A group of scientists studying the flow of plastic into the ocean have found a startling amount of pollution exiting South Asia's largest river systems. The scientists calculated that the Ganges and two nearby waterways are responsible for pumping as much as three billion microplastic particles into the Indian Ocean each day.
The study was conducted as part of National Geographic's Sea to Source project, which aims to tackle the problem of plastic pollution by investigating how it can be prevented from reaching the ocean. In December, scientists working on this project published research detailing just how far tagged plastic bottles can travel along the Ganges river, washiing thousands of kilometers downstream into the Indian Ocean.
As part of this endeavor, project scientists have now carried out what they say is the first investigation of microplastic abundance along the Ganges river, collecting water samples from 10 sites, with 60 taken pre-monsoon and 60 taken post-monsoon.
In a laboratory at the University of Plymouth, scientists analyzed these samples to find that 72 percent of those taken pre-monsoon contained microplastics, which are particles measuring less than 5 mm in size, as did 62 percent of those taken post-monsoon. More than 90 percent of the plastics were fibers commonly used in clothing, such as rayon and acrylic.
The Ganges River runs from the Himalaya through India and Bangladesh and drains into the Indian Ocean at the Bay of Bengal, joining with the Brahmaputra and Meghna rivers along the way. The researchers calculate that the flows of these three rivers, which combine to be the largest in South Asia, pump between one and three billion microplastic particles into the Bay of Bengal each day. This river basin is described as the most populous in the world, with more than 655 million people relying on it as a source of water.
The study also provided a picture of how different spots along the river were subjected to more pollution, with the sites chosen to represent a mix of rural, urban, agricultural, tourism and religious locations. The largest amounts were found closer to the river mouth at Bhola in Bangladesh, where concentrations were as much as four times that found closer to the river source at Harsil.
“We know that rivers are a substantial source of microplastics in the ocean," says Professor Richard Thompson, study co-author. "But the information like this can help identify the key sources and pathways of microplastic and hence inform management interventions. With this type of evidence, we can progress toward using plastics more responsibly so as to get the many benefits they can bring without unnecessary contamination of the environment.”
The research was published in the journal Environmental Pollution.
Source: University of Plymouth
