Baseline concentrations of some trace elements in Alfisols of Sri Lanka

Abstract

A study was conducted to establish the geochemical baseline concentrations of Cu, Pb, Ni, Zn and Cd to assess the possible trace metal contamination in a mapping unit in Sri Lanka consisting of Alfisols. Soils were analyzed for organic carbon (OC), clay %, pH, electrical conductivity (EC), and HNO3 acid soluble metals. Standard reference material (SRM-2586) from National Institute of Standard and Technology was used for the quality assurance. Nitric acid soluble Cu, Pb, Ni, Zn and Cd concentrations of soils were ranged from 1.56–33.5, 2.19–19.2, 1.58–32.2, 7.44–71.3 and 0.13–1.22mgkg−1 respectively. Established upper limits of the baseline ranges of Cu, Pb, Ni, Zn and Cd were 26.5, 18.0, 33.9, 51.2 and 1.38mgkg−1 respectively. All the tested metals have not reached the contamination level compared with the derived upper baseline limits except very few samples for Cu, Zn and Pb. According to the results of correlation analysis of metal–soil properties and metal–metal, the sources of Cd in studied soils can be different from the sources of other measured elements. Principal component analysis of trace metals identified two principal components (PCs) attributing 67.1% of the total variability. Accordingly, Cu, Pb, Ni and Zn were associated with PC 1 and Cd was associated with PC 2. Based on the correlation analysis and principal component analysis, source of origin for Cu, Pb, Ni and Zn could be suggested as lithogenic while an anthropogenic origin was evident for Cd in studied soils.