3种植物对红壤中镉的富集特性研究

重金属超富集植物是重金属污染土壤植物修复的基础，研究了3种重金属富集植物羽叶鬼针草、美洲商陆和紫叶芥菜对重金属Cd的吸收积累规律，为植物修复Cd污染的农田和生态环境建设提供科学依据。采用盆栽方法，在不同浓度（0、20、35、50、65、80mg·kg^-1）Cd处理下，分别测定3种植物地上部与根部Cd的含量，计算了地上部Cd迁移量、根系耐性指数、富集系数，研究了土壤中Cd添加量与植物富集Cd量的相关性。结果表明，随着土壤中Cd离子浓度的升高，3种植物地上部和根系中的Cd含量也在增加，相关系数都大于0．99；综合地上部与根部Cd含量，地上部Cd迁移量，根系耐性指数和富集系数，3种植物对Cd的富集能力的相对顺序为：羽叶鬼针草〉美洲商陆〉紫叶芥菜。羽叶鬼针草、美洲商陆种植在Cd处理浓度为65mg·kg^-1的土壤中和紫叶芥菜种植在Cd处理浓度为80mg·kg^-1的土壤中栽培时，3种植物地上部与根部的Cd含量均超过了100mg·kg^-1，达到了Cd超富集量的标准。羽叶鬼针草、美洲商陆和紫叶芥菜对Cd有很强的耐受性和富集性，可以作为先锋植物去修复被Cd污染的土壤。

Accumulation Characteristics of Cadmium for Three Plants in Red Soil

Hyperaccumulators are the basis of phytoremediation of soil. It is difficuh to find ideal hyperaccumulators that can effectively remediate the soil contaminated with heavy metals. The phytoextraction of Cadmium（ Cd ）from contaminated soil is a hotspot of environmental protection. Pot experiments were carried out to identify tolerance and accumulation of plants to heavy metal Cd and to elucidate the characteristics of Cd uptake by three plant species（Bidens maximowicziana, Phytolacca americana, Brassicajuncea）in red soil. Cd^2＋ at 20, 35, 50, 65 or 80 mg-kg^-1 was applied in a pot. The concentrations of Cd in the roots and shoots were determined by atomic absorption spectrophotometer. Bioaccumulation coefficient, total translocation of Cd, root tolerance index and coefficient of correlation between Cd concentration in soil and plant bioaccumulation were calculated. In the three herbaceous plants, Cd content of above-ground parts and roots of Bidens maximowicziana, Phytolacca americana and Brassicajuncea increased linearly with Cd concentration in the soil, with the correlation coefficient of over 0.99. From these calculated indices, Bidens maximowicziana had the highest Cd uptake while Brassicajuncea the lowest. The plants accumulated 100Cd mg·kg^-1 when Bidens maximowicziana and Phytolacca Americana were planted in the soil of over 65Cd mg·kg^-1 while Brassica juncea was grown in the soil of 80Cd mg·kg^-1, which suggesting the three plants meet the criteria for Cd hyperaccumulator. These results confirmed that Bidens maximowicziana, Phytolacca A mericana and Brassicajuncea have the strong ability of tolerance and enrichment to Cd, and may be exploited in phytoremediation of a Cd-contaminated soil.