Collaborative Research: Vulnerability of carbon in buried soils to climate change and landscape disturbance

合作研究：埋藏土壤中碳对气候变化和景观干扰的脆弱性

• 批准号: 1623814
• 负责人: Erika Marin-Spiotta
• 金额: $ 39.99万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1623814&HistoricalAwards=false
• 关键词: Collaborative; Research; Vulnerability; carbon; buried

A greater understanding of the amount of carbon stored in soils and the risk of its accumulation in the atmosphere is fundamental for improving predictions of future changes in climate so that our society and agriculture can best adapt to a changing environment. Over geologic time scales, the amount of carbon stored and released from soils has influenced atmospheric carbon dioxide concentrations and global climate. On shorter time scales, the storage of plant carbon in soils is estimated to have offset a fraction of carbon emissions from human activities. To predict the vulnerability of soil carbon to landscape disturbance, this project aims to identify the processes contributing to the persistence or loss of ancient carbon from paleosols and quantify how quickly previously protected carbon can be released to the atmosphere in response to changing environmental conditions. Paleosols, or buried soils that represent former landscape surfaces, can store more carbon than expected deep underground and provide unique opportunities for asking questions relevant for modern and future projections of interactions among carbon, disturbance and climate. The proposed research will inform predictions of the response of soil carbon to two realistic climate change impacts in the U.S. central Great Plains. More frequent extreme rainfall events can lead to erosion and increase exposure of formerly buried soils to modern surface conditions. Efforts to extend irrigation in response to a drying and warming climate could trigger microbial activity in the paleosol, releasing ancient carbon to the atmosphere. The project will provide research and career training to three graduate students and at least four undergraduates and foster new collaborations among a diverse team with expertise in biogeochemistry, soil science, microbial ecology and geomorphology. The PIs have a successful record of training students from historically underrepresented groups in the geosciences and will provide professional development for early-career researchers. Dissemination of the research will include traditional venues, such as conference presentations and peer-reviewed publications, as well as outreach activities to communicate the importance of soils to our climate, in the form of a lab demonstration for schoolchildren and participation in a science festival, free and open to the public.The proposed research will test the potential for deep buried soil organic matter to become a carbon source in response to changes in climate or land use that affect the connectivity of buried soils to the atmosphere. The research aims to understand (1) how soil burial contributes to the persistence of carbon in the form of soil organic matter and (2) whether exposure to surface conditions can trigger the decomposition of ancient carbon. The proposed study site is located in the U.S. Great Plains, where climate-driven loess deposition during the late Pleistocene and Holocene resulted in sequences of buried soils in thick loess deposits. The molecular composition, state of oxidation, degree of microbial processing and potential sources of organic matter in a buried soil, or paleosol, and in the overlying modern surface soil will be characterized using a suite of advanced spectroscopic methods and high-resolution mass spectrometry. Soil physical, chemical and microbiological properties will be measured to investigate the relative effectiveness of the mechanisms that contribute to carbon persistence in the paleosol. The vulnerability of ancient organic matter to changing environmental conditions will be measured in two ways. First, changes in organic matter age, composition and bioavailability will be quantified along eroding and depositional field toposequences, where the paleosol exists at varying degrees of isolation from the modern landscape surface. Second, laboratory manipulations will measure the effects of carbon substrates, nitrogen availability, and microbial composition on ancient organic matter decomposition and mobilization in gaseous and dissolved forms. This study combines a geomorphic approach drawing from paleoclimatic reconstructions with advanced geochemical, spectroscopic and metagenomic techniques to generate new knowledge on environmental controls on carbon biogeochemistry.This project is jointly supported by the Ecosystem Science Program in the Biological Sciences Directorate and the Geobiology and Low-Temperature Geochemistry Program in the Geosciences Directorate.

对土壤中储存的碳量以及其在大气中积累的风险有了更大的了解，这是改善对气候未来变化的预测，以便我们的社会和农业可以最好地适应不断变化的环境。在地质时间尺度上，从土壤中存储和释放的碳量影响了大气二氧化碳浓度和全球气候。在较短的时间尺度上，估计植物碳的储存量估计抵消了人类活动中碳排放的一部分。为了预测土壤碳对景观干扰的脆弱性，该项目旨在确定导致古代碳持续或丧失古碳的持续或损失的过程，并量化以响应不断变化的环境条件的响应，可以将以前保护的碳释放到大气中。古代或代表以前景观表面的掩埋土壤可以存储比地下深处更多的碳，并为询问与现代和未来的碳，干扰和气候相互作用相关的问题提供了独特的机会。拟议的研究将为美国中部大平原的两种现实气候变化影响的反应提供预测。更频繁的极端降雨事件会导致侵蚀并增加以前被埋葬的土壤对现代表面条件的暴露。响应干燥和变暖的气候来扩展灌溉的努力可能会引发古溶胶中的微生物活动，从而将古代碳释放到大气中。该项目将为三名研究生和至少四名本科生提供研究和职业培训，并在一个具有生物地球化学，土壤科学，微生物生态学和地貌学专业知识的多元化团队中培养新的合作。 PI成功地记录了地球科学中历史悠久代表性不足的群体的培训学生，并将为早期研究人员提供专业发展。研究的传播将包括传统场所，例如会议演讲和同行评审的出版物，以及外展活动，以传达土壤对我们气候的重要性，以实验室展示对我们的气候的重要性，并为学童提供了实验室，并参与学童免费并与公众开放。到气氛。该研究旨在了解（1）土壤埋葬是如何以土壤有机物形式的碳持续性以及（2）暴露于表面条件的形式的持续性。拟议的研究地点位于美国大平原，在更新世晚期和全新世期间，气候驱动的黄土沉积导致厚实的牛皮矿床中埋藏的土壤序列。分子组成，氧化状态，微生物加工的程度和埋入的有机物的潜在来源，在埋入的土壤或古溶质中，在上面的现代表面土壤中，将使用先进的光谱方法和高分辨率质谱法来表征。将测量土壤物理，化学和微生物学特性，以研究有助于古溶质中碳持久性的机制的相对有效性。古代有机物对不断变化的环境条件的脆弱性将以两种方式衡量。首先，有机物年龄，成分和生物利用度的变化将沿着侵蚀和沉积场的possequences进行量化，其中古溶质以不同程度的隔离现代景观表面存在。其次，实验室操作将测量碳底物，氮的可用性以及微生物组成对古代有机物分解和动员气态和溶解形式的影响。这项研究结合了一种地貌方法，从古气候重建以及先进的地球化学，光谱和元基因组技术，以产生有关碳生物地球化学环境控制的新知识。该项目由生态系统科学局在生物科学局和地理位置上的地理位置研究中的生态系统科学计划共同支持。