铅镉复合污染对台湾相思生长和元素吸收的影响

Effects of Combined Pollution of Pb and Cd on the Growth and Element Uptake of Acacia confusa

采用盆栽试验,研究不同浓度Pb、Cd复合污染对台湾相思生长、根系形态、养分元素和重金属元素吸收的影响。结果表明:台湾相思株高生长在1 500 mg/kg Pb, 25 mg/kg Cd和1 500 mg/kg Pb, 50 mg/kg Cd下受显著抑制,与CK相比分别减少了30.15%和34.23%,而各处理对地径生长均无显著影响。复合污染条件下各部位生物量、总生物量和根长均受显著抑制,根平均直径受显著促进,对根体积则无显著影响。植株各部位养分元素中,仅根部N含量在1 500 mg/kg Pb, 50 mg/kg Cd处理下受显著促进,较CK增加42.00%。复合污染处理显著增加台湾相思根、茎及叶的Pb、Cd含量,其中根Pb含量随污染浓度升高呈现先升后降的趋势,并在1 500 mg/kg Pb, 25 mg/kg Cd处理下达到显著最大值(289 mg/kg),叶Pb含量和根Cd含量随污染浓度升高而显著增加。台湾相思对Pb、Cd复合污染具有较强的耐性,且对Pb、Cd具有一定的吸收能力,能够通过改变根系形态及豆科植物具有的根瘤来抵抗重金属污染,在中低浓度Pb、Cd污染土壤的生态修复方面具有一定的应用潜力。

A pot experiment was conducted to study the effects of Pb-Cd combined pollution on the growth,root morphology, nutrient and heavy metal element absorption of Acacia confusa. The results showed that the plant height of A. confusa under Pb 1 500 mg/kg, Cd 25 mg/kg and Pb 1 500 mg/kg, Cd 50 mg/kg conditions was inhibited, and decreased by 30.15% and 34.23% respectively compared with that of the control. The ground diameter growth was not significantly affected by the pollution. The biomass of roots, stems, leaves, total biomass and root length under combined contamination conditions were suppressed, the average root diameter was promoted, while the root volume was not significantly affected. Among the nutrient elements(N, P, K) in all parts of the plant, only the N element of roots were significantly promoted by the treatment of Pb 1 500 mg/kg, Cd 50 mg/kg, which was 42.00% higher than CK. The content of Pb and Cd in roots, stems and leaves of A. confusa were significantly promoted by Pb-Cd combined contamination. The root Pb content increased at first, and then decreased with increasing concentration of contamination, and reached a significant maximum(289 mg/kg) under the treatment of Pb 1 500 mg/kg, Cd 25 mg/kg. The content of Pb in leaves and Cd in roots increased significantly with the increase of pollution concentration. A. confusa has strong resistance and certain absorptive capacity to Pb and Cd, and can resist combined contamination through root nodules and altering root morphology. A. confusa has application potential in the ecological restoration of low and medium concentration of Pb-Cd contaminated soil.