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首页> 外文期刊>Atmospheric chemistry and physics >Sources and photochemistry of volatile organic compounds in the remote atmosphere of western China: results from the Mt. Waliguan Observatory
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Sources and photochemistry of volatile organic compounds in the remote atmosphere of western China: results from the Mt. Waliguan Observatory

机译：中国西部偏远大气中挥发性有机化合物的来源和光化学：来自山瓦里关天文台

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The chemistry of the natural atmosphere and the influence by long-range transport of air pollution are key issues in the atmospheric sciences. Here we present two intensive field measurements of volatile organic compounds (VOCs) in late spring and summer of 2003 at Mt. Waliguan (WLG, 36.28° N, 100.90° E, 3816 m a.s.l.), a baseline station in the northeast part of the Qinghai-Tibetan Plateau. Most VOC species exhibited higher concentrations in late spring than in summer. A typical diurnal variation was observed with higher nighttime levels, in contrast to results from other mountainous sites. Five different air masses were identified from backward trajectory analysis showing distinct VOC speciation. Air masses originating from the central Eurasian continent contained the lowest VOC levels compared to the others that were impacted by anthropogenic emissions from China and the Indian subcontinent. A photochemical box model based on the Master Chemical Mechanism (version 3.2) and constrained by a full suite of measurements was developed to probe the photochemistry of atmosphere at WLG. Our results show net ozone production from in situ photochemistry during both late spring and summer. Oxidation of nitric oxide (NO) by the hydroperoxyl radical (HOsub2/sub) dominates the ozone production relative to the oxidation by the organic peroxy radicals (ROsub2/sub), and the ozone is primarily destroyed by photolysis and reactions with the HOsubx/sub (HOsubx/sub = OH + HOsub2/sub) radicals. Ozone photolysis is the predominant primary source of radicals (ROsubx/sub = OH + HOsub2/sub + ROsub2/sub), followed by the photolysis of secondary oxygenated VOCs and hydrogen peroxides. The radical losses are governed by the self and cross reactions among the radicals. Overall, the findings of the present study provide insights into the background chemistry and the impacts of pollution transport on the pristine atmosphere over the Eurasian continent.
机译：自然大气的化学作用和空气污染的远距离迁移的影响是大气科学中的关键问题。在这里，我们介绍了2003年春末和夏季在山上进行的两次挥发性有机化合物（VOC）的密集测量。瓦里关（WLG，北纬36.28°，东经100.90°，3816 m.s.l.）是青藏高原东北部的基准站。春季末大多数挥发性有机化合物的浓度高于夏季。与其他山区的结果相比，夜间水平较高时，通常会观察到典型的昼夜变化。从向后轨迹分析中发现了五种不同的空气质量，显示出不同的VOC形态。与其他受中国和印度次大陆人为排放影响的空气相比，源自欧亚大陆中部的空气质量的VOC含量最低。建立了基于主化学机理（3.2版）并受全套测量约束的光化学箱模型，以探测WLG大气的光化学。我们的结果表明，在春季末和夏季，原位光化学产生的净臭氧量都很高。相对于有机过氧自由基（RO 2 ）和臭氧的氧化作用，氢过氧化自由基（HO 2 ）对一氧化氮（NO）的氧化作用占主导地位。主要被光解和与HO x （HO x = OH + HO 2 ）自由基反应破坏。臭氧的光解是自由基的主要主要来源（RO x = OH + HO 2 + RO 2 ），其次是二次氧化的光解。 VOC和过氧化氢。自由基的损失受自由基之间的自我和交叉反应支配。总体而言，本研究的发现提供了对背景化学以及欧亚大陆上原始大气污染传输的影响的见解。

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