Shahid Muhammad, Dumat Camille, Khalid Sana, Niazi Nabeel Khan, Antunes Paula M C
Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari, 61100, Pakistan.
Centre d'Etude et de Recherche Travail Organisation Pouvoir (CERTOP), UMR5044, Université J. Jaurès-Toulouse II, 5 Allée Antonio Machado, 31058, Toulouse Cedex 9, France.
Rev Environ Contam Toxicol. 2017;241:73-137. doi: 10.1007/398_2016_8.
This review summarizes the findings of the most recent studies, published from 2000 to 2016, which focus on the biogeochemical behavior of Cd in soil-plant systems and its impact on the ecosystem. For animals and people not subjected to a Cd-contaminated environment, consumption of Cd contaminated food (vegetables, cereals, pulses and legumes) is the main source of Cd exposure. As Cd does not have any known biological function, and can further cause serious deleterious effects both in plants and mammalian consumers, cycling of Cd within the soil-plant system is of high global relevance.The main source of Cd in soil is that which originates as emissions from various industrial processes. Within soil, Cd occurs in various chemical forms which differ greatly with respect to their lability and phytoavailability. Cadmium has a high phytoaccumulation index because of its low adsorption coefficient and high soil-plant mobility and thereby may enter the food chain. Plant uptake of Cd is believed to occur mainly via roots by specific and non-specific transporters of essential nutrients, as no Cd-specific transporter has yet been identified. Within plants, Cd causes phytotoxicity by decreasing nutrient uptake, inhibiting photosynthesis, plant growth and respiration, inducing lipid peroxidation and altering the antioxidant system and functioning of membranes. Plants tackle Cd toxicity via different defense strategies such as decreased Cd uptake or sequestration into vacuoles. In addition, various antioxidants combat Cd-induced overproduction of ROS. Other mechanisms involve the induction of phytochelatins, glutathione and salicylic acid.
本综述总结了2000年至2016年发表的最新研究结果，这些研究聚焦于土壤-植物系统中镉的生物地球化学行为及其对生态系统的影响。对于未处于镉污染环境中的动物和人类而言，食用镉污染的食物（蔬菜、谷物、豆类和豆科植物）是镉暴露的主要来源。由于镉没有任何已知的生物学功能，并且会对植物和哺乳动物消费者造成严重的有害影响，因此土壤-植物系统中的镉循环具有高度的全球相关性。土壤中镉的主要来源是各种工业过程的排放。在土壤中，镉以各种化学形式存在，其活性和植物有效性差异很大。镉具有较高的植物积累指数，因为其吸附系数低且在土壤-植物间的迁移性高，从而可能进入食物链。据信植物对镉的吸收主要通过根系中必需养分的特异性和非特异性转运体进行，因为尚未鉴定出镉特异性转运体。在植物体内，镉通过减少养分吸收、抑制光合作用、植物生长和呼吸作用、诱导脂质过氧化以及改变抗氧化系统和膜功能来导致植物毒性。植物通过不同的防御策略应对镉毒性，例如减少镉吸收或将其隔离到液泡中。此外，各种抗氧化剂对抗镉诱导的活性氧过量产生。其他机制包括诱导植物螯合肽、谷胱甘肽和水杨酸。
