Biological Impacts on Planetary Atmospheres: Lessons from a Salt Flat

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9816409 Nealson For most of the history of the Earth, the biosphere was dominated by simpler organisms, such as algal mats that exist today in Baja California. A fundamental question is how did this primitive biosphere impact the global chemical and physical environment of the planet? The answer to this question is important not only for the past history of Earth, but for other planets in the solar system and extra-solar planets. Recent progress in modeling of planetary atmospheres suggests that an essentially correct understanding of the atmospheric radiative and chemical environment can be attained once the chemical forcing is prescribed. This research effort is a first step in answering these questions by focusing on the interaction between a simple biosphere and the atmospheres of Earth and Mars. Drs. Kenneth Nealson and Yuk Yung will (1) monitor gas fluxes over the surfaces of algal mats; (2) monitor gas concentrations as a function of depth in the mats; (3) perform molecular analyses of the mat populations as a function of depth in order to define the major phylogenetic groups present in the stratified mat communities; and (4) model the impact of gas emissions on the atmosphere. Funding for this project is shared between the Division of Astronomical Sciences and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate.