Singh Praveen Kumar, Adhikary Bhupesh, Chen Xintong, Kang Shichang, Poudel Shankar Prasad, Tashi Tshering, Goswami Ajanta, Puppala Siva Praveen
International Centre for Integrated Mountain Development (ICIMOD), G.P.O. Box 3226, Kathmandu, Nepal; Centre of Excellence in Disaster Mitigation and Management, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India.
International Centre for Integrated Mountain Development (ICIMOD), G.P.O. Box 3226, Kathmandu, Nepal.
Sci Total Environ. 2023 Feb 1;858(Pt 3):160137. doi: 10.1016/j.scitotenv.2022.160137. Epub 2022 Nov 11.
During 2015-2018, eight black carbon (BC) monitoring sites were established in Nepal and Bhutan to fill a significant data gap regarding BC measurement in Central Himalaya. This manuscript analyzes and presents data from these eight stations and one additional station on the Tibetan plateau (TP). Complex topography, varied emission sources, and atmospheric transport pathways significantly impacted the BC concentrations across these stations, with annual mean concentrations varying from 36 ng m to 45,737 ng m. Higher annual mean concentrations (5609 ± 4515 ng m) were recorded at low-altitude sites than in other locations, with seasonal concentrations highest in the winter (7316 ± 2541 ng m). In contrast, the annual mean concentrations were lowest at high-altitude sites (376 ± 448 ng m); the BC concentrations at these sites peaked during the pre-monsoon season (930 ± 685 ng m). Potential source contributions to the total observed BC were analyzed using the absorption angstrom exponent (AAE). AAE analysis showed the dominance of biomass burning sources (>50 %), except in Kathmandu. By combining our data with previously published literature, we put our measurements in perspective by presenting a comprehensive assessment of BC concentrations and their variability over the Hindu Kush Himalayan (HKH) region. The BC levels in all three geographic regions, high, mid, and low altitude significantly influenced by the persistent seasonal meteorology. However, the mid-altitude stations were substantially affected by valley dynamics and urbanization. The low-altitude stations experienced high BC concentrations during the winter and post-monsoon seasons. Concentration weighted trajectory (CWT) and frequency analyses revealed the dominance of long-range transported pollution during winter over HKH, from west to east. South Asian sources remained significant during the monsoon season. During pre- and post-monsoon, the local, regional, and long-distance pollution varied depending on the location of the receptor site.
2015年至2018年期间，尼泊尔和不丹建立了8个黑碳（BC）监测站点，以填补喜马拉雅中部BC测量方面的重大数据空白。本手稿分析并展示了这8个站点以及青藏高原（TP）上另一个站点的数据。复杂的地形、多样的排放源和大气传输路径对这些站点的BC浓度产生了显著影响，年平均浓度从36 ng/m³到45737 ng/m³不等。低海拔站点的年平均浓度较高（5609±4515 ng/m³），高于其他地点，季节浓度在冬季最高（7316±2541 ng/m³）。相比之下，高海拔站点的年平均浓度最低（376±448 ng/m³）；这些站点的BC浓度在季风前季节达到峰值（930±685 ng/m³）。使用吸收埃指数（AAE）分析了对观测到的总BC的潜在源贡献。AAE分析表明，除了加德满都，生物质燃烧源占主导地位（>50%）。通过将我们的数据与先前发表的文献相结合，我们通过对兴都库什喜马拉雅（HKH）地区的BC浓度及其变异性进行全面评估，来正确看待我们的测量结果。所有三个地理区域（高、中、低海拔）的BC水平都受到持续季节气象的显著影响。然而，中海拔站点受到山谷动态和城市化的严重影响。低海拔站点在冬季和季风后季节经历了高BC浓度。浓度加权轨迹（CWT）和频率分析表明，冬季HKH上空长距离传输污染占主导地位，从西向东。南亚源在季风季节仍然很重要。在季风前和季风后，本地、区域和远距离污染因受体站点的位置而异。
