Study of chemical forms of heavy metals collected from the sediments of tin mining catchment

Abstract

The chemical speciation of heavy metals (arsenic, chromium, copper, lead, zinc and tin) in the sediments of the former tin mining catchment Bestari Jaya, Peninsular Malaysia was determined using the latest version of the Community Bureau of Reference, the BCR 3-step, sequential extraction procedure. A fourth step was introduced for the digestion and analysis of the residue. The analysis of total metal content was carried out using microwave-assisted acid digestion. The percentage of each metal obtained from the four steps extraction (acid-soluble + reducible + oxidisable + residual) is in good agreement with the percentage of total metal content obtained from microwave digestion, which implies that the accuracy of the procedure. The degree of pollution in catchment sediments was assessed using geoaccumulation index I geo and pollution intensity I POLL . The results indicates that: (1) the sediments have been polluted with arsenic (8.8%), chromium (12.9%), copper (17.4%), lead (19.5%), zinc (14.9%) and tin (33.8%) and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggests that catchment sediments have background concentrations of all the studied metals (Igeo < 0); (3) high I POLL showed that all of these heavy metals pose a high environmental risk; and (4) the mobility order of metals in sediments at S1 and S2 was Sn>Pb>Zn>Cr >Cu >As, whereas at S3, S4 and S5 it was Cu>Pb>Zn>Cr>Sn>As. In conclusion, acidic pH, total organic carbon, scavenging ability and co-precipitation (inclusion, occlusion and adsorption) of studied metals with nonmetals could account for changes in the geochemistry of the catchment sediments.

Impact of copper sulfate application at an urban Brazilian reservoir: A geostatistical and ecotoxicological approach

“…In terms of the total amount of copper applied per water body, the Guarapiranga reservoir showed the highest value. Its sediment copper concentration is now so high that it is comparable to levels in mining reject pools (Bai et al, 2011;Ashraf et al, 2012;Chen et al, 2013;Gharibreza et al, 2013). Hanson and Stefan (1984) also found copper concentrations in water samples that suggested copper sulfate did not become strongly fixed in the sediment.…”