清洁取暖对保定市采暖期PM_(2.5)中碳质气溶胶的影响

Effect of Clean Heating on Carbonaceous Aerosols in PM_(2.5)During the Heating Period in Baoding

为了研究清洁取暖措施对保定市PM_(2.5)中碳质气溶胶浓度和来源的影响,于2014年和2019年冬季采暖期在保定市采集PM_(2.5)样品,用DRI Model 2001A热光碳分析仪测定样品中OC和EC的浓度.结果表明,2014年采暖期PM_(2.5)中ρ(OC)和ρ(EC)平均值分别为60.92μg·m^(-3)和18.15μg·m^(-3),2019年采暖期PM_(2.5)中ρ(OC)和ρ(EC)平均值分别为36.63μg·m^(-3)和6.07μg·m^(-3),与2014年相比2019年OC、EC浓度分别下降了39.87%和66.56%,EC下降幅度大于OC,且2019年气象条件与2014年相比更不利于污染物扩散.通过对OC和EC相关性分析和SOC估算,发现2014年和2019年保定市OC和EC相关性R^(2)分别为0.874和0.811,表明保定市OC和EC具有较为一致的来源.2014年和2019年ρ(SOC)的平均值分别为16.59μg·m^(-3)和11.31μg·m^(-3),对OC的贡献率分别为27.23%和30.87%,表明与2014年相比2019年一次污染下降但二次污染上升,说明大气氧化性增强.对碳质气溶胶的污染来源分析发现,清洁取暖实施前后2014年和2019年大气中的碳质气溶胶均主要来自生物质燃烧、煤燃烧和汽车尾气排放,但2019年与2014年相比来自生物质燃烧和燃煤的贡献减少.OC和EC浓度的下降得益于清洁取暖对燃煤源和生物质燃烧源的管控,同时,清洁取暖措施的实施降低了一次排放对保定市PM_(2.5)中碳质气溶胶的贡献.

In order to study the effects of clean heating measures on the concentration and source of carbonaceous aerosols in PM_(2.5)in Baoding,we collected PM_(2.5)samples in Baoding during the winter heating periods of 2014 and 2019.The concentrations of OC and EC in the samples were determined by using a DRI Model 2001A thermo-optical carbon analyzer.The results showed that the average values of ρ(OC)andρ(EC)in the heating period in 2014 were 60.92μg·m^(-3)and 18.15μg·m^(-3),and the average values of ρ(OC)and ρ(EC)in the heating period in 2019 were 36.63μg·m^(-3)and 6.07μg·m^(-3).Compared with those in 2014,the concentrations of OC and EC decreased by 39.87% and 66.56%,respectively,in 2019;the decrease in EC was larger than that in OC,and the meteorological conditions in 2019 were more severe than those in 2014,which was not conducive to the spread of pollutants.The correlation analysis and SOC estimation of OC and EC indicated that the correlation R^(2) of OC and EC in Baoding in 2014 and 2019 were 0.874 and 0.811,respectively,indicating that OC and EC in Baoding had relatively consistent sources.The average values of ρ(SOC)in 2014 and 2019 were 16.59μg·m^(-3)and 11.31μg·m^(-3),respectively,and the contribution rates to OC were 27.23% and 30.87%,respectively.This showed that in 2019,compared with that in 2014,the primary pollution decreased,but the secondary pollution increased,and the atmospheric oxidation increased.The analysis of the pollution sources of carbonaceous aerosols revealed that in 2014 and 2019 before and after the implementation of clean heating,the carbonaceous aerosols in the atmosphere were mainly from biomass combustion,coal combustion,and vehicle exhaust emissions.However,the contribution from biomass burning and coal burning decreased in 2019 compared to that in 2014.The decrease in OC and EC concentrations was attributed to the control of coal-fired and biomass-fired sources by clean heating.At the same time,the implementation of clean heating measures reduced the contribution of primary emissions to carbonaceous aerosols in PM_(2.5)in Baoding City.