Nitrilotriacetic acid enhanced lead accumulation in Athyrium wardii (Hook.) Makino by modifying rhizosphere characteristics

Abstract Chelant-assisted phytoremediation may modify plant rhizosphere, which is closely relevant to heavy metal (HM) accumulation in plants. This work focused on the effects of nitrilotriacetic acid (NTA) on rhizosphere characteristics to investigate the mechanism of lead (Pb) accumulation in Athyrium wardii (Hook.) Makino with exposure to 800 mg kg− 1 Pb. After NTA application, Pb accumulation in the underground part of A. wardii increased by 14.3%, accompanying with some changes for the rhizosphere soils. Soil pH decreased by 0.37 and the dissolved organic carbon (DOC) content in the rhizosphere soils significantly increased by 7.6%. The urease, acid phosphatase and catalase activities in the rhizophere soils significantly increased by 104.8%, 19.7% and 27.1%, respectively. However, a slight inhibition on microbial activities was observed in the rhizosphere of A. wardii after NTA application. Soil respiration decreased by 8.9% and microbial biomass carbon