State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, 300072, China.
Environ Pollut. 2023 Jun 15;327:121569. doi: 10.1016/j.envpol.2023.121569. Epub 2023 Apr 5.
To understand the source, formation, and seasonality of biogenic secondary organic aerosol (BSOA), a nine-stage cascade impactor was utilized to collect size-segregated particulate samples from April 2017 to January 2018 in Beijing, China. BSOA tracers derived from isoprene, monoterpene, and sesquiterpene were measured with gas chromatography-mass spectrometry. Isoprene and monoterpene SOA tracers exhibited significant seasonal variations, with a summer maximum and a winter minimum. Dominance of 2-methyltetrols (isoprene SOA tracers) with a good correlation with levoglucosan (a biomass burning tracer), which was combined with the detection of methyltartaric acids (possible indicators for aged isoprene) in summer, implies possible biomass burning and long-range transport. In contrast, sesquiterpene SOA tracer (β-caryophyllinic acid) was dominant in winter and was probably associated with the local burning of biomass. Bimodal size distributions were observed for most isoprene SOA tracers, consistent with previous laboratory experiments and field studies showing that they can be formed not only in the aerosol phase but also in the gas phase. Monoterpene SOA tracers cis-pinonic acid and pinic acid showed a coarse-mode peak (5.8-9.0 μm) in four seasons due to their volatile nature. Sesquiterpene SOA tracer β-caryophyllinic acid showed a unimodal pattern with a major fine-mode peak (1.1-2.1 μm), which is linked to local biomass burning. The tracer-yield method was used to quantify the contributions of isoprene, monoterpene, and sesquiterpene to secondary organic carbon (SOC) and SOA. The highest isoprene SOC and SOA concentrations occurred in summer (2.00 μgC m and 4.93 μg m, respectively), contributing to 1.61% of OC and 5.22% of PM, respectively. These results suggest that BSOA tracers are promising tracers for understanding the source, formation, and seasonality of BSOA.
为了了解生物成因二次有机气溶胶（BSOA）的来源、形成和季节性，本研究利用九级冲击器采集了 2017 年 4 月至 2018 年 1 月北京大气中不同粒径的颗粒物样品。采用气相色谱-质谱联用仪测定了异戊二烯、单萜烯和倍半萜烯衍生的 BSOA 示踪剂。异戊二烯和单萜烯 SOA 示踪剂表现出明显的季节性变化，夏季最高，冬季最低。2-甲基四醇（异戊二烯 SOA 示踪剂）的优势与左旋葡聚糖（生物量燃烧示踪剂）具有良好的相关性，这与夏季检测到的甲基酒石酸（可能是老化异戊二烯的指示物）相结合，表明可能存在生物质燃烧和长距离传输。相比之下，倍半萜烯 SOA 示踪剂（β-石竹烯酸）在冬季占主导地位，可能与当地生物质燃烧有关。大多数异戊二烯 SOA 示踪剂的粒径分布呈双峰模式，与以前的实验室实验和实地研究一致，表明它们不仅可以在气溶胶相中形成，也可以在气相中形成。由于顺式-蒎烯和蒎烯具有挥发性，它们的单萜烯 SOA 示踪剂 cis- pinonic 酸和 pinic 酸在四个季节均呈现粗模态峰值（5.8-9.0μm）。倍半萜烯 SOA 示踪剂 β-石竹烯酸呈现单峰模式，主要在细模态峰值（1.1-2.1μm），与当地生物质燃烧有关。示踪剂产率法用于量化异戊二烯、单萜烯和倍半萜烯对二次有机碳（SOC）和 SOA 的贡献。夏季异戊二烯 SOC 和 SOA 的浓度最高（分别为 2.00μgC m 和 4.93μg m ），分别占 OC 的 1.61%和 PM 的 5.22%。这些结果表明，BSOA 示踪剂是了解 BSOA 来源、形成和季节性的有前途的示踪剂。
