叶片大气重金属吸收对植物的影响研究进展

Impact of leaf absorption of atmospheric heavy metals on plants:a review

化石燃料燃烧、汽车尾气排放、冶金工业排放、矿山开采等人类活动向大气排放了大量重金属,导致重金属污染日趋严重,严重威胁土壤、水体环境质量和植物安全。大气中的重金属经干湿沉降后,将参与植物系统的生物化学循环。与根系相比,人们对植物叶片吸收重金属的机制知之甚少。本文对前人相关研究结果进行了整理,系统综述了植物叶片吸收、转运大气重金属的机制。植物叶面主要通过气孔和角质层吸收重金属,随后利用质外体或共质体途径转运到韧皮部,最终以与光合产物运输相同的方式向叶、果实、根等器官转运;重金属的形态变化与吸收转运过程有关;毒性机制主要涉及机械损伤、光合相关过程抑制和氧化应激;植物的解毒机制包括植物细胞壁中的滞留、植物可溶性部分中的分隔以及抗氧化系统的防御等。

Fossil fuel combustion,vehicle exhaust emissions,metallurgical industry emissions,and mining activities discharge significant amounts of heavy metals into the atmosphere.This has intensified heavy metal pollution,posing serious threats to the environmental quality of soil,water,and plants.After dry and wet deposition from the atmosphere,these heavy metals participate in plant biochemical cycles.While root-based heavy metal uptake is well-documented,the mechanisms and impact of heavy metal absorption by leaves remain poorly studied.This paper summarizes previous work,offering a systematic review of the mechanisms governing plant leaf absorption and transport of atmospheric heavy metals.Plant leaves primarily absorb heavy metals through their stomata and cuticles,with subsequent transport to the phloem through the apoplast or symplast pathway,and final deposition in the leaves,fruits,roots,and other organs,similar to photosynthetic products.Morphological changes in heavy metals in the plant are associated with absorption and transport processes.Toxicity mechanisms primarily involve mechanical damage,inhibition of photosynthesisrelated processes,and oxidative stress.Detoxification mechanisms in plants include retention within the cell walls,sequestration in the soluble parts of plants,and defense by the antioxidant system.