| Today,the global biomass burning volume shows an accelerating trend,among which straw and fallen leaves,as common biomass,are often burned directly in the open air,generating a large number of pollutants that have negative impacts on air quality and human health,thus attracting widespread attention from experts and scholars in the world.However,the current research still suffers from the lack of data and insufficient information on the emission factors of biomass combustion pollutants,which leads to large uncertainties in emission inventory results.At the same time,the open burning of biomass due to the variability of time and space and the arbitrariness of combustion methods and means,and the proportion of open burning of biomass in various places is mainly determined by the income level of farmers,labor input and the cost of biomass utilization.The factors affecting biomass combustion are numerous and extremely complex,which makes it difficult to accurately calculate the emission characteristics and emissions of gaseous pollution products.In southern China,the climate is suitable and biomass resources are abundant.However,because of the scattered planting,open-air burning is difficult to prohibit,and its contribution to air pollution cannot be ignored.For the reason above,seven kinds of typical biomass in Guangxi province were selected for experiments in this study and were burned on the stove to simulate the traditional biomass burning,the flue gas emitted from open-air burning was collected,the pollutant emission factors were then calculated,and the difference of pollutant emission factors,component characteristics,and chemical reaction activity produced by different kinds of biomass combustion was finally analyzed.The emissions of pollutants carbon dioxide（CO2）,carbon monoxide（CO）,methane（CH4）,non-methane volatile organic compounds（NMVOCs）,organic carbon（OC）,black carbon（BC）,sulfur dioxide（SO2）,nitrogen oxide（NOx）,ammonia（NH3）,fine particulate matter(PM2.5),and carbonyl compounds（CCs）from biomass straw combustion from 2011 to 2020 were calculated using the emission factor method,and the trend of the impact of open burning of biomass straw on air quality in Guangxi province was explored.In this study,the emission inventory of pollutants from straw burning in cities and counties in Guangxi province was established in 2020,the per capita emission of pollutants from straw burning in cities in Guangxi province was calculated and was then evaluated,and the emission intensity of main air pollutants in major cities in Guangxi province was spatially displayed by using geographic information statistics system.The research results were concluded as listed in the follows:（1）In terms of emission factor levels of conventional pollutants,the average emission factors of CO and NOx for various types of biomass ranged from 31.66 to41.12 g/kg and 1.39 to 2.30 g/kg,respectively,while the average emission factors of CH4 and NMVOCs ranged from 0.24 to 1.71 g/kg and 0.17 to 5.29 g/kg,respectively.（2）Based on the level of emission factors of carbonyl pollutants,the average total carbonyl pollutants emission factor of three straws tested was 1209.5±437.4 mg/kg,the average total carbonyl pollutants emission factor of the four fallen leaves was748.4±243.6 mg/kg,and the emission factor of straw was greater than that of fallen leaves.（3）The total OFP of carbonyl pollutants of the seven biomasses ranged from 6.73to 18.58 mg/m3.The total OFP emissions of carbonyl pollutants from straw and leaf litter combustion were 14.91±1.78 mg/m3 and 9.94±5.77 mg/m3,respectively;the species with higher potential for ozone generation in order were formaldehyde,acetaldehyde,and acrolein.（4）The total production of major straws in Guangxi province showed an increasing trend from 2011 to 2020,and the total straw production increased by 3.11%.Emissions of various pollutants increased year by year,and the contribution of similar pollutants is larger with rice and sugarcane straw.In 2020,rice,corn,and sugarcane straw production accounted for 49.76%,11.46%,and 33.08%of the total,respectively,and was the main source of straw contribution in Guangxi province.（5）The uncertainty range of CO2,CO,CH4,NMVOCs,OC,BC,SO2,NOx,NH3,PM2.5,and CCs emitted by straw burning emission in Guangxi province in 2020 were between-38%and 45%,and the emission intensity of these pollutants was between 0.01t/km2 and 2.23 t/km2.Overall,these high-value areas of air pollutant emission intensity were mainly concentrated in the central and southern parts of Guangxi province. |
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