城市隧道内棕碳气溶胶的吸光效应与分子组成特征

谭探探; 强凯龙; 刘思睿; 黄雨秋; 李彦鹏

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中国环境科学 ›› 2026, Vol. 46 ›› Issue (1) : 109-119.

大气污染与控制

城市隧道内棕碳气溶胶的吸光效应与分子组成特征

谭探探¹, 强凯龙¹, 刘思睿¹, 黄雨秋¹, 李彦鹏^1,2

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Light-absorbing and molecular composition characteristics of brown carbon in urbantunnel

TAN Tan-tan¹, QIANG Kai-long¹, LIU Si-rui¹, HUANG Yu-qiu¹, LI Yan-peng^1,2

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摘要

以西安市典型城市隧道(金花隧道)为研究对象,通过气溶胶粒径谱观测、PM_2.5化学组分分析,结合紫外-可见分光光度计与傅里叶变换离子回旋共振质谱,探究机动车排放BrC的光吸收特性、分子组成特征及其对能见度的影响.研究发现,金花隧道内气溶胶以超细颗粒(0.3~0.6μm)为主,中间段尤为突出(数浓度达2.38×10⁵#/cm³),并且与车流量变化一致.PM_2.5中OC(31.11μg/m³)和EC(7.97μg/m³)浓度显著高于开放环境,且SO₄^2-与Ca²⁺占比突出,表明机动车一次排放与二次气溶胶生成的协同作用.光学层面,BrC在紫外波段(200nm)吸光系数高达329.2Mm^-1(休息日).而在可见光波段(550nm)吸光贡献占总消光0.32%,但由于未考虑可见光全波段及粒径差异的影响,其贡献可能被低估.分子层面,共鉴定出12548个分子式,以CHO(57.7%)、CHOS(19.6%)、CHON(17.3%)类化合物为主,其中CHON呈现强吸光性(34.5% DBE/C>0.5),而CHONS因极低挥发性(ELVOC占比91.3%)更易在颗粒相累积.研究揭示隧道内BrC分子共轭性、杂原子协同作用与吸光能力的关联性,量化其能见度效应,为交通源BrC的精细化管控与隧道空气质量的改善和通风照明条件的优化提供数据基础.

Abstract

Taking the typical urban tunnel (Jinhua Tunnel) in Xi'an as the research object, the light-absorption characteristics, molecular composition, and impact on visibility of brown carbon (BrC)from vehicle emissionswere investigated by employing aerosol size distribution measurements, PM_2.5 chemical speciation, combined withUV-vis spectrophotometry, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that aerosols within the tunnel were predominantly ultrafine particles (0.3~0.6μm), with the highest number concentration (2.38×10⁵#/cm³) observed in the internal section, consistent with traffic flow patterns.OC (31.11μg/m³) and EC (7.97μg/m³)concentrations in PM_2.5 were significantly higher than those in the open atmosphere.Elevated levels of SO₄^2-and Ca²⁺ indicated the synergistic effect of primary vehicle emissions and secondary aerosol formation. Optical analysis revealed a high BrC absorption coefficient of 329.2 Mm^-1 in the UV region (200nm) during weekends. At 550nm, the absorption contribution to total extinction was 0.32%. However, this contribution might be underestimated because the full visible spectrum and particle size effects were not considered. At the molecular level, 12548 molecular formulas were identified, primarily categorized as CHO (57.7%), CHOS (19.6%), and CHON (17.3%) compounds. CHON compounds exhibited strong light absorption (34.5% with DBE/C>0.5), while CHONS compounds, characterized by extremely low volatility (91.3% identified as ELVOCs), were more likely to accumulate in the particle phase. This study elucidated the relationships between molecular conjugation, heteroatom interactions, and the light-absorbing capacity of BrC within the tunnel. The visibility effects were quantified, providing a data basis for the refined management of traffic-related BrC, and for improving tunnel air quality and optimizing ventilation and lighting conditions.

导出引用

谭探探, 强凯龙, 刘思睿, 黄雨秋, 李彦鹏. 城市隧道内棕碳气溶胶的吸光效应与分子组成特征[J]. 中国环境科学. 2026, 46(1): 109-119

TAN Tan-tan, QIANG Kai-long, LIU Si-rui, HUANG Yu-qiu, LI Yan-peng. Light-absorbing and molecular composition characteristics of brown carbon in urbantunnel[J]. China Environmental Science. 2026, 46(1): 109-119

中图分类号： X513

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