Sea-ice Snow Microbial Communities’ Impact on Antarctic Bromocarbon Budgets and Processes

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The ozone hole that develops over the Antarctic continent every spring is one of the features attributed to human activity, in particular production of the CFC (chlorofluorocarbons in refrigerants) released to the atmosphere. In spite of the CFC ban from the Montreal Protocol established in the year 1987, the recovery has been slower than predicted. Bromocarbons, known to produce the stratospheric ozone depletion, have recently been estimated to contribute to the pool of bromines in the lower atmosphere. What is the origin of the bromocarbons in Antarctic sea ice? Is this an additional source of chemicals creating the ozone hole? This project will test if bromocarbons in sea ice are produced and degraded by microalgae and bacteria found in sea ice, in snow and the interface between the two. The project will collect a suite of chemical and biological measurements of sea ice and snow to determine bromocarbon concentrations, microbial activity associated with them, and intra-cellular genes and proteins involved in bromocarbon metabolism. This project benefits NSF’s goals of expanding fundamental knowledge of Antarctic systems, biota, and processes, and improving the understanding of interactions among the Antarctic systems, cryosphere and organisms. The work will be carried out at McMurdo Station in late austral spring, including sampling of snow and ice that will be concentrated in the laboratory, and 24-hour experiments to measure algal and bacterial activity. Genes controlling synthesis of enzymes involved in bromocarbon metabolism are of interest in biotechnology and bioremediation, including products that repair damaged skin from UltraViolet Radiation. The project will train undergraduate students on chemical and biological techniques. The Principal Investigators will be involved in the Pacific Science Center in Seattle with ~10,000 visitors per weekend where they will develop a project-specific exhibit.The microbial processes in snow and ice associated with bromocarbon synthesis and degradation have not been studied in Antarctica during winter and spring. This study will inform about microbial activity in relation to the release of bromocarbons compounds from the snow and ice surfaces, compounds known to degrade stratospheric ozone. The estimation of chemical bromocarbons will be combined with metagenomics and metaproteomics approaches for understanding the potential role of microbes in snow and sea ice. The environmental, chemical and biological data will be synthesized with multivariate analysis and significant differences between sites and experimental treatments with ANOVA. A collaborator from the University of Goteborg in Sweden will collaborate on bromocarbon analyses. The study will also address “saline snow” a new environment not previously studied for microbial life. In addition, this is the first study of meta-proteomics in snow and ice. The Principal Investigators expect their results will help inform ozone hole recovery in the 21st century.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.