Sorption thermodymamics and aggregation as controls of substrate use and mineralization

吸附热力学和聚集作为底物使用和矿化的控制

• 批准号: 465123895
• 负责人: Professorin Dr. Friederike Lang
• 金额: --
• 依托单位: Professur für Bodenökologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/465123895?language=en
• 关键词: Sorption; thermodymamics; aggregation; controls; substrate

Sorption strength of organic molecules to minerals and the stability of aggregates protecting organic substrates are among the boundary conditions that “shape the channel for energy and matter use” by the microbial community of soil systems (overall Hypothesis C of SPP 2223). Although the stabilization of organic matter against microbial use and mineralization in soil has been linked to sorption, its relationship to the thermodynamics of sorption processes has not been quantified so far. Furthermore, the impact of soil aggregation and soil microbial diversity on this relationship is unknown. To analyze the boundary conditions shaping the channel for energy and matter use, we will test the following hypotheses: (H I) sorption and desorption energies increase with increasing polarity and degree of oxidation of the sorbate and increasing number of surface hydroxyl groups of the sorbent, (H II) microbial substrate use decreases with decreasing deltaG, increasing thermodynamic sorption hysteresis and activation energy of desorption with thermodynamic thresholds for the use of sorbed substrates, (H III) thermodynamic thresholds for microbial use of sorbed substrates increases with increasing functional diversity of the soil microbial community and (H IV) high physical protection of substrates within aggregates undermines the importance of sorption thermodynamics for microbial substrate use. We will test these hypotheses in four corresponding workpackages. In WP1 we will be determine Gibbs free energies deltaG of sorption reactions, sorption enthalpies (deltaH) and entropies (deltaS), activation energies Ea of desorption reactions and losses of molar free energy due to sorption hysteresis (Tii) for 6 model substrates and three model minerals via sorption-desorption experiments at different temperatures, Arrhenius plots and microcalorimety. WP2 will use miniaturized incubation experiments with SPP soil samples to determine use and mineralization of 14C labelled model substrates adsorbed to model mineral mixed into 4 SPP soils. The role of functional diversity in mineralization will be studied in WP3 by a second incubation experiment with SPP soils spiked with extracted microbes to manipulate microbial diversity or nutrients based on enzymatic analyses using ecoplates. Finally, in WP 4, the mineralization of selected 13C-labelled model substances adsorbed to dispersed and aggregated soil systems that were characterized morphologically and physically will be measured. Combining the expected results, our project will deliver essential insights for the integration of sorption processes and aggregation into thermodynamic concepts of soil ecosystem functioning and development.

有机分子对矿物质的吸附强度和保护有机基质的团聚体的稳定性是土壤系统微生物群落“形成能量和物质利用通道”的边界条件之一（SPP 2223的总体假设C）。虽然有机质的稳定性对微生物的使用和矿化土壤中已被链接到吸附，其关系到吸附过程的热力学尚未量化。此外，土壤团聚体和土壤微生物多样性对这种关系的影响是未知的。为了分析形成能量和物质使用通道的边界条件，我们将测试以下假设：（H I）吸附和解吸能量随着吸附剂的极性和氧化程度的增加以及吸附剂的表面羟基数目的增加而增加，（H II）微生物底物的使用随着Δ G的降低而降低，增加热力学吸附滞后和解吸的活化能，具有使用吸附基质的热力学阈值，（H III）微生物利用吸附基质的热力学阈值随着土壤微生物群落功能多样性的增加而增加，以及（H IV）聚集体内基质的高度物理保护破坏了微生物基质使用的吸附热力学的重要性。我们将在四个相应的工作包中测试这些假设。在WP 1中，我们将通过不同温度下的吸附-脱附实验、阿伦尼乌斯图和微量热来确定6种模型基质和三种模型矿物的吸附反应的吉布斯自由能deltaG、吸附焓（deltaH）和熵（deltaS）、脱附反应的活化能Ea以及由于吸附滞后而损失的摩尔自由能（Tii）。WP 2将使用SPP土壤样品的小型化孵育实验，以确定14 C标记的模型基质的使用和矿化，该基质吸附到混合到4种SPP土壤中的模型矿物中。功能多样性在矿化中的作用将在WP 3中通过第二次培养实验进行研究，该实验使用掺入提取的微生物的SPP土壤，以基于使用生态板的酶分析来操纵微生物多样性或营养物质。最后，在WP 4中，将测量吸附在分散和聚集土壤系统中的选定13 C标记模型物质的矿化作用，这些系统在形态和物理上具有特征。结合预期的结果，我们的项目将提供必要的见解，吸附过程和聚集到土壤生态系统功能和发展的热力学概念的整合。