Occurrence, distribution, and ecological risk of microplastics in Chinese surface waters: a systematic review and multi-model assessment.

Microplastics are widely detected in Chinese surface waters, posing potential threats to ecosystems and human health. We conducted a systematic review of literature published from January 2014 to March 2026 based on predefined search and eligibility criteria, and integrated data from 40 eligible studies.Using the Pollution Load Index (PLI), the Potential Ecological Risk Index (PERI), the Species Sensitivity Distribution (SSD), and health risk models (Target Hazard Quotient, THQ; Cancer Risk, CR), we analyzed the spatial distribution, morphology, and multi-dimensional risks of microplastics. Results showed pronounced spatial heterogeneity, with hotspots in northwestern inland rivers, northern industrialized basins, and the southeastern coast. Fibers dominated (47.6-59.5%), particles < 1 mm accounted for 62.8%, and polyethylene (PE, 25.5%) and polypropylene (PP, 23.4%) were predominant. PLI indicated 62.5% of basins had low pollution and 5% heavy pollution; PERI showed low ecological risk in 67.6% of basins, but 5.9% exhibited extremely high risk due to PVC toxicity. The SSD-derived PNEC was 129.1 n L-1. Human health risk assessment estimated THQ = 0.019 and CR = 1.32×10-5 under the assumed exposure scenarios. Overall, microplastic contamination and associated risks varied among regions, with hotspots requiring further monitoring. These findings provide useful information for ecological risk assessment and future management strategies.