Collaborative Research: Radical Chemistry over Sunlit Snow at Summit, Greenland

合作研究：格陵兰山顶阳光照射下的雪上的自由基化学

• 批准号: 0612136
• 负责人: Barry Lefer
• 金额: $ 9万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-10-01 至 2009-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0612136&HistoricalAwards=false
• 关键词: Collaborative; Research; Radical; Chemistry; over

This project addresses the role of halogens in atmospheric chemistry at Summit, Greenland. Recent studies of chemical processing above and within sunlit snow have shown that polar regions are photochemically active and strongly oxidizing. In previous measurement campaigns at Summit, HO2 (peroxy radical) concentrations were found to be high and consistent with photochemical models; however, levels of OH (hydroxyl radical) were significantly elevated compared to steady-state model simulations. This occurred primarily during periods of high wind. This suggests two, not mutually exclusive, hypotheses: (1) episodic transport of reactive halogens from the marine boundary layer or free troposphere could lead to halogen activation in firn by heterogeneous reactions, and (2) local formation of reactive halogens in the photochemically active snow pack or on airborne ice during windy periods. This project involves measurements of a variety of chemical species in the Summit Greenland surface layer, including O3 (ozone), NO (nitrogen oxide), NO2 (nitrogen dioxide), H2O (water vapor), HONO (nitrous acid), RONO2 (organic nitrates), HCHO (formaldehyde), HCOOH (formic acid), CH3COOH (acetic acid), CO (carbon monoxide), CH4 (methane), reactive NMHCs (non-methane hydrocarbons), and a variety of halogen species, including BrO (bromine monoxide), IO (iodine monoxide), and OIO (iodine dioxide), as well as soluble gas phase bromide. Rates of photochemical reactions will be determined above and within the snow. Intensive sampling seasons are planned for summer 2007 (when sunlight is at a maximum), and spring 2008 (during rapid temperature changes). Measurements over a wide range of environmental conditions as well as transport regimes will help to discriminate the relative importance of halogens on the photochemical cycling of reactive hydrogen radicals (HOx). Field measurements will be interpreted with the aid of back trajectory tools (specifically, the FLEXPART model) and by employing a photochemical steady-state box model to determine the HOx cycling within the Summit boundary layer. If successful, this project will produce novel insights in chemical processes in an environment typical of polar regions, and improve our understanding of fundamental processes involving halogen compounds. The project will provide opportunities for graduate and undergraduate students to gain research experience. A broad program of public outreach is planned as well.

该项目探讨了卤素在格陵兰岛萨米特大气化学中的作用。最近对阳光积雪内部和内化学处理的研究表明，极性区域具有光化活性和强烈氧化。在先前在Summit的测量运动中，HO2（过氧自由基）浓度很高，并且与光化学模型一致。然而，与稳态模拟相比，OH（羟基自由基）的水平显着升高。这主要发生在大风时期。这表明两个，而不是相互排斥的假设：（1）来自海洋边界层反应性卤素或对流层游离的反应性卤素的发作可能导致通过异构反应的FIRN激活卤素，（2）在风能活跃的雪堆或在风能的冰上播放的局部反应性卤素局部形成。 This project involves measurements of a variety of chemical species in the Summit Greenland surface layer, including O3 (ozone), NO (nitrogen oxide), NO2 (nitrogen dioxide), H2O (water vapor), HONO (nitrous acid), RONO2 (organic nitrates), HCHO (formaldehyde), HCOOH (formic acid), CH3COOH (acetic acid), CO（一氧化碳），CH4（甲烷），反应性NMHC（非甲烷烃）和各种卤素种类，包括BRO（一氧化碳），IO（一氧化碘）和OIO（碘二氧化碳），以及可溶性的气相溴化物。光化学反应的速率将在上面和雪内确定。计划在2007年夏季（最大阳光时）和2008年春季（在快速温度变化时）进行密集的采样季节。在各种环境条件以及运输方案中的测量将有助于区分卤素对反应性氢自由基（HOX）的光化学循环的相对重要性。将借助背部轨迹工具（特别是FlexPart模型）来解释现场测量值，并使用光化学稳态框模型来确定峰顶边界层内的HOX循环。如果成功的话，该项目将在典型的极地区域中产生化学过程中的新见解，并提高我们对涉及卤素化合物的基本过程的理解。该项目将为研究生和本科生提供研究经验的机会。也计划了广泛的公共宣传计划。