State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Wuhan University, School of Resource and Environmental Sciences, 430079, China.
Sci Total Environ. 2024 Oct 15;947:174565. doi: 10.1016/j.scitotenv.2024.174565. Epub 2024 Jul 8.
Long-term waste accumulation (LTWA) in soil not only alters its physical and chemical properties but also affects heavy metals and microorganisms in polluted soil through the dissolved organic matter (DOM) it produces. However, research on the impact of DOM from LTWA on heavy metals and microorganisms in polluted soil is limited, which has resulted in an incomplete understanding of the mechanisms involved in LTWA soils remediation. This study focuses on the DOM generated by waste accumulation and analyses the physicochemical properties, microbial community structure, and vertical distribution of heavy metals in four types of LTWA soils at different depths (0-100 cm). A causal analysis is conducted using structural equation modelling. The results indicate that due to the retention effect of the soil and microorganisms, heavy metal pollution is concentrated on the soil surface layer (>30 cm). With increasing depth, there is a decrease in heavy metal concentration and an increase in microbial diversity and abundance. DOM plays a significant role in regulating the concentration of soil heavy metals and the diversity and abundance of microorganisms. The DOM from different soils gradually transforms into substances dominated by tyrosine, tryptophan, and fulvic acid, which sustain the normal life activities and gene expression of microorganisms. Bacteria such as Pseudarthrobacter, Desulfurivibrio, Thiobacillus, and Sulfurimonas, which are involved in energy transformation, along with genes such as water channel protein and YDIF, which enhance heavy metal metabolism, ensure that microbial communities can maintain basic life processes in polluted environments and gradually select for dominant species that are adapted to heavy metal pollution. These novel discoveries illuminate the potential for modulating the composition of DOM to amplify microbial activity, while concurrently offering insights into the migration patterns of various long-term exogenous pollutants. This foundational knowledge provides a foundation for the development of efficacious remediation strategies.
长期废物积累（LTWA）不仅会改变土壤的物理和化学性质，还会通过其产生的溶解有机质（DOM）影响污染土壤中的重金属和微生物。然而，对于 LTWA 土壤中 DOM 对重金属和微生物的影响的研究有限，这导致了对 LTWA 土壤修复机制的不完全理解。本研究聚焦于废物积累产生的 DOM，并分析了四种不同深度（0-100cm）的 LTWA 土壤中重金属的理化性质、微生物群落结构和垂直分布。使用结构方程模型进行因果分析。结果表明，由于土壤和微生物的截留效应，重金属污染集中在土壤表层（>30cm）。随着深度的增加，重金属浓度降低，微生物多样性和丰度增加。DOM 在调节土壤重金属浓度和微生物多样性和丰度方面起着重要作用。不同土壤的 DOM 逐渐转化为以酪氨酸、色氨酸和富里酸为主的物质，维持了微生物的正常生命活动和基因表达。涉及能量转化的假单胞菌、脱硫弧菌、硫杆菌和硫单胞菌等细菌，以及增强重金属代谢的水通道蛋白和 YDIF 等基因，确保了微生物群落能够在污染环境中维持基本的生命过程，并逐渐选择适应重金属污染的优势物种。这些新发现阐明了调节 DOM 组成以放大微生物活性的潜力，同时为了解各种长期外源污染物的迁移模式提供了思路。这些基础知识为开发有效的修复策略提供了基础。
