Lead, cadmium, nickel, and zinc contamination of ground water around Hussain Sagar lake, Hyderabad, India

Abstract

Metals and metallic compounds are important components of the human environment and many of these compounds are essential for human health. The mobilization of various toxic metals in our environment, however, can cause excessive exposures which may be hazardous to human health (Underwood, 1979). Metal pollution comes from both natural and anthropogenic sources (Moore and Ramamoorthy, 1984). Of the various sources of water pollution, one of the most important is however, industrial waste water directly entering aquatic systems. This has resulted in the transformation of lakes into sewage lagoons. Lake Hussain Sagar is a typical example of an industrially polluted lake, situated in the heart of Hyderabad city. The lake is heavily contaminated by various metats~ (Mazharuddin et at 1985). The lake has an area of 4.83 Km Z with mean depth of 2.5 m. Apart from minor inflows from the city, the source of water to the lake is the Kukatpatty channel, which passes through the industrial zone of the city (Fig. 1). More than 400 industrial units which manufacture chemicals, drugs, paints and machine toots are located on its banks (Simhachatam, 1975). The source of the heavy metal pollution is leakage from overloaded sewers draining the industrial belt which run in to this channel. Some of the industries dump their untreated and partially treated effluent directly into the lake. In the past 2 decades the quality of the water in the lake has deteriorated due to the impact of rapid urbanisation and industriatisatio n. A study of heavy metal contamination by Zafar et al. (1976) has revealed that heavy metals in different parts of the lake basin exceeded normal limits. In the recent past attempts were made to study water chemistry and heavy metal impact in the water and sediment of Hussain Sagar take (Khan 1983, Khan and Seenayya 1985, Prahtad and Seenayya 1987). However, the impact of metal contaminated lake on the quality of ground water by seepage has been overlooked. Because the ground water is used in addition to municipal surface water, to augment water supply during summer by more than half a million city's