Collaborative Research: The role of phyllosilicate minerals in mediating the temperature sensitivity of soil organic matter decomposition

土壤含有丰富的有机碳，主要与细粒的层状硅酸盐矿物（可互换称为粘土矿物）密切相关。矿物相关有机碳被认为是稳定的微生物呼吸，因为各种保护机制，最终减少温室气体的排放量。然而，目前预测温室效应的生物地球化学模型并没有充分考虑这种碳储量的复杂性，而且模型预测往往与实验证据不一致。这种模型与实验的不一致要求我们需要更好地理解与矿物相关的有机碳是如何以及在多大程度上可用于微生物分解的。该项目的最终目的是研究黏土矿物在响应变暖温度下介导土壤有机质微生物分解的作用。各种土壤有机质-粘土矿物相互作用实验将在温度范围内的良好控制条件下进行。实验数据将用于推导可纳入生物地球化学模型的参数，以更好地预测微生物对土壤有机质的分解对温度的响应。可靠的土壤碳周转预测对于加强粮食安全、减少土壤退化和缓解生物多样性丧失至关重要。对未来温室气体排放和环境变化的预测模型的改进将使我们的社会能够更好地发展可持续农业，并应对最近频繁发生的极端天气和自然灾害。目的是评估层状硅酸盐在调节土壤有机质分解的温度敏感性中的作用。该假说认为，土壤层状硅酸盐矿物控制着底物的生物利用度和酶活性，因此，通过扩展，控制着土壤中底物分解的温度敏感性。为了证实这一观点，研究人员提出将机械实验研究与创新的生物地球化学（BGC）建模相结合。由于层状硅酸盐在土壤中的重要性和现有知识的差距，他们将重点关注无处不在的层状硅酸盐。在这个为期一年的示范项目中，他们将进行酶-碳底物-矿物相互作用（吸附）实验的实验室实验。将使用普通的土壤粘土矿物。有机聚合物代表蛋白质，纤维素和木质素的功能将被选择作为底物代理和-葡萄糖苷酶，亮氨酸氨基肽酶和酚氧化酶作为酶指标。动力学吸附数据将拟合得出：1)不同底物（和酶）对矿物表面的吸附能力和亲和力；(2)酶-底物相互作用的Vmax和亲和参数。这些参数及其温度依赖性将用于参数化平衡化学近似动力学。改进的BGC模型将减少目前预测土壤有机碳储量对持续变暖温度响应的不确定性。除了通过学生参与、出版物和报告定期发布数据外，研究结果还将纳入课程。特定内容的视频片段将在博物馆展出。所有调查人员将努力访问代表性不足的K-12学校，进行普通科学讲座并领导各种科学活动。

Soils contain abundant organic carbon, mostly in intimate association with fine-grained phyllosilicate minerals (interchangeably called clay minerals). Mineral-associated organic carbon is believed to be stable against microbial respiration because of various protection mechanisms, which ultimately decrease the amount of greenhouse gas emission. However, current biogeochemical models that predict greenhouse effect do not adequately consider the complexity of this carbon stock, and model prediction is often at odds with experimental evidence. This model-experiment inconsistency calls for need for an improved understanding of how and to what extent mineral-associated organic carbon is available to microbial decomposition. The ultimate goal of this project is to study the role of clay minerals in mediating microbial decomposition of soil organic matter in response to warming temperature. Various soil organic matter-clay mineral interaction experiments will be performed under well-controlled conditions across a range of temperatures. Experimental data will be used to derive parameters that can be incorporated into biogeochemical models to better predict microbial decomposition of soil organic matter in response to temperature. Reliable predictions of soil carbon turnover are essential to enhanced food security, reduced soil degradation, and mitigation of biodiversity loss. An improved model prediction of future greenhouse emission and environmental change will better enable our society to develop sustainable agriculture and to deal with recently frequent extreme weather and natural disasters.The goal of this proposal is to assess the role of phyllosilicates in mediating the temperature sensitivity of soil organic matter decomposition. The hypothesis posits that soil phyllosilicate minerals control substrate bioavailability and enzyme activity, and thus, by extension, the temperature sensitivity of substrate decomposition in soil. To corroborate this view, investigators propose to integrate mechanistic experimental investigation with innovative biogeochemical (BGC) modeling. They will focus on the ubiquitous phyllosilicates because of their importance in soils and existing knowledge gap. In this one-year demonstration project, they will perform laboratory experiments of enzyme-carbon substrate-mineral interaction (adsorption) experiments. Common soil clay minerals will be used. Organic polymers representing the functionalities of proteins, cellulose, and lignin will be selected as substrate proxies and â-glucosidase, leucine aminopeptidase, and phenol oxidase as enzyme indicators. Kinetic adsorption data will be fitted to derive: 1) the adsorption capacity and affinity of different substrates (and enzymes) onto mineral surfaces; and (2) Vmax and affinity parameters for enzyme-substrate interactions. These parameters and their temperature dependence will be used to parameterize the Equilibrium Chemistry Approximation kinetics. An improved BGC model will reduce uncertainty in current predictions of the response of soil organic carbon stocks to ongoing warming temperature. In addition of regular data dissemination through student involvement, publications, and presentations, results will be incorporated into courses. Content-specific video clips will be exhibited in museums. All investigators will make efforts to visit under-represented K-12 schools to deliver general science lectures and lead various science activities.