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

溶解有机碳(DOC)是环境中最重要的可移动碳类型之一，因为它可以稳定地存在于土壤中。越来越多的证据表明，土壤效应主导着碳循环过程，特别是与DOC有关的过程。因此，将DOC储存在土壤中是缓解全球变暖的一种方法。然而，直接测量DOC如何在土壤中储存和移动，以及水、DOC和地下微生物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性的。因此，在土壤-孔隙尺度上，关于DOC的许多问题仍然存在。例如，孔隙尺度仅仅是DOC吸附或解吸到土壤团聚体上的环境，或者局部的微生物-水-DOC-孔隙结构相互作用是否有这种尺度所特有的新现象？在这种规模下，有没有什么现象是基于流程的大规模模型和解释无法解决的？孔隙尺度很重要，因为水-微生物-DOC相互作用和运输等生物地球化学过程发生在土壤的孔隙内，导致了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稳定的动力学至关重要。这一建议旨在了解稳定DOC的过程是如何受到土壤中的水分和流动、土壤中的空间异质性、DOC的有效性和运移以及土壤中的微生物活动的驱动。我们将使用嵌入了基于个体的模型(IBM)的格子Boltzmann模型(LBM)和双重Arrhenius-Michaelis-Menten(DAMM)动力学模型来模拟所有这些过程。我们已经开发的格子Boltzmann程序将提供一个数学框架来模拟土壤-孔隙尺度上的多种物种的迁移和降解(例如，DOC、水、氧和产物)。IBM将使我们能够模拟微生物的生长和养分消耗，并建立实验来验证模型。这种对系统的分析将以物理、化学和生物学的基本规律为基础，将强制对概念和假设进行定量和全面的澄清，并将采用合理的方法来处理问题。我们的结果不仅将提供均匀和非均质土壤结构中DOC稳定性的详细比较，还将量化使用DAMM计算的土壤非均质性对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.