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

标题：全新世北极土壤碳的生物有效性：化学成分与稳定性之间的关系研究环境操纵研究清楚地表明，温度、养分输入和水分在驱动地上生物量生产和微生物呼吸中起着关键作用。然而，观测到的变化尚未与过去生态系统生产力的地下过程联系起来，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加工。本项目旨在探讨全新世早期以来北极土壤碳的化学组成与生物有效性之间的关系。该项目将导致北极土壤碳利用驱动因素的潜在变革性参数化，这可能适用于全球。这项研究与了解影响北极土壤碳的过程直接相关，并将支持早期职业研究人员。这项研究将为一名研究生（南卡罗来纳大学地球科学博士生）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（美国国家科学基金会资助的南加州大学海洋生物地球化学REU）接受培训。外联和信息传播战略包括：1)招募少数民族本科生参与暑期研究并展示他们的发现，2)将全新世气候数据纳入本科和研究生的高级课程，3)创建项目网站以突出项目的主要发现，4)与记者合作，在国际发布的播客上分享研究。5)通过在顶级期刊上发表论文和在国内或国际会议上发表演讲，与其他科学家交流研究结果。在微生物细胞膜采用其食物来源的放射性碳特征的前提下，这项工作将在从北极圈到加拿大高北极的一系列土壤中识别原位碳利用作为土壤化学极性、当代湿度条件和全新世气候变化的函数。工作假设是土壤碳的生物有效性受到有机质化学极性的强烈影响。预计潮湿的条件有利于产生更多的化学极性化合物和增加有机物的微生物再加工，因此北极全新世湿度的变化与土壤碳的生物可利用性有关。建立土壤化学和生物可利用性之间的关系将使土壤碳在地球系统模型中得到更准确的表示，这在北极地区尤为重要。

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.