- The Ganges and its tributaries are major rivers that carry huge loads of plastics into the ocean.
- Besides the Ganges, many researchers investigating the presence of plastics, in other freshwater lakes and rivers in India are finding microplastics (plastic particles less than 5 mm in size) in every sample tested.
- Plastic litter and plastic equipment used in the fishing industry are major sources of the plastic waste generated as per multiple studies.
In an effort to identify plastic accumulation and leakage hotspots along the Ganges river, a recent project in three north Indian cities found that roughly 10–25% of all the plastic waste generated was littered and was not routed into recycling or appropriate waste disposal channels.
This litter, which is either generated in or accumulates in the different cities’ hotspots is a major source of plastic leaking into the riverine system in the area, especially during the rainy season. Much of the litter was multilayer plastic packaging, disposable bottles and cutlery, nylon sacks, and polythene bags.
The CounterMEASURE project by the United Nations Environment Programme (UNEP) with funding from Japan, launched in 2020 to track and survey the leakage and movement of plastic waste in Asia and the Pacific, particularly in Ganges and Mekong rivers. In India, the project has been deployed in Haridwar, Agra, and Prayagraj (also known as Allahabad) along the Ganges to identify plastic accumulation and leakage hotspots – places within and around the cities where a higher than normal amount of plastic piles up and eventually enters the river.
In each city, physical surveys of geographical areas were combined with data from GIS (Geographical Information System) mapping to chart out land and drainage topologies and human land-use patterns, outlines a report published by the National Productivity Council (NPC) in partnership with the United Nations Environment Programme (UNEP). Surveys and clean-up drives then provided information on plastic litter, which was combined with the physical survey data to gain an understanding of the plastic accumulation and leakage hotspots within each city.
The clean-up drives to assess plastic litter were held in select hotspots. “Each clean-up session at a hotspot required at least 40–50 volunteers and safai karamcharis from the local municipality to work for an entire day to collect, segregate, and pack the plastic waste for further analysis at our laboratories,” said Amit Jain, Technical and Plastic Pollution Consultant at UNEP India for the project CounterMEASURE at the NPC.
The clean-up drives were conducted in a scientific manner with clearly marked grids and turned out to be good learning opportunities for those involved, said an NPC team member. “At one of our clean-up drives in Agra near the Yamuna river, we needed 40–50 gunny bags to hold all the waste collected,” she added.
Haridwar, the second-largest city in the northern state of Uttarakhand generates close to 11 tonnes of plastic waste as untreated waste and litter on a regular day. The city, regarded as a holy place in the Hindu religion, may generate more than twice this amount of plastic waste during festivals, found the CounterMEASURE project. Much of this plastic waste is either directly dumped at the Ganges ghats (embankments on the banks of the Ganges where pilgrims bathe and offer prayers) or is illegally dumped at vacant sites. The project identified 17 leakage hotspots in Haridwar including areas such as vacant lots, slums/areas with open drains, and sluice valves at barrages.
In the neighbouring state of Uttar Pradesh, in the city of Agra, an estimated 10–30 tonnes of plastic waste from 9 hotspots make their way into the Yamuna river, which is a major tributary of the Ganges. Much of this leakage seems to occur from riverside slums where garbage collection is poor, and plastic waste enters the river through open drains. A significant amount of the plastic in the river also consists of thin plastic sheets (used in sweet shops) or comes from the industrial sector as trimmings of synthetic leather and synthetic rubber from the footwear industry.
Meanwhile in Prayagraj, about 500 kilometres from Agra, roughly eight tonnes of plastic litter per day are estimated to leak into land and riverine ecosystems. A majority of this is household plastic waste often dumped in open areas, many of which are in flood zones. The leakage scenario in Pragyaraj appears to be the most diffuse of all three cities with almost 100 hotspots identified across the city limits.
World’s water bodies turning into plastic soup
Plastics are now found in almost every ocean, sea, river, wetland and lake on the earth. Even remote areas like the alpine lake Sassolo in Switzerland, which is hundreds of kilometres away from any human habitation, have been contaminated by plastics.
The first ever report of plastic in the oceans has been traced to 1965 when an old-fashioned metal box used to monitor plankton snagged a plastic bag off the coast of Ireland. However, the issue of marine plastic litter truly came into the spotlight with the discovery of the Great Pacific Garbage Patch in 1997. This patch stretches across 1.6 million square kilometres, and contains plastic not only on its surface, but all through the water column and on the ocean floor.
Research has shown that rivers are like highways that transport 0.4–4 million metric tonnes of plastic from human inhabited land into the oceans.
A recent study, published in April this year, states that roughly 1000 rivers account for 80% of all the riverine plastic waste that flows into marine environments. While previous research from 2018 identified ten of the largest rivers in the world as the top plastic waste carriers — including the Indus, Brahmaputra, and Ganges from India — this new study reports a more complicated picture. It finds that smaller rivers that pass through heavily populated areas can often carry more plastic than larger rivers.
As of now, much of the data on plastic waste in water bodies is from marine environments as research has mostly been focused on plastic pollution in the oceans. Research on fresh water bodies has lagged behind; consequently, little is known about how plastic leaks into and is transported by riverine systems.
In 2018–2019, one of the first expeditions to assess the full extent of plastic waste carried by the Ganges was undertaken by an all-women crew of scientists and engineers in India and Bangladesh. The Sea to source: Ganges River expedition, backed by the National Geographic Society, was at that time the world’s first ground-truthing effort to verify the quantum of plastic load that a freshwater body carries to the sea and substantiate theory as well as models proposed in research.
