Characterization of Particle Pollution Changes in Dianshan Lake Area of Shanghai and Its Possible Impact on Ozone
Based on the monitoring data measured at Dianshan Lake Superstation during 2017-2021,this study systematically analyzed the characteristics of PM2.5 concentration and composition,optical scattering and absorption properties of particles,as well as their influencing factors in Dianshan Lake area of Shanghai.The results showed that the PM2.5 concentration in Dianshan Lake area decreased year by year,with an average annual decrease rate of 2.1%;the weather patterns dominated by the northwestern region and local influences had the largest improvement rate and showed significant interannual trends,with an average annual reduction rate of 6.1-7.8 μg/m3 in PM2.5,while the weather patterns dominated by the coastal area had a smaller reduction rate with insignificant trend.Sulfate decreased significantly,but the proportion of nitrate and secondary organic components was high and increasing,indicating a more significant contribution of secondary formation to PM2.5.With the significant decrease of PM2.5 concentration,the scattering coefficient of particulate matter showed a decreasing trend,and the decreasing rate in winter was up to 30.6%per year,which was the largest decrease in the four seasons.However,the absorption coefficient did not show significant improvement.The study also evaluated the impact of particle optical properties on O3,as well as PM2.5 concentration on NO2 photolysis rate.It was found that absorbing particles had an inhibitory effect on O3 generation,but the correlation between scattering particles and O3 varies with seasons:in winter and spring,O3 was affected by the"aerosol inhibition mechanism",while in summer and autumn,scattering particles and O3 were positively correlated.The reasons of the discrepancy might be related to different sources of particles in different seasons,changes in solar zenith angle,and the impact of particle scattering on near-surface photochemical radiation flux.The positive correlation between J(NO2)and PM2.5 in summer and fall further verified the inference that the increase in particle concentration may enhance the multiple scattering effect and increase the photochemical radiation flux in favor of J(NO2)elevation and O3 generation when solar radiation is stronger.
particlesPM2.5O3pollution characteristicsNO2 photolysis rateDianshan Lake area of Shanghai
万方数据
维普
