ASSESSMENT OF HEAVY METAL CONTAMINATION IN WATER AND SURFACE SEDIMENTS OF THE MAHARLU SALINE LAKE, SW IRAN

Maharlu saline Lake is located in the SW of Iran. To assess the environmental pollution of the lake, the total concentrations of As, Cr, Co, Cu, Cd, Pb, Zn, Ni, Fe, and Mn were determined in the surface sediments and water of the lake. As and Cr were not detected in the water samples, however, the mean concentrations of other dissolved metals in Maharlu Lake water were 0.28 mg/l for Cu, 0.28 1 mu g/l for Cd, 5.17 mu g/l for Pb, 0.37 mg/l for Zn, 2.36 mu g/l for Ni, 2.88 mu g/l for Co, 10.4 mg/l for Fe, and 1.5 mg/l for Mn. Different water and sediment quality assessment approaches indicated that in this lake, metals can be divided into three different groups: (a) Co, Pb, and Cd. These metals have the highest enrichment factors (the mean values are 35.8, 76.9, and >36.6, respectively), geoaccumulation indexes (the mean values are >3), and contamination factors (11.1, 29, and 8, respectively) compared with other studied elements; thus, the Maharlu Lake is highly polluted with these metals, and they are mainly from anthropogenic sources; (b) Cu, Zn, and Ni. Their mean enrichment factor values are 6.6, 3.4, and 6, respectively; their mean geoacumulation indexes are <1, and their mean contamination factor values are 2, 1.1, and 2, respectively. The enrichment factor of these metals is higher than 10 only north of the lake. The Maharlu Lake is moderately polluted with these metals, and they are from both natural and anthropogenic sources; (c) Cr, As, Fe, and Mn. These elements have the lowest mean enrichment factor (1, 3.5, 2, and 4.2, respectively), geoaccumulation indexes (<= 0), and contamination factor (0.32, 0.91, 0.63, and 1.5, respectively) values; thus the Maharlu Lake is not polluted with these elements, and they are mainly from natural sources. Results indicated that the Maharlu Lake sediments have a high contamination degree (56.66). Comparisons with consensus-sediment quality guidelines reveal that Ni and Pb pose the greatest environmental threat to aquatic organisms. In order to protect the lake from further contamination, the treatment and recycling of wastewaters discharged into the lake is needed.