Effects of [S,S]-ethylenediaminedisuccinic acid and nitrilotriacetic acid on the efficiency of Pb phytostabilization by Athyrium wardii (Hook.) grown in Pb-contaminated soils

Abstract

Chelate-assisted phytoextraction with biodegradable chelants has been demonstrated as an efficient method to enhance heavy metal remediation efficiency by plants, while there is little available information on phytostabilization. A pot experiment was conducted to investigate the effects of biodegradable [S,S]-ethylenediaminedisuccinic acid (EDDS) and nitrilotriacetic acid (NTA) on plant growth and Pb accumulation of Pb phytostabilizer Athyrium wardii (Hook.) grown in Pb contaminated soils and to explore the feasibility of chelate-assisted phytostabilization. Greater adverse effects on plant biomass under high EDDS treatments were observed than NTA treatments. Significant increase of shoot Pb concentrations of A. wardii was noticed with increasing NTA and EDDS dosages, while EDDS induced higher shoot Pb concentrations than NTA. Moreover, root Pb concentrations of A. wardii under NTA treatments were 1.18–1.28-time higher than EDDS treatments, and a peak value of root Pb concentrations was observed at 2 mmol kg−1 of NTA. Shoot Pb accumulations significantly increased with increasing dosages, and EDDS treatments caused a 1.44–1.6-time increase of shoot Pb accumulation than NTA. Root Pb accumulations under NTA treatments were 1.18–1.28-time higher than EDDS treatments. Maximum root Pb accumulation (155.5 mg plant−1) was found at 2 mmol kg−1 of NTA on the 14th day. Higher BCF values and lower TF values were found under NTA treatments as compared to EDDS treatments. Available Pb concentrations in soil significantly increased on the 7th day with increasing NTA and EDDS dosages, then gradually decreased on the 14th day. Soil pH slightly decreased with increasing NTA and EDDS dosages. Therefore, chelate-assisted phytostabilization could be a feasible way to enhance the efficiency of Pb phytostabilization by A. wardii.