Spatial patterns of organic matter formation in subsoil: Hierarchical preferential flow pathways

底土中有机质形成的空间模式：分层优先流路径

• 批准号: 452510514
• 负责人: Professor Dr. Jörg Bachmann
• 金额: --
• 依托单位: Geographisches Institut
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452510514?language=en
• 关键词: Spatial; patterns; organic; matter; formation

Previous results of the Research Unit suggest that decoupling of biological and physical processes by spatial separation of organic matter (OM), microorganisms and extracellular enzyme activity is apparently one of the most important mechanisms leading to the protection and stabilization of litter- and topsoil-derived dissolved organic carbon (DOC) in deeper subsoil layers. The occurrence of preferential flow (PF) paths is supposed to be a major driver for the formation of hot spots of microbial activity and OM transformation and stabilization in subsoil. Consequently, employing the globally unique subsoil observatories at Grinderwald, our new research initiative aims at investigating the spatial patterns of OM formation in subsoil. The following aspects will be covered in the complementary research activity:- Hierarchical preferential flow pathways - Microbial carbon retention and turnover - Nutritional control of microbial hot spot formation and dynamics - Formation of mineral-associated organic matter Our project is the attempt of a multi-scale approach to capture active and less active transport zones in soil. Experimental evidence already confirmed a stable network of PF pathways on the cm to dm scale over years. We assume that this meso-scaled flow heterogeneity can be captured with fluorescent dye irrigation experiments in the field. Subsequent dye-guided sampling will identify locations with systematic differences regarding active or less active flow domains. The newly developed technique to extract undisturbed flow cells (FC) allows a comprehensive analysis of the in situ state by highly resolved measurements and imaging of important physicochemical and microbiological surface properties (e.g. wettability, functional groups, exoenzyme activity on the mm- to cm-scale). Corresponding sampling strategy will allow to quantify nested PF structures. To assess DOC transport and transformation we will simulate flow processes using 13C-labeled DOC. The percolation experiments will be conducted with two undisturbed serial FC under realistic in situ moisture, DOC concentration, flow rate and temperature conditions, simulating the average flux rate at the sampling site during the winter drainage season. The microbial status of soils sampled from active vs. less active transport domains will be compared to investigate differences in microbial community patterns (in cooperation with Kandeler et al.). Here, we aim to achieve a complete 13C mass balance recovery by quantifying 13C (i) adsorbed to the solid phase, (ii) incorporated into microbial biomass, (iii) released as CO2, and (iv) transported as DOC. This approach (in cooperation with all projects) will finally allow to evaluate the importance of micro-PF patterns versus field scale PF pathways to elucidate the mechanisms triggering the spatial pattern of microbial hot spots.

研究单位的先前结果表明，通过空间分离有机物（OM），微生物和细胞外酶活性来解耦，这显然是最重要的机制之一，从而在深层层中散布和稳定垃圾和外层溶解的有机有机碳（DOC）。优先流动（PF）路径的发生被认为是形成微生物活性热点以及OM转化和稳定稳定的主要驱动因素。因此，我们在Grinderwald上采用全球独特的底土观测器，我们的新研究计划旨在研究底土OM形成的空间模式。互补研究活动将涵盖以下方面： - 分层优先流动途径 - 微生物碳的保留和周转 - 微生物热点形成和动态的营养控制 - 形成矿物质相关有机物我们的项目是尝试捕获多种规模的方法来捕获活跃和较少的活跃运输Zones。实验证据已经证实了多年来在CM上达到DM量表的PF途径的稳定网络。我们假设这种中量表的流动异质性可以通过该场中的荧光染料灌溉实验来捕获。随后的染料引导的采样将识别有关活动或不太活跃流动域的系统差异的位置。提取不受干扰的流动细胞（FC）的新开发的技术可以通过高度分辨的测量以及对重要的物理化学和微生物表面特性进行成像（例如，官能团，官能团，外酶活性在MM--至CM-SCALE上）对现场状态进行全面分析。相应的采样策略将允许量化嵌套的PF结构。为了评估DOC的运输和转换，我们将使用13C标记的DOC模拟流程。渗透实验将在现实的原位水分，DOC浓度，流速和温度条件下使用两个不受干扰的串行FC进行，从而模拟冬季排水季节采样部位的平均通量速率。将比较从活跃的运输结构域中采样的土壤的微生物状态，以研究微生物群落模式的差异（与Kandeler等人合作）。在这里，我们旨在通过量化吸附到固相的13C（i），（ii）纳入微生物生物量的13C（i），以CO2的释放，（III）以CO2和（IV）作为DOC运输的（IV）来实现完整的13c质量平衡恢复。这种方法（与所有项目合作）最终将允许评估微PF模式与场尺度PF途径的重要性，以阐明触发微生物热点空间模式的机制。