The determinants of China's national and regional energy-related mercury emission changes

As the world's largest energy-related mercury emitter, proper reduction policy is urgently needed in China. However, a quantitative analysis on how different factors affect China's national and regional mercury emissions has been lacking, which hinders the design and implementation of mercury control strategies. To fill the knowledge gap, this study applies a temporal and spatial logarithmic mean divisia index (LMDI) model to reveal the important determinants of mercury emissions across China from 2007 to 2015. The results show a descendant trend generally in energy-related mercury emissions at both national and regional level. Economic scale is the main driving factor while its effect is largely offset by the decreasing mercury emission and energy intensities. However, Jiangsu and Shanxi in 2012-2015 are exceptions with emission growth because of their rebounded emission factors and energy intensities. Moreover, a decoupling effect between energy-related mercury emissions and GDP growth is found, reflecting that there is ongoing green energy transition in China. The spatial decomposition verifies that effects of economic scale and energy intensity are the mainly determinants for mercury emission differences between national average and provincial emissions. Other factors' effects are prominent in several provinces such as Xinjiang, Chongqing and Heilongjiang, where the emission gap is primarily resulted by the differences between national and local mercury intensities. By identifying the determinants of emission changes as well as the differences between the national average and provincial emissions, this study provides insights for formulating more targeted mercury mitigation strategies.