DISSERTATION RESEARCH: Rhizosphere Control of Soil Carbon Protection on Mineral Surfaces

土壤中碳的储存引起了生态系统科学家的高度兴趣，因为它可以提高土壤肥力，并有可能减少二氧化碳和甲烷等气体的产生。植物根系提供了土壤碳的主要输入，将从大气中捕获的二氧化碳转移到土壤系统中。土壤中的微生物是这种碳的主要消费者和分解者，并能将其转化为二氧化碳或甲烷。由此可见，微生物与植物根系接触的土壤部分是碳转化的热点。这个研究生研究项目将跟踪土壤中根源碳的命运，研究土壤微生物群落和相关土壤矿物质在碳稳定中的作用。该项目将涉及与国家实验室的科学家合作，并促进来自代表性不足群体的学生参与研究。虽然碳(C)与土壤矿物质的结合被认为是土壤C稳定的关键步骤，但其潜在机制-特别是矿物-碳结合的持久性-知之甚少。学生将在土壤微观环境中13CO2的环境下种植常见的一年生草Avena barbata（野生燕麦），从而使她能够跟踪根源c的命运。使用一种称为稳定同位素探测（SIP）的技术，她将从植物中追踪13C进入土壤微生物和土壤矿物质。在这个项目中，研究人员将调查存在于矿物质或土壤微生物中的C的长期命运如何受到巴巴塔草存在与否的影响。该研究将考察(1)矿物相关碳的命运，(2)矿物学的影响，(3)根际的影响，植物根系影响的区域，以及(4)微生物群落的作用。通过限制矿物质-碳关联和持久性的机制，研究人员可以开始理解和量化这些关联在碳循环和环境变化模型中的重要性。

Storage of carbon in soil is of high interest to ecosystem scientists because it enhances soil fertility and potentially decreases the production of gases like carbon dioxide and methane. Plant roots provide the major input of soil carbon, transferring carbon dioxide captured from the atmosphere into the soil system. Microorganisms in the soil are the primary consumers and decomposers of this carbon, and can transform it back into carbon dioxide, or into methane. It follows that the part of the soil where microorganisms come in contact with plant roots is a hotspot for carbon transformation. This graduate student research research project will follow the fate of root-derived carbon in soil, examining the role of soil microbial communities and associated soil minerals in carbon stabilization. The project will involve collaboration with scientists at national laboratories and promote participation of students from under-represented groups in the research. While carbon (C) association with soil minerals is thought to be a critical step in soil C stabilization, the underlying mechanisms - particularly in the persistence of mineral-carbon associations - are poorly understood. The student will grow the common annual grass, Avena barbata, (wild oat) under a 13CO2 atmosphere in soil microcosms, thus enabling her to follow the fate of the root-derived C. Using a technique called stable isotope probing (SIP), she will trace the 13C derived from the plant into soil microbes and on to soil minerals. In this project, the researchers will investigate how the longer term fate of C, present on minerals or in soil microorganisms is effected by the presence or absence of A. barbata. The research will examine (1) the fate of mineral-associated C, (2) the influence of mineralogy, (3) the influence of the rhizosphere, the zone of plant root influence, and (4) the role of the microbial community. By constraining both the mechanisms of mineral-C association and persistence, the researchers can begin to understand and quantify the importance of these associations in C cycling and environmental change models.