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湿地植物对重金属污染的去除机制研究进展

Research progress on removal mechanism of heavy metal pollution by wetland plants

  • 摘要: 湿地作为全球生物多样性和生态功能最丰富的生态系统,其面临日益严重的环境污染问题,尤其是重金属污染已经成为亟待解决的研究热点之一。植物作为人工湿地的核心,因其成本低且不易造成二次污染,在水体净化过程中发挥着重要作用。本文综述了国内外关于利用湿地植物去除重金属污染的研究现状,深入探讨了常见湿地植物在重金属富集与去除过程中的能力和机制,对植物修复湿地重金属污染具有重要意义。国内外广泛应用植物对湿地重金属污染土壤进行修复,芦苇(Phragmites australis)、香蒲(Typha orientalis)和狐尾藻(Myriophyllum verticillatum)等常见植物在湿地中均表现出较强的修复能力。植物通过向根际环境释放根系分泌物、形成根表铁膜以及根系泌氧作用等多种机制,提高植物对重金属的富集能力。当重金属进入植物体后,与植物螯合肽发生螯合作用,并通过特定金属转运蛋白转运至液泡中储存,或通过调节植物抗氧化系统清除过剩的活性氧,以减轻重金属对植物的毒害。未来研究应加强基因工程和联合修复技术的应用,以提升植物修复湿地重金属污染的效率,进一步强化植物修复技术在湿地污染中的应用价值。

     

    Abstract: As ecosystems with the highest biodiversity and ecological roles in the world, wetlands are confronted with a growing number of environmental pollution problems, especially heavy metal contamination, which has emerged as a crucial area of study. As a result, it has become essential to preserve wetland ecosystems. Plants, the fundamental component of constructed wetlands, are extensively utilized in the treatment of heavy metals in effluent, industrial wastewater, and residential sewage since they are low cost, low risk of secondary environmental damage, and superior ecological benefits for the environment. They play an important role in the purification of water bodies. Applying phytoremediation technology effectively requires an understanding of the mechanisms behind plant-based heavy metal remediation. This is crucial for improving the effectiveness of heavy metal pollution remediation in wetlands and lowering ecological concerns. This study examines recent local and international studies on the use of wetland plants for heavy metal pollution remediation. The importance of phytoremediation in wetland restoration is highlighted as it explores the capacities and processes of common wetland plants in the buildup and removal of heavy metals. Research shows that common plants in China and overseas, such as Phragmites australis, Typha orientalis, Thalia dealbata, and Myriophyllum verticillatum, have potent remediation abilities for wetland soils contaminated with heavy metals. Through a multitude of processes, including the release of root exudates (Res) into the rhizosphere environment, the formation of iron plaques on root surfaces, and radial oxygen loss (ROL), plants improve their capacity to accumulate heavy metals. Specifically, by releasing root exudates and causing radial oxygen loss, plants change the rhizosphere's pH, redox potentials, and microbial activities. It alters the solubility and mobility of heavy metals and encourages plant absorption of them. In addition, plants can form iron plaques on their roots to fix heavy metals and prevent them from entering the plant and causing toxicity. Heavy metals enter plant tissues, bind to phytochelatins to form heavy metal-phytochelatin complexes, and are subsequently carried into vacuoles by specific metal transporters, among which are cation diffusion facilitators (CDF), metal transporter P1B-ATPases, and iron-regulated transporter-like protein (ZIP). Furthermore, by controlling the activity of antioxidant enzymes like superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidases (APX), and catalase (CAT), plants can be used to increase their resistance to heavy metal toxicity under heavy metal stress conditions. This provides an efficient antioxidant defense mechanism that eliminates an excessive amount of reactive oxygen species (ROS), reducing the oxidative harm that reactive oxygen species inflict. Future research should focus on the application of genetic engineering and integrated remediation technologies that will enhance both the effectiveness of phytoremediation and its practicality when dealing with wetland heavy metal contamination.

     

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