A Source-Based Accounting of Microplastic Release into Freshwater in Mainland China from 2000 to 2022: Priorities and Gaps

Microplastics (MPs), mostly stemming from terrestrial activities, can be easily transported once they enter freshwater. Limited national-level accounting has constrained accurate global estimates, investigations of environmental fate, and the development of targeted management measures for MP pollution. In this context, this study estimated MP generation and its release into freshwater in China from 2000 to 2022, with a focus on 21 typical inland activities and products. An accumulation of 6.36 × 1021 MPs (36.39 million tonnes, Mt) was generated, of which 2.39 × 1021 items (20.12 Mt) were released into freshwater, equivalent to 1.82 trillion and 1.01 trillion 20-g plastic bottles, respectively. Urban and rural areas made distinct contributions to MP generation, with urban areas contributing a greater quantity (59.12%) and rural areas contributing a greater mass (79.60%). The most critical contributors to MP generation and freshwater release were identified as transportation-related sources by number (>99.9%) and agricultural sources by mass (>59.9%). This study provides a methodological basis for MP accounting, especially in areas lacking monitoring capabilities, and helps identify effective and efficient MP control strategies.