Bhowmik Himadri S, Tripathi Sachchida N, Shukla Ashutosh K, Lalchandani Vipul, Murari Vishnu, Devaprasad M, Shivam Ajay, Bhushan Ravi, Prévôt André S H, Rastogi Neeraj
Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
Department of Civil Engineering and Sustainable Energy Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
Sci Total Environ. 2024 Feb 20;912:168655. doi: 10.1016/j.scitotenv.2023.168655. Epub 2023 Nov 21.
Delhi, among the world's most polluted megacities, is a hotspot of particulate matter emissions, with high contribution from organic aerosol (OA), affecting health and climate in the entire northern India. While the primary organic aerosol (POA) sources can be effectively identified, an incomplete source apportionment of secondary organic aerosol (SOA) causes significant ambiguity in the management of air quality and the assessment of climate change. Present study uses positive matrix factorization analysis on the water-soluble organic aerosol (WSOA) data from the offline-aerosol mass spectrometry (AMS). It revealed POA as the dominant source of WSOA, with biomass-burning OA (31-34 %) and solid fuel combustion OA (∼21 %) being two major contributors. Here we use water-solubility fingerprints to track the SOA precursors, such as oxalates or organic nitrates, instead of identifying them based on their O:C ratio. Non-fossil precursors dominate in more oxidized oxygenated organic carbon (MO-OOC) (∼90 %), a proxy for aged secondary organic carbon (SOC), by coupling offline-AMS with C measurements. On the contrary, the oxidation of fossil fuel emissions produces a large quantity of fresh fossil SOC, which accounts for ∼75 % of less oxidized oxygenated organic carbon (LO-OOC). Our study reveals that apart from major POA contributions, large fractions of fossil (10-14 %) and biomass-derived SOA (23-30 %) contribute significantly to the total WSOA load, having impact on climate and air quality of the Delhi megacity. Our study reveals that large-scale unregulated biomass burning was not only found to dominate in POA but was also observed to be a significant contributor to SOA with implications on human health, highlighting the need for effective control strategies.
德里是世界上污染最严重的特大城市之一，是颗粒物排放的热点地区，有机气溶胶（OA）贡献很大，影响着整个印度北部的健康和气候。虽然可以有效识别一次有机气溶胶（POA）的来源，但二次有机气溶胶（SOA）的源分配不完整，导致空气质量管理和气候变化评估存在重大不确定性。本研究对离线气溶胶质谱（AMS）的水溶性有机气溶胶（WSOA）数据进行了正定矩阵因子分解分析。结果表明，POA是WSOA的主要来源，生物质燃烧OA（31%-34%）和固体燃料燃烧OA（约21%）是两个主要贡献者。在这里，我们使用水溶性指纹图谱来追踪SOA前体，如草酸盐或有机硝酸盐，而不是根据它们的O:C比来识别它们。通过将离线AMS与碳测量相结合，非化石前体在更多氧化的含氧有机碳（MO-OOC）（约90%）中占主导地位，MO-OOC是老化二次有机碳（SOC）的替代指标。相反，化石燃料排放的氧化产生大量新鲜的化石SOC，占较少氧化的含氧有机碳（LO-OOC）的约75%。我们的研究表明，除了主要的POA贡献外，很大一部分化石来源的SOA（10%-14%）和生物质来源的SOA（23%-30%）对WSOA的总负荷有显著贡献，对德里特大城市的气候和空气质量产生影响。我们的研究表明，大规模无管制的生物质燃烧不仅在POA中占主导地位，而且被观察到是SOA的重要贡献者，对人类健康有影响，突出了有效控制策略的必要性。
