Lead Phytostabilization and Cationic Micronutrient Uptake by Maize as Influenced by Pb Levels and Application of Low Molecular Weight Organic Acids

ABSTRACT

Phytoremediation is a promising technique to clean up toxic heavy metals including lead (Pb). A greenhouse trial was conducted to evaluate the effectiveness of citric, succinic, malonic and oxalic acids on micronutrient uptake and phytoremediation of Pb contaminated soil by maize under different Pb levels. Mean root and shoot dry weights of maize decreased with increasing Pb levels. At the lowest Pb level, application of citric and oxalic acids caused increase effects on root and shoot dry weight, respectively, as compared to the absence of organic acid. As Pb levels increased, micronutrient uptake in maize shoot decreased. Among the studied organic acids, only the application of oxalic acid increased uptake of all micronutrients in maize shoot as compared to control at the lowest Pb level. Mean root and shoot Pb concentration and uptake and also uptake index noticeably increased at the highest Pb level. All tested acids increased Pb concentration and uptake in maize root. At the highest Pb level, organic acids, except for citric acid, significantly increased shoot Pb uptake and uptake index as compared to the absence of organic acid. Translocation factors less than 1, demonstrated that most of Pb taken up by maize accumulated in root as compared to shoot. According to results reported herein, application of malonic, succinic and oxalic acids is a good strategy to enhance phytostabilization potential of Pb by maize in pb-polluted soils.