Emissions Of Open Biomass Burning And Its Impacts On Atmospheric Environment In The Northeastern China

Open filed biomass burning is a major contributor to airborne particulate matter and reactive trace gases during the post-harvest season in the Northeastern China.Due to prevailing weather conditions and high emission density,this region is prone to the accumulation of air pollutants that often leads to severe haze events.In this study,we combined satellite and ground observations,and a regional air quality modeling system quantified the contribution of open biomass burning to surface PM_2.5（particulate matter with diameter less than 2.5μm）concentrations during the severe haze episode.Firstly,high resolution active fire products from the multi-source satellite and locally measured emission factors were used to determine the open biomass burning emissions that can be directly applied to air quality model.Secondly,a regional chemical transport model,the WRF-CMAQ driven by localized fire emissions,was capable of simulating the spatial and temporal variations of surface PM_2.5 concentrations during the severe regional haze events.The main conclusions of this study are as follows:A large quantity of pollutants was emitted from the Northeastern China in the year 2015,totaling about 406.0 Gg PM_2.5,2820.0 Gg CO,380.0 Gg NMVOC,44.7Gg NH₃,28.9 Gg SO₂,147.0 Gg NOx,228.0 Gg OC,and 17.4 Gg EC.Compared with the other emission inventories,our study improved the accuracy of the open biomass burning emissions.Open biomass burning was one of the major causes of two haze episodes.Model simulations showed that open biomass burning contributed to 52.0%and 24.6%of PM_2.5 concentrations over the Northeastern China in autumn and spring respectively.The burning ban has caused a drastic decrease（93.8%）in active fire spots and open biomass burning emissions during the post-harvest season in 2018,compared to the same period in 2015 when the emission regulation was effectively enforced.We estimated that the burning ban enforced in 2018 have resulted in the decreasing of PM_2.5 concentrations by 67.10%,53.23%,and 10.06%in the Heilongjiang,Jilin,and Liaoning provinces respectively,when compared with 2015.If the biomass burning ban in 2018 had been implemented in 2015,the PM_2.5 concentrations could have decreased by at least 48.1%.