上海淀山湖地区颗粒物污染特征及其对臭氧的可能影响  

Characterization of Particle Pollution Changes in Dianshan Lake Area of Shanghai and Its Possible Impact on Ozone

作　　者：林燕芬 LIN Yanfen(Shanghai Environmental Monitoring Center,Shanghai 200235,China)

机构地区：[1]上海市环境监测中心,上海200235

出　　处：《中国环境监测》2024年第6期62-69,共8页Environmental Monitoring in China

基　　金：科技部国家重点研发计划项目“湾区特征污染物立体监测体系和排放清单研究”(2022YFC3703501);上海市科委项目“上海大气PM_(2.5)和O_(3)精细化监测预报及关键前体污染物防控关键技术研究与应用示范”(20DZ1204000)。

摘　　要：基于上海淀山湖超级站2017—2021年的监测数据,系统分析了PM_(2.5)浓度和组分、颗粒物光学散射和吸收特性的变化特征及其影响因素。结果表明:淀山湖地区PM_(2.5)浓度逐年下降,年均下降率约为2.1%。以西北区域和本地影响为主导的天气型PM_(2.5)改善幅度最大且具有显著年际变化趋势,年均降幅为6.1~7.8μg/m^(3);而以滨海区域影响为主的天气型PM_(2.5)改善幅度较小且变化趋势不显著。硫酸盐浓度大幅下降,但硝酸盐和二次有机组分的占比较高且处于上升趋势,PM_(2.5)二次生成贡献愈加显著。随着PM_(2.5)浓度的显著下降,颗粒物散射系数也呈逐年下降趋势,冬季下降率可达30.6%,在4个季节里下降幅度最大,但吸收系数则无明显改善。初步评估颗粒物对O_(3)和NO_(2)光解速率的影响发现,吸收性颗粒物对O_(3)生成起抑制作用,散射性颗粒物与O_(3)之间的相关性则存在季节差异。具体来说,冬春季O_(3)受“气溶胶抑制机制”影响,夏秋季节两者呈正相关的协同污染特征,其影响因素可能包括季节间的颗粒物不同来源,太阳天顶角的变化以及颗粒物散射效应对近地面光化辐射通量的影响差异。夏秋季J(NO_(2))与PM_(2.5)呈正相关,进一步验证了太阳辐射较强时,颗粒物浓度增加可能使多次散射效应增强,增加光化辐射通量,有利于J(NO_(2))升高和O_(3)生成的推论。Based on the monitoring data measured at Dianshan Lake Superstation during 2017-2021,this study systematically analyzed the characteristics of PM_(2.5) 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 PM_(2.5) 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 6.1-7.8μg/m^(3) in PM_(2.5),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 PM_(2.5).With the significant decrease of PM_(2.5) 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 O_(3),as well as PM_(2.5) concentration on NO_(2) photolysis rate.It was found that absorbing particles had an inhibitory effect on O_(3) generation,but the correlation between scattering particles and O_(3) varies with seasons:in winter and spring,O_(3) was affected by the“aerosol inhibition mechanism”,while in summer and autumn,scattering particles and O_(3) 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(NO_(2))and PM_(2.5) in summer and fal

关 键 词：颗粒物 PM_(2.5) O_(3) 污染特征 NO_(2)光解速率 上海淀山湖地区 

分 类 号：X823[环境科学与工程—环境工程]