Nano-scale biogeochemistry of organic carbon across a long-term mineralogical gradient

长期矿物学梯度下有机碳的纳米级生物地球化学

• 批准号: 0819689
• 负责人: Johannes Lehmann
• 金额: $ 29.95万
• 依托单位: Cornell Univ - State: AWDS MADE PRIOR MAY 2010
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0819689&HistoricalAwards=false
• 关键词: Nano; scale; biogeochemistry; organic; carbon

Soil represents the largest reservoir of terrestrial organic carbon (C) on the global scale. In light of predicted climate change, the soil?s ability to accumulate and retain C has received growing interest. The Kyoto Protocol on climate change demands a fundamental understanding of mechanisms that control C stabilization and release from soils. Yet, the underlying geobiological mechanisms for the long-term stabilization of C in soils are still not well understood, and the potential for C sequestration in the uppermost layers of the Earth?s surface remains unknown. Current conceptual models of soil organic C turnover build on destructive macroscopic analytical approaches are not fully process-oriented, and usually fail to provide explicit molecular-level information about the linkage between mineralogy and organic C functionalities, as well as the spatial features of organomineral assemblages. The objective of the proposed project is to design novel experimental and non-destructive high resolution spectromicroscopic (STXM and NEXAFS) approaches that enable us to obtain first-hand process-oriented biogeochemical evidence regarding: (i) the in situ spatial arrangement of minerals, polyvalent metal-ions, organic C functionalities and other architectural features of organomineral assemblages at the microscopic and sub-microscopic level, and (ii) element-specific information about local structural and compositional environments of adsorbing atoms and surficial interactions, micro- and nano-scale heterogeneity in spatial allocations and other molecular-level features of organomineral assemblages. Of particular interest are the long-term changes along a mineralogical gradient developed during pedogenesis. We plan to conduct the proposed investigation on samples that will be collected from a long-term soil chronosequence at Merced-California, where the underlying geomorphologic units range in age from 3 to 3000 Kyr. Intellectual merit: This project aims to develop innovative analytical approaches involving the use of synchrotron-based direct microscopic and spectroscopic techniques. These novel methods will reveal high-resolution information on a molecular- and atomic-level providing a detailed mechanistic understanding of organic C stabilization due to spatial organization and surficial biogeochemical interactions. This project will be the first of its kind and advance knowledge about long-term stabilization of organic C and global biogeochemical C cycling driven by the complex interaction of C, soil minerals and the emergent soil properties in the critical zone. For the broader scientific community, project outcomes will significantly strengthen climate change and environmental research of Earth?s C cycles. Broader impacts: This project will build local capacity in teaching, learning and research. Students at the undergraduate, graduate and post-graduate levels will be trained using a wide array of new technologies and their applications. A particular effort will be made to actively recruit non-traditional, minority and female students. The innovative nature of the analytical approach affords the possibility of developing a short collaborative hands-on training program on ?The potentials and applications of synchrotron-based infrared and X-ray spectromicroscopic techniques in environmental geobiology? to environmental scientists who are at early stage of career development. We also plan to organize a symposium on ?Synchrotron-based micro- and nano-scale mapping of organomineral assemblages in the environment? make an effort to introduce these spectromicroscopy techniques to a wider audience as emerging environmental research techniques in conjunction with international geosciences meetings. The results of the project will be communicated to the scientific community through annual presentations and publications in peer reviewed international journals. This project joins a number of others ecosystems research programs in Western US, and communicate results directly to organizations involved in education, research and policy making.

土壤是全球最大的陆地有机碳(C)储存库。根据预测的气候变化，土壤？S积累和保留碳的能力受到了越来越多的关注。关于气候变化的《京都议定书》要求从根本上理解控制土壤中碳的稳定和释放的机制。然而，土壤中碳长期稳定的潜在地质生物学机制仍不是很清楚，地球最上层的碳固定的潜力也仍然未知？S表面。目前建立在破坏性宏观分析方法基础上的土壤有机碳周转概念模型并不完全面向过程，通常不能提供关于矿物学和有机C功能之间的联系以及有机矿物组合的空间特征的明确的分子水平信息。该项目的目标是设计新的实验性和非破坏性的高分辨率光谱显微镜(STXM和NEXAFS)方法，使我们能够获得有关以下方面的第一手面向过程的生物地球化学证据：(I)在微观和亚微观水平上有机矿物组合的原位空间排列、多价金属离子、有机碳功能和其他结构特征；(Ii)关于吸附原子和表面相互作用的局部结构和组成环境、空间分配中的微米和纳米尺度非均质性以及有机矿物组合的其他分子水平特征的特定元素信息。特别令人感兴趣的是沿成土过程中形成的矿物学梯度的长期变化。我们计划对从加利福尼亚州默塞德的长期土壤年代序列中收集的样本进行拟议的调查，那里的基本地貌单位的年龄从3到3000 Kyr不等。智力优势：该项目旨在开发创新的分析方法，包括使用基于同步加速器的直接显微镜和光谱技术。这些新的方法将揭示分子和原子水平上的高分辨率信息，提供由于空间组织和表面生物地球化学相互作用而导致的有机碳稳定的详细机制。该项目将是这类项目中的第一个，是关于有机碳的长期稳定和全球生物地球化学碳循环的高级知识，受碳、土壤矿物和临界区新出现的土壤性质的复杂相互作用的驱动。对于更广泛的科学界来说，项目成果将显著加强气候变化和地球环境研究--S C周期。更广泛的影响：该项目将建设当地的教学、学习和研究能力。本科生、研究生和研究生将接受各种新技术及其应用的培训。将特别努力积极招收非传统、少数民族和女性学生。分析方法的创新性质使我们有可能就同步加速器红外和X射线光谱显微技术在环境地质生物学中的潜力和应用开发一个短期的协作动手培训计划。给处于职业发展早期阶段的环境科学家。我们还计划组织一次基于同步加速器的微纳尺度环境中有机矿物组合作图的研讨会。结合国际地球科学会议，努力将这些光谱显微镜技术作为新兴的环境研究技术介绍给更广泛的受众。该项目的成果将通过年度报告和同行评议的国际期刊上的出版物向科学界通报。该项目加入了美国西部的许多其他生态系统研究项目，并将结果直接传达给参与教育、研究和政策制定的组织。