Microplastics Pollution in the Brahmaputra River and its Associated Ecosystems: a Transboundary Perspective Through Meta-Analysis

This meta-analysis provides a comprehensive understanding of the status of microplastic (MPs) pollution in the Brahmaputra River basin, focusing mainly on water, sediment and fish. Relevant ten studies were found with most reports from the lower stretch (Bangladesh) as compared to the middle (India) and upper stretch (Tibet-China). Studies were mostly focused on MPs pollution in water and sediment; and research on fish contamination is predominantly limited to the lower stretch. In water, MPs abundance ranges from 90 items m−3 in the Yarlung Tsangpo at Najiuxiang, Tibet, to 109,300 items m−3 in the Meghna River, Bangladesh. Sediment contamination also varies widely, from 80 items kg−1 in Zhangmaicun, Tibet, to 6,476.66 items kg−1 in the Meghna River. In the middle stretch, the highest water contamination was reported from Jia Bharali River at Tezpur (37,000 items m−3) and the highest sediment contamination was reported from Guwahati (2,889 items kg−1). Fish species like Labeo rohita, Channa marulius and Notopterus notopterus demonstrate substantial MPs ingestion (7.67 ± 1.26 to 12.11 ± 2.13 particles individual−1). Principal component analysis revealed a negative correlation of MPs abundance with elevation and a strong positive correlation exists with population density and industrial activities. Scatter matrix correlation analysis revealed weaker correlations between the number of factories and MPs in water (r = 0.1134) and sediment (r = 0.2434) suggesting additional pollution sources like runoff, improper solid waste disposal, etc. The meta-analysis gives a comprehensive summary of MPs pollution in the Brahmaputra River basin, highlighting the need for further research and policy regulation for possible mitigation approaches.