Metal/metalloid contamination and isotopic composition of lead in edible mushrooms and forest soils originating from a smelting area

Abstract

High metal contents in edible mushrooms growing in severely contaminated industrial areas pose an important toxicological risk. In the presented study, trace element (Pb, Cd, Zn, Cu, Ag, As, Se) contents were determined in caps and stipes of three different edible mushroom species ( Boletus edulis Bull. Fr., Xerocomus badius Fr. Gilb., Xerocomus chrysenteron Bull. Quél.). Additionally, information about the chemical fractionation of metals in separate soil horizons and Pb isotopic data from soils and fruiting bodies allowed a more detailed insight on the uptake mechanisms of metals by the studied mushroom species. Total metal and metalloid concentrations in the organic soil horizons reached 36 234 mg Pb kg − 1 ; 11.9 mg Cd kg − 1 ; 519 mg Zn kg − 1 ; 488 mg Cu kg − 1 ; 25.1 mg Ag kg − 1 ; 120 mg As kg − 1 and 5.88 Se mg kg − 1 . In order to evaluate the accumulation capacity of the studied species, bioconcentration factors (BCF) were calculated for separate trace elements. For selected metals (Pb, Cd, Zn, Cu), a modified BCF calculation (using EDTA-extractable concentrations of metals in soil) was proposed. High contents of Pb (up to 165 mg kg − 1 ) and Cd (up to 55 mg kg − 1 ) exceeded all the regulatory limits in all the studied species. This was also the case for Se (up to 57 mg kg − 1 ) in B. edulis. Intensive consumption of this species grown in such polluted areas can therefore pose toxicological risks for human health. A novel finding was that X. badius can act as an Ag accumulating species when grown at polluted sites due to the high concentrations of Ag (up to 190 mg kg − 1 ) in caps. Pb isotopic data showed that Pb originating from the recent air pollution control residues is present mainly in the exchangeable/acid-extractable fraction of the organic horizons and is taken up by fruiting bodies; especially in the case of B. edulis, where fast Pb accumulation occurs. Due to the high species-dependent variations of metal contents, the studied mushrooms are not suitable as bioindicators of environmental pollution.