Advancing Carbonyl Sulfide (OCS) as an Independent Atmospheric Ttracer for Global Photosynthesis through Quantification of Microbial-mediated Sources and Sinks in Soils

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This collaborative project seeks to increase understanding of how plants impact the atmospheric carbon cycle by using carbonyl sulfide (OCS) as a tracer. OCS has shown potential to help estimate the amount of carbon taken up by plants, yet, its use has been limited by the fact that OCS also is consumed by microbes in the soil. The objective of the proposed work is to quantify and predict this OCS sink and to extend acquired knowledge to regional scales so that the role of plants and soils on the overall carbon budget is better constrained. The project aims at closing the gap of current understanding of soil microbial uptake mechanisms of OCS. Soil microbial genomics data will be linked to direct measurements of OCS fluxes, thereby building a framework to improve quantification and prediction of OCS uptake from individual microbial isolates to communities and further to regional ecosystems. The multi-disciplinary approach involves (i) growing laboratory fungal cultivations while measuring OCS uptake, (ii) field sampling in Alaska, (iii) obtaining and processing fungal genome data from the enzyme carbonic anhydrase (CA, the OCS specific uptake enzyme), and (iv) building iterative trait models that parametrize OCS uptake based on CA genomics. The outcome of this work may be used by other groups with potential impact in larger scale models of plant and soil impacts on the carbon cycle. One graduate student and one postdoctoral researcher will carry out the laboratory and field work, and the team will develop education and outreach materials to be integrated into Biosphere 2, where currently a tour exhibit on high latitude ecosystems is absent. The proposal is co-funded by the Atmospheric Chemistry and Ecosystems Science Programs.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.