State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China.
Nat Commun. 2022 Aug 31;13(1):5115. doi: 10.1038/s41467-022-32863-3.
Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δC and ΔC) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality.
对二次有机气溶胶 (SOA) 来源的不完全了解导致空气质量管理和气候变化评估存在很大的不确定性。大气水相中的化学反应是 SOA 质量的一个重要来源，但人为排放对水相 SOA (aqSOA) 的影响还没有得到很好的控制。在这里，我们使用主要 aqSOA 分子（如草酸）的特征双碳同位素指纹（δC 和 ΔC）来追踪 aqSOA 的前体来源和形成机制。 aqSOA 分子的大量稳定碳同位素分馏为广泛的水相处理提供了有力的证据。与这些 aqSOA 化合物主要来源于生物的范式相反，基于放射性碳的源分配表明，化石前体产生了超过一半的 aqSOA 分子。大量源自化石的 aqSOA 对总水溶性有机气溶胶负荷有很大贡献，从而影响空气质量和人为辐射强迫的预测。我们的研究结果表明，化石排放对 aqSOA 的重要性，对气候和空气质量有影响。
