冻融作用驱动微塑料影响土壤镉形态转化的研究进展
Research progress on the impact of freeze-thaw action driven by microplastics on the transformation of cadmium forms in soil
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摘要:
微塑料作为一种新型环境污染物,因其独特的表面性质可吸附重金属或通过改变土壤理化性质及微生物活性来影响镉的形态转化过程,这种复合污染对土壤生态安全和人类健康构成威胁。在寒冷地区,冻融循环是普遍存在的自然现象,可通过季节性温度变化显著影响土壤微塑料的老化过程及镉的赋存形态。尽管已有研究探讨了冻融作用和微塑料对镉形态的单独影响,但关于冻融作用下微塑料影响土壤镉形态转化的相关机制,目前对其了解仍存在不足。本文主要综述了冻融与微塑料对土壤镉的交互作用机制,首先阐述了土壤中镉的赋存形态及其影响因素,分析了冻融作用通过改变土壤理化性质进而影响镉形态转化的过程;其次讨论了微塑料对镉赋存形态的作用机制及重要影响因素,包括微塑料的物理化学性质(类型、粒径、剂量和老化程度等)和环境条件(pH、有机质等);进而深入探究了冻融-微塑料协同作用下对镉形态变化的影响机制。最后,提出了未来研究应该重视的3方面工作,以增强对于气候变化背景下冻融区土壤重金属的环境行为的理解和认识,为污染物环境风险管控技术开发和政策制定等提供理论依据。
Abstract:Microplastics, as a new type of environmental pollutant, due to their unique surface properties, can adsorb heavy metals or significantly affect the morphological transformation process of cadmium by altering the physicochemical properties of soil and the activity of microorganisms. This compound pollution poses a threat to soil ecological security and human health. In cold regions, freeze-thaw cycle is a common natural phenomenon, which can significantly affect the aging process of soil microplastics and the occurrence form of cadmium through seasonal temperature changes. Although existing studies have explored the individual effects of freeze-thaw action and microplastics on the form of cadmium, however, there is still a lack of understanding about the relevant mechanisms of how microplastics affect the transformation of cadmium forms in soil under freeze-thaw conditions. This article mainly reviews the interaction mechanism of freeze-thaw and microplastics on cadmium in soil. Firstly, it elaborates on the occurrence forms of cadmium in soil and its influencing factors. The process by which freeze-thaw action affects the morphological transformation of cadmium by altering the physicochemical properties of the soil is analyzed. Secondly, the mechanism of action of microplastics on the occurrence form of cadmium and the important influencing factors are discussed, including the physicochemical properties of microplastics (type, particle size, abundance and aging, etc.) and environmental conditions (pH, organic matter, etc.), Furthermore, the influence mechanism of the synergistic effect of freeze-thaw and microplastics on the morphological changes of cadmium is explored. Finally, three aspects are highlighted for the future research, which will enhance the understanding and recognition of the environmental behavior of heavy metals in soil in freeze-thaw areas under the background of climate change, and provide a theoretical basis for the development of environmental risk control technologies and policy-making for pollutants.
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