Friday, September 30, 2011

Increasing pollution levels choking India’s lakes

By The Economic Times - India

Increasing pollution levels are threatening fresh water bodies worldwide, but the problem is assuming the shape of an environmental crisis in a developing country like India.

A study of lakes in Thane, Maharashtra, undertaken by environmental chemist Pravin Singare of Bhavan's College, Mumbai, and colleagues, shows how they are being contaminated by the byproducts of urbanisation and industrial boom, symptomatic of the slow death of most of India's water bodies.

Thane's burgeoning population, thanks to its proximity to Mumbai, and the metro's heavy industrial profile, are apparently choking its six lakes, with the unchecked discharge of sewage, pesticides and industrial effluents. The lakes are - Jail, Upavan, Masunda, Makhmali, Rewale and Kalwa.

The discharge of sewage results in large-scale outbreak of water-borne infections and diseases, epidemics and the growth of wild weeds, M.S. Kodarkar, secretary, Indian Association of Aquatic Biologists (IAAB), Hyderabad, told IANS.

"Classic examples" are lakes in Loktak (Manipur), Ropar and Kanjli (Punjab), Sukna (Chandigarh), Bhopal and the Pong dam (Himachal Pradesh), where the growth of water hyacinth, a wild weed, became instrumental in causing endemic diseases, according to a report by M.S. Reddy and N.V.V. Char, former secretary and former commissioner (Eastern Rivers), respectively, in the union water resources ministry.

Studies have shown presence of high levels of lead, cadmium, arsenic and manganese in Srinagar's Dal Lake which find their way into the fish consumed by people, posing health risks.

Some of the biggest polluters are hundreds of houseboats which dump waste into the lake. Pesticides used on floating vegetable gardens are also seeping into the waters.

"The lakes are primarily most easily accessible sources of freshwater," which bestows "a number of ecological, economical and socio-cultural benefits on its immediate environment", says Kodarkar, also a member of the International Lake Environment Committee.

Water bodies are known to recharge the groundwater table, act as a source of water supply, boost aquaculture (fisheries, prawns), regulate and control floods, condition climate, sustain biodiversity and provide nutrient-rich silt as manure.

In the larger context, South Asia, with over a fifth of the world's population, is facing a serious water crisis, warns Kodarkar. This region is "in the grip of flood and drought cycles and there is a need to have a long-term strategy for management of its water resources".

The presence of heavy metals like iron, copper, nickel and zinc, detected in Thane lakes above permissible levels, and also the alarming concentrations of mercury, arsenic and cadmium are wrecking their complex and fragile ecosystem.

Exposure to mercury and its compounds can damage the brain, kidneys and developing foetuses. Studies have found it may cause irritability, affect vision, hearing and memory. It also inhibits growth of aquatic plants, says Singare.

Arsenic poisoning through water can cause liver and nervous system damage, vascular diseases and skin cancer. Plants absorb arsenic easily and so they could be present in the food chain. In the recent past, arsenic was found in drinking water in six West Bengal districts.


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