Scholarlink

<p>As a light-absorbing component of organic aerosols, Brown Carbon (BrC) significantly influences radiative forcing and regional air quality. To investigate the optical properties, seasonal variations, and sources of BrC in an urban environment, this study conducted online measurements using an AE33 aethalometer in Tianjin, China, during the non-heating (September 2023) and heating (December 2023) seasons. Positive Matrix Factorization (PMF) was employed to apportion the absorption coefficient of BrC (Abs) and its mass absorption efficiency (MAE). Results showed that the average BrC Abs at 370&#xa0;nm in the heating season (27.02 ± 23.15&#xa0;Mm⁻¹) was 4.3 times higher than in the non-heating season (6.31 ± 5.32&#xa0;Mm⁻¹), accounting for 33.8% and 13.2% of the total aerosol absorption, respectively. The MAE of BrC increased from 3.03 ± 3.69&#xa0;m²/g (non-heating) to 8.37 ± 5.84&#xa0;m²/g (heating), indicating enhanced light-absorbing capacity per unit mass. Diurnal analysis revealed that secondary BrC accounted for 42% of total BrC absorption in non-heating season, but was strongly correlated with primary emissions (<i>r</i> = 0.95 with BC) in heating season. Correlation analyses further revealed distinct formation mechanisms: secBrC was moderately correlated with NO₂ at night (<i>r</i> = 0.45) in the non-heating season, but with ammonium/nitrate species (<i>r</i> = 0.29–0.41) in the heating season. PMF identified secondary processes (42%) and traffic (47.3%) as major sources in non-heating season, while coal combustion (67.5%) and biomass burning (14.0%) dominated in heating season. These findings underscore that heating activities markedly enhance BrC radiative effects, while secondary formation prevails in the non-heating season, providing critical insights for targeted mitigation of carbonaceous aerosols in northern Chinese cities.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Seasonal variation and source apportionment of brown carbon light absorption in Tianjin, China: Insights from online monitoring and PMF modeling

  • 期刊论文

  • 发表日期：

    2026年3月9日

查看全文
  • Rui Qiao,
  • Kaishe Su,
  • Jingwen Zhang,
  • Bolong Wang,
  • Ziwei Zhan,
  • Jinqiu Zhang,
  • Jianhui Wu

摘要

As a light-absorbing component of organic aerosols, Brown Carbon (BrC) significantly influences radiative forcing and regional air quality. To investigate the optical properties, seasonal variations, and sources of BrC in an urban environment, this study conducted online measurements using an AE33 aethalometer in Tianjin, China, during the non-heating (September 2023) and heating (December 2023) seasons. Positive Matrix Factorization (PMF) was employed to apportion the absorption coefficient of BrC (Abs) and its mass absorption efficiency (MAE). Results showed that the average BrC Abs at 370 nm in the heating season (27.02 ± 23.15 Mm⁻¹) was 4.3 times higher than in the non-heating season (6.31 ± 5.32 Mm⁻¹), accounting for 33.8% and 13.2% of the total aerosol absorption, respectively. The MAE of BrC increased from 3.03 ± 3.69 m²/g (non-heating) to 8.37 ± 5.84 m²/g (heating), indicating enhanced light-absorbing capacity per unit mass. Diurnal analysis revealed that secondary BrC accounted for 42% of total BrC absorption in non-heating season, but was strongly correlated with primary emissions (r = 0.95 with BC) in heating season. Correlation analyses further revealed distinct formation mechanisms: secBrC was moderately correlated with NO₂ at night (r = 0.45) in the non-heating season, but with ammonium/nitrate species (r = 0.29–0.41) in the heating season. PMF identified secondary processes (42%) and traffic (47.3%) as major sources in non-heating season, while coal combustion (67.5%) and biomass burning (14.0%) dominated in heating season. These findings underscore that heating activities markedly enhance BrC radiative effects, while secondary formation prevails in the non-heating season, providing critical insights for targeted mitigation of carbonaceous aerosols in northern Chinese cities.