Morphology and Polymeric Composition-Based Source Apportionment of Microplastics in Surface Water and Sediment of Drinking Water Supply Reservoirs in Ranchi, India

We investigated the occurrence of microplastics (MPs), a burgeoning environmental pollutant, in three drinking water supplying reservoirs situated in Ranchi, India.Through comprehensive water and sediment samples analysis, the study attempted to evaluate spatial distribution, conduct morphological examinations, perform polymeric analysis, and conduct source apportionment to pinpoint significant contributors. Morphological examinations were conducted utilizing a stereomicroscope equipped with a fluorescence adapter, while polymeric composition analysis was done on FTIR. Additionally, various indices, such as the MP Diversity Index and Pollution Load Index, were calculated alongside other statistical analyses. The findings revealed the omnipresence of MP particles- fragments, films, fibers, and foams—in all 180 water samples (total count: 3699—6873) and 144 sediment samples (total count: 1038—5166) at notably high concentrations. Eight polymer types could be identified from the FTIR analysis, with PET and HDPE dominance. ANOVA analysis indicated significant sediment differences among the reservoirs, although regression analysis did not show substantial particle settling from surface water to sediment. The MP Pollution Load Index classified two reservoirs as high-risk (Hazard level II). Finally, a source apportionment study based on the potential source items, their categories, relative score, and individual contributory score suggested single-use plastic items and household plastic items to be the major contributor to the MP contamination in these reservoirs.This source apportionment-driven model holds promise for addressing MP contamination in lakes and reservoirs worldwide, facilitating the identification of major contributing factors and informing stakeholders to develop policies in line with Sustainable Development Goals (SDG 6 and SDG 14) for clean water systems.