Assessment of Lead and Cadmium Levels in Selected Soils of Anuradhapura District of Sri Lanka

Abstract

Various heavy metals have been reported as dangerous agents to the human health and wildlife when they occur in the environment at high concentrations. Cadmium (Cd) and lead (Pb) compounds are classified as hazardous metals. In this study, concentrations of Cd and Pb were investigated in cultivated and uncultivated lands of both upland and lowland areas at two depths (0-15 cm, 15-30 cm) in soils of Anuradhapura district. The design was Completely Randomized Design (CRD) in three factor factorial with three replicates. Total Cd and Pb and available cadmium and lead in the soils were determined. In addition other soil properties such as total organic carbon (TOC), microbial biomass carbon (MBC), water soluble carbon (WSC), and permanganate oxidizable carbon (POC) were also measured. Cd was not detected (detection limit 0.02 mg/kg) in any of the samples. The total Pb and available Pb ranged between 1.61 to 11.72 mg/ kg and 0.982 to 7.202 mg/kg, respectively. Total Pb and available Pb did not show any significant difference with elevation, land-use and depth. As the maximum permissible level of soil Pb is 150-300 mg/kg, according to European Community standard, values of the tested soils are safe in terms of Pb hazard. Total Pb and available Pb showed a highly negative correlation with distance from main road. Both total and available Pb showed weak negative correlations with TOC and water soluble carbon whereas both total and available Pb showed significant negative correlation at 95% confidence level with MBC.