Collaborative Research: Studies of Chlorine, Bromine and Iodine Chemistry in the Arctic, and its Impacts

该项目旨在提高我们对北极卤素（氯、溴和碘）化学影响的定量认识，以便能够更可靠地进行未来海冰和积雪条件变化对大气成分影响的模型模拟。在地球的非极地地区，大气通过涉及臭氧的光化学进行自我清洁，而海冰覆盖区域上方的大气至少部分通过涉及卤素原子（氯、溴和碘）的化学进行自我清洁。 这种卤素化学有时会通过在低层大气中非常快速地（与大气中的其他部分相比，非常不寻常）消耗臭氧和元素汞而表现出来，消耗到接近于零的水平。臭氧是一种极其重要的大气成分，是一种强大的清洁剂，但它对植物和人类呼吸系统也有毒，并且是一种受管制的空气污染物。单质汞在氧化时可转化为剧毒形式，例如汞。甲基汞。由于这种极性卤素化学是独特的，因此需要从其全球影响以及北极发生的快速环境变化的背景来理解它。这笔赠款将资助一个合作团队，对阿拉斯加巴罗盐积雪中的 Cl2、Br2 和 I2 通量（即排放率）进行测量。将使用雪室、在巴罗收集的各种雪和冰样本以及通过直接测量巴罗附近积雪的排放来研究决定通量的控制环境变量（例如阳光、臭氧的存在、pH值、盐浓度、雪成分）。然后，该团队将使用测得的卤素通量和垂直混合信息来约束一维（垂直尺度）数值模型，以研究地表通量的垂直尺度影响，并研究随着地表性质随气候变化而变化，这种影响可能会如何变化。这项工作的发现部分的一个重要部分将集中在分子碘和碘化学上，迄今为止，北极地区对此的探索还很少。更广泛的影响旨在了解北极，以便更好地预测北极变化的影响以及北极变化对地球系统其他部分的影响。该项目的重点是对下一代学者、教师和研究人员进行有关科学和不断变化的地球的教育和启发。三位首席研究员中的每一位都将在该项目过程中指导本科生和研究生。参与巴罗实地工作的学生受益于在恶劣环境中进行实验、管理偏远地区科学物流以及与北极人民建立科学和教育伙伴关系的独特经验。与该项目合作，冒险和自然作家 Peter Lourie 将撰写一本关于海冰、科学家如何研究它、为什么它对人类和地球很重要以及它如何变化的新书。他还将制作有关北极海冰和科学的在线教育材料，针对中学教育。所有参与的科学家都将参与一系列外展活动，包括在学校进行演讲、参与“公众门户”——一个全国性的非正式科学教育工作网络——以及积极招募代表性不足的群体来从事科学和教育事业。

This project aims to improve our quantitative understanding of the impact of halogen (chlorine, bromine, and iodine) chemistry in the Arctic, so that model simulations of the impact of future changes in sea ice and snowpack conditions on atmospheric composition can be more reliably conducted. While in non-polar regions of the planet the atmosphere cleans itself through photochemistry that involves ozone, the atmosphere above sea-ice covered regions cleans itself at least in part through chemistry involving halogen atoms - chlorine, bromine and iodine. This halogen chemistry sometimes manifests itself through the very rapid (and very unusual, compared to the rest of the atmosphere) consumption of ozone and elemental mercury, to near-zero levels, in the lower atmosphere. Ozone is a critically important atmospheric constituent that is a powerful cleaning agent, but it is also toxic to plants and to the human respiratory system, and is a regulated air pollutant. Elemental mercury, when oxidized, can be converted to highly toxic forms, e.g. methyl mercury. Since this polar halogen chemistry is unique, it needs to be understood in terms of its global impact, and in the context of the rapid environmental change occurring in the Arctic.The grant would fund a collaborative team to conduct measurements of fluxes (i.e. rates of emission) of Cl2, Br2, and I2, from the saline snowpack at Barrow, Alaska. The controlling environmental variables (e.g. sunlight, presence of ozone, pH, salt concentrations, snow composition) that determine the fluxes will be studied using a snow chamber, using a variety of snow and ice samples collected at Barrow, and through direct measurements of the emission from the snowpack near Barrow. The team will then use the measured halogen fluxes and vertical mixing information to constrain a one-dimensional (vertical scale) numerical model to investigate the vertical scale impact of the surface fluxes, and to examine how this might change as the nature of the surface changes with climate change. A significant part of the discovery component of the effort will focus on molecular iodine and iodine chemistry, which has been little-explored in the Arctic to date. The broader impacts are oriented toward the goal of understanding the Arctic in order to inform better prediction of the impacts of change in the Arctic, and of the impact of Arctic change on other parts of the Earth system. A focus of this project will be the education and inspiration of the next generation of scholars, teachers, and researchers about science and the changing planet. Each of the three lead investigators will mentor both undergraduate and graduate students in the course of this project. Students who participate in the field effort at Barrow benefit from a unique experience in conducting experiments in harsh environments, managing science logistics in remote locations, and engaging in science and education partnerships with Arctic people. In partnership with this project an adventure and nature writer, Peter Lourie, will write a new book about sea ice, how scientists study it, why it is important to humans and to the planet, and how it is changing. He will also produce on-line educational material about sea ice and science in the Arctic, aimed at middle-school education. All of the participating scientists will be engaged in a range of outreach activities, including presentations at schools, involvement with "Portal to the Public" - a nationwide network of informal science education efforts - and with the active recruitment of underrepresented groups to pursue careers in science and education.