Environmental Sciences Section, Bose Institute, Kolkata, India.
PLoS One. 2010 Jun 16;5(6):e11122. doi: 10.1371/journal.pone.0011122.
There is an urgent need for an improved understanding of the sources, distributions and properties of atmospheric aerosol in order to control the atmospheric pollution over northeastern Himalayas where rising anthropogenic interferences from rapid urbanization and development is becoming an increasing concern.
METHODOLOGY/PRINCIPAL FINDINGS: An extensive aerosol sampling program was conducted in Darjeeling (altitude approximately 2200 meter above sea level (masl), latitude 27 degrees 01'N and longitude 88 degrees 15'E), a high altitude station in northeastern Himalayas, during January-December 2005. Samples were collected using a respirable dust sampler and a fine dust sampler simultaneously. Ion chromatograph was used to analyze the water soluble ionic species of aerosol. The average concentrations of fine and coarse mode aerosol were found to be 29.5+/-20.8 microg m(-3) and 19.6+/-11.1 microg m(-3) respectively. Fine mode aerosol dominated during dry seasons and coarse mode aerosol dominated during monsoon. Nitrate existed as NH(4)NO(3) in fine mode aerosol during winter and as NaNO(3) in coarse mode aerosol during monsoon. Gas phase photochemical oxidation of SO(2) during premonsoon and aqueous phase oxidation during winter and postmonsoon were the major pathways for the formation of SO(4)(2-) in the atmosphere. Long range transport of dust aerosol from arid regions of western India was observed during premonsoon. The acidity of fine mode aerosol was higher in dry seasons compared to monsoon whereas the coarse mode acidity was higher in monsoon compared to dry seasons. Biomass burning, vehicular emissions and dust particles were the major types of aerosol from local and continental regions whereas sea salt particles were the major types of aerosol from marine source regions.
CONCLUSIONS/SIGNIFICANCE: The year-long data presented in this paper provide substantial improvements to the heretofore poor knowledge regarding aerosol chemistry over northeastern Himalayas, and should be useful to policy makers in making control strategies.
为了控制东北喜马拉雅地区的大气污染，迫切需要更好地了解大气气溶胶的来源、分布和特性。东北喜马拉雅地区由于快速城市化和发展带来的人为干扰不断增加，已经引起了越来越多的关注。
方法/主要发现：2005 年 1 月至 12 月，在东北喜马拉雅地区的一个高海拔站——大吉岭（海拔约 2200 米，北纬 27 度 01'，东经 88 度 15'）进行了一项广泛的气溶胶采样计划。使用可吸入粉尘采样器和细粉尘采样器同时采集样品。离子色谱仪用于分析气溶胶中水溶性离子物种。发现细颗粒和粗颗粒气溶胶的平均浓度分别为 29.5+/-20.8 微克/立方米和 19.6+/-11.1 微克/立方米。在旱季，细颗粒气溶胶占主导地位，在季风期间，粗颗粒气溶胶占主导地位。冬季，细颗粒气溶胶中的硝酸盐以 NH(4)NO(3)的形式存在，季风期间，粗颗粒气溶胶中的硝酸盐以 NaNO(3)的形式存在。前季风期间 SO(2)的气相光化学氧化和冬季及后季风期间的水相氧化是大气中 SO(4)(2-)形成的主要途径。旱季来自印度西部干旱地区的风尘气溶胶的长程传输在季风前观察到。与季风相比，旱季细颗粒气溶胶的酸度较高，而季风期间粗颗粒气溶胶的酸度较高。来自本地和大陆地区的主要气溶胶类型是生物质燃烧、车辆排放和粉尘颗粒，而来自海洋源地区的主要气溶胶类型是海盐颗粒。
结论/意义：本文提供了长达一年的数据，大大提高了人们对东北喜马拉雅地区气溶胶化学的认识，这对于决策者制定控制策略应该是有用的。
