Physicochemical Aging Mechanisms in Soil Organic Matter (SOM- AGING): II. Hydration-dehydration mechanisms at Biogeochemical Interfaces

土壤有机质（SOM）控制着土壤生物地球化学界面上发生的大部分过程，并可能有助于有机化学物质的封存。我们的中心假设是有机化学物质的封存是由物理化学SOM基质老化驱动的。潜在的过程是水分子（WAMB）和多价阳离子（CAB）在单个SOM段之间或SOM与矿物质之间与水化和脱水机制密切相互作用的分子间桥的形成和破坏。了解这些介导的相互作用的作用将为控制生物地球化学界面（BGI）的功能和动力学过程提供新的思路。我们将通过先进的固态核磁共振技术和解吸动力学来评估SOM结构元素和吸附的有机化学物质的迁移率，并结合1h -核磁共振弛缓测量和先进的热分析方法，包括DSC、TGADSC- MS和afm -纳米热分析。通过控制加热/冷却循环、润湿/干燥循环和SOM的靶向修饰，通过计算化学（与Gerzabek合作）重建我们的模型假设，并参与SPP内的两个更大的联合实验，我们将建立SOM的封存潜力、SOM结构特征、水合脱水机制、生物活性和生物化学功能之间的关系。这将把在分子尺度上运作的过程与更高尺度上的现象联系起来。

Soil organic matter (SOM) controls large part of the processes occurring at biogeochemical interfaces in soil and may contribute to sequestration of organic chemicals. Our central hypothesis is that sequestration of organic chemicals is driven by physicochemical SOM matrix aging. The underlying processes are the formation and disruption of intermolecular bridges of water molecules (WAMB) and of multivalent cations (CAB) between individual SOM segments or between SOM and minerals in close interaction with hydration and dehydration mechanisms. Understanding the role of these mediated interactions will shed new light on the processes controlling functioning and dynamics of biogeochemical interfaces (BGI). We will assess mobility of SOM structural elements and sorbed organic chemicals via advanced solid state NMR techniques and desorption kinetics and combine these with 1H-NMR-Relaxometry and advanced methods of thermal analysis including DSC, TGADSC- MS and AFM-nanothermal analysis. Via controlled heating/cooling cycles, moistening/drying cycles and targeted modification of SOM, reconstruction of our model hypotheses by computational chemistry (collaboration Gerzabek) and participation at two larger joint experiments within the SPP, we will establish the relation between SOM sequestration potential, SOM structural characteristics, hydration-dehydration mechanisms, biological activity and biogechemical functioning. This will link processes operative on the molecular scale to phenomena on higher scales.