Influence of Physico-Chemical Parameters in Spatial Distribution and Risk Estimation of Potentially Toxic Elements of Chembarambakkam Lake Sediments, Tamilnadu, India

The spatial distributions of potentially toxic elements (PTEs) (As, Cr, Cu, Ni, Pb and Zn) were measured for surface sediments of Chembarambakkam Lake, Tamilnadu, India. The measured PTEs are compared with sediment quality guidelines (SQG) to evaluate the toxicity level of sediments. The mean concentrations of As, Cr, Cu, Ni, Pb and Zn are 6.55, 106.23, 118.18, 33.93, 16.73, and 174.05 mg/kg, respectively. The concentrations of Cr, Cu, Ni, and Zn frequently exceeded some SQG. Observed elevated Pb concentrations (up to 245.00 mg/kg) in some sites of the Inflow Water Region (IWR) suggest significant impacts from traffic and industrial activities. All the calculated risk indices (Contamination Factor (CF), Degree of contamination (Cd), Modified degree of contamination (mCd), Pollution Load Index (PLI), Potential Ecological Risk (PER) and Mean ERM Quotient (mERM-Q)) are higher in Inflow Water Region (IWR) than the Outflow Water Region (OWR). While the overall PLI indicated no widespread pollution (mean = 0.37), values greater than 1.0 in several IWR sites pointed to localized contamination hotspots. Multivariate statistical analyses indicate that the physico-chemical characteristics, such as magnetic parameters (both Magnetic Susceptibility (MS) and Weight percentage of magnetic minerals (Wt. %), organic matter (OM %) and fine grain sized particles (silt and clay) influencing the concentration of PTEs and all calculated risk indices (PLI, PER and mERM-Q). Analysis of PTEs and their risk indices of randomly selected sand samples from IWR confirms that fine grain sediments (silt and clay) have the capacity to absorb the physico-chemical characteristics such as magnetic parameters (both MS and Wt. %) and OM (%) and also influencing PTEs concentrations and their risk levels. From this study, the people around the lake may get awareness about the influence of sediment characteristics in spatial distribution of PTEs and their contamination level of Chembarambakkam Lake sediments.