NSF Postdoctoral Fellowship in Biology FY 2020: Controls on the formation and persistence of mineral-associated organic matter

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This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Research Using Biological Collections. The fellowship supports research and training of the Fellow that will utilize biological collections in innovative ways. The project will identify the environmental conditions that best support long term soil carbon storage in forests across the U.S. Soils act as an enormous reservoir of carbon, trapping organic matter below ground and slowing the accumulation of carbon dioxide in the atmosphere. Soil is therefore an important resource for mitigating further environmental change. However, the understanding of the amount of carbon that soil can sequester is continually evolving. This research will explore how the vegetation type, soil microbial communities, and physical structure of soil minerals affect the ability of ecosystems to effectively store carbon over long time periods. The Fellow will test these ideas using soil collected from sites across the U.S. operated by the National Ecological Observatory Network (NEON). The Fellow will also participate in a K-12 teacher training course and several student-outreach programs to advance scientific literacy. Data generated through this work will be used for hands-on lessons about analyzing and interpreting environmental data.Mineral soil from the sample archives of thirteen forested NEON sites will be separated into mineral-associated organic matter (MAOM) and other organic matter pools using sequential density fractionation. Using existing vegetation and microbial data from the NEON data portal, the Fellow will assess how variation in tree species, microbial communities, and soil mineralogy influence the proportion of soil carbon stored as MAOM at both the within-site and across-site levels. Further, the Fellow will investigate MAOM stability using organic matter labeled with both 13C and 15N isotopes. Simulated rhizosphere conditions will be generated in experimental mesocosms using a flow-through system with a synthetic root exudate solution of organic acids. Dual-labeled MAOM will be subjected to these conditions and destabilization from mineral surfaces will be quantified with isotope ratio mass spectrometry. The remaining material will be visualized with advanced imaging techniques to identify the particular organo-mineral bonds that resist desorption. The Fellow will create an online lesson plan with the Data Nuggets program to teach high school students about the process of analyzing ecological data. The Fellow will work with underrepresented groups in science during a summer research program for local high school students, and will participate in a K-12 teacher training course designing effective strategies for teaching about climate change.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.