Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
PGE metal-rich black shales in south China: mechanism of metal enrichment and environmental aspects – results in 2003
Abstract
The influence of Lower Cambrian metal-rich black shales and locally exploited and damped black shale-hosted Ni-Mo ore layers of south China on the concentrations of selected toxic trace elements in soils was evaluated, in order to better understand the mobility and to evaluate a potential risk of toxic trace element contamination for the environment, a sequential extraction analysis from A, B, C1 and C2 soil horizons in the area of the Jiepo-Ling Mo-Ni prospect (Zunyi region) was carried out, Geochimical analyses confirmed a significant enrichment of A-horizon in As, Mo, V and slightly also in Pb and Ni when compared with the local reference sample of blank soil, The study of the distribution of trace elements within the individual soil horizons revealed an anthropogenic contamination of A-horizon by As, Mo, Ni, Pb and Zn most likely by particles of metal-rich black shales blown out of exploitation and waste damp sites in the study area, The distribution of V and Cr in soils is controlled by the host rock, The results of sequential extraction analyses from individual soil horizons showed that almost all As, Ni, V, Cr and Zn are bound to residual fraction. A part of Mo (15,13-39,75 %) was found to be associated with organic matter/sulfide fraction, The distribution of Pb and Hg is rather erratic, indicating considerable mobility of these elements in the soil profile, in Hg-enriched horizons (B and C1) most of Hg (78,21-78,95 % of the total content) occurs in organic matter/sulfide fraction, The concentrations of Mo, Ni, Cr, V, Zn and Hg found in different parts of selected agricultural plants (e,g, tobacco leaf, corn grain, corn leaf, corn stalk) exceed normal values given by Kabata-Pendias and Pendias (1984), it is important to stress that a long-term consumption of these products could result in serious health problems to human population and domestic animals, Arsenic and lead were found in a range of normal values given for agricultural plants.
