Quantification and evaluation of atmospheric pollutant emissions from open biomass burning with multiple methods: a case study for the Yangtze River Delta region, China

摘要

Air pollutant emissions from open biomass burning (OBB) in the Yangtze River Delta (YRD) were estimated for 2005-2015 using three (traditional bottom-up, fire radiative power (FRP), and constraining) approaches, and the differences among those methods and their sources were analyzed. The species included PM10, PM2.5, organic carbon (OC), elemental carbon (EC), CH4, non-methane volatile organic compounds (NMVOCs), CO, CO2, NOx, SO2 and NH3. The interannual trends in emissions with FRP-based and constraining methods were similar to the fire counts in 2005-2012, while those with the traditional method were not. For most years, emissions of all species estimated with the constraining method were smaller than those with the traditional method except for NMVOCs, while they were larger than those with the FRP-based method except for EC, CH4 and NH3. Such discrepancies result mainly from different masses of crop residue burned in the field (CRBF) estimated in the three methods. Chemistry transport modeling (CTM) was applied using the three OBB inventories. The simulated PM10 concentrations with constrained emissions were closest to the available observations, implying that the constraining method provided the best emission estimates. CO emissions in the three methods were compared with other studies. Similar temporal variations were found for the constrained emissions, FRP-based emissions, GFASv1.0 and GFEDv4.1s, with the largest and the lowest emissions estimated for 2012 and 2006, respectively. The temporal variations in the emissions based on the traditional method, GFEDv3.0, and the method of Xia et al. (2016) were different. The constrained CO emissions in this study were commonly smaller than those based on the traditional bottom-up method and larger than those based on burned area or FRP in other studies. In particular, the constrained emissions were close to GFEDv4.1s that contained emissions from small fires. The contributions of OBB to two particulate pollution ev