State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
Himalayan Environment Research Institute (HERI), Kathmandu, Nepal.
Environ Sci Pollut Res Int. 2017 Nov;24(31):24454-24472. doi: 10.1007/s11356-017-0077-0. Epub 2017 Sep 12.
In order to investigate the spatial and temporal variations of aerosols and its soluble chemical compositions of the data gap zone in the central Himalayan region, aerosol samples were collected at four sites. The sampling location were characterized by four different categories, such as urban (Bode), semi-urban site in the northern Indo-Gangetic Plain (Lumbini), rural (Dhunche), and semiarid rural (Jomsom). A total of 230 aerosol samples were collected from four representative sites for a yearlong period and analyzed for water-soluble inorganic ions (WSIIs). The annual average aerosol mass concentration followed the sequence as Bode (238.24 ± 162.24 μg/m)> Lumbini (161.14 ± 105.95 μg/m)> Dhunche (112.40 ± 40.30 μg/m)> Jomsom (78.85 ± 34.28 μg/m), suggesting heavier particulate pollution in the urban and semi-urban sites. The total soluble ions contributed to 12.61-28.19% of TSP aerosol mass. The results revealed that SO and NO were the major anion and Ca and NH were the major cation influencing the aerosol composition over the central Himalayas. Calcium played a major role in neutralizing aerosol acidity followed by NH at all the sites. The major compound of aerosol was (NH)SO and NHHSO in the central Himalayas. Clear seasonality was observed at three observation sites, with higher concentrations during non-monsoon (dry periods) and lower during monsoon (wet period), suggesting washing out of aerosol particles by heavy precipitation during monsoon. In contrast, semiarid sites did not show the clear seasonal trend due to limited precipitation. Stationary sources were predominant over the mobile sources mostly in the remote sites. Principal component analysis confirmed that the major sources of WSIIs in the region were industrial emissions, fossil fuel and biomass burning, and crustal fugitive dusts. Nevertheless, transboundary aerosol transport over the region from polluted cities from south Asia could not be ignored as indicated by the clusters of air mass backward trajectory analysis.
为了研究喜马拉雅山脉中部数据空白区气溶胶及其可溶性化学成分的时空变化，在四个地点采集了气溶胶样本。采样地点的特征是四个不同的类别，如城市（博尔德）、北印度恒河平原的半城市地区（蓝毗尼）、农村（敦乔）和半干旱农村（乔姆索姆）。在一年的时间里，从四个具有代表性的地点共采集了 230 个气溶胶样本，并对其进行了水溶性无机离子（WSIIs）分析。年平均气溶胶质量浓度的顺序为博尔德（238.24±162.24μg/m）>蓝毗尼（161.14±105.95μg/m）>敦乔（112.40±40.30μg/m）>乔姆索姆（78.85±34.28μg/m），这表明城市和半城市地区的颗粒物污染更严重。总可溶性离子占 TSP 气溶胶质量的 12.61-28.19%。结果表明，SO 和 NO 是影响喜马拉雅山脉中部气溶胶组成的主要阴离子和阳离子，Ca 和 NH 也是如此。在所有站点，Ca 都起到了中和气溶胶酸度的主要作用，其次是 NH。喜马拉雅山脉中部气溶胶的主要化合物是（NH）SO 和 NHHSO。在三个观测点观察到明显的季节性，在非季风（干燥期）期间浓度较高，在季风（湿润期）期间浓度较低，这表明季风期间大量降水冲洗了气溶胶颗粒。相比之下，由于降水有限，半干旱地区没有明显的季节性趋势。固定源对移动源的影响较大，尤其是在偏远地区。主成分分析证实，该地区 WSIIs 的主要来源是工业排放、化石燃料和生物质燃烧以及地壳扬尘。然而，从空气团后向轨迹聚类分析可以看出，南亚污染城市向该地区输送的跨界气溶胶不容忽视。
