Integrated approach for analyzing water-microbe-DOC-oxygen interaction in soil micropores

溶解有机碳（DOC）是环境中最重要的移动碳类型之一，因为它可以在土壤中稳定下来。越来越多的证据表明，土壤效应正在主导碳循环过程，特别是与 DOC 相关的过程。因此，在土壤中储存 DOC 是缓解全球变暖的一种方法。然而，直接测量 DOC 在土壤中的储存和移动方式以及水、DOC 和微生物在地下如何相互作用是非常困难的。此外，从微观尺度到田间尺度，土壤结构和微生物活动在空间上是异质的。因此，关于土壤孔隙尺度的 DOC 仍然存在许多问题。例如，孔隙尺度仅仅是 DOC 吸附或解吸到土壤团聚体的环境吗？或者局部微生物-水-DOC-孔隙结构相互作用是否具有该尺度特有的涌现现象？是否有任何这种规模的现象无法在大规模基于过程的模型和解释中解决？孔隙尺度很重要，因为水-微生物-DOC相互作用和传输等生物地​​球化学过程发生在土壤孔隙内，从而产生新的生物地球化学行为，而仅考虑更小或更大的尺度可能无法理解或预测这些行为。因此，量化土壤孔隙中发生的变化对于理解 DOC 稳定的动态至关重要。该提案旨在了解稳定 DOC 的过程是如何由含水量和流量、土壤的空间异质性、DOC 的可用性和运动以及土壤中的微生物活动驱动的。我们将使用嵌入基于个体的模型 (iBM) 的格子玻尔兹曼模型 (LBM) 和双阿伦尼乌斯和米氏 (DAMM) 动力学模型来模拟所有这些过程。我们已经开发的格子玻尔兹曼代码将提供一个数学框架来模拟土壤孔隙尺度的多物质传输和降解（例如，DOC、水、氧气和产物）。 iBM 将使我们能够模拟微生物生长和营养消耗，并建立实验来验证模型。对系统的分析将基于物理、化学和生物学的基本定律；它将强制对概念和假设进行定量和全面的澄清；它将强制采用合理的方法来解决问题。我们的结果不仅将提供均质和异质土壤结构中 DOC 稳定性的详细比较，而且还将量化土壤异质性对使用 DAMM 计算的 DOC 稳定性的影响。这些知识可以通过在土壤中储存更多的 DOC 来帮助缓解全球变暖。

Dissolved organic carbon (DOC) is one of the most important mobile types of carbon environmentally, because it can become stabilized in soils. Increasing evidence shows that soil effects are dominating carbon cycling processes, particularly in relation to DOC. Storing DOC in soil is thus an approach to mitigate global warming. However, directly measuring how DOC is stored and moves in soil and how water, DOC, and microbes interact below ground is very difficult. Moreover, soil architectures and microbial activities are spatially heterogeneous from the micro-scale to the field scale. Consequently, many questions remain regarding DOC at the soil-pore scale. For example, is the pore scale merely an environment in which DOC adsorbs or desorbs to soil aggregates, or do the local microbe-water-DOC-pore structure interactions have emergent phenomena unique to this scale? Are there any phenomena at this scale that cannot be addressed in large-scale process-based models and interpretations? The pore scale is important because biogeochemical processes such as water-microorganism-DOC interactions and transport occur within the pores of the soil, giving rise to new biogeochemical behaviour that might not be understood or predicted by considering smaller or larger scales alone. Therefore, quantifying the changes happening in soil pores will be crucial for understanding the dynamics of DOC stabilization. This proposal aims to understand how processes that stabilize DOC are driven by water content and flow, spatial heterogeneity in soils, the availability and movement of DOC, and microbial activities in soils. We will simulate all these processes using the lattice Boltzmann model (LBM) embedded with an individual-based model (iBM) and the Dual Arrhenius and Michaelis-Menten (DAMM) kinetics model. The lattice Boltzmann codes we have already developed will provide a mathematical framework to simulate multi-species transport and degradation (e.g., DOC, water, oxygen, and product) at the soil-pore scale. The iBM will enable us to simulate microorganism growth and nutrient consumption and to set up experiments for the validation of the model. This analysis of the system will be based on the fundamental laws of physics, chemistry, and biology; it will enforce quantitative and comprehensive clarification of concepts and assumptions; and it will impose rational methods for approaching the problem. Our results will provide not only a detailed comparison of DOC stabilization in homogeneous and heterogeneous soil architectures but also quantifying influence of soil heterogeneity on DOC stabilization calculated using the DAMM. This knowledge could help to mitigate global warming by enabling the storage of greater levels of DOC in soil.