Organic matter stabilization processes in subsoils: Impact of small-scale physical heterogeneity of soil particle interfaces

底土中的有机物稳定过程：土壤颗粒界面小尺度物理异质性的影响

• 批准号: 233430855
• 负责人: Professor Dr. Jörg Bachmann
• 金额: --
• 依托单位: Institut für Bodenkunde (IFBK)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/233430855?language=en
• 关键词: Organic; matter; stabilization; processes; subsoils

The spatial separation between degraders and substrate is considered as a major factor controlling subsoil organic carbon variability, stability and dynamics. Processes in soils take place at solid particle surfaces, emphasizing the relevance of interfacial properties for physical, chemical and biological processes due to large solid-surface to mass ratios. However, mostly ignored is at present the importance of the solid interfaces that may enhance spatial and temporal heterogeneity in soils. Accordingly, it still needs to be answered which soil-specific factors are governing the carbon budget in subsoils and what the respective scales for capturing stabilizing mechanisms are.One innovative element of subproject P4 is the development of a flow cell soil sampling technique to assess small-scale soil properties and processes and to reduce 3-dimensional transport processes to quasi 2-d which allows a direct link between soil heterogeneity and processes of interest. Flow cell sampling provide the option to sample within one frame (i.e. 8 x 12 cm) simultaneously up to 5 undisturbed soil slices as a sandwich. Due to the small thickness of a single sandwich layer (5 to 10 mm), undisturbed samples can be used as quasi-replicates. Two approaches will be made to link interfacial properties with chemical and biological processes in order to identify biological hot spots. Using a cascade of flow cells of different depths, a virtual soil profile will be simulated by connected cells and depth-dependent breakthrough behavior of infiltrating DO13C solution can be analyzed. Using single flow cells, physical, chemical, and biological properties can be mapped on the undisturbed soil particle interfaces. Two central questions are addressed: (i) whether and how are hotspots of microorganisms activity related to either physical or physicochemical properties of the spore space and (ii) what are the specific physical and interfacial interactions between soil and roots with special focus on root stage (root density, morphology) and rhizosphere wettability. To answer these questions, mapping of various parameters will be done in close cooperation with partner projects. Physicochemical behavior of the interfaces is assessed by wettability measurements (sessile drop contact angle determination, ESEM condensation experiments), whereas soil organic matter content and quality, i.e. hydrophobicity index derived by DRIFT-mapping,is assessed by calibrated MIR spectroscopy. Biological parameters (respiration, exo-enzyme activity, decay of 14C labeled glucose) will be measured to relate interfacial properties with respective biological responses. Flow cells will be sampled on 3 sites with different parent material in close cooperation with other projects. Overall, this study aims to offer new insights on the assessment and the relevance of small-scale structural and interfacial heterogeneity for SOM stabilization processes in less structured forest subsoils.

降解器和底物之间的空间分离被认为是控制底土有机碳变异性，稳定性和动力学的主要因素。土壤中的过程发生在固体颗粒表面，强调了界面特性与物理，化学和生物学过程的相关性，这是由于较大的固体表面与质量比。但是，最被忽略的是目前固体界面的重要性，这些界面可能会增强土壤中的空间和时间异质性。因此，仍然需要回答哪些特异性因素正在管理碳预算中的碳预算以及捕获稳定机制的各个尺度是什么。 兴趣。流动池采样提供了在一个框架内（即8 x 12厘米）中采样的选项，同时最多5个不受干扰的土壤切片作为三明治。由于单个三明治层的厚度很小（5至10毫米），因此不受干扰的样品可用作准复制物。将采用两种方法将界面特性与化学和生物过程联系起来，以鉴定生物热点。使用不同深度的流动细胞的级联反应，可以通过连接的细胞模拟虚拟土壤曲线，并且可以分析浸润DO13C溶液的深度依赖性突破性行为。使用单流细胞，可以将物理，化学和生物学特性映射到未受干扰的土壤粒子界面上。解决了两个主要问题：（i）微生物活性的热点与孢子空间的物理或物理化学特性有关，以及（ii）土壤和根之间的特定物理和界面相互作用是什么，与根阶段（根密度，形态学）和根茎颗粒性湿润性有关。为了回答这些问题，将与合作伙伴项目密切合作进行各种参数的映射。通过润湿性测量值（无梗底接触角，ESEM凝结实验）评估界面的物理化学行为，而通过校准的miR光谱法评估了土壤有机物含量和质量，即通过漂移映射得出的疏水性指数。将测量生物学参数（呼吸，外酶活活性，标记为葡萄糖的14C衰减），以将界面特性与各自的生物学反应相关联。流动单元将在3个站点上进行采样，并与其他项目密切合作。总体而言，这项研究旨在提供有关小型结构和界面异质性在结构较低的森林地下土壤中SOM稳定过程的评估和相关性的新见解。