Multimedia Mercury Emissions from Key Industries in China and Implications for Mercury Control

Mercury is a toxic and persistent pollutant that cycles through the atmosphere, hydrosphere, and pedosphere. Understanding temporal trends and driving factors of multimedia mercury emissions is crucial for effective mercury pollution control. This study employed material flow analysis to quantify multimedia mercury emissions─to air, water, and waste─from coal-fired power plants, coal-fired industrial boilers, nonferrous metal smelting, cement production, and municipal solid waste incineration in China during1978-2021. Additionally, the logarithmic mean Divisia index decomposition was used to analyze the drivers of changes in these emissions. Over this period, China's multimedia mercury emissions increased significantly. Mercury entering waste rose from 14.6 to 1662.1 tons, and aquatic releases grew from 0.30 to 31.3 tons. Atmospheric emissions increased from 91.3 tons in 1978 to a peak of 468.9 tons in 2011, before declining to 288.8 tons in 2021. Economic growth dominated multimedia emission increases, whereas structural adjustments partially offset them. End-of-pipe control was the main factor reducing atmospheric mercury emissions and aquatic mercury releases, but it led to the cross-media transfer of mercury to waste. Notably, 80% of multimedia mercury emissions originated from 10% of the total point sources in 2021, highlighting the need for whole-process mercury pollution control targeting key point sources.