Transport of semivolatile organic compounds to the Tibetan plateau: spatial and temporal variation in air concentrations in mountainous Western Sichuan, China.
Transport of semivolatile organic compounds to the Tibetan plateau: spatial and temporal variation in air concentrations in mountainous Western Sichuan, China.
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DOI：
10.1021/es902764z
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发表时间：
2010-02
影响因子：
11.4
通讯作者：
Wen-jie Liu;Dazhou Chen;Xiande Liu;Xiaoyan Zheng;Wen Yang;John N. Westgate;F. Wania
中科院分区：
文献类型：
--
作者：
Wen-jie Liu;Dazhou Chen;Xiande Liu;Xiaoyan Zheng;Wen Yang;John N. Westgate;F. Wania
2005年至2008年，在海拔1242~4485m的7个采样点，连续6个月对中国西部巴朗山空气中有机氯农药和多氯联苯的分布进行了连续6个月的监测。通过气相色谱-高分辨质谱仪分析，六氯苯的浓度最高，其次是六氯环己烷、滴滴涕相关化合物和多氯联苯同系物28和52。除六氯苯在空间和时间上的浓度基本一致外，其余均有明显的季节变化，夏季浓度高于冬季。除了少数例外，浓度随海拔变化不大的情况表明，该地区这些化学物质的存在几乎完全是由于大气输送，最有可能来自成都平原。不同化合物相对丰度的相似性以及在成都市区和山区测得的夏季和冬季浓度的差异支持了这一点。此外，在采样期内，空气质量轨迹往往源自东部，在到达采样点之前经过四川盆地的西部，包括成都平原。山区夏季时间值较高是由于更多受污染的空气被吹入该地区，据推测，这要么是因为夏季杀虫剂使用量增加，要么是因为更高的温度导致源头地区更高的蒸发量。该地区空气和土壤中α-六氯环己烷、伽马-六氯环己烷和六氯联苯处于平衡状态，而p，p‘-DDE和p，p’-DDT则处于净沉积状态。
The distribution of organochlorine pesticides and polychlorinated biphenyls in air along an altitudinal transect on Balang Mountain in western China was measured by deploying XAD-2 resin based passive air samplers in duplicate at seven sites with elevations ranging from 1242 to 4485 m above sea level for five consecutive six-month periods between 2005 and 2008. Analyzed by gas chromatography-high resolution mass spectrometry, concentrations of hexachlorobenzene were highest, followed by hexachlorocyclohexanes, DDT-related compounds and PCB congeners 28 and 52. Except for hexachlorobenzene, which had largely uniform concentrations in space and time, there were clear seasonal variations with concentrations in summer being higher than in winter. With a few exceptions, concentrations that vary little with altitude suggest that the presence of these chemicals in the area is almost entirely due to atmospheric transport, most likely from the Chengdu plain. This is supported by similarities in the relative abundance of different compounds and in the differences between summer and winter concentrations measured in the city of Chengdu and in the mountains. Furthermore, air mass trajectories during the sampling period often originate to the East, passing over the Western part of the Sichuan basin, including the Chengdu plain, prior to arriving at the sampling sites. Higher summer time values in the mountains are due to more contaminated air being blown into the region, presumably due either to higher pesticide usage in summer or due to higher temperatures leading to higher evaporation in source regions. Air and soil from the region are in equilibrium with respect to alpha-HCH, gamma-HCH, and HCB, whereas a situation of net deposition prevails for p,p'-DDE and p,p'-DDT.