Heavy Metals in Mycorrhizal Rhizospheres Contaminated By Zn–Pb Mining and Smelting Around Olkusz in Southern Poland

Abstract

Soils in areas of mining and smelting of Pb–Zn ores in Southern Poland are strongly enriched in heavy metals (Zn, Pb, Fe, Cd, Tl, As). The highest concentrations of Zn (<55,506 mg kg−1), Pb (<8,262 mg kg−1), Cd (<220 mg kg−1) and Tl (<67 mg kg−1) are linked to the fine fractions of upper soil layers in sites contaminated by past exploitation and processing of ores. The high stress of metals, and the negative influence of acid waste drainage has limited the development of flora and fauna in these areas. The increasing ability of plants to grow is due to the positive symbiotic action of fungi and bacteria. The mycorrhizal communities were identified in rhizospheres rich in unstable Zn–Pb–Fe sulphides such as sphalerite, galena, pyrite and marcasite and carbonates of Zn (smithsonite) and Pb (cerussite). They occur in associations with sulphates, e.g., gypsum. In parts of fungi, secondary mineral phases containing Zn, Pb, Fe and Mn occur. Metal-bearing aggregates formed during symbiotic action between myccorhiza and bacteria connected with them. They enhance the binding of bio-available ions of Zn, Pb and Mn in the most unstable phases. Metal contents in the mycorrhizal parts of the rhizospheric soils were determined by Atomic Absorption Spectroscopy. Mineralogical investigations involved X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry.