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

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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.