Study reveals the extent of microplastic contamination in the Ganges River

The Ganges River, also known as the Ganga, is one of the most significant and sacred water bodies in India and has a deep cultural, spiritual, and historical importance to millions of people. 

The Ganges originates from the Gangotri Glacier in the central Himalayas. It flows southeast through the plains of northern India, passing through cities like Rishikesh, Haridwar, Kanpur, Allahabad, Varanasi, and Patna. 

After entering the state of West Bengal in India, the river divides into several distributaries and forms the Ganges Delta before flowing into the Bay of Bengal through Bangladesh.

Microplastics in the Ganges

In a recent study, scientists analyzed plastic pollution in the Ganges. The goal was to gain a better understanding of the characteristics and flow of plastics in a major river system

The results showed that microplastics were present throughout the Ganges River system – in the water, sediment, and even in the surrounding air. 

This research is the first-ever study to analyze the prevalence of microplastics in these three key environments surrounding a major river system.

Microplastic abundance 

The researchers found an average of 41 microplastic particles settling from the atmosphere per square meter per day. 

Furthermore, sediment from the riverbed contained an average of 57 particles per kilogram, and there was one particle found in every 20 liters of water.

The true scale of contamination 

Study lead author Dr. Imogen Napper is a research fellow at the University of Plymouth and National Geographic Explorer.

“We have known for some time that rivers are key pathways for the transfer of microplastics to marine environments. However, there has always been uncertainty about the sheer amounts being transported, and whether they represent long-term sinks,” said Dr. Napper.

“This study goes some way to unraveling that mystery, and revealing the true scale of microplastic contamination that our river systems can represent.”

Focus of the study 

The experts analyzed samples that had been collected by an international team during the National Geographic Society’s Sea to Source: Ganges expedition. 

Many of the scientists involved in this research also contributed to a 2021 study suggesting that the Ganges River and its tributaries may contribute up to 3 billion microplastic particles daily to the Bay of Bengal.

Types of microplastics found 

In terms of the types of microplastics found in this recent study, fibers emerged as the dominant form, accounting for up to 99% of microplastics in certain samples. 

Among these fibers, rayon – a synthetically altered cellulose – was by far the most prevalent polymer, followed by acrylic and polyester. Additionally, blue emerged as the most frequently found color.

The experts found that areas with higher population densities showed increased amounts of microplastics in both air and water samples. Meanwhile, sediment samples had denser microplastic particles compared to those in water and air.

Study implications 

The revelations from this research highlight the pervasive nature of microplastic contamination, emphasizing the need for broader studies and comprehensive strategies to address the issue.

The researchers believe clothing is likely the prominent source of microplastics in this particular river system, influenced by atmospheric deposition, wastewater, and direct inputs such as the handwashing of clothes in the Ganges.

Professor Heather Koldewey of the Zoological Society of London said: “Our research shows that clothing is the major source of microplastics in the air, water and sediment of this vast river system, enabling us to work with partners and policy makers to seek locally appropriate solutions.” 

“These can be informed and supported by the brilliant scientists from Bangladesh and India who were key members of the team involved in this paper.”

Future research

Dr. Anju Baroth from the Wildlife Institute of India noted that the study could be used to further explore the theory on major sinks and sources of microplastics in major river systems of the world.

“Earlier studies based on modeling had reported rivers in Asia as one the largest source of microplastic pollution to sea,” said Dr. Baroth. 

“This research based on primary field data has provided clear insight on the levels of microplastics in different environmental matrices of river Ganges and that several major river systems of the world have reported comparatively higher microplastics than the Ganges.” 

The study is published in the journal Science of the Total Environment.

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