摘要
京南地区PM_(2.5)浓度在北京市各区处于高位水平,对其化学组分特征和二次粒子分析有利于其溯源防治.因此,在2023年1月20日—2月20日对北京南部地区的细颗粒物质量浓度和化学组分进行观测,并分析细颗粒物组分特征与二次气溶胶生成水平.观测期间出现4次污染过程,第一次污染过程主要为春节期间烟花爆竹燃放导致,其他3次污染过程主要以不利气象条件导致的二次转化为主导.观测期间,平均风速为1.41 m·s^(-1),平均相对湿度为32.47%,水溶性离子日均值总量为29.41μg·m^(-3),占PM_(2.5)质量浓度的62.20%;OC与EC日均值总量为9.14μg·m^(-3),占PM_(2.5)质量浓度的20.74%.在污染期,平均风速为1.15 m·s^(-1),平均相对湿度为52.01%,二次无机盐在PM_(2.5)中的占比为35.40%~86.39%,二次有机气溶胶占比约10%左右.NH_(4)^(+)/(2SO_(4)^(2-)+NO_(3)^(-))的日平均物质的量的比值为1.13(比值>1),所以NH_(4)^(+)能够完全中和酸性离子;且NH_(4)^(+)与NO_(3)^(-)(R^(2)=0.97)和SO_(4)^(2-)(R^(2)=0.82)的物质的量浓度均呈正相关关系,说明高浓度NH_(3)对二次无机离子的生成有促进作用.结果显示,SOR、NOR、SNA和SOC与相对湿度呈正相关关系,且风速增大使污染物浓度降低,因此稳压环境对二次粒子生成有明显的促进作用;大气环境在富氨状态下对二次无机盐的生成有促进作用,控制前体物NO_(x)和NH_(3)的排放水平是持续改善空气质量的有效手段.
The PM_(2.5)concentration in the southern region of Beijing is at a high level compared to other districts in the city.The chemical composition and secondary particle analysis of PM_(2.5)are beneficial for source tracing and control.Therefore,observations were conducted on the mass concentration and chemical composition of PM_(2.5)in the southern region of Beijing from January 20 to February 20,2023.The characteristics of PM_(2.5)components and the level of secondary aerosol generation were analyzed.During the observation period,four pollution episodes occurred.The first episode was mainly caused by fireworks during the Spring Festival,while the other three episodes were primarily due to secondary conversion under unfavorable meteorological conditions.During the observation period,the average wind speed was 1.41 m·s^(-1),the average relative humidity was 32.47%.The daily average concentration of water-soluble ions was 29.41μg·m^(-3),accounting for 62.20%of PM_(2.5)mass concentration.The daily average concentrations of organic carbon(OC)and elemental carbon(EC)were 9.14μg·m^(-3),accounting for 20.74%of PM_(2.5)mass concentration.In the pollution period,the average wind speed was 1.15 m·s^(-1),the average relative humidity was 52.01%.The proportion of secondary inorganic salts in PM_(2.5)ranged from 35.40%to 86.39%,and the proportion of secondary organic aerosols was approximately 10%.The daily average molar ratio of NH^(-)_(4)^(+)(/2SO_(4)^(2)+NO^(-)_(3))was 1.13(ratio>1),indicating that NH^(--)_(4)^(+)can fully neutralize acidic ions.Both NH_(4)^(+)and NO_(3)(R^(2)=0.97)and SO_(4)^(2)(R^(2)=0.82)showed positive correlations,indicating that high NH_(3)concentration promotes the formation of secondary inorganic ions.The results showed that SOR,NOR,SNA,and SOC were positively correlated with relative humidity.Increased wind speed led to a decrease in pollutant concentrations,indicating that stable atmospheric conditions have a significant promoting effect on the generation of secondary particles.Ammonia-rich a
作者
崔景文
李澳
王德来
李云凤
王亚飞
CUI Jingwen;LI Ao;WANG Delai;LI Yunfeng;WAGN Yafei(Joint Laboratory of Collaborative Control and Assessment for Eco-Environmental Pollution and Carbon Emission,Beijing Institute of Petrochemical Technology,Beijing 102617)
出处
《环境科学学报》
CAS
CSCD
北大核心
2024年第4期238-251,共14页
Acta Scientiae Circumstantiae
基金
国家自然科学基金资助项目(No.21806011)
北京石油化工学院交叉科研探索项目(No.BIPTCSF-018)。
