摘要
植物修复有许多优点,但当用于重金属含量较高的土壤时,通常修复效率较低。研究了添加外源柠檬酸、草酸、苹果酸对镉超积累植物小飞扬草（Euphorbia thymifolia L.）富集Cd的影响,以及3种外源有机酸对土壤p H、Cd形态及小飞扬草根系生理生化特性的影响,探讨利用有机酸强化小飞扬草修复镉污染土壤的可能性及其作用机制。结果表明,土壤Cd含量为247 mg/kg时,种植15 d后,3种有机酸均提高了小飞扬草根和地上部Cd含量,强化效果：草酸〉柠檬酸〉苹果酸,10 mmol/kg草酸的加入使小飞扬草地上部分Cd含量达最大值77.21 mg/kg,比对照组提高87.72%。加入有机酸使土壤p H从7.65下降至6.01~7.45,BCR三步提取法分析土壤Cd形态结果表明,酸溶态Cd含量增加,残渣态Cd含量减小。加入20 mmol/kg苹果酸降低了根系的活力和ATP酶活性,根细胞膜透性与对照组无显著性差异,而加入5、10和20mmol/kg的柠檬酸、草酸和5、10 mmol/kg的苹果酸均显著增加了小飞扬草根系的活力和ATP酶活性,减小了根细胞膜透性。说明添加3种外源有机酸能强化小飞扬草修复Cd污染土壤,利用外源有机酸很有可能成为提高重金属污染土壤植物修复效率的有效途径。
Phytoremediation has many advantages,but is usually not so effective in soils contaminated by high levels of heavy metals. In order to explore the feasibility and mechanism of the phytoremediaton enhancement of Cd-contaminated soil by Euphorbia thymifolia L. with the addition of organic acids,pot experiments were conducted to investigate the effects of exogenous citric acid,oxalic acid and malic acid on Cd accumulation in Euphorbia thymifolia L.,as well as on p H and Cd speciation of soils,and on the physiological and biochemical characteristics of the root system of the plants. The results showed that when the Cd concentration in soil was247 mg / kg and the implantation duration of Euphorbia thymifolia L. was 15 d,all the three added organic acids enhanced Cd uptake and accumulation in both root and aboveground part of Euphorbia thymifolia L.,with the enhancing trend： oxalic acid citric acid malic acid. Cd content in the aboveground part of Euphorbia thymifolia L. reached the maximum value of 77. 21 mg / kg,when it was treated with the oxalic acid in 10 mmol / kg;which was 87. 72% higher than the control. The addition of the three organic acids all resulted in the drop of the soil p H（ from 7. 65 to 6. 01—7. 45）. The chemical speciation of Cd in soils analyzed by BCR three-step extraction showed the decrease of residual Cd and the increase of acid-soluble Cd in soils. Addition of 20 mmol / kg malic acid decreased the vitality of root system and the activity of ATPase in roots,but had insignificant effect on the membrane permeability of root cells. However,addition of 5,10,and 20 mmol / kg of citric acid or oxalic acid and5,10 mmol / kg malic acid both enhanced the vitality of root system and the activity of ATPase in roots,and reduced the membrane permeability of root cells. Overall,the addition of citric acid,oxalic acid or malic acid enhanced the Cd phytoremediation by hyperaccumulator-Euphorbia thymifolia L. in Cd-contaminated soils,which means that the addition of exogenous organic acids may be an effective way for improving the phytoremediaton efficiency of heavy-metal-contaminated soils.
出处
《环境工程学报》
CAS
CSCD
北大核心
2015年第10期5096-5102,共7页
Chinese Journal of Environmental Engineering
基金
广东省中山市科技计划项目(2013A3FC0244)
关键词
小飞扬草
镉污染土壤
外源有机酸
强化修复
Euphorbia thymifolia L.
Cd-contaminated soil
exogenous organic acids
intensifying phytoremediation
作者简介
詹淑威（1990-），女，硕士研究生，研究方向为生态工程与环境修复。E-mail：115715717@qq．com
通讯联系人，E-mail：ppwbpan@scut．edu．cn
