Seasonal variation in physicochemical parameters and heavy metals in water of Upper Lake of Bhopal.

Heavy metal pollution of fresh water is the single most important environmental threat to the future. Upper Lake is a freshwater lake, which is the major source of drinking water in the city of Bhopal, the capital city of M.P., the central province of India, but due to anthropogenic activities this lake is being polluted. During the investigation heavy metals and physicochemical parameters were analyzed to determine the water quality seasonally in the year of 2006 and 2007. All the physicochemical parameters except DO (6.50-6.97 mg l⁻¹), Free CO2 (0.8-1.6 mg l⁻¹) and BOD (5.47-6.85 mg l⁻¹) were below the prescribed limit as recommended by Bureau of Indian Standards (BIS) for drinking water standards. In case of heavy metals, Ni (0.173-0.253 mg l⁻¹) and Cr (0.047-0.087 mg l⁻¹) were found beyond the prescribed limits (0.02 and 0.05 mg l⁻¹, respectively), whereas Pb (0.057-0.087 mg l⁻¹), Cu (0.016-0.020 mg l⁻¹) and Hg (0.0006-0.0011 mg l⁻¹) were within the safe limit. This study reveals that water of upper lake is partially polluted with heavy metals. It is recommended that strict vigilance and constant monitoring are needed to maintain water quality of the lake, which is a major source of potable water for the Bhopal city.

Bioaccumulation of heavy metals in fish tissues of a freshwater lake of Bhopal.

Contamination of heavy metals, namely, lead, cadmium, zinc, nickel, copper, chromium and mercury was evaluated in the samples of water and tissues of Labeo rohita and Ctenopharyngodon idella of Upper Lake of Bhopal collected during summer, rainy and winter seasons of 2005-2006. Different organs of the fishes accumulated varying quantities of different heavy metals. In L. rohita, accumulation of heavy metals was in the sequence liver>kidney>gills>muscles, and in C. idella, it was gills>liver>kidney>muscles. Zn was the highest accumulating metal in fish, whilst Hg was the lowest and was well corroborated with those of water. The values of heavy metals were so far well within the maximum permissible standard value of heavy metals for drinking water and for fish culture as prescribed by various national and international agencies.