Impact of combined iodine and bromine release on the Arctic atmosphere (COBRA).

碘和溴混合释放对北极大气的影响 (COBRA)。

• 批准号: NE/D006104/1
• 负责人: Lucy Carpenter
• 金额: $ 7.46万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD006104%2F1
• 关键词: Impact; combined; iodine; bromine; release

Polar sunrise ozone and mercury depletion events are yearly phenomena that occur throughout the Arctic and Antarctic coastal regions, and have implications for the atmospheric oxidative capacity, climate and health. These events are believed to be caused by oxidation of ozone and mercury by bromine-containing radicals formed from photolysis of inorganic bromine (Br2, BrCl) released from the sea-ice surface. Recent studies suggest that 'frost flowers' (FF) - ice crystals that grow on newly formed sea ice - may be the dominant source of polar bromine. The exact nature of emissions from frost flowers is not well established and so far there are no field studies to confirm or otherwise the important role of FF in bromine release, compared to sea salt on sea-ice/snow-pack. Further, little is known about the role and sources of iodine in polar boundary layer chemistry. Iodine-containing aerosol has been associated with ozone depletion at polar sunrise but also appears in autumn - this is not consistent with the only known source of Arctic iodine, the under-ice spring bloom of ice algae. COBRA investigators have recently observed iodine oxide radicals in Antarctica and reactive organic iodine compounds in the Arctic. These so far unpublished observations, in separate polar locations, suggest a widespread and likely abiotic/photochemical source of iodine to the polar atmosphere. Recent theoretical studies indicate that iodine compounds emitted to the Arctic atmosphere have a significantly greater ozone and mercury depletion effect than additional bromine molecules, so our observations may be significant for polar halogen chemistry research. COBRA (Impact of combined iodine and bromine release on the Arctic atmosphere) is essentially a targeted process study, combining field, laboratory and modelling techniques in a consortium of scientists with strong track records in halogen and polar chemistry and physics to: develop understanding of the role of iodine (in concert with bromine) in Arctic gas phase photochemistry and aerosol production and evolution; investigate the relative/combined roles of frost flowers, older sea-ice/snow pack, sea salt aerosol and biological sources in releasing halogens to the Arctic atmosphere; increase understanding of the temporal and spatial variability of halogen-related ozone and mercury depletion events in the Arctic; and develop and evaluate parameterisations for emission of halogens to the Arctic atmosphere based upon observable ice and meteorological conditions, and use these to develop improved models of Arctic chemistry and emissions and their effect and feedbacks on regional/global atmospheric chemistry and climate. We will undertake two ground-based field campaigns, deploying a range of trace gas and aerosol techniques to measure inorganic and halogen compounds and a comprehensive suite of supporting data, in spring and autumn at a coastal site in the north of Hudson Bay, an area with high potential for frost flower growth and a bromine 'hot spot'. The autumn campaign will be augmented by ship-based measurements to determine the wider extent of mercury and ozone depletion episodes and organic halogen concentrations in the region. In addition to concentration measurements at the coastal site, we will measure particle, ozone and halogen concentrations and fluxes from frost flowers formed on artificial leads created in the sea-ice, and from older sea-ice/snow pack and any identified surface diatoms. We will characterise the various sea-ice surfaces in the field and investigate chemical mechanisms of formation from frost flowers in the laboratory. The combined impact of various forms of halogens on depletion of ozone and mercury will be investigated using a detailed process model, and on a wider scale using a global chemistry-transport model.

极地日出臭氧和汞消耗事件是每年发生在整个北极和南极沿海地区的现象，并对大气氧化能力、气候和健康产生影响。据信，这些事件是由海冰表面释放的无机溴（Br 2，BrCl）光解形成的含溴自由基氧化臭氧和汞造成的。最近的研究表明，“霜花”（FF）--生长在新形成的海冰上的冰晶--可能是极性溴的主要来源。霜花排放的确切性质尚未完全确定，到目前为止，还没有实地研究来证实FF在溴释放中的重要作用，与海冰/积雪上的海盐相比。此外，人们对碘在极地边界层化学中的作用和来源知之甚少。含碘气溶胶与极地日出时的臭氧消耗有关，但也出现在秋季--这与北极碘的唯一已知来源--冰下春季冰藻水华--不一致。COBRA研究人员最近在南极洲观察到碘氧化物自由基，在北极观察到活性有机碘化合物。这些迄今未发表的观测结果，在不同的极地位置，表明一个广泛的和可能的非生物/光化学碘源的极地大气。最近的理论研究表明，碘化合物排放到北极大气中有一个显着更大的臭氧和汞消耗效果比额外的溴分子，所以我们的观察可能是有意义的极性卤素化学研究。眼镜蛇（碘和溴的共同释放对北极大气的影响）基本上是一项有针对性的过程研究，由在卤素和极性化学和物理学方面有着良好记录的科学家组成的一个联合会，将实地、实验室和建模技术结合起来，以：（与溴一起）用于北极气相光化学和气溶胶的产生和演变;调查霜花、较老的海冰/积雪、海盐气溶胶和生物来源在向北极大气释放卤素方面的相对/综合作用;加深对北极与卤素有关的臭氧和汞消耗事件的时空变异性的了解;根据可观测到的冰和气象条件，制定和评估向北极大气排放卤素的参数，并利用这些参数制定北极化学和排放及其对区域/全球大气化学和气候的影响和反馈的改进模型。我们将在春季和秋季在哈德逊湾北部的一个沿海地点进行两次地面实地活动，部署一系列痕量气体和气溶胶技术来测量无机和卤素化合物以及一套全面的支持数据，该地区具有很高的霜花生长潜力和溴的“热点”。秋季运动将通过船舶测量来扩大，以确定该区域汞和臭氧消耗事件的更广泛程度以及有机卤素浓度。除了在沿海站点进行浓度测量外，我们还将测量海冰中人工铅上形成的霜花以及较老的海冰/雪包和任何已确定的表面硅藻的颗粒、臭氧和卤素浓度和通量。我们将在野外观察各种海冰表面，并在实验室研究霜花形成的化学机制。将使用详细的过程模型并在更大范围内使用全球化学传输模型来研究各种形式的卤素对臭氧和汞消耗的综合影响。

项目成果

A mechanism for biologically induced iodine emissions from sea ice

海冰生物诱导碘排放的机制

• DOI: 10.5194/acp-15-9731-2015
• 发表时间: 2015
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: Saiz-Lopez A

Evidence of reactive iodine chemistry in the Arctic boundary layer

北极边界层中活性碘化学的证据

• DOI: 10.1029/2009jd013665
• 发表时间: 2010
• 期刊: Journal of Geophysical Research
• 作者: Mahajan;M. Shaw;H. Oetjen;K. E. Hornsby;L. J. Carpenter;L. Kaleschke;X. Tian-Kunze;J. D. Lee;S. J. Moller;P. Edwards;R. Commane;T. Ingham;D. E. Heard;J. M. C. Plane
• 通讯作者: J. M. C. Plane

Particle fluxes and condensational uptake over sea ice during COBRA

COBRA 期间海冰上的粒子通量和凝结吸收

• DOI: 10.1029/2012jd017798
• 发表时间: 2012
• 期刊: Atmospheres
• 作者: Whitehead J

Halocarbons associated with Arctic sea ice

与北极海冰相关的卤化碳

• DOI: 10.1016/j.dsr.2014.05.012
• 发表时间: 2014
• 期刊: Oceanographic Research Papers
• 作者: Atkinson H