柠檬酸废水联合豆科植物修复镉污染土壤的影响研究

王瑛 罗 鹏 刘林

摘要 [目的]探究柠檬酸废水施加对植物镉吸收效率的影响。[方法]在植物生长过程中施加柠檬酸废水，使用Tessier五步连续提取法检测土壤中镉形态的变化情况。[结果]添加柠檬酸废水能够提高植物对总镉的吸收，并且吸收效率随着施加柠檬酸废水浓度的升高及试验时间的延长而升高。与总镉吸收情况不同的是75%的柠檬酸废水浓度对可交换态镉的吸收效率最高。在整个试验周期中，土壤中可交换态镉在总镉中的占比都有所提升，其中75%的柠檬酸废水处理下可交换态镉在总镉中的占比提升最明显;残渣态镉及碳酸盐结合态在总镉中的比例则出现了逐渐下降的趋势;而铁锰氧化态和有机态的占比在试验周期内没有明显变化。[结论]随着柠檬酸废水的施加，残渣态镉和碳酸盐结合态镉有向可交换态镉转化的趋势。其中，高浓度柠檬酸废水（如75%与100%）转化趋势比低浓度柠檬酸废水及去离子水更明显。

关键词 镉污染;植物修复;低分子量有机酸;柠檬酸废水;Tessier五步连续提取法

中图分类号 X53 文献标识码 A 文章编号 0517-6611（2020）14-0069-03

doi：10.3969/j.issn.0517-6611.2020.14.019

Abstract [Objective]To explore effects of citric acid wastewater on plant cadmium absorption efficiency. [Method]Citric acid wastewater was added into soil during the growth of plants， and the soil Cd was divided into five forms by Tessier classification method to understand the dynamic changes of Cd in soil. [Result]Results showed that citric acid wastewater increased the adsorption of total Cd by plants and the adsorption rates were rising with the increasing of citric acid wastewater concentrations and prolong of time. Different to the total Cd， the highest adsorption rates of exchangeable Cd occurred under the 75% relative concentration of citric acid wastewater. During the whole test， the proportion of exchangeable Cd was increased， especially under the treatment of 75% citric acid wastewater; the proportions of residual Cd and carbonate-bounding Cd were decreased gradually; while proportions of Fe-Mn oxidation Cd and organic Cd didnt change significantly. [Conclusion]With the application of citric acid wastewater， residual Cd and carbonate-bounding Cd have a tendency to convert to exchangeable Cd. Among them， the conversion trend of high concentration citric acid wastewater （such as 75% and 100%） is more obvious than that of low concentration citric acid wastewater and deionized water.

Key words Cadmium contamination;Phytoremediation;Low molecular weight organic acid;Citric acid wastewater;Tessier five-step continuous extraction method

土壤鎘污染是一个世界范围的环境问题。2014年4月17日公布的《全国土壤污染状况调查公报》显示，镉的点位超标比例占全国所有调查点位的7% [1]。由于镉污染问题突出，有关镉污染土壤的修复研究也得到了广泛关注。众多研究人员发现，普遍存在于土壤和根系分泌物中的低分子量有机酸会对土壤中镉的形态和生物有效性产生影响[2-4]。……