撒哈拉以南非洲是生物质燃烧(BB)衍生的碳质气溶胶的热点,包括光吸收有机(棕色)碳(BrC)。然而,尚未完全了解该地区BB气溶胶中BrC的化学复杂性。我们通过共同的撒哈拉以南非洲生物质燃料(硬木,牛粪,稀树草原草,和叶子)。我们量化了基于测量计的,含BrC的富含有机物的BB气溶胶的实时光吸收特性,考虑波长的变化,燃料类型,相对湿度,和光化学老化条件。在冬天从腔室和博茨瓦纳收集的过滤器样本中,我们鉴定出182个BrC物种,分类为木质素热解产物,硝基芳烃,香豆素,二苯乙烯,和类黄酮.使用一套广泛的标准,我们确定了特定物种的质量和排放因子。我们的分析显示,结合的BrC物种对腔室测量的BB气溶胶质量的贡献(0.4-14%)与370nm(0.2-2.2m2g-1)的质量吸收截面之间呈线性关系。分层聚类从BrC矩阵中解析出关键的分子级成分,叶子和牛粪燃烧产生的光化学老化排放物显示出与博茨瓦纳气溶胶相似的BrC指纹。这些定量发现可能有助于完善气候模型预测,协助进行来源分配,并为人类健康和全球气候提供有效的空气质量管理政策。
Sub-Saharan Africa is a hotspot for biomass burning (BB)-derived carbonaceous aerosols, including light-absorbing organic (brown) carbon (BrC). However, the chemically complex nature of BrC in BB aerosols from this region is not fully understood. We generated smoke in a chamber through smoldering combustion of common sub-Saharan African biomass fuels (hardwoods, cow dung, savanna grass, and leaves). We quantified
aethalometer-based, real-time light-absorption properties of BrC-containing organic-rich BB aerosols, accounting for variations in wavelength, fuel type, relative humidity, and photochemical aging conditions. In filter samples collected from the chamber and Botswana in the winter, we identified 182 BrC species, classified into lignin pyrolysis products, nitroaromatics, coumarins, stilbenes, and flavonoids. Using an extensive set of standards, we determined species-specific mass and emission factors. Our analysis revealed a linear relationship between the combined BrC species contribution to chamber-measured BB aerosol mass (0.4-14%) and the mass-absorption cross-section at 370 nm (0.2-2.2 m2 g-1). Hierarchical clustering resolved key molecular-level components from the BrC matrix, with photochemically aged emissions from leaf and cow-dung burning showing BrC fingerprints similar to those found in Botswana aerosols. These quantitative findings could potentially help refine climate model predictions, aid in source apportionment, and inform effective air quality management policies for human health and the global climate.