Atmospheric emission inventory of cadmium from anthropogenic sources

To demonstrate the atmospheric emission characteristics of cadmium (Cd), which is considered an important contaminant to human health and environment, a comprehensive emission inventory of Cd has been established by applying the best available emission factors and activity data for the first time. This inventory covers major anthropogenic sources in China and a bottom-up approach is adopted to compile the inventory for the sources where possible. The total emissions of Cd are estimated at about 743.77 metric tons for the year 2009, of which the contributions of industrial processes and combustion sources are approximately 56.6 and 43.4 %, respectively. Nonferrous metals smelting including copper, lead, and zinc, ranks as the leading source accounting for about 40.6 % of the total. The high contribution results from the rapid growth of nonferrous metallurgical industry that reflects a new focus of Cd emission pollution in China. Cd emissions from coal combustion are estimated at approximately 273.69 metric tons, with a share of 36.8 %, in which industrial coal-burning sector is thought to be the primary source. Moreover, Cd emissions are spatially allocated onto grid cells with a resolution of 0.5° × 0.5°, indicating that the emissions are mainly distributed among the regions of eastern, central and southern China. In addition, the uncertainties in the inventory are quantified by using a Monte Carlo simulation, and the overall uncertainty falls within a range of −15 to 48 %. It implies that more field tests for industrial coal combustion and metals smelting process are very necessary.