A comprehensive biomass burning emission inventory with high spatial and temporal resolution in China
Authors: Zhou Ying , Xing Xiaofan , Lang Jianlei , Chen Dongsheng , Cheng Shuiyuan , Wei Lin , Wei Xiao , Liu Chao 
Published: July 2016

Abstract. Biomass burning injects many different gases and aerosols into the atmosphere, which could have a harmful effect on air quality, climate change and human health. In this study, a comprehensive biomass burning emission inventory including crop straw domestic combustion and in field burning, firewood and livestock excrement combustion, forest and grassland fire was developed for mainland China in 2012 based on county-level activity data and updated source-specific emission factors (EFs). The emission inventory within 1 × 1 km grid was generated using geographical information system (GIS) technology according to source-based spatial surrogates. A range of key information related to emission estimation (e.g., province-specific proportion of crop straw domestic burning and open burning, detailed firewood combustion quantities, uneven temporal distribution coefficient) was obtained from field investigation, systematic combing of the latest research and regression analysis of statistical data. The established emission inventory includes the major precursors of complex pollution, greenhouse gases and heavy metal released from biomass burning. The results show that the emissions of SO2, NOx, PM10, PM2.5, VOC, NH3, CO, EC, OC, CO2, CH4 and Hg in 2012 were 332.8 Gg, 972.5 Gg, 3676.0 Gg, 3479.4 Gg, 3429.6 Gg, 395.8 Gg, 33987.9 Gg, 367.1 Gg, 1151.7 Gg, 665989.0 Gg, 2076.5 Gg and 3.65 Mg, respectively. Indoor and outdoor burning of straw and firewood combustion are identified as the dominant biomass burning sources. The largest contributing source is different for various pollutants. Straw indoor burning is the major source of SO2, CO, CH4 and Hg emission; firewood contributes most to EC and NH3 emission. Corn, rice and wheat represent the major crop straws, with their total emission contribution exceeding 80 % for each pollutant. Corn straw burning has the greatest contribution to EC, NOx and SO2 emissions; rice straw burning is dominant contributor to CO2, VOC, CH4 and NH3 emissions. Heilongjiang, Shandong, and Henan provinces located in northeast and central-south region of China have higher emissions. Gridded emissions, which were obtained through spatial allocation based on the gridded rural population and fire point data from emission inventory at county resolution, could better represent the actual situation. Higher biomass burning emissions are concentrated in the areas with greater agricultural and rural activity. The temporal distribution shows that higher emissions occurred in April, September, and October during the whole year. There’s regional difference in monthly variation due to the diversity of main planted crop and the climate conditions. Furthermore, PM2.5 component results showed that OC, Cl−, EC, K+, NH4+, K element and SO42− are the main PM2.5 species accounting for 80 % of the total emissions. The species with relatively higher contribution to VOCs emission including ethylene, propylene, toluene, mp-xylene and halocarbons which are key species for the formation of secondary air pollution. The detailed biomass burning emission inventory generated by this study could provide useful information for air quality modelling and support the development of appropriate pollution control strategies.