Investigation of phosphatic-vermiculite-heavy metal interaction and the implication to pollution of Solati River in Limpopo Province, South Africa

摘要

A phosphate mine in Limpopo Province of South Africa disposes of substantial phosphate-vermiculite sludge as a by-product. This study investigated the implication of phosphate-vermiculite interaction with heavy trace metals to pollution of a nearby river, evaluating the possibility of using the phosphate-vermiculite mix as a sink and possible agent of reduction of metal solubility. Analytical data of Zn, Cd and Pb were compiled using three sets of samples; namely from the aqueous phase by conventional grab sampling for total concentrations, data from diffusive gradient in thin-films (DGTs) for bioavailable concentration and total concentration from stream sediments (solid phase). The samples from the three different methods were analysed for trace metals using IC and ICPMS whereas samples of phosphatic-vermiculite admixture were characterized using XRD, XRF, as well as physical and physico-chemical properties of the phosphate-vermiculite material.