Urbanization and population resources affect microplastic concentration in surface water of the River Ganga

Microplastic (MP) pollution has received increasing attention as a serious threat to aquatic ecosystem. The River Ganga is one of the longest rivers in India and supports an enormous species diversity. The major Indian cities situated on its bank discharge untreated domestic and industrial waste in River Ganga and are largely responsible for generating MPs. Every day millions of people use the river recreationally, for bathing and for drinking water. This study is the first to elucidate the distribution of MPs according to their shape, size and type in River Ganga from the Rishikesh to Farakka in India. Surface water samples of the river were obtained at 22 locations of the riverbank. Microplastic particles were identified using binocular microscope and categorized by shape, size and type. MPs were found in all surface water samples along the River Ganga and highest concentrations of MPs were found within Kanpur city (average 206 ± 31.9 particles m−3). The average MPs concentration was 92.85± 50.69 (SD) particles m−3 (∼0.1 particle L−1) of surface water. In addition, MPs distribution was dominated by filament particle (polyester and nylon fibre). The MPs concentration was positively correlated with population density in the vicinity (r = 0.65; p<0.001) and sewage volume discharged (r = 0.5; p<0.01) in the river. The MPs in Ganga water may pose potential risk to the devotees through direct consumption of Ganga water on the occasions of ritualistic bathing. The present work adds new knowledge and understanding of MPs pollution in the Ganga River and the effects of highly urbanized cities on MPs pollution, which may be used as baseline data to evaluate precise mitigation.