Oxidized Nitrogen‐Containing Organic Compounds Formation Enhanced the Light Absorption of PM 2.5 Brown Carbon

作者：Diwei Wang, Zhenxing Shen, Gezi Bai, Leiming Zhang, Shasha Huang, Honghao Zheng, Cailan Li, Jian Sun, Hongmei Xu, Junji Cao · 发表于：Journal of Geophysical Research Atmospheres · 年份：2025 · DOI：10.1029/2024jd042960 · 被引用次数：4 · 研究领域：Atmospheric chemistry and aerosols、Gas Sensing Nanomaterials and Sensors、Catalytic Processes in Materials Science

Abstract Brown carbon (BrC) is known to have a great impact on atmospheric radiative forcing, but its absorption characteristics at the molecular level is not well understood. This study investigated the seasonal variations of light absorption characteristics and molecular composition of BrC in Xi'an, China. Results showed that BrC exhibited higher light absorption capacity in cold (autumn and winter) than warm seasons (spring and summer). Nitrogen‐containing organic compounds were identified as important BrC chromophores. Oxidized‐N compounds originated from biomass burning emissions and NO x /NO 3 − mediated oxidation reactions were predominant in cold seasons, whereas reduced‐N compounds mainly formed from NH 3 /NH 4 + mediated reactions were abundant in warm seasons. These results contribute to a better understanding of formation mechanisms and light absorption characteristics of nitrogen‐containing BrC chromophores in PM 2.5 .