Origin and Spatial Distribution of Heavy Metals in a Soil Map Unit of Sri Lanka

Abstract

Total concentrations and spatial distribution of heavy metals and their relationship with soil properties in soils are important in sustainable soil management. Therefore, a study was conducted to examine the total concentration of Cu, Pb, Ni, Zn and Cd and their relationships with soil properties and spatial distribution of these elements in Madawachchiya-Ranorawa- Elayapattuwa- Hurathgama-Nawagattegama soil association of the dry-zone of Sri Lanka. Soils were analyzed for organic carbon (OC), pH, EC, clay %, total Cu, Pb, Ni, Zn and Cd. Measured OC, pH, EC and clay ranged between 0.12-1.90 %, 4 .1 -8 .0 ,0.02-0.41 dS/m and 2-42 %, respectively. The concentrations of Cu, Pb, Ni, Zn and Cd concentrations ranged from 1.6-33.0, 2-19,1.6-32.0, 7-71 and 0.13-1.22 mg/kg, respectively. Significant correlations were observed between total Cu, Pb, Zn and OC in the soil. Total Pb was correlated with the clay %. Significant negative correlation was observed between Zn and EC. Principal Component Analysis (PCA) showed high loadings of Cu, Ni, Zn and OC on PCI whereas Cd and clay on PC3. Lead had high loadings on both PCI and PC3. Soil pH and EC showed high loadings on PC2. Significant correlation among Cu, Pb, Ni and Zn indicated a common source of origin for these four metals while Cd is having different source of origin. Similar spatial distribution pattern of total Pb, Ni, Cd and OC were observed. Clay % and OC content were the two important soil properties affect on the accumulation and distribution of analyzed heavy metals in these soils.