生态环境学报 ›› 2023, Vol. 32 ›› Issue (9): 1654-1662.DOI: 10.16258/j.cnki.1674-5906.2023.09.012

• 研究论文 • 上一篇    下一篇

基于多同位素的珠三角PM2.5中二次无机气溶胶来源解析

温丽容1,3(), 林勃机2, 李婷婷2, 张子洋2, 张正恩2, 江明1, 周炎1, 张涛1, 李军2,*(), 张干2   

  1. 1.国家环境保护区域空气质量监测重点实验室/广东省生态环境监测中心,广东 广州 510308
    2.广东省环境资源利用与保护重点实验室/有机地球化学国家重点实验室/中国科学院广州地球化学研究所,广东 广州 510640
    3.广东省环境辐射监测中心,广东 广州 510300
  • 收稿日期:2023-05-19 出版日期:2023-09-18 发布日期:2023-12-11
  • 通讯作者: *李军。E-mail: junli@gig.ac.cn
  • 作者简介:温丽容(1975年生),女,副高级工程师,硕士,主要研究方向环境空气质量监测与研究。E-mail: 105771055@qq.com
  • 基金资助:
    广东省重点领域研发计划项目(2020B1111360003);国家自然科学基金项目(41977177)

Source Apportionment of Ammonium in Atmospheric PM2.5 in the Pearl River Delta Based on Nitrogen Isotope

WEN Lirong1,3(), LIN Boji2, LI Tingting2, ZHANG Ziyang2, ZHANG Zhengen2, JIANG Ming1, ZHOU Yan1, ZHANG Tao1, LI Jun2,*(), ZHANG Gan2   

  1. 1. National Key Laboratory for Regional Air Quality Monitoring of Environmental Protection/Guangdong Ecological Environment Monitoring Center, Guangzhou 510308, P. R. China
    2. Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization/State Key Laboratory of organic geochemistry/Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
    3. Guangdong Environmental Radiation Monitoring Center, Guangzhou 510300, P. R. China
  • Received:2023-05-19 Online:2023-09-18 Published:2023-12-11

摘要:

二次无机气溶胶(SIA,Secondary inorganic aerosol)是PM2.5中的重要组成部分,其快速形成是导致大气能见度下降的重要原因。二次无机气溶胶主要包括硫酸根、硝酸根和铵根离子,其来源广、生成途径复杂,识别其来源存在一定的挑战。最近,基于稳定同位素(δ34S-SO42−δ15N-NO3δ18O-NO3δ15N-NH4+)的源解析方法被应用到相应污染物的来源解析。选取珠三角鹤山大气超级站作为研究地点,开展了为期1年的大气PM2.5样品采集,在分析了70个样品的水溶性离子、痕量金属元素、有机碳、无机碳的基础上,选取其中的37个大气PM2.5样品,分析了相应的δ34S-SO42−δ15N-NO3δ18O-NO3δ15N-NH4+同位素值,结合稳定同位素平衡和优化的贝叶斯模型进行源解析,定量了各污染源对二次无机气溶胶的影响。结果表明,PM2.5年平均质量浓度为39.8 μg•m−3。PM2.5中SIA占比年均29.8%,呈现春季>冬季>夏季>秋季的季节变化规律,冬季二次污染程度较2013年明显下降;年均各SIA对颗粒质量浓度贡献顺序为硫酸根>硝酸根>铵根。δ34S-SO42−值范围为1.8‰-9.6‰,平均值为4.5‰±1.7‰。源解析结果显示采样期间燃煤、燃油、生物成因硫排放对鹤山SO42−分别贡献了41.8%、32.9%、25.3%。δ15N-NO3范围为0.8‰-8.3‰,平均值为4.7‰±2.0‰。贝叶斯源解析结果显示,燃煤排放是鹤山NO3最主要来源,年均贡献率达到41.6%,其余污染源年均贡献率排序为,生物质燃烧 (BB)>汽油车>船舶>土壤微生物,贡献率依次为20.9%、15.6%、13.9%、8.0%。将各SIA浓度与对应的源解析结果合并,结果表明非化石源对总SIA贡献最大,为37.2%,其次为燃煤源及燃油源,分别为35.6%、27.2%。排放清单法可能低估了非化石源对SIA的贡献,在珠三角地区低估值约为10%。清洁大气时期燃油对SIA的贡献显著高于轻度污染与重度污染时期,最高可达48.4%。

关键词: 珠三角, PM2.5, 二次无机气溶胶, 氮同位素, 硫同位素, 贝叶斯模型

Abstract:

Secondary inorganic aerosol (SIA) is an important element of PM2.5, and its rapid formation is a significant cause of the decline of atmospheric visibility. Sulfate, nitrate and ammonium ions primarily constitute secondary inorganic aerosols, which have a wide range of sources and complex generation pathways, making it challenging to quantify their origins. Recently, stable isotopes (δ34S-SO42−, δ15N-NO3, δ18O-NO3, δ15N-NH4+) have been used to determine the sources of corresponding pollutants through source apportionment. In this study, we collected atmospheric PM2.5 samples for one year at the Pearl River Delta Heshan Atmospheric Supersite. Based on the analysis of 70 samples, including water-soluble ions, trace metal elements, organic carbon and elemental carbon, we selected 37 samples for further isotopic analysis ( δ34S-SO42−, δ15N-NO3, δ18O-NO3 and δ15N-NH4+ ). We combined stable isotope balance and Bayesian model to quantify the relative contribution of various pollution sources to secondary inorganic aerosols. The results showed that the annual average PM2.5 mass concentration was 39.8μg•m−3, with total SIA accounting for 29.8% of the annual average PM2.5 mass concentration. Seasonal variation patterns showed that spring> winter>summer>autumn, with a significant decrease in winter compared to that in 2013. The order of contribution of SIA to particle mass concentration was sulfate>nitrate>ammonium. The δ34S-SO42− values ranged from 1.8‰ to 9.6‰, with an average of 4.5‰±1.7‰. The results of source apportionment showed that coal combustion, oil combustion and biogenic sulfur accounted for 41.8%, 32.9% and 25.3% respectively of SO42− in Heshan. The δ15N-NO3 values ranged from 0.8‰ to 8.3‰, with an average of 4.7‰±2.0‰. The Bayesian isotope mixing model revealed that coal combustion was the main source of NO3 in Heshan, with an average annual contribution rate of 41.6%. The relative contribution of other pollution sources was ranked as biomass burning (BB)>gasoline vehicle>ship emission>biogenic soil emission, with percentages of 20.9%, 15.6%, 13.9% and 8.0%, respectively. The combined results of SIA analysis and source apportionment showed that non-fossil source contributed the most to total SIA (37.2%), followed by coal combustion (35.6%) and oil combustion (27.2%). The contribution of oil combustion to SIA was higher in the clean atmosphere period (up to 48.4%) than in the light and heavy pollution periods. The emission inventory method may have underestimated the contribution of non-fossil sources to SIA, by approximately 10% in the PRD region. Overall, the findings highlight the significance of non-fossil sources and the varying contribution of oil combustion to SIA.

Key words: Pearl River Delta, PM2.5, secondary inorganic aerosol, nitrogen isotope, sulfur isotope, Bayesian model

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