| In the past three years,Shenzhen has faced atmospheric combined pollution caused by the coexistence of soot and photochemical pollution in the Pearl River Delta region.Ozone and PM2.5 are the two main pollutants of atmospheric combined pollution.Atmospheric combined pollution made it encounters many bottlenecks in emission reduction.Due to the lack of relevance and effectiveness of traceability,it was often useless or a “one size fits all” when reducing emissions of ozone and PM2.5 simultaneously.At present,source apportionment of various pollutants was becoming mature,and the concept of collaborative management was valued by the government and scholars increasingly.However,there is a lack of quantitative analysis of the contribution coefficient of pollutants to ozone and PM2.5 synergistic emission reduction based on source apportionment.The purpose of this study was to synergistically reduce emissions of ozone and PM2.5,focusing on the concentration and composition characteristics of common precursor VOCs of ozone and PM2.5 in Shenzhen.The qualitative and quantitative relationship between VOCs reactivity,ozone generation potential and secondary organic aerosol production potential were studied.Source apportionment of VOCs,ozone,and PM2.5 using?EPA?PMF 5.0.Applying the structural equation model AMOS to study the load factor of ozone and PM2.5 synergistic emission reduction of various VOCs species and emission sources.qualitatively and quantitatively study the synergistic relationship between the ozone and PM2.5.In the experiment,ozone,PM2.5 and nitrogen oxides were observed all day by using online detection instruments,and 18 kinds of VOCs were actively sampled and quantitatively analyzed by TD-GC-MS.The concentration characteristics,composition characteristics and daily variation characteristics of the above various pollutants were analyzed.The results of the observation period showed that the total concentration of VOCs varied from?25.42 to 127.93??g·m-3,and the overall average concentration were?34.33±27.03??g·m-3.The composition of VOCs were 54.92 % for aromatics,41.32 % for alkanes and 3.76% for alkenes.The average concentration of NOx was?24.48±6.07??g·m-3,the average concentration of NO was?1.90±0.40??g·m-3,and the average concentration of NO2 was?24.48±5.68??g·m-3.The maximum concentration of ozone for eight hours was?100.30±5.96??g·m-3,and the average concentration of PM2.5 was?18.59±7.99??g·m-3.VOCs,NO and NO2 showed a bimodal change.Ozone and PM2.5 concentrations were high concentrations in daytime and low concentrations in nighttime.Various generation coefficients of VOCs were studied and source apportionment of VOCs,ozone and PM2.5 were performed using?EPA?PMF 5.0.It showed that there are four main sources of VOCs: road vehicle emission source?29 %?,solvent and paint use source?31 %?,chemical industry source?23 %?,and stationary combustion source?17 %?.The results of ozone analysis showed that the distribution ratio of total emission to total OFP were as follows: solvent and paint use source?42 %?,road vehicle emission source?26 %?,chemical industrial source?16 %?,and stationary combustion source?16 %?.The results of secondary organic aerosol analysis were: road vehicle emission source 31%,chemical industrial source 29 %,solvent and paint use source 27 %,and stationary combustion source 13 %.The structural equation AMOS was be used to study the load factors of ozone and PM2.5 synergistic emission reduction.The standard factor loads of the road vehicle emission source,chemical industrial source,stationary combustion source,solvent and paint use source,and the industrial chemical source are 0.39,0.32,0.71,0.56,respectively.The top three species contributing to the synergistic load were o-xylene,ndecane and toluene.The synergistic effect coefficients were 58.9 %,40.9%,and 40.5 %,respectively.The results of this study can provide qualitative and quantitative technical support for synergistic emission reduction in Shenzhen. |
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