Based on an analysis of measured data and distribution factors, we developed the China Aquatic Mercury Release (CAMR) model, which we used to calculate an inventory of mercury (Hg) that was released to aquatic environments from primary anthropogenic sources in China. We estimated a total release of 98 tons of Hg in 2012, including coal-fired power plants (17%), nonferrous metal smelting (33%), coal mining and washing (25%), domestic sewage (17%), and other sectors (8.3%). The total primary anthropogenic Hg released to aquatic environments in China decreased at an annual average rate of 1.7% between 2001 and 2012, even though GDP grew at an annual average rate of 10% during this period. In addition to the Hg that was released to aquatic environments in China's provinces, we estimated the Hg release amounts and intensities (in g/km(2)·yr) for China's 58 secondary river basins. The highest aquatic Hg release intensities in China were associated with industrial wastewater on the North China Plain and domestic sewage in eastern China and southern China. We found that the overall uncertainty of our inventory ranges from -22% to 32%. We suggest that the inventory provided by this study can help establish a more accurate map of regional and global Hg cycling; it also has implications for water quality management in China.

Exports from mainland China are a significant source of mercury (Hg) in the adjacent seas (Bohai Sea, Yellow Sea, East China Sea, and South China Sea) near China. A total of 240 ± 23 Mg was contributed in 2012 (30% from natural sources and 70% from anthropogenic sources), including Hg from rivers, industrial wastewater, domestic sewage, groundwater, nonpoint sources, and coastal erosion. Among the various sources, the Hg from rivers amounts to 160 ± 21 Mg and plays a dominant role. The Hg that is exported from mainland China increased from 1984 to 2013; the contributions from rivers, industrial wastewater, domestic sewage and groundwater increased, and the contributions from nonpoint sources and coastal erosion remained stable. A box model is constructed to simulate the mass balance of Hg in these seas and quantify the sources, sinks and Hg biogeochemical cycle in the seas. In total, 160 Mg of Hg was transported to the Pacific Ocean and other oceans from these seas through oceanic currents in 2012, which could have negative impacts on the marine ecosystem. A prediction of the changes in Hg exportation through 2030 shows that the impacts of terrestrial export might worsen without effective pollution reduction measures and that the Hg load in these seas will increase, especially in the seawater of the Bohai Sea, Yellow Sea, and East China Sea and in the sea margin sediments of the Bohai Sea and East China Sea.

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