| 南京北郊大气棕碳吸光特性、来源及其季节变化特征 |
| 摘要点击 1002 全文点击 286 投稿时间：2022-12-26 修订日期：2023-02-23 |
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| 中文关键词 棕碳(BrC) 黑碳仪(AE33) 吸光 来源 最小相关性法(MRS) |
| 英文关键词 brown carbon(BrC) aethalometer(AE33) light absorption source minimum correlation method (MRS) |
| 作者 | 单位 | E-mail | | 陈星州 | 南京信息工程大学化学与材料学院, 南京 210044
南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | Chanxingzhou@163.com | | 崔世杰 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 张运江 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 先久坤 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 王镜雲 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 汪俊峰 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 盖鑫磊 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | caxinra@163.com |
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| 中文摘要 |
| 大气棕碳（BrC）是对大气颗粒物中具有吸光能力的一类有机物的总称，其对空气能见度及气候系统均有重要影响.自2021年3月至2022年2月底于南京北郊利用黑碳仪测定了气溶胶中BrC的光吸收系数，利用最小相关性法分别定量一次（BrCpri）和二次棕碳（BrCsec）贡献，结合后向轨迹、潜在来源和日均变化，分析季节变化特征.结果表明，观测期间BrC的平均光吸收系数（370 nm）为（7.76±7.17） Mm-1，对于总气溶胶光吸收贡献率为（22.0±8.8）%.不同波长下棕碳吸光系数在四季呈现U字形变化，即春季和冬季高，夏季和秋季低.BrCpri和BrCsec（370 nm）全年光吸收贡献分别为（62.9±21.4）%和（37.1±21.4）%；前者在四季均占主导，但随着波长增加，BrCsec的贡献逐渐增加并最终占主导（如在660 nm时）.除冬季以外，BrC在其他季节受到来自海上气团的显著影响，而冬季受当地及周边地区排放影响更为显著.交通排放在春、夏和秋季对一次排放BrC影响比冬季大，而燃煤和生物质燃烧则对冬季一次排放BrC影响较大.光化学和液相反应过程在不同季节对二次BrC有不同程度的影响，夏季主要来源于光化学反应，而冬季则主要来源于液相反应，而这两种反应也均是春季和秋季二次BrC重要生成途径. |
| 英文摘要 |
| Brown carbon (BrC) refers to a group of organic compounds in fine atmospheric particles (PM2.5) that are able to absorb light in the ultraviolet and visible range. They have a significant impact on the visibility of air and on the earth's climate. In this study, we used a black carbon analyzer (Model AE33) to conduct field measurements in northern suburban Nanjing from March 2021 to February 2022. We measured the light absorption coefficients of BrC in PM2.5 and quantified the contributions of primary (BrCpri) and secondary brown carbon (BrCsec) in BrC by using the minimum correlation method (MRS), combined with the backward trajectories,potential source contribution function (PSCF) analysis, and diurnal patterns to analyze the seasonal characteristics of BrC. The results showed that the annual average light absorption of BrC was(7.76±7.17)Mm-1 (at 370 nm), and its contribution to the total aerosol light absorption was (22.0±8.8)%. BrC light absorption at different wavelengths all showed a U-shape seasonal variation of high in spring and winter and low in summer and fall. MRS analysis showed that the annual average contributions of BrCpri and BrCsec were (62.9±21.4)% and (37.1±21.4)% (at 370 nm), respectively; however, the contribution of BrCsec increased with the increase in wavelength, and it became dominant in longer wavelengths such as 660 nm. Backward trajectory and PSCF analysis showed that BrC was heavily influenced by air masses from the sea in spring, summer, and fall but was influenced greatly by local and regional continental emissions in winter. Traffic emissions in spring, summer, and fall were more intense to contribute to BrCpri than that in winter, whereas coal and biomass combustion had a greater impact on BrCpri in winter. Detailed analysis revealed that gas-phase photochemistry and aqueous chemistry had different influences on BrCsec formation in different seasons. It was mainly from gas-phase photochemistry in summer but was dominated by aqueous process in winter; both processes, however, were important pathways to BrCsec in spring and fall. |
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