Distribution characteristics and risk assessment of microplastics in Lake Bosten

As emerging global contaminants, microplastics (MPs)’ environmental fate and risks have expanded from marine to freshwater systems, yet semi-closed arid lakes remain understudied. This study systematically evaluates MPs pollution in Bosten Lake, revealing abundances of 1.33–9.43 n/L (surface water) and 151.55–953.31 n/kg (sediments) with pronounced spatiotemporal heterogeneity. Spatial hotspots correlated with functional zones: pastoral (B8), transportation (B2, B10), and tourism areas (B11, B12) were primary sources, driven by agricultural plastics, tire wear particles, and tourism debris. Temporally, dry season MPs in water increased by 32.4% due to prolonged hydraulic retention. White (54.09%) and black (30.07%) are the dominant components of MPs in Lake Bosten, with 0.1–0.5 mm, fibrous polypropylene MPs being the most common. Ecological Risk Index (RI) showed seasonal divergence: 92.3% of wet season sediment sites exhibited extreme risks (RI > 1000, e.g., inflow area B13), while dry season RI declined to moderate levels (e.g., B8 decreased from 1335.13 to 188.22) via reduced terrestrial inputs and degradation. This highlights dual “hydrological-anthropogenic” drivers, necessitating dynamic controls during tourism peaks, fishing, and traffic surges to mitigate MPs risks in arid closed-basin lakes.