Ambient concentration of soil heavy metals in Indonesian tertiary and quaternary geologic formations: an explorative study

Abstract

Abstract In natural conditions, heavy metals in soils are inherited from rocks and minerals weathering. This study aims to determine the ambient concentration of heavy metals in soils developed from several rock types from tertiary and quaternary geological formations and their relationships. Composite soil samples were taken at 0-30 cm depth in sites far away from anthropogenic contamination of heavy metals, roads, and lands where solid and liquid wastes were probably discharged. Total concentrations of Aqua Regia extracted soil Cd, Cr, Cu, Ni, Pb and Zn were determined by AAS. Soil mineral types and amount in sand fraction were determined by polarization microscopy. The overall ambient total concentrations of soil Cd, Cr, Cu, Ni, Pb, and Zn in mg.kg−1 were 2.0-19.7; 0.4-5.3; 1.1-73.3; 0.9-30.5; 17.8-62.9; and 8.1-419.5, respectively. The relationship between soil minerals and ambient concentrations of these metals was unclear. However, among the soil samples analysed, high concentrations in mg.kg−1 of Cd (10.5-19.7) were found in soils developed from clay and sand sedimentary and intermediary volcanic tuff rocks, Ni (15.0-30.5) in soils on andesitic-basaltic and volcanic tuff rocks, Pb (57.4-62.9) in soils on granitic rocks, and Zn (119.6-419.5) in soils on andesitic-basaltic rocks, while for Cr and Cu was spread evenly across all parent rock types.