Wetland facing threat

Private industries, public sector units such as Cochin Port Trust and Cochin Shipyard and Kochi city are upsetting the ecosystem of Vembanad kole wetland system by unloading huge quantities of chemical and industrial refuses and sewage into the wetland system each day.The State of Environment Report brought out by the Kerala State Council for Science, Technology and Environment of the State Government has detailed the hazards faced by Vembanad, which is one of the three Ramsar sites in the State.The chemical and engineering industries located at the industrial belt of the Greater Cochin area are discharging around 260 million litres of industrial effluents into Vembanad Estuary every day. The Vembanad estuary receives effluents from chemical and engineering industries, food and drug manufacturing units and also from paper, rayon, rubber, textiles and plywood industries.Like the private industrial units, the public sector undertakings are also contributing to the pollution and environmental damage of the lake. The Cochin Shipyard and the Cochin Port are releasing sizable quantities of waste oil, paints, metal and paint scrapings into the estuary. The Vembanad wetland is the worst affected wetland in Kerala due to urbanisation and population growth, industrial development, agriculture, aquaculture, transport and tourism, the report said.
Kochi City alone generates 2,550 MLD of urban sewage that enters the Vembanad directly. Waste from slaughterhouses, markets and hospitals also reach the system through the extensive network of canals in Kochi and through the rivers. Authorised and unauthorised sand-mining is common in all areas of Vembanad wetland system. The uncontrolled mining of shells from the lake is also posing a threat to its ecosystem, warned the report.The Vembanad estuary serves as a sink for domestic and urban sewage from Kochi. The sewage from other municipalities is also directly discharged into the Vembanad Lake without any treatment. The sewage collection system of the Kochi Corporation empties its waste containing high particulate organic matter into the estuary through Padiyathukulam, Kalvathy, Rameswaram, Pulimutty and Thevara canals.
High level of pollution
Sixteen major industries discharge nearly 260 tons of organic waste into the system each day. The industries also contribute to the heavy load of ammonia in water. The effluents from industries carried heavy load of ammonia into the system. The load of ammonia was found to be ranging between 432 and 560 parts per million against the accepted lethal limit of 2 to 5 parts per million. This, along with pollutants like acids and suspended solids contribute to the extreme toxic levels in the system. It was observed that pollutants like Copper, Zinc, Lead, Nickel and Iron were highest at the effluent discharge point and decreased gradually towards the bar mouth.The threats posed by activities of the most stakeholders on the health of the Vembanad ecosystem are severe and dangerous to the levels exceeding the carrying capacity of the system. Studies on the biological process of Cochin Estuary revealed that the biodiversity of Cochin backwaters was on the decline, the study pointed out.
Shrinkage of lake
The report pointed out that the shrinkage of the Lake to 37 per cent of its original area due to land reclamation was the most important factor of environmental consequence. It is estimated that 21 per cent of the reclamation of the Lake took place during the last 15 years.
The depth of the lake has also been reduced by 40 to 50 per cent in all zones except between Aroor and Wellingdon Island and Cochin Port zone.

The Hindu , sep 24