柠檬酸对鱼腥草吸收累积铅锌矿区土壤中重金属的影响

Effects of Citric Acid Addition on Absorption and Accumulation of Heavy Metals by Houttuynia cordata Thunb in the Soil of Lead-Zinc Mining Area

采用矿区实地田间试验,通过外源添加柠檬酸(1mmol/kg,3mmol/kg,6mmol/kg和9mmol/kg)处理,研究鱼腥草对重金属复合污染土壤Pb、Zn、Cd、Cr和Cu 5种重金属元素的吸收累积特性,并确定最佳的柠檬酸调控浓度。结果表明,柠檬酸添加浓度为1mmol/kg时能显著促进鱼腥草生物量的提高,比对照增产11.64%,其他处理浓度的柠檬酸对鱼腥草生物量有抑制作用,但不显著;柠檬酸处理能显著提高鱼腥草对Pb、Zn、Cd和Cr这4种重金属元素的吸收累积能力,对Pb和Zn吸收累积能力大于Cd和Cr,对Cu的吸收累积无明显促进作用。但当柠檬酸添加浓度为1mmol/kg时每667m2鱼腥草提取Pb、Zn、Cr和Cu的量分别比对照增加了35.16%,34.39%,59.00%和18.93%,对Cd无明显促进作用。鱼腥草在矿区重金属复合污染土壤上能正常生长,并对多种重金属胁迫具有一定的耐受能力和吸收累积能力,可用于矿区重金属复合污染土壤的植物修复。

In this study,we carry out a field experiment in the lead-zinc mining area to investigate the absorption and accumulation characteristics of 5types of heavy metals（Pb,Zn,Cd,Cr and Cu）by Houttuynia cordata Thunb in the heavy metal contaminated soil.By adding citric acid（1mmol/kg,3mmol/kg,6mmol/kg and 9mmol/kg）to field,we determined the optimal regulation concentration of citric acid.The results showed that compared to control treatment,the citric acid could enhance the biomass of Houttuynia cordata Thunb substantially by 11.64% when the concentration of citric acid in added solution was 1mmol/kg,while slight negative effects of citric acid were observed in treatments with other concentrations of citric acid.The application of citric acid to the mining area could significantly improve the ability of Houttuynia cordata Thunb to absorb and accumulate Pb,Zn,Cd and Cr.Moreover,absorption and enrichment of Pb and Zn exceeded those of Cd and Cr,and no effect of citric acid was found on absorption and enrichment of Cu.When the concentration of citric acid in added solution was 1mmol/kg,the accumulation of Pb,Zn,Cr and Cu in Houttuynia cordata Thunb in 667 m2 increased by 35.16%,34.39%,59.00% and 18.93%,respectively,while Cd accumulation did not obviously changed.In conclusion,Houttuynia cordata Thunb could grow up normally on heavy metal contaminated soil with a certain tolerance of stress and accumulation ability for various heavy metals.Thus,Houttuynia cordata Thunb could be applied in the phytoremediation of heavy metal contaminated soil in mining areas.