Significant spatiotemporal changes in atmospheric particulate mercury pollution in China: Insights from meta-analysis...

PM_2.5 bound mercury (PBM_2.5) in the atmosphere is a major component of total mercury, which is a pollutant of global concern and a potent neurotoxicant when converted to methylmercury. Despite its importance, comprehensive macroanalyses of PBM_2.5 on large scales are still lacking. To explore the driving factors, spatiotemporal pollution distribution, and associated health risks, we compiled a comprehensive dataset consisting of PBM_2.5 concentrations and spatiotemporal information across China from 2000 to 2023 that was collected from the published scientific literature with valid data. By incorporating corresponding multidimensional predicting variables, the best-fitted random forest model was applied to predict PBM_2.5 concentrations with a high spatial resolution of 0.25° × 0.25°, and the health risk assessment model was used for subsequent health risk assessment. Our results indicated that population density and PM_2.5 emissions from power generation were the main contributors to PBM_2.5 concentrations. In 2020, the pollution was primarily concentrated in northern, central, and eastern China, with the highest annual average concentration of 815.91 pg/m³ in Shanghai. Beijing experienced the most significant seasonal increase, with PBM_2.5 concentrations rising by 146.92 % from summer to winter. Nationally, the annual average PBM_2.5 pollution decreased extensively and markedly from 2015 to 2020. The non-carcinogenic risk of PBM_2.5 alone was negligible in 2020, with HQ values generally <0.02 in winter. This study may provide an important assessment of the effectiveness of China's measures against mercury pollution and offer valuable insights for future prevention and control of PBM_2.5 pollution.