Vembanad Lake among most polluted in the world, microplastic found in it can contaminate food web

Microplastic particles (MPs) were recovered from all the sediment samples, indicating that they are distributed extensively in the lake.

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Vembanad Lake, the longest lake in India and the largest in Kerala, is one of the most polluted water body in the world.

According a study that maps the most polluted marine places in the world, it was found that microplastics were present in all the sediment samples taken from the Vembanad Lake. An emerging pollutant, microplastics are less than 5 mm in size and can be very hazardous to the environment. Researchers from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research in Germany have compiled over 1,000 scientific studies in marine pollution and have created LITTERBASE, an interactive global distribution map.

Vembanad Lake, which features on LITTERBASE, is a Ramsar site, which means it is a wetland of international importance. The study by S Sruthy and EV Ramasamy collected samples from ten sites across the lake. Microplastic particles (MPs) were recovered from all the sediment samples, indicating that they are distributed extensively in the lake. Low density polythene was found to be the dominant polymer type.

The researchers stated that this poses a risk of contaminating the food chain since the locals consume fishes and clams from the lake. "As clams and fishes are the major source of protein to the local population, the presence of MPs in the lake becomes critically important, posing a severe threat of contaminating the food web of this lake. This study, being the first report from India on MPs in lake sediments, provide impetus for further research on the distribution and impact of this emerging pollutant on the biota of many aquatic systems spread across India," the authors wrote.

A study conducted by the National Centre for Earth Science Studies (NCESS) last year stated that Vembanad lake may vanish in 50 years. "Presenting the findings at a workshop on climate change here, former scientist Ajayakumar Varma, who led the study, said 55,000 hectares of backwaters had been reclaimed and converted into polders for paddy cultivation. The carrying capacity of the lake had gone down from 2.45 to 0.56 cubic km, registering a decline of 78 per cent, while the urban agglomeration had increased five times over the last 50 years," The Hindu reported.

LITTERBASE presents the distribution of litter across the world and its interaction with wildlife, with a focus on the marine realm, i.e. beach, sea surface, water column, seafloor, etc. "Interaction," the site explains, "refers to encounters between wildlife and litter items. Ingestion was the most frequently observed interaction, followed by entanglement, which affects motility, often with fatal consequences. In addition, many species can settle on floating litter. If floating litter is carried over long distances by ocean currents, associated rafters can invade new areas."1,249 species of organisms have been affected across the world by litter. And some of the most common causes of litter are glass, metal, rope, textile, cardboard, plastic and cigarette buds.

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