Virtual atmospheric mercury emission network in China.

Top-down analysis of virtual atmospheric mercury emission networks can direct efficient demand-side policy making on mercury reductions. Taking China-the world's top atmospheric mercury emitter-as a case, we identify key contributors to China's atmospheric mercury emissions from both the producer and the consumer perspectives. China totally discharged 794.9 tonnes of atmospheric mercury emissions in 2007. China's production-side control policies should mainly focus on key direct mercury emitters such as Liaoning, Hebei, Shandong, Shanxi, Henan, Hunan, Guizhou, Yunnan, and Inner Mongolia provinces and sectors producing metals, nonmetallic mineral products, and electricity and heat power, while demand-side policies should mainly focus on key underlying drivers of mercury emissions such as Shandong, Jiangsu, Zhejiang, and Guangdong provinces and sectors of construction activities and equipment manufacturing. China's interregional embodied atmospheric mercury flows are generally moving from the inland to the east coast. Beijing-Tianjin (with 4.8 tonnes of net mercury inflows) and South Coast (with 3.3 tonnes of net mercury inflows) are two largest net-inflow regions, while North (with 5.3 tonnes of net mercury outflows) is the largest net-outflow region. We also identify primary supply chains contributing to China's virtual atmospheric mercury emission network, which can be used to trace the transfers of production-side and demand-side policy effects.