Spatial-temporal variation characteristics of air pollution in Henan of China: Localized emission inventory, WRF/Chem simulations and potential source contribution analysis.

Henan is the most populous province and one of the most seriously polluted areas in China at present. In this study, we establish an integrated atmospheric emission inventory of primary air pollutants in Henan province for the target year of 2012. The inventory developed here accounts for detailed activity levels of 11 categories of primary anthropogenic emission sources, and determines the best available representation of emission factors. Further, we allocate the annual emissions into a high spatial resolution of 3km×3km with ArcGIS methodology and surrogate indices, such as regional population distribution and gross domestic product (GDP). Our results show that the emissions of VOCs, SO2, PM10, PM2.5, NOX, NH3, CO, BC and OC are about 1.15, 1.24, 1.29, 0.70, 1.93, 1.05, 7.92, 0.27 and 0.25milliontons, respectively. The majority of these pollutant emissions comes from the Central Plain Urban Agglomeration (CPUA) region, particularly Zhengzhou and Pingdingshan. By combining with the emission inventory with the WRF/Chem modeling and backward trajectory analysis, we investigate the temporal and spatial variability of air pollution in the province and explore the causes of higher pollutants concentrations in the region of CPUA during the heavily polluted period of January. The results demonstrate that intensive pollutants emissions and unfavorable meteorological conditions are the main causes of the heavy pollution. Besides, Weighted Potential Source Contribution Function (WPSCF) analysis indicates that local emissions remain the major contributor of PM2.5 in Henan province, although emissions from the neighboring provinces (e.g. Shanxi, Shaanxi, Anhui, and Shandong) are also important contributors.