天津市PM_(2.5)中氮含量及同位素的昼夜及季节变化  

Diurnal and seasonal variations of nitrogen contents and isotopic composition of total nitrogen in PM_(2.5)in Tianjin.

作　　者：董志超 徐占杰 王爽[1] 李培森 赵雪琰 傅平青 刘丛强[1] Chandra Mouli Pavuluri DONG Zhi-chao;XU Zhan-jie;WANG Shuang;LI Pei-sen;ZHAO Xue-yan;FU Ping-qing;LIU Cong-qiang;Chandra Mouli Pavuluri(Institute of Surface-Earth System Science,School of Earth System Science,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学地球系统科学学院,表层地球系统科学研究院,天津300072

出　　处：《中国环境科学》2021年第3期1014-1023,共10页China Environmental Science

基　　金：国家重点研发计划(2017YFC0212700);国家自然科学基金资助项目(41651001,41775120)。

摘　　要：为研究天津市大气气溶胶中氮的来源,分析了2016年夏、冬两季昼夜采集的细颗粒物气溶胶(PM_(2.5))中无机离子浓度和氮同位素组成(δ^(15)N).结果显示:天津市冬季平均PM_(2.5)质量浓度(207μg/m^(3))远高于夏季(40.1μg/m^(3)),冬季PM_(2.5)的δ^(15)N值(+5.1‰)低于夏季(+10.7‰),即夏季PM_(2.5)较冬季更富集15N;夏季PM_(2.5)中NH^(4+)的平均浓度高于c(NO_(3)^(–)),但是冬季NO_(3)^(–)浓度最高,其次是c(NH^(4+))>c(SO_(4)^(2–));此外,通过对比昼夜样品,夏季PM_(2.5)中氮含量和氮同位素组成在昼夜均表现出明显差异,而冬季不明显.结果表明,天津市夏季气溶胶中含氮化合物在昼夜受海陆风的影响,即白天受海洋气溶胶影响较大而夜间则为陆源气溶胶物质影响,然而冬季受东亚季风的影响削弱了海陆风对海陆间大气气溶胶的交换作用,且在冬季化石燃料燃烧源氮贡献较大.In order to understand the sources of nitrogen in atmospheric aerosols in Tianjin,the concentration of inorganic ions and nitrogen isotopic composition(δ^(15)N)of total nitrogen(TN)in fine aerosols(PM_(2.5))collected on day and night basis in summer and winter of 2016 were studied.The results showed that the average mass concentration of PM_(2.5)in winter(207μg/m^(3))was much higher than that in summer(40.1μg/m^(3)),and theδ^(15)N value of TN in PM_(2.5)in winter(+5.1‰)was lower than that in summer(+10.7‰),with high enrichment of 15N in the summer.The average concentration of NH^(4+)in PM_(2.5)in summer was higher than that of NO_(3)^(–)(c(NO_(3)^(–))),whereas in winter,it was opposite:c(NO_(3)^(–))was higher than c(NH^(4+)),followed by c(SO_(4)^(2–)).In addition,both nitrogen contents andδ^(15)N of TN in PM_(2.5)showed significant differences between day and night in summer,but not in winter.The results demonstrated that the nitrogen loading in summer aerosols in Tianjin was significantly affected by the sea-land circulation,that is,with ocean aerosols during the day and terrestrial aerosols at night.However,East Asian monsoon in winter weakened the exchange effect of sea-land circulation,while the contribution of fossil fuel combustion source to nitrogen was more significant in winter.

关 键 词：大气气溶胶 氮 氮同位素 海陆风 天津 

分 类 号：X513[环境科学与工程—环境工程]