Department of Chemistry, University of Pune, Pune, India, 411007,
Environ Sci Pollut Res Int. 2014;21(14):8678-91. doi: 10.1007/s11356-014-2768-0. Epub 2014 Apr 11.
Agra, one of the oldest cities "World Heritage site", and Delhi, the capital city of India are both located in the border of Indo-Gangetic Plains (IGP) and heavily loaded with atmospheric aerosols due to tourist place, anthropogenic activities, and its topography, respectively. Therefore, there is need for monitoring of atmospheric aerosols to perceive the scenario and effects of particles over northern part of India. The present study was carried out at Agra (AGR) as well as Delhi (DEL) during winter period from November 2011 to February 2012 of fine particulate (PM₂.₅: d < 2.5 μm) as well as associated carbonaceous aerosols. PM₂.₅ was collected at both places using medium volume air sampler (offline measurement) and analyzed for organic carbon (OC) and elemental carbon (EC). Also, simultaneously, black carbon (BC) was measured (online) at DEL. The average mass concentration of PM₂.₅ was 165.42 ± 119.46 μg m(-3) at AGR while at DEL it was 211.67 ± 41.94 μg m(-3) which is ~27% higher at DEL than AGR whereas the BC mass concentration was 10.60 μg m(-3). The PM₂.₅ was substantially higher than the annual standard stipulated by central pollution control board and United States Environmental Protection Agency standards. The average concentrations of OC and EC were 69.96 ± 34.42 and 9.53 ± 7.27 μm m(-3), respectively. Total carbon (TC) was 79.01 ± 38.98 μg m(-3) at AGR, while it was 50.11 ± 11.93 (OC), 10.67 ± 3.56 μg m(-3) (EC), and 60.78 ± 14.56 μg m(-3) (TC) at DEL. The OC/EC ratio was 13.75 at (AGR) and 5.45 at (DEL). The higher OC/EC ratio at Agra indicates that the formation of secondary organic aerosol which emitted from variable primary sources. Significant correlation between PM₂.₅ and its carbonaceous species were observed indicating similarity in sources at both sites. The average concentrations of secondary organic carbon (SOC) and primary organic carbon (POC) at AGR were 48.16 and 26.52 μg m(-3) while at DEL it was 38.78 and 27.55 μg m(-3), respectively. In the case of POC, similar concentrations were observed at both places but in the case of SOC higher over AGR by 24 in comparison to DEL, it is due to the high concentration of OC over AGR. Secondary organic aerosol (SOA) was 42% higher at AGR than DEL which confirms the formation of secondary aerosol at AGR due to rural environment with higher concentrations of coarse mode particles. The SOA contribution in PM₂.₅ was also estimated and was ~32 and 12% at AGR and DEL respectively. Being high loading of fine particles along with carbonaceous aerosol, it is suggested to take necessary and immediate action in mitigation of the emission of carbonaceous aerosol in the northern part of India.
阿格拉是世界遗产地之一，也是印度的首都德里，都位于印度-恒河平原（IGP）的边界，由于旅游胜地、人为活动和地形的原因，分别承载着大量的大气气溶胶。因此，需要监测大气气溶胶，以了解印度北部地区颗粒的情况和影响。本研究在 2011 年 11 月至 2012 年 2 月期间在阿格拉（AGR）和德里（DEL）进行，研究对象是细颗粒物（PM₂.₅：d < 2.5 μm）和相关的碳质气溶胶。在这两个地方，使用中体积空气采样器（离线测量）收集 PM₂.₅，并分析有机碳（OC）和元素碳（EC）。同时，在 DEL 进行黑碳（BC）的在线测量。AGR 的 PM₂.₅平均质量浓度为 165.42 ± 119.46 μg m(-3)，而 DEL 的 PM₂.₅平均质量浓度为 211.67 ± 41.94 μg m(-3)，DEL 比 AGR 高约 27%，而 BC 质量浓度为 10.60 μg m(-3)。PM₂.₅的浓度明显高于印度中央污染控制委员会和美国环境保护署规定的年度标准。OC 和 EC 的平均浓度分别为 69.96 ± 34.42 和 9.53 ± 7.27 μm m(-3)。AGR 的总碳（TC）浓度为 79.01 ± 38.98 μg m(-3)，而 DEL 的 OC、EC 和 TC 浓度分别为 50.11 ± 11.93 (OC)、10.67 ± 3.56 μg m(-3) (EC)和 60.78 ± 14.56 μg m(-3) (TC)。AGR 的 OC/EC 比值为 13.75，DEL 的 OC/EC 比值为 5.45。AGR 的 OC/EC 比值较高，表明二次有机气溶胶的形成来自不同的原始来源。PM₂.₅及其碳质物质之间存在显著的相关性，表明这两个地点的来源相似。AGR 的二次有机碳（SOC）和一次有机碳（POC）的平均浓度分别为 48.16 和 26.52 μg m(-3)，而 DEL 的平均浓度分别为 38.78 和 27.55 μg m(-3)。在 POC 方面，两个地方的浓度相似，但在 SOC 方面，AGR 的浓度比 DEL 高 24%，这是由于 AGR 上 OC 的浓度较高。AGR 的二次有机气溶胶（SOA）比 DEL 高 42%，这证实了由于农村环境中粗模态颗粒浓度较高，AGR 形成了二次气溶胶。还估计了 PM₂.₅中的 SOA 贡献，分别为 AGR 和 DEL 的 32%和 12%。由于细颗粒物和碳质气溶胶的高负荷，建议在印度北部地区采取必要的和即时的行动，减轻碳质气溶胶的排放。
