When you casually fling a plastic bottle or a wrapper out the car window, you could be sending the plastic on an odyssey that may eventually take it to the sea — even if that is thousands of kilometres away — via the nearest drain that could be emptying into a stream, which may be meeting a river that merges with a bigger river, which finally snakes its way to a sea or an ocean.
Seems far-fetched? Consider this. In 2021, scientists at Japan’s Kyushu University estimated that there were 24.4 trillion microplastic pieces in the world’s upper oceans — roughly equivalent to 30 billion half-litre water bottles. It’s estimated that 80% of the plastic in the ocean comes from land-based sources, although this percentage may vary by region.
Oceans have turned into one of the biggest sinks for plastics. IUCN estimates that while over 400 million tonnes of plastic are produced annually across the world, at least 14 million tonnes end up in the ocean each year — that’s equivalent in weight to around 157 aircraft-carrier warships. Plastics make up 80% of all marine debris found from surface waters to deep-sea sediments.
This is an ocean-sized problem in multiple ways. To begin with, the ocean is not a permanent sink. What goes around comes around. Plastic doesn’t decompose but the action of water currents and sunlight breaks it into tinier and tinier pieces. These microplastic pieces are consumed by fish and other marine creatures. Microplastics return to land — and on the dinner plates of people — via the fish caught in the seas (or rivers and other water bodies).
Plastic impacts life in the oceans, making animals sick and starving them by filling up their guts. Hundreds of marine species suffocate or get entangled in the material. Plastics disturb the food webs, block sunlight from reaching plankton and algae, and wreak havoc on marine ecosystems in many other ways.
In India, recent research shows that the threat of microplastics spreading to humans through fish is looming large, as the level of these plastic pollutants in the sea is increasing. A study by the Tamil Nadu Pollution Control Board (TNPCB) showed that people living near 19 estuaries in the state were likely to consume nearly 800 pieces of microplastics through fish and around 2,800 items of microplastics by consuming shellfish.
Adyar estuary in Chennai had the highest microplastics pollution which is likely due to indiscriminate discharge of treated and untreated domestic and industrial waste. Apart from studying the water and sediment samples, a survey was conducted among 70 families living near the estuaries on the quantity of fish and shellfish consumption. In 2021, researchers found microplastics in 80% of the seven popular fish species sold in Pattinapakkam fish market, one of the four major fish landing centres in Chennai.
The Central Institute of Fisheries Education (CIFE) had found in abundance a variety of microplastics in the gastrointestinal tracts and gills of croaker fish off Mumbai's coastal waters in a survey conducted in 2019-20 and published in the Elsevier journal. It found that the gastro-intestinal tract and gills of croaker fish contained microplastics less than 100 micron in size. “Black and blue were the most predominant colours of microplastics inside the tissues," said the study.
Rising pollution from untreated sewage and free-flowing domestic garbage entering the sea is causing fish to move further and further away from the coast. Latest case studies suggest 79% of the waste flowing into Mumbai’s creeks and rivers is plastic. Compared to a few decades ago when most fish used to be netted along the Mumbai shoreline, hundreds of fishermen are today taking their trawlers up to 24km into the sea. Most of them stay out for three to four days, burning diesel to maximise the catch. The cost of fishing has thus gone up substantially over the last few decades, and so have prices for the consumer.
Such is the build-up of waste in the sea that the disaster management cell of the Mumbai’s municipal corporation (BMC) fears that flood waters in the event of a severe deluge may not recede fast as the garbage pile-up along the shoreline has upset the gradient needed for water to flow freely into the sea.
There are no quick fixes to the plastic pollution of our oceans. The solutions lie in tightening and modernising our waste disposal systems; bringing more and more waste into the recycling loop; guarding more zealously the gateways to the seas (the rivers and estuaries) and, finally, creating less waste by consciously using fewer plastics and shifting to sustainable consumption.
-- with inputs from U Tejonmayam & Chittaranjan Tembhekar