Structure and composition of soil organic matter-mineral aggregates in organic surface layers of forest soils after one year of litter bag f

Soil organic matter (SOM) in organic surface layers of forest soils (forest floors; FF) is susceptible to P losses and conversion of soil carbon into atmospheric CO2 by global warming. Formation of SOM-mineral associations and aggregates stabilizes forest floor SOM against decomposition and reduces undesired ecosystem C and P losses; The mechanisms involved in this process and the microspatial structure of the formed SOM-mineral associations are largely unknown. We aim to reduce this knowledge deficit by conducting µ-XRF and P µ-XANES analyses on FF samples obtained from a field litter bag experiment with FF material after one year of SOM decomposition with vs. without prior addition of soil-typical minerals. The experiment shall be conducted at ID 21 of ESRF. Combined with results from mass and element analysis, NanoSIMS and NMR studiesconducted on the same samples, the results of our experiment will provide clues on key processes of SOM-mineral association formation in forest soils.

森林土壤有机表层（枯落物层，FF）中的土壤有机质（Soil Organic Matter, SOM）易受全球变暖影响，发生磷素流失，且土壤碳会被转化为大气中的CO₂。土壤有机质-矿物结合体与团聚体的形成可提升枯落物层SOM的抗分解稳定性，并减少生态系统中非预期的碳、磷流失。目前，该过程的内在作用机制以及所形成的土壤有机质-矿物结合体的微观空间结构仍有待阐明。本研究拟通过野外枯落物袋培养实验填补这一认知缺口：将枯落物层材料分为两组，分别经预先添加典型土壤矿物与不添加典型土壤矿物处理后，开展为期一年的SOM分解培养，随后对获取的FF样本进行微X射线荧光光谱（µ-XRF）与磷微X射线吸收近边结构光谱（P µ-XANES）分析。本实验将在欧洲同步辐射光源（ESRF）的ID21光束线进行。结合对同一样本开展的质量与元素分析、纳米级二次离子质谱（NanoSIMS）以及核磁共振（NMR）研究结果，本实验的成果将为森林土壤中土壤有机质-矿物结合体形成的关键过程提供关键科学线索。