The Distribution Characteristics Of Chemical Components At Different Particle Sizes In Typical Combustion Sources And The Autumn Atmosphere Of Nanjing

In this study,different coal and rice,wheat and corn stalks in different regions were selected for combustion experiments to determine the PM,carbonaceous components,water-soluble ions,sulfur and carbon isotopic compositions of different particle sizes.The results showed that the particle size distribution of chemical component emission factors in the combustion source was consistent on the whole,it increasing as the particle size decreased,and the particle size difference of straw dust was more significant,and the emission factors of PM_>2.1-10,PM_>1.1-2.1and PM_1.1were 0.39?1.55,0.84?6.66 and 4.23?18.88g/kg,respectively.Under the same particle size,the emission characteristics of the same chemical components in coal or straw dust vary with the species and origin.There are significant differences in the OC/EC and WSOC/OC values of straw dust and coal dust,indicating that these two combustion sources can be distinguished according to the carbonaceous characteristic values.Among the water-soluble ions,the content of K⁺and Cl^-in straw dust was the highest,and the two account for 40%?52%of the total water-soluble ions in the fine particle size respectively.The content of SO₄^2-in coal soot is the largest,and the percentage of coarse particle size is the highest at 44%.Sulfur and carbon isotopes of different combustion sources showed significant differences.Heavy carbon was enriched in corn(?¹³C=-15.66‰)and heavy sulfur was enriched in rice and wheat(?³⁴S=3.9‰and 4.2‰,respectively).In the three kinds of coal soot,coal B and C are rich in heavy carbon,?¹³C value is-24.3‰and 26.16‰,respectively,while coal C is rich in heavy sulfur,?³⁴S value is 15‰.The sulfur and carbon isotopes in the same kind of straw dust are different according to the different origins,as the values of?¹³C and?³⁴S in Nanjing wheat straw dust are-29.72‰and 2.8‰,which are leaner in heavy carbon and heavy sulfur than wheat straw in other places,so it is of great significance to establish a local combustion source sulfur and carbon isotope source spectrum.In order to obtain the sources of atmospheric aerosols with different particle sizes,atmospheric samples were collected in the northern suburb of nanjing from October 26 to November 15,2019 to determine the chemical components and sulfur and carbon isotopes in the samples,and the particle size distribution characteristics were analyzed.The results showed that the chemical components and pollution sources of aerosol had significant differences in particle size.During the sampling period,the PM concentration was133.8±49.57?g/m³,19.37±6.11?g/m³and 43.27±13.37?g/m³in>2.1-10,>1.1-2.1 and?1.1?m livingm particle size,respectively.The pollution level of coarse particles was significantly higher than that of fine particles,and the particle size distribution of the chemical component concentration was consistent.Based on the analysis of water-soluble ion factor and the characteristic values of chemical components,it is speculated that the secondary source is the primary pollution source of atmospheric aerosols with various particle sizes.In>2.1-10,>1.1-2.1 and?1.1?m,the primary emission sources are dust,vehicle exhaust and biomass combustion respectively.The?³⁴S value in atmospheric PM_2.1is 3.66‰,so it is speculated that sulfate pollution sources are mainly responsible for biomass combustion.SO₄^2-in particle size?1.1?m contributes more to PM_2.1SO₄^2-,so biomass combustion contributes more to the particle size sulfate.The TC isotopes in>2.1-10,>1.1-2.1 and?1.1?m were-25.68±1.45‰,-27.24±0.61‰and-27.28±0.37‰,respectively,so it was judged that the main carbon sources in each particle size were coal-burning sources,motor vehicles and biomass combustion.