concentrations in soils were drawn based on 15-20 screening points located in each area. Arsenic distribution in soils in a mini-scale was examined by collecting multiple samples from several spots (each with an area of 1-10 m²). Gangue rock material disposed on the dumps was highly heterogeneous and locally contained over 1% of As. Total As concentrations in soil samples varied in a broad range: 72–193000 mg/kg, and the highest local enrichment in As was identified in alluvial soils along a stream affected by acid mine drainage. Various factors responsible for As concentrations in soils, including the amounts inherited from the parent rocks as well as various processes of redistribution, transport and secondary enrichment were discusses. Related environmental risk associated with a likely processes of further As mobilization and transport has been assessed with considering various scenarios. Additionally, soil enrichment and contamination indices, commonly used in the literature, such as geoaccumulation index Igeo, enrichment factor EF according to Sutherland and Nemerow pollution index PI, were calculated for each of the areas under study. Their ambiguity and limited suitability for the assessment of soil contamination with As were critically discussed.   

This research was funded by the National Science Centre of Poland; Project No. 2016/21/B/ST10/02221