CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India.
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India; Chubu Institute of Advanced Sciences, Chubu University, Kasugai-shi, Aichi 4878501, Japan.
Sci Total Environ. 2022 Jun 25;827:154260. doi: 10.1016/j.scitotenv.2022.154260. Epub 2022 Mar 4.
The isotopic composition of stable carbon (δC) and nitrogen (δN) in marine aerosols influenced by the continental outflows are useful proxies for understanding the aging and secondary formation processes. Every winter, the haze pollutants transported from South Asia significantly affect the chemical composition of marine atmospheric boundary layer of the Arabian Sea. Here, we assessed the δC of total carbon (TC) and δN of total nitrogen (TN) in marine aerosols collected over the Arabian Sea during a winter cruise (6-24 December 2018). TC (2.1-13.4 μg m) is strongly correlated with TN (0.9-5.0 μg m), likely because of their common source-emissions, biomass burning and fossil-fuel combustion in the Indo-Gangetic Plain and South Asia (corroborated by backward-air mass trajectories and satellite fire counts). Besides, the linear relationship between the mass ratios of water-soluble organic carbon (WSOC) to TC (0.04-0.65) and δC (-25.1‰ to -22.9‰) underscores the importance of aging process. This means oxidation of organic aerosols during transport not only influences the WSOC levels but also affects their δC Likewise, the prevalent inverse linear relationship between the equivalent mass ratio of (NH/non-sea-salt- or nss-SO) and δN (+15.3‰ to +25.1‰) emphasizes the overall significance of neutralization reactions between major acidic ([nss-SO] ≫ [NO]) and alkaline species (NH) in aerosols. Higher δN values in winter than the spring inter-monsoon clearly emphasizes the significance of the anthropogenic combustion sources (i.e., biomass burning) in the South Asian outflow. A comparison of δC and δN with the source emissions revealed that crop-residue burning emissions followed by the coal fired power plants mostly dictate the atmospheric abundance of organic aerosols in the wider South Asian outflow.
海洋气溶胶中稳定碳（δC）和氮（δN）的同位素组成是了解老化和二次形成过程的有用示踪剂。每年冬季，来自南亚的雾霾污染物都会显著影响阿拉伯海大气边界层的化学成分。在这里，我们评估了 2018 年 12 月 6 日至 24 日冬季航次期间在阿拉伯海收集的海洋气溶胶中的总碳（TC）的 δC 和总氮（TN）的 δN。TC（2.1-13.4μg m）与 TN（0.9-5.0μg m）强烈相关，这可能是因为它们的共同源排放、生物质燃烧和化石燃料燃烧在印度恒河平原和南亚（通过后向气团轨迹和卫星火灾计数得到证实）。此外，水溶性有机碳（WSOC）与 TC 的质量比（0.04-0.65）与 δC（-25.1‰至-22.9‰）之间的线性关系强调了老化过程的重要性。这意味着在运输过程中有机气溶胶的氧化不仅会影响 WSOC 水平，还会影响其 δC。同样，（NH/非海-盐或 nss-SO）与 δN（+15.3‰至+25.1‰）之间普遍存在的逆线性关系强调了主要酸性（[nss-SO]≫[NO]）和碱性（NH）物质之间中和反应在气溶胶中的总体重要性。冬季比春季季风间的 δN 值更高，这清楚地强调了南亚流出物中人为燃烧源（即生物质燃烧）的重要性。δC 和 δN 与源排放的比较表明，农作物残余物燃烧排放，其次是燃煤电厂，主要决定了更广泛的南亚流出物中有机气溶胶的大气丰度。
