Tracing the Anthropocene through microplastic sedimentary records: Drivers and spatiotemporal heterogeneity in Baiyangdian Lake, North China

Beyond being emerging contaminants, microplastics (MPs) may serve as novel environmental proxies for the Anthropocene; yet the links between their accumulation in sediments and the evolution of shallow lakes under human-nature interactions remain unclear. In this study we reconstruct MP sedimentary sequences of three sediment spanning the past 80 years in Baiyangdian Lake, North China. Evidence derived from Analyses using Rate of Change (RoC), coupling models, and Partial Least Squares Path Modeling (PLS-PM) indicate that MP sedimentary patterns during this period underwent two critical transitions, viz. an initial increase triggered by weakened hydrological connectivity due to dam construction in 1963, and a subsequent accelerated accumulation phase driven by intensified human activities in the the catchment from around 2000. Spatially, MP abundance in cores DC-1 (mean 37,229.7 items kg-1) and CPT-1 core (8,493.0 items kg-1), was significantly greater than in core SCD-1 (3,648.6 items kg-1), located within the nature reserve. Random Forest modeling further reveals that nutrient accumulation and hydrodynamic intensity jointly drive spatial heterogeneity in MP abundance. Together, these findings suggest that MPs can serve as effective indicators of anthropogenic intensity and provide important insights into the mechanisms shaping the environmental evolution of shallow lakes during the Anthropocene.