Microplastics are present in Mhigher quantities farther out Min the sea than along India’s eastern coastline, researchers have found. Experts from the National Centre for Coastal Research (NCCR) studied the pollution levels along 1,200 km of the east coast and found higher concentrations of microplastics at about 10km into the sea compared to 3km from the coast. The findings could mean far-reaching implications for human health and environment. Plastics release greenhouse gases when they degrade and break down, contributing to climate change. They can also cause an increase in sea surface temperature and sealevel rise, and pose threats to ocean life and marine ecosystems.
The NCCR study found an average concentration of 53,000 particles per sq km in the water and between 110 and 308 particles per kg sediment. More than 50% of the particles found, particularly in the offshore area, were less than 1mm in size, making them easily ingestible by fish and other aquatic lifeforms.
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The study found that major rivers and lakes flowing into the Bay of Bengal are carriers of tiny plastic particles. Though this was known before, it’s the first time that Indian researchers have mapped the path of transportation of microplastics from its source, on land, to sink in the Bay of Bengal.
The study found an abundance of microplastics in both water and sediment 10 km offshore from Krishna River, Penna River, and Chilika Lake. Nearshore and offshore samples collected from Pulicat Lake in Tamil Nadu had the lowest concentration of microplastics. “Chilika Lake has become a sink, receiving plastic wastes from 192 villages, 52 rivers and rivulets, tributaries of the Mahanadi river, and from 2 lakh fishermen,” says NCCR scientist Pravakar Mishra.
By comparison, Pulicat Lake sees less anthropogenic activities. The lake’s mouth is blocked with sand for large parts of the year, thereby not allowing pollutants to enter the sea. “Sources such as effluent treatment plants, stormwater drains and dumping of solid waste near riverbanks, turn rivers into carriers of plastics,” says Mishra.
Most particles found at the study locations were polyethylene and polypropylene, used in packaging material. As microplastics break down, tiny specks are transported to the sea from rivers and lakes. The currents push them further deep. The size, shape, gravity, density, water depth, distance from shoreline affect the transport of particles.
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As these particles reach the marine ecosystem, the chemicals added during the manufacturing process begin to leach, affecting aquatic life. Marine organisms ingest these particles thinking it’s food. When humans consume these seafoods, they are exposed to microplastics and the associated pollutants.
“The results from our study will serve as the primary data in framing the National Marine Litter Policy, which is expected to be unveiled in six months. The policy can help in regulating or stopping activities along the coast that may be the source of pollution,” says Mishra. (Times of India)
