Integrating Point Sources to Map Anthropogenic Atmospheric Mercury Emissions in China, 1978–2021.

Mercury emissions from human activities persist in the environment, posing risks to humans and ecosystem, and are regulated by the Minamata Convention. Understanding the historical emissions of mercury is critical for explaining the presence of mercury in the environment. In recent years, some studies have looked at the historical trends of atmospheric emission inventory. The spatial resolution of inventories for relatively recent years have improved. However, limited inventories have combined both long time scales and high spatial resolution, which is essential for evaluating the legacy impacts of anthropogenic mercury emissions, particularly in regions with high levels of mercury emissions. Here we compile a new comprehensive point source database by fusing multiple data source, and integrate it with previous China Atmospheric Mercury Emission Model to create an annual point source and gridded emission inventory for China covering 1978–2021. Integrating point source emission inventory (P-CAME) improves the accuracy of the gridded emissions, reducing the normalized mean error for all grids by 108 % compared to not using point sources in the most recent year of 2021. The improved gridded emissions inventory notably enhances the simulation of atmospheric mercury concentrations, particularly in urban areas. P-CAME inventory resulted in a 20–23 % reduction in the normalized mean bias. The improved gridded emission data identifies potential polluted grids characterized by high cumulative emissions. It indicates that 20 % of cumulative emissions originate from just 0.3 % of the grids, primarily distributed in Gansu, Yunnan, and Hunan Provinces. These areas are predominantly dominated by non-ferrous metal smelters or a mix of emissions sources including coal-fired industries and cement production. With the improvements in simulation accuracy and the identification of highly polluted regions, this updated inventory would greatly facilitate the assessment of mercury exposure, legacy impacts, and effective management of cross-media mercury pollution. [ABSTRACT FROM AUTHOR]