Atmospheric aerosol characteristics from the Western Ghats (WG), a region that plays a prominent role in modulating the Indian monsoon, was evaluated to study the impacts of long-range transport, local sources, and cloud processing on their chemical properties. Size-segregated aerosols collected from Ponmudi (8.8°N, 77.1°E), a tropical high altitude location (960 m a.s.l.) in the southern part of the WG, during the continental to marine air-mass transition phase (January–April 2020–2021) were analysed for major chemical components, including carbonaceous species, water-soluble ionic species, metallic elements and aerosol liquid water (ALW). The major aerosol components during the north-east monsoon period were identified as (NH4)2SO4, organic matter, and ALW derived from long-range transported biomass emission plumes undergoing cloud processing and aqueous-phase reactions with SO2. Positive Matrix Factorization (PMF) analysis revealed the presence of aged and mixed aerosol types, with influence from local anthropogenic emissions and secondary formation processes. The source profiles for different air-masses indicate that the IGP air-mass is dominated by anthropogenic continental sources rich in sulphates, while the East Asian air-mass comprises highly aged continental emissions rich in organics and mixed with marine emissions from the Bay of Bengal. Fine mode aerosol mass was reconstructed, and organic matter to organic carbon conversion factor was estimated after mass closure, which revealed relatively high values for East-Asian air-mass, providing evidence for their oxidation during long-range transport. The hill station was also influenced by local urban valley emissions transported to the site via daytime convection and sea-breeze circulation. Consequently, the aerosol system over this region exhibited a complex mixture, with elemental carbon particles coexisting with sea-salt, sulphate, and secondary water-soluble organics. The findings highlight the need for further studies to understand the role of chemically processed and mixed aerosol system in modifying regional climate dynamics and air quality over such sensitive ecosystems.

中文翻译：

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印度半岛热带西高止山脉环境大陆到海洋气团过渡阶段气溶胶的尺寸规格化学


评估了西高止山脉 （WG） 的大气气溶胶特征，该地区在调节印度季风方面起着重要作用，以研究远程传输、本地来源和云处理对其化学性质的影响。在大陆到海洋气团过渡阶段（2020-2021 年 1 月至 4 月），分析了从工作组南部热带高海拔地区（海拔 960 米）庞穆迪（8.8°N，77.1°E）收集的粒径分离气溶胶的主要化学成分，包括碳质物质、水溶性离子物质、金属元素和气溶胶液态水 （ALW）。东北季风期间的主要气溶胶成分被确定为 （NH4）2SO4、有机物和 ALW，这些气溶胶来自经历云处理和与 SO2 水相反反应的远程运输生物质排放羽流。正矩阵分解 （PMF） 分析揭示了老化和混合气溶胶类型的存在，受到当地人为排放和次生形成过程的影响。不同气团的来源剖面表明，IGP 气团以富含硫酸盐的人为大陆来源为主，而东亚气团包括富含有机物的高度老化的大陆排放物，并与孟加拉湾的海洋排放物混合。重建了精细模式气溶胶质量，并估计了质量闭合后有机物到有机碳的转换因子，这揭示了东亚气团的值相对较高，为它们在远程传输过程中的氧化提供了证据。山地站还受到当地城市山谷排放物的影响，这些排放物通过白天对流和海风环流输送到现场。 因此，该区域的气溶胶系统表现出复杂的混合物，元素碳颗粒与海盐、硫酸盐和次生水溶性有机物共存。这些发现强调需要进一步研究，以了解化学加工和混合气溶胶系统在改变此类敏感生态系统的区域气候动态和空气质量方面的作用。