| Summary: | Environmental manipulation studies clearly demonstrate that temperature, nutrient input and moisture play key roles in driving above ground biomass production and microbial respiration. However, observed changes have yet to be linked to below ground processes of past ecosystem productivity and specifically how natural variations in moisture and temperature during the Holocene influenced microbial processing of soil organic matter. This project is to explore the relationship between chemical composition and bioavailability of Arctic soil carbon accumulated since the early Holocene. The project will result in a potentially transformative parameterization of the drivers of Arctic soil carbon usage that may be applicable globally. This research is directly related to understanding processes affecting Arctic soil carbon and will support an early career researcher. This study will provide training opportunities for a graduate student (Ph.D. student in Earth Sciences at the University of South Carolina) and several undergraduate students, who will be trained through existing summer research programs (NSF funded REU in Marine Biogeochemistry at USC). Strategies for outreach and information dissemination include: 1) recruitment of minority undergraduate to participate in summer research and present their findings, 2) inclusion of the Holocene climate data in upper level undergraduate and graduate courses, 3) creation of a project website to highlight the main findings of the project, 4) working with journalists to share the research on an internationally distributed Podcast, and 5) communicating the findings with other scientists through publishing in top-tier journals and through presentations at national or international meetings. Capitalizing on the premise that microbial cell membranes adopt the radiocarbon signature of their food sources, this work will fingerprint in situ carbon usage as a function of soil chemical polarity, contemporary moisture conditions and Holocene climate variability in a range of soils from the Arctic Circle to the Canadian high Arctic. The working hypothesis is that soil carbon bioavailability is strongly influenced by the chemical polarity of organic matter. It is expected that moist conditions favor both the production of more chemically polar compounds and increased microbial reworking of organic matter, such that variations in Arctic Holocene moisture are coupled to soil carbon bioavailability. Establishing a relationship between the soil chemistry and bioavailability will enable more accurate representation of soil carbon in Earth System models, which is especially critical in the Arctic.
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