由于其复杂性,研究土壤有机质(SOM)的微尺度组装和功能具有挑战性。本研究构建了相对现实的SOM模型,包括不同的成分,如好又多的腐殖酸(LHA),脂质,肽,碳水化合物,还有木质素,通过微秒粗粒分子动力学模拟揭示其在介观尺度上的自发自组装行为。我们发现了有序的SOM聚集,从其疏水核心到水相形成层状相,导致O/C比增加和结构两亲性下降。值得注意的是,两亲性脂质形成双层膜,与木质素合作构成SOM的疏水核心。LHA,尽管形成了一层,嵌入在这个结构中。这种复杂架构的形成是由组件之间的非键合相互作用驱动的。我们的分析揭示了SOM系统中与组分相关的扩散效应。脂质,肽,木质素对自扩散有抑制作用,而碳水化合物促进扩散。这项研究为SOM组件的动态行为和装配提供了新的见解,介绍了一种研究水生环境中动态SOM机制的有效方法。
Investigating soil organic matter\'s (SOM) microscale assembly and functionality is challenging due to its complexity. This
study constructs comparatively realistic SOM models, including diverse components such as Leonardite humic acid (LHA), lipids, peptides, carbohydrates, and lignin, to unveil their spontaneous self-assembly behavior at the mesoscopic scale through microsecond coarse-grained molecular dynamics simulations. We discovered an ordered SOM aggregation creating a layered phase from its hydrophobic core to the aqueous phase, resulting in an increasing O/C ratio and declining structural amphiphilicity. Notably, the amphiphilic lipids formed a bilayer membrane, partnering with lignin to constitute SOM\'s hydrophobic core. LHA, despite forming a layer, was embedded within this structure. The formation of such complex architectures was driven by nonbonded interactions between components. Our analysis revealed component-dependent diffusion effects within the SOM system. Lipids, peptides, and lignin showed inhibitory effects on self-diffusion, while carbohydrates facilitated diffusion. This
study offers novel insights into the dynamic behavior and assembly of SOM components, introducing an effective approach for studying dynamic SOM mechanisms in aquatic environments.