Bioavailability of Arctic Soil Carbon: Examining the Relationship Between Chemical Composition and Lability During the Holocene

标题：北极土壤碳的生物有效性：研究全新世期间化学成分和稳定性之间的关系环境操纵研究清楚地表明，温度、养分输入和水分在推动地上生物量生产和微生物呼吸方面发挥着关键作用。然而，观察到的变化尚未与过去生态系统生产力的地下过程联系在一起，特别是全新世期间水分和温度的自然变化如何影响土壤有机质的微生物处理。本项目旨在探讨自早全新世以来北极土壤碳的化学组成与生物有效性之间的关系。该项目将导致一个可能具有变革性的北极土壤碳使用驱动因素的参数化，这可能适用于全球。这项研究直接关系到了解影响北极土壤碳的过程，并将为早期职业研究人员提供支持。这项研究将为一名研究生(南卡罗来纳大学地球科学博士研究生)和几名本科生提供培训机会，他们将通过现有的夏季研究项目(南加州大学国家科学基金会资助的海洋生物地球化学REU)进行培训。推广和传播信息的策略包括：1)招募少数族裔本科生参与夏季研究并展示他们的研究结果；2)将全新世气候数据纳入高级本科和研究生课程；3)创建一个项目网站以突出该项目的主要发现；4)与记者合作分享国际分布的播客的研究成果；5)通过在顶级期刊上发表文章以及通过在国内或国际会议上的演讲与其他科学家交流研究结果。这项工作的资本假设是微生物细胞膜采用其食物来源的放射性碳标记，这项工作将根据土壤化学极性确定原位碳使用情况，从北极圈到加拿大北极高地的一系列土壤中的当代水分条件和全新世气候变异性。工作假说是土壤碳的生物有效性强烈地受到有机质化学极性的影响。预计潮湿的条件既有利于产生更具化学性的极性化合物，也有利于增加有机质的微生物再加工，从而使北极全新世湿度的变化与土壤碳的生物有效性相关联。建立土壤化学和生物有效性之间的关系将能够在地球系统模型中更准确地表示土壤碳，这在北极尤为关键。

Title: Bioavailability of Arctic Soil Carbon: Examining the Relationship Between Chemical Composition and Lability During the HoloceneEnvironmental 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.