Macroplastics and microplastics in the Ganges
In addition to the plastic litter, another source of plastic pollution in the Ganges is ghost fishing gear — abandoned, lost, or discarded nets and other plastic equipment used by the fishing industry. A 2020 study on riverine plastic pollution from fisheries, which included sampling sites along the length of the Ganges from the Bangladesh coast to the Himalayas in India, found higher levels of waste fishing gear near the sea. This is probably due to higher levels of fishing activity and downstream accumulation of the fishing gear in these areas, indicates the study. It is widely known that the nets, ropes, string, floats and line, which comprise the ghost fishing gear can entangle and kill freshwater animals such as Gangetic dolphins, turtles, and smooth-coated otters.
The leakage hotspot analyses and work on ghost fishing gear, however, only expose the tip of the plastic waste iceberg in the Ganges as they deal solely with macroplastics – plastic pieces that are larger than 5 mm in size and usually clearly visible to the naked eye. Macroplastics entangle, choke, and kill millions of aquatic animals every year; macroplastics floating on ocean surfaces may also affect surface temperatures and optical properties of water columns and through them, cause unanticipated climate change effects. Besides these effects, macroplastics cause further issues by fragmenting into smaller pieces known as microplastics.
Microplastic particles are smaller than 5 mm in size and are either generated from macroplastic disintegration or manufactured as microbeads (less than 1 mm in size) that are used in biomedical devices and personal care products like face washes, scrubs, and tooth pastes.
These tiny pieces of plastic, however, have big impacts. Microplastics are often hotbeds of antibiotic resistance as they support the formation of layers of adherent microorganisms. They may also be vectors of heavy metal contamination in ground and surface water systems. In addition, microplastics are ingested by a wide variety of aquatic life forms including plankton, fish, and molluscs. These particles have infiltrated the entire marine food web, and eventually also end up in humans. While microplastics are known to harm aquatic life, their effects on humans are still being studied.
A study in April this year, used water samples from 10 sites along a 2575 km stretch of the Ganges to estimate microplastic contamination in the river. The results indicate that Ganges surface waters contain 0.026–0.051 microplastic particles per litre (or 26–51 particles per cubic metre); roughly 90% of these were plastic fibres, while the rest were plastic fragments. Based on the water flow rates at different sites, the study estimates that combined with the flow from the Brahmaputra and Meghna rivers, the Ganges probably releases 1–3 billion microplastic particles into the Bay of Bengal. Another study from 2019, by ICAR-Central Inland Fisheries Research Institute, reports that 100–400 microplastic particles per kg of river sediment were present in samples collected across 7 locations in the lower and estuarine reaches of the Ganges; a majority of the microplastics were composed of polythene terephthalate (used to make PET bottles) and polyethylene. Similar studies on the Indus and Brahmaputra rivers as well as the Alaknanda (a tributary of the Ganges) indicate that hundreds to thousands of microplastic particles are present in river sediments and water.
Different systems, similar results; but are they comparable?
Besides the Ganges and its tributaries, several other freshwater systems in India have been investigated for the presence of plastic pollution. Clean-up drives on the Karamana river in Kerala have shown that macroplastics make up 80% of the trash found in the river and along its banks; most of this comes from household waste and litter.
Another study on the Netravathi river—which originates in Kudremukh in Karnataka and flows through the major pilgrimage centres of Dharmasthala and Subrahmanya to empty into the Arabian sea—concludes that the river is contaminated with microplastics from its source to its sink. On an average, hundreds of microplastic particles are found in every cubic meter of water and kilo of sediment from the river. Much like what was found in the Ganges and its tributaries, most of these microplastics are fibres released from garment washing or bits of polyethylene and PET. A study on the Sabarmati river found hundreds of microplastic particles per kilo of river sediment. Investigations on the Adayar and Kosasthalaiyar rivers in Chennai indicate that they may be responsible for discharging 11.6 trillion microplastic particles into the Bay of Bengal. The same study also indicates that remote mountain rivers with low anthropogenic influences (the Muthirappuzhayar River, that flows along the Southern Western Ghats) may contain microplastic particle levels as high as 0.2 particles per litre (or 200 particles per m3).
While the presence of microplastics in India’s fresh water systems is alarming, the levels of microplastics in most of these systems are fairly low, especially when compared to those of the Pearl river in China (which contains 10,000–20,000 microplastic particles per m3 of water).
However, the values of microplastic particles from these different systems may not be comparable, warns an NPC team member from the CounterMEASURE project. “As of now, there is need for commonly adopted standardised methods for all the groups working on microplastics across the world”, she says.
Sampling methods and analysis systems vary widely in most of the published studies on microplastic abundance in water bodies. Many studies only look at microplastics in surface water or in sediments, but rarely in the entire column from surface water to sediment. Some studies use microscopes to detect microplastic particles, whereas others use FTIR (Fourier Transform Infrared Spectroscopy), a technique which can detect smaller microplastic particles than microscopes.
“We are finding microplastics in our seas, our rivers and lakes, ground water, and even drinking water sources. But there’s no harmony between researchers’ efforts when it comes to work on microplastics”, says the NPC team member. “There is scope for connects to be made between scientists, and a need for mutual sharing of knowledge if we are to tackle this huge problem of microplastics contaminating the natural world.”
Banner image: Plastic litter on a river bank in India. Photo by PJeganathan/Wikimedia Commons.