Presence of micro plastic found in air, water, sediment

The presence of micro plastic was found at a dangerous level in air, surface water and sediment within the Ganges basin of Bangladesh and India, according to a study.

The study titled “The distribution and characterisation of micro plastics in air, surface water and sediment within a major river system” was published in the journal Science of Total Environment in the Netherlands. The study was jointly conducted by scientists from Bangladesh and India and it was the first research that assessed the presence of micro plastic on such a large scale.

As Bangladesh tackles the impact of climate change, another study found micro plastic accelerates climate change.

Amid this circumstance, 22 April marked World Earth Day 2024 focusing on the theme "Planet vs Plastics."

A total of 10 sampling sites in India and Bangladesh were selected along the length of the mainstream river to represent the whole length of the Ganges and three sites were located in Bangladesh: Bhola, Chandpur and Rajbari.

Three different environmental mediums were collected from the Ganges River and within its vicinity: water, sediment, and air samples. The samples were collected in May-June 2019. Once collected, all samples were transported to either labs within the University of Dhaka in Bangladesh, the Wildlife Institute of India, or the University of Plymouth in the UK for laboratory analysis.

Gawsia Wahidunnessa Chowdhury, professor of Zoology at the University of Dhaka, led the Bangladesh team for the study. She told Prothom Alo, “Previously, no study was carried out on the level of presence of micro plastic in air, water and sediment of the vast area of the Gangs Basin, and we have studied it for the first time. We focused on sources of micro plastic concentration in the river that reached through air and water. We think the effect of micro plastic on ecology and public health will help policymakers of both countries formulate their policies.”

Plastics in the micro plastic size range less than 5 millilitres. The study found huge quantity of micro plastics reached the Bay of Bengal mixing in water and sediments. Rayon and blue were dominant element and colour.

The study found the presence of at least a micro plastic in every 20 litres of water in the Ganges Basin, 57 micro plastics in per kilogram of sediment and 41 micro plastic in per square meter of air.

Research estimated that the Ganges river system, with the combined flows of its branches, could release up to 1–3 billion micro plastics into the Bay of Bengal every day.

Across all sites and environmental mediums (water, air and sediment), rayon (synthetically altered cellulose) was the dominant polymer (54–82 per cent), followed by acrylic (6–23 per cent) and polyester (9–17 per cent). Fibres were the dominant shape (95–99 per) and blue was the most common colour (48–79 per cent.

The study states, “It is expected that the abundance of micro plastics would be positively correlated with the degree of urbanization and population density and places involving frequent human activities or near sewage outlets.” The study reports that micro plastic abundance significantly increased with higher population densities in air and water but not in sediment.

For air samples, Varanasi in India had the highest quantities of micro plastics and the largest population; this may be due to the site being of strong religious and heritage significance and a higher quantity of transient population including tourists from all across the globe. Whereas Rajbari in Bangladesh had the lowest quantity of micro plastic and had the lowest population.

Besides, another study titled “The Ecological Impact of Plastic Pollution in a Changing Climate” found that micro plastics emit various gases including carbon dioxide and contributed to 10 per cent of the total pollution in the country. Bangladesh also ranked 31st among the countries contributing to mixing micro plastics to sea due to mismanagement.

Regarding this study, as well as the risk of micro plastic, Firoz Khan, a former professor of environment science at North South University, told Prothom Alo the size of micro plastic get smaller from the upstream area of India to the downstream area of Bangladesh, posing the risk of the presence of micro plastic in seafood. There, however, are methods of processing micro plastics, but no initiative is being taken on this matter, he added.