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以及保护有机基质的聚集体的稳定性是土壤系统微生物群落“塑造能量和物质利用通道”的边界条件（SPP 2223 的总体假设 C）。尽管有机质在土壤中抵抗微生物利用和矿化的稳定性与吸附有关，但其与吸附过程热力学的关系迄今为止尚未量化。此外，土壤团聚和土壤微生物多样性对这种关系的影响尚不清楚。为了分析塑造能量和物质利用通道的边界条件，我们将测试以下假设：（H I）吸附和解吸能随着吸附剂极性和氧化程度的增加以及吸附剂表面羟基数量的增加而增加，（H II）微生物底物的使用随着 deltaG 的减少而减少，热力学吸附滞后和解吸活化能的增加 使用吸附基质的热力学阈值，（H III）微生物使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，（H IV）聚集体内基质的高度物理保护削弱了吸附热力学对于微生物基质使用的重要性。我们将在四个相应的工作包中测试这些假设。在 WP1 中，我们将通过不同温度下的吸附-解吸实验、阿伦尼乌斯图和 确定吸附反应的吉布斯自由能 deltaG、吸附熵 (deltaH) 和熵 (deltaS)、解吸反应的活化能 Ea 以及吸附滞后引起的摩尔自由能损失 (Tii)。 微热量。 WP2 将使用 SPP 土壤样品进行小型化孵化实验，以确定 14C 标记模型基质的使用和矿化，这些基质吸附到混合到 4 个 SPP 土壤中的模型矿物上。功能多样性在矿化中的作用将在 WP3 中通过第二次孵化实验来研究，该实验在 SPP 土壤中添加了提取的微生物，以使用生态板进行酶分析来操纵微生物多样性或营养物质。最后，在 WP 4 中，将测量吸附到分散和聚集土壤系统中的选定 13C 标记模型物质的矿化，这些土壤系统具有形态和物理特征。结合预期结果，我们的项目将为将吸附过程和聚集整合到土壤生态系统功能和发展的热力学概念中提供重要的见解。