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

溶解性有机碳（DOC）是环境中最重要的可移动碳类型之一，因为它可以在土壤中变得稳定。越来越多的证据表明，土壤效应主导着碳循环过程，尤其是与DOC有关的过程。因此，在土壤中储存DOC是缓解全球变暖的一种方法。然而，直接测量土壤中DOC的储存和移动方式以及地下水、DOC和微生物的相互作用是非常困难的。此外，从微观尺度到大田尺度，土壤结构和微生物活动都具有空间异质性。因此，土壤孔隙尺度上的DOC还存在许多问题。例如，孔隙尺度是否仅仅是DOC向土壤团聚体吸附或解吸的环境，还是局部微生物-水-DOC-孔隙结构相互作用具有该尺度特有的涌现现象？在这个尺度上，是否有任何现象不能在大规模的基于过程的模型和解释中解决？孔隙尺度很重要，因为生物地球化学过程，如水-微生物- doc的相互作用和运输发生在土壤的孔隙中，产生了新的生物地球化学行为，这些行为可能无法通过单独考虑较小或较大的尺度来理解或预测。因此，量化土壤孔隙的变化对于理解DOC稳定化动力学至关重要。本研究旨在了解水分和流量、土壤空间异质性、土壤中DOC的有效性和移动以及微生物活动如何驱动DOC的稳定过程。我们将使用嵌入基于个体的模型（iBM）和Dual Arrhenius and Michaelis-Menten （DAMM）动力学模型的晶格玻尔兹曼模型（LBM）来模拟所有这些过程。我们已经开发的晶格玻尔兹曼代码将提供一个数学框架来模拟土壤孔隙尺度上的多物种运输和降解（例如，DOC，水，氧和产品）。iBM将使我们能够模拟微生物的生长和营养消耗，并为验证模型建立实验。这种对系统的分析将基于物理、化学和生物学的基本定律；它将强制从数量上和全面地澄清概念和假设；而且，它将为解决这个问题强加合理的方法。我们的研究结果不仅将提供均匀和非均匀土壤结构中DOC稳定性的详细比较，而且还将量化土壤非均匀性对使用DAMM计算DOC稳定性的影响。这一知识可以通过在土壤中储存更高水平的DOC来帮助减缓全球变暖。

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.