Mutual interactions of organic matter with soil minerals: kinetics, adsorption modes, transformation and stability of complexes

土壤有机质是陆地生态系统中最重要的有机碳汇。矿物表面对SOM的吸附是减缓SOM分解的主要稳定机制之一。SOM由多种具有不同化学结构和性质的有机化合物组成，可能与矿物质相互作用。然而，这些化合物与土壤矿物质相互作用的机制，以及这些相互作用对SOM-矿物复合物中SOM和矿物质稳定性的影响尚不清楚。在该项目中，我们提出了一种考虑SOM和矿物组成和结构的新方法。我们计划对SOM的重要成分（酚酸、角质单体、多肽）与土壤矿物质（蒙脱土）、不同结晶度的铁锰氧化物（水合铁、硼镁矿）的相互作用进行系统研究。我们将研究快速动力学来估计矿物对SOM的吸附模式和能量。我们将运用最先进的分析技术（LC/MS和XPS）来阐明矿物对不同SOM化合物的竞争或合作吸附和转化机制，以及这些相互作用对氧化物稳定性/改变的影响。我们将采用两种情况来研究有机化合物被矿物吸附和转化，并阐明在自然条件下som -矿物复合物的形成：同时将化合物添加到矿物中，或在预先吸附的化合物中向矿物中添加竞争对手。我们还将研究改变氧化还原条件对SOM和SOM-矿物复合物稳定性的影响。我们的新实验结果和概念结论将促进对SOM-矿物复合体形成机制的理解，并阐明SOM和矿物的环境命运。

Soil organic matter (SOM) is the most important sink for organic carbon in terrestrial ecosystems. Adsorption of SOM by mineral surfaces is one of the major stabilization mechanisms that decelerate the decomposition of SOM. SOM comprises a variety of organic compounds with different chemical structures and properties, potentially interacting with minerals. However, the mechanisms of the mutual interactions of these chemical compounds with soil minerals, and the impacts of these interactions on the stability of both SOM and minerals in SOM-mineral complexes are not yet clarified. In the proposed project, we suggest a novel approach considering composition and structure of both SOM and minerals. We plan to carry out a systematic study on the mutual interactions of important SOM constituents (phenolic acids, cutin monomers, peptides) with soil minerals – montmorillonite, and Fe and Mn oxides (ferrihydrite, birnessite) of varying crystallinity. We will study the fast kinetics to estimate the mode and energy of SOM adsorption by minerals. We will apply state-of-the-art analytical techniques (LC/MS and XPS) to elucidate the mechanisms of competitive or cooperative adsorption and transformation of different SOM compounds by minerals, and the impact of these interactions on the stability/alteration of the oxides. We will apply two scenarios to investigate adsorption and transformation of organic compounds by minerals, and to shed light on the formation of SOM-mineral complexes under natural conditions: simultaneous addition of the compounds to minerals, or addition of a competitor to a mineral with pre-adsorbed compounds. We will also investigate the impact of changing redox conditions on the stability of SOM and SOM-mineral complexes. Our novel experimental results and conceptual conclusions will advance the understanding of the mechanisms of SOM-mineral complex formation, and elucidate the environmental fate of SOM and minerals.