groundwater in Ankleshwar Industrial Estate in Bharuch district in Gujarat is highly contaminated. The contamination is a result of more than 3,000 industrial units in the estate: around 270 million litres of liquid waste and 50,000 tonnes of solid waste is generated annually. This often becomes a problem for people living in villages around the industrial estate because they depend on groundwater to meet their daily needs. Even crops growing on contaminated soil absorb the pollutants.
Researchers from the department of geology, Pune University, are carrying out studies on heavy metal contamination in groundwater in the area, the first ever scientific evaluation, to develop a mitigation strategy. There will be further studies on heavy metal contamination in soil and plants followed by the impact of pollutants on the Arabian sea where the effluents finally reach.
The study, published in the March issue of Environmental Geology, mapped nine heavy metals in groundwater using Geographic Information System. The researchers collected 37 samples from wells and one sample from Amla Khadi, a tributary of Narmada river. They found that water samples, taken before monsoon, had high levels of molybdenum followed by zinc, lead, nickel, cobalt, iron, cadmium and chromium.
The highest concentration of molybdenum was 2,760 parts per billion (ppb), whereas the who standard is 70 ppb. High concentration of chromium was linked to the pigment and pharmaceutical industry; lead was linked to fertilizer and paint industry and the highway (nh-8). Cobalt was high in areas where coal was used as the major source of energy for brick kilns (see box: Heavy weights). The researchers found that Amla Khadi was among the major sources of the heavy metals. Other sources included effluent-laden channels, oil field areas and highways.
They also collected groundwater samples after monsoon and found that the concentration of heavy metals increased in groundwater after the rains. Using this, they developed an index, which was published in the April issue of Current Science.
Though a mitigation strategy is yet to be finalized, measures such as lining the stream to control the percolation of heavy metals into the soil, and thus groundwater, may be employed, says N J Pawar, head of department of geology at Pune, and the lead researcher. Releasing the effluents according to the carrying capacity of the stream will also be considered, he added.
Mitigation measures will address the problem of groundwater contamination and benefit villagers living around the industrial estate. The state currently follows a supreme court order directing the government to provide safe drinking water. But not everyone gets it, says Rohit Prajapati, Paryavaran Suraksha Samiti, Vadodara, an ngo in Gujarat.
Although studies on the chemicals impact on health have not been carried out, a high incidence of cancer, asthma and kidney problems have been reported. Industry consultants test the water and say that everything is under permissible limits. With so many industries in the area, this is hard to believe, says Pravin P Sheth, a local journalist.
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