Alarming levels of mercury found in Vembanad sediments

Expert warns of possible entry of heavy metals into human system through fishes

Cause for concern:The presence of mercury was found to be 20 times higher than the permissible level at one point in the industrial region of the Periyar.

The sediments on the floor of Vembanad Lake near the industrial belt in Kochi are flush with toxic heavy metals like mercury at alarming levels, posing serious health hazards.

The presence of mercury was found to be 20 times higher than the permissible level at one point in the industrial region of the Periyar.

KUFOS study

This was revealed in an investigation carried out by the researchers of the Kerala University of Fisheries and Ocean Studies (Kufos) along the lake system.

The presence of mercury was found to be exceeding the permissible limits of 1 part per million in 10 of the 32 sample collection points. The carcinogenic heavy metal might have found its way to the lake system from the effluents released by the industries located on the banks of the river. It was near the effluent discharge points of some industrial units that the value of the toxic metal was found at alarming levels.

The study area was confined to the northern arm of the lake at the Periyar region to the southern arm at Thanneermukkam, said Anu Gopinath, Assistant Professor of the University, and also the Principal Investigator of the project. Martin Gopurathingal, Jose Mathew, Emi Sebastian and C.S. Neenu are the other researchers associated with the project.

The data analysis indicated that the value of mercury was at negligible levels when it proceeded to the southern region. Moreover, the value of mercury indicated threefold increase when compared to the earlier studies conducted in the ‘industrially polluted area of the Periyar’ in 1992, said Ms. Gopinath.

The entry of heavy metals into the human system through fishes could have disastrous health hazards. It would be the benthic fishes that would be quickly falling prey to the mercury contamination. The contamination of drinking water by traces of heavy metal is also a matter of concern, she said.

UNEP warning

The United Nations Environment Programme (UNEP), in a Global Mercury Assessment 2013 report, had pointed out that ‘mercury in aquatic environments can be transformed into methyl mercury, which is far more toxic to humans and animals and can enter and biomagnify in food webs more readily than other forms of mercury.” Considering the possibility of the heavy metal finding its way to benthic fishes, the researchers of Kufos were planning to conduct assessment in fishes, she said.