Effects of NTA on Pb phytostabilization efficiency of Athyrium wardii (Hook.) grown in a Pb-contaminated soil

Abstract

Chelate-assisted phytoremediation with biodegradable chelates has been considered to be a promising technique to enhance phytoremediation efficiency, while little information is available on phytostabilization. This study aims to assess NTA-assisted phytostabilization of Pb-contaminated soils by Athyrium wardii (Hook.). A pot experiment was carried out to investigate the effects of different application days (1, 3, 5, 7, 10, 14, 21) of nitrilotriacetic acid (NTA) on plant growth, Pb accumulation, and Pb availability in rhizosphere soils of A. wardii grown in soils contaminated with low (200 mg kg−1) and high (800 mg kg−1) concentrations of Pb. With the application of NTA, better growth for A. wardii was observed when treated with NTA for 5–14 days for both low and high Pb soils, suggesting potential harvest time. Pb concentrations and Pb accumulation in underground parts of A. wardii grown in low and high Pb soils increased with increasing application time of NTA generally. Similar changes were also found for bioaccumulation coefficients (BCFs) of A. wardii. The greatest remediation factors (RFs) for underground parts and whole plant of A. wardii were observed for NTA application time of 7 and 5 days for low and high Pb soils, suggesting the greatest remediation efficiency. Furthermore, plant growth, BCF, and RF of A. wardii grown in low Pb-contaminated soils were greater than those grown in high Pb-contaminated soils. Pb availability in rhizosphere soils of A. wardii grown in low Pb soils was lower than those in high Pb-contaminated soils. It seems to be the optimum for A. wardii to phytostabilize slightly Pb-contaminated soils with the application of NTA for 7 days as taking plant growth, Pb remediation efficiency, and environmental risk into consideration.