Dynamic substance flow analysis of lead in the fossil fuel system of China from 1980 to 2018

Lead is mostly found with zinc ores, but is also abundant in fossil fuels. However, the anthropogenic cycle of lead in fossil fuel system has rarely been reported. This study expounds on the evolution of lead metabolism in China's fossil fuel system from 1980 to 2018 through dynamic substance flow analysis. The quantities and structures of lead flows and stocks in the system changed significantly. After the prohibition of leaded gasoline, raw coal became the main source of lead in the system, reaching 101 kt Pb/yr in 2018. The lead outflow of the system underwent a transformation from gas phase to solid phase. The atmospheric lead emission dropped from the highest 20 kt/yr to 4 kt/yr. Most of the lead in the system accumulated in coal-based solid waste. In the past 40 years, 677 kt of lead accumulated in constructions due to the utilization of coal-based solid waste, and 657 kt of lead was left in the redundant coal-based solid waste. The main lead emission stage gradually shifted from the use stage to the waste management stage. Although the flow of lead in fossil fuels is small, there is no significant difference between unintentional (consider only fossil fuels) and intentional use of lead emissions to the atmosphere and landfills. China should improve the utilization of coal-based solid waste, and strengthen the management of landfills and dumps and the surrounding environmental monitoring.