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.