不同高山树种中重金属镉迁移富集研究

Study on Migration and Enrichment of Heavy Metal Cadmium in Different Alpine Tree Species

土壤中重金属的过量存在不仅破环土壤理化性状,影响植物的正常生长,而且通过食物链传递,也会影响人体的健康安全。本文通过外源添加镉(10 mg/kg、30 mg/kg、50 mg/kg)在盆栽土壤中,模拟自然条件下不同污染程度,采用富集系数、转运系数等指标分析重金属镉在高山松、高山栎两个高山地区特有树种中的污染特征,探究重金属在土壤-植物系统里的转移富集规律,为污染土壤实行生物修复提供一定依据。结果表明:(1)90 d以后,高山松、高山栎体内的镉含量与土壤中镉含量呈正相关,主要积累在地下部。(2)高山松地上部、地下部的富集系数随土壤镉浓度的增加均表现为先升后降,在镉处理浓度为30 mg/kg时达到最大;转运系数随土壤镉浓度的增加呈递增趋势。(3)高山栎地上部、地下部的富集系数与土壤镉浓度呈负相关,在镉处理浓度为10 mg/kg时最大;转运系数随土壤镉浓度的增加呈递减趋势。

The excessive existence of heavy metals in soil not only destroys the physical and chemical properties of soil and affects the normal growth of plants,but also affects the health and safety of human body through food chain transmission.By adding exogenous cadmium(10 mg/kg,30 mg/kg,50 mg/kg)to potted soil,different pollution levels under natural conditions were simulated in this paper,and the pollution characteristics of heavy metal cadmium in two endemic tree species of alpine pine and alpine oak were analyzed by using enrichment coefficient and transport coefficient,so as to explore the transfer and enrichment law of heavy metals in soil-plant system,and provide some basis for bioremediation of polluted soil.The results showed that:(1)After 90 days,the cadmium content in Pinus densata Mast.and Quercus semicarpifolia Smith was positively correlated with the cadmium content in the soil,and mainly accumulated in the underground.(2)With the increase of soil cadmium concentration,the enrichment coefficient of aboveground and underground parts of Pinus densata Mast.increased first and then decreased,and reached the maximum when the cadmium concentration was 30 mg/kg.The transport coefficient increased with the increase of soil cadmium concentration.(3)The enrichment coefficient of aerial and underground parts of Quercus semicarpifolia Smith was negatively correlated with soil cadmium concentration,and reached the maximum when the cadmium concentration was 10 mg/kg.The transport coefficient decreases with the increase of cadmium concentration in soil.