HEAVY METAL CONTAMINATION IN BOTTOM SEDIMENTS OF FIVE LARGE LAKES OF RAIPUR, CHHATTISGARH, INDIA

Abstract

Entry of heavy metals into aquatic environments generally takes place due to human activities like agriculture, combustion, industrial plants, sewage and settlements. Once entered into the aquatic system the heavy metals from different sources pose risk to the aquatic ecosystem. Therefore, a detailed investigation of heavy metals (Mn, Fe, Zn, Cr, Ni, Cu, Pb, V, Co, As, Mo and Cd) concentration in the bottom sediments of five large Lakes of Raipur was carried out. The data were interpreted in terms of Geoaccumulation Index (Igeo), Enrichment factor (EF), Contamination Factor (CF), Pollution Load Index (PLI) and Modified Degree of Contamination (mCd). The study indicates that the degree of heavy metal contamination in the bottom sediments of the five large lakes of Raipur follow the order Maharaja Bandh Talab> Budha Talab > Sarju Bandh Talab > Bhaiya Taraiya Talab > Khokho Talab. Fe, Zn, Cr, Cu, Pb and Mn pose problems to the ecosystem of the Lakes. The contamination level of elements follow the order Zn>Fe>Cr>Mn>Pb. The high Fe, Cr, Cu, Zn, Pb concentrations in the sediments of Lakes are mainly caused by the use of pesticide and fertilizer in agricultural areas and runoff from settlements without sewage systems. The highly toxic heavy metals can have adverse impact on the aquatic organisms including fishes. This study warrants a detailed ecotoxicological investigation in the lakes followed by execution of Lake rejuvenation programme.