IPY: Halogen Chemistry and Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) Chemical Exchange During IPY

本项目的目标是开发一种新的仪器，用于超痕量水平测定北冰洋上空空气中的卤素原子（Cl，Br和I）和自由基（ClO，BrO和IO）浓度。该仪器的开发将有助于解决以下假设：来自海冰表面盐的卤素原子化学对北极大气边界层的氧化能力有很大影响。这反过来又导致云凝结核的产生，从而影响云量。然而，需要开发直接测量卤素原子浓度的能力，以便在未来几十年随着海冰覆盖的变化，可以监测这种重要的化学物质（导致北极春季臭氧和汞的快速消耗）。即将开发的仪器包括将空气采样到石英流管中，卤素原子在其中与三氟丙烯快速反应，产生卤代酮，可以使用色谱技术以极高的灵敏度检测。在该项目期间，将完成这种实地校准方法的开发，并将在国际极地年期间在各种极地海洋环境中实施。实地考察将于2008年春季在加拿大破冰船“阿蒙森”号上进行，2008年夏季在瑞典破冰船“奥登”号上进行，2009年早春在巴罗和一个浮冰营地进行。现场测量的解释将有助于1-D，多相，反应物种之间的相互作用，混合和运输的数值模拟。该项目的一项重要成果是研制出一个经过充分测试的、坚固耐用的便携式取样装置，随着北极海冰覆盖面的变化，该装置将有助于作为北极观测网络的一部分对卤素原子化学进行长期测量。更广泛的影响包括：（1）参与作家Peter Lourie的实地工作，他正计划写一本关于全球气候变化的书;（2）与普渡大学气候研究中心合作，开发与北极气候变化有关的公共宣传和研究生课程。

The objective of this project is to develop a novel instrument for ultra-trace level determination of the halogen atom (Cl, Br, and I) and radical (ClO, BrO and IO) concentrations in the air above the Arctic Ocean. The development of the instrument will help to address the hypothesis that halogen atom chemistry derived from salt associated with the surface of the sea ice has a very large impact on the oxidizing power of the Arctic atmospheric boundary layer. This in turn results in production of cloud condensation nuclei, which in turn influence cloud cover. However, the ability to directly measure halogen atom concentrations needs to be developed, so that this important chemistry (that results in rapid depletion of ozone and mercury during Arctic spring) can be monitored as sea ice cover changes in the coming decades. The instrument to be developed involves sampling air into a quartz flowtube, in which the halogen atoms react rapidly with trifluoropropene, to produce a halogenated ketone that can be detected with great sensitivity using chromatographic techniques. During this project the development of this field-calibrated method will be completed, and it will be implemented in a variety of polar marine environments during the International Polar Year. Fieldwork will be done aboard the Canadian icebreaker 'Amundsen' in spring 2008 and the Swedish icebreaker 'Oden' in summer 2008, and at Barrow and a pack ice camp in early spring 2009. Interpretation of the field measurements will be aided by 1-D, multiphase, numerical modeling of interactions among reactive species, and mixing and transport. An important outcome of the project will be a fully-tested, robust, portable sampling device that will facilitate long-term measurements of halogen atom chemistry as part of the Arctic Observing Network as the sea ice cover in the Arctic changes. Broader impacts include (1) participation in the fieldwork of a writer, Peter Lourie, who is planning to write a book about global climate change, and (2), development of public outreach and graduate courses related to Arctic climate change in partnership with the Purdue Climate Research Center.