A study on microplastics in the sediments of Vembanad, a Ramsar site, has indicated its extensive distribution in the lake. The abundance of microplastics recorded from the sediment samples was in the range of 96-496 particles per square metre. Its presence poses a severe threat of contaminating the food web through the clams and fishes in the lake.
The study, conducted by E.V. Ramasamy, Director, School of Environmental Sciences, M.G. University in association with S. Sruthy, research fellow, was published in the international journal Elsevier and included in Litterbase an international collection of over 1,000 studies brought out by marine researchers from the Alfred Wegener Institute (AWI), Germany, recently.
Microplastics are emerging pollutants of increasing environmental concern with particle size of less than 5 mm, which originate from successive degradation of larger plastic debris. The impact of microplastics pollution on the environment is not well known. The Vembanad study was the first of its kind, Mr.Ramasamy told The Hindu . Sediment samples were collected from 10 sites along the southern part of Vembanad lake during pre-monsoon. Two sites were located in the salt water dominant zone on the north of Thanneermukkam bund and the remaining eight were in the fresh water dominant zone on the south of the bund. The abundance of microplastics recorded from the sediment samples was in the range of 96-496 particles per square metre. Low density polyethylene (LDPE) was identified as the dominant type of polymer component of microplastics.
The lake receives discharge from seven major rivers and many streams and canals, and is a sink for many contaminants, including heavy metals. The local population largely depend on this lake for their livelihood such as agriculture, farming and fishing.
The ‘water residence time’ for the entire Vemband lake ranges between 114 and 185 days. “The Thanneermukkam bund remains closed for 4-6 months in a year, which prevents salinity intrusion from north of the bund to south.