Chemical Characterization and Source Apportionment of Organic Aerosols in the Coastal City of Chennai, India: Impact of Marine Air Masses on Aerosol Chemical Composition and Potential for Secondary Organic Aerosol Formation
Chemical Characterization and Source Apportionment of Organic Aerosols in the Coastal City of Chennai, India: Impact of Marine Air Masses on Aerosol Chemical Composition and Potential for Secondary Organic Aerosol Formation
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DOI：
10.1021/acsearthspacechem.1c00276
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发表时间：
2021-10
影响因子：
3.4
通讯作者：
Snehitha M. Kommula;Panda Upasana;Amit Sharma;S. Raj;Ernesto Reyes-villegas;Tianji Liu;James Allan-Jam
中科院分区：
文献类型：
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作者：
Snehitha M. Kommula;Panda Upasana;Amit Sharma;S. Raj;Ernesto Reyes-villegas;Tianji Liu;James Allan-Jam
在印度钦奈的一个沿海城市站点，使用ACSM（气溶胶化学形态监测仪）对NR-PM 1（≤1 μm的非难降解颗粒物）进行了在线化学表征。运行期间NR-PM 1的平均质量浓度为30.4 ± 28.3 μg/m3（算术平均值±标准差），其中有机物占主要部分，占47.4%，其次是硫酸盐（占33.3%）。后向轨迹分析和STILT模型模拟使得能够确定一个相对清洁的时期，主要是海洋气团。在此期间，NR-PM 1的平均质量浓度为7.1 ± 2.8 μg/m3，比其余活动（从大陆和海洋采样的空气质量）（33.3 ± 29.1 μg/m3）低2.5倍。这一减少主要是由于更清洁的海洋流入稀释了当地的一次排放。采用正矩阵分解法（PMF）对有机组分进行了综合源解析。虽然相同的贡献的主要（1049%）和次要（1051%）的有机因素观察到的其余活动，更多的氧化-氧化有机气溶胶（MO-OOA）因素占主导地位的OA和占总OA质量的1082%在清洁期。同时，在清洁期间，观察到有机液体水的分数显著增加。研究了海洋入流对增强的二次有机气溶胶（SOA）组分的影响。简而言之，我们的研究结果表明，海风和气象条件的化学成分和环境气溶胶质量负担在沿海站点的意义。此外，这项研究强调，海洋流入可以导致本地污染的稀释，并可以显示不同的化学成分对本地气溶胶特性的影响。
Online chemical characterization of NR-PM1(nonrefractory particulate matter ≤1 μm) has been carried out using an ACSM (Aerosol Chemical Speciation Monitor) at a coastal urban site in Chennai, India. The average mass concentration of NR-PM1during the campaign was 30.4 ± 28.3 μg/m3(arithmetic mean ± standard deviation) with organics accounting for a major fraction of ∼47.4% followed by sulfate (∼33.3%). Back trajectory analysis and STILT model simulations enabled the identification of a relatively clean period with prevailing air masses from ocean. During this period, the average NR-PM1mass concentration was 7.1 ± 2.8 μg/m3, which is ∼5 times lower than that of the rest of the campaign (with air masses sampled from both continent and ocean) (33.3 ± 29.1 μg/m3). This reduction was primarily attributed to the dilution of local primary emissions due to cleaner marine influx. Comprehensive source apportionment for the organic fraction was performed using Positive Matrix Factorization (PMF). While equal contributions of primary (∼49%) and secondary (∼51%) organic factors were observed for the rest of the campaign, more oxidized-oxygenated organic aerosol (MO-OOA) factor dominated the OA and accounted for ∼82% of the total OA mass during the clean period. Simultaneously, during the clean period a significant increase in the fraction of organic liquid water was observed. We studied the effect of marine influx on the enhanced secondary organic aerosol (SOA) fraction. In brief, our results demonstrate the significance of marine winds and meteorological conditions on the chemical composition and ambient aerosol mass burden at a coastal site. Further, this study emphasizes that marine influx can cause the dilution in local pollution and can demonstrate distinct chemical composition with impacts on local aerosol properties.