Potentially toxic element distribution in soils from the Ag-smelting slag of Kutná Hora (Czech Republic): Descriptive and prediction analyses

The distribution and environmental hazard of potentially toxic elements in the vicinity of a large smelter heap located in the traditional mining town of Kutná Hora, Czech Republic were studied. To understand their occurrence and to predict their mobility and deposition, trends and patterns in PTE distribution were related to soil properties and environmental variables. Slag samples and slag impacted soils were characterized by high 2 M HNO3 extractable PTE contents which generally increased with depth, but relatively low plant available fractions; Cd and Mn were the most available elements. Manganese availability was significantly higher in soils under vegetation canopy whereas availability of Cu decreased. Organic matter and pH were identified as significant variables controlling availability of Mn, As and Mn, Zn respectively. Availability of Pb and Cu had significant negative correlation with soil clay content. Mean values of Pb, Mn, Cu, Zn and As from sediment samples exceeded the background value for non-polluted alluvial sediment by 1.8, 1.5, 3.4, 9.8 and 1.3 times respectively. Despite the elevated presence of PTE in river sediments, only Mn and Zn were detected in water samples, but at levels which are not considered hazardous. Included in the paper is a method proposal for quickly and easily identifying threshold values of a chosen soil property which control accumulation of PTE in soil respective of their source. The slag heap at Kutná Hora is a proven source of PTE with evidence of their mobility/transport into the surrounding environment. Although the environment is highly heterogeneous, and the mobility of PTE can be dependent upon pedogenic, geologic, ecological, hydrological and climatic variables, overall the study area was characterized by relatively low availability of PTE, with a limited threat to healthy plant development in the immediate surroundings of the smelter slag heap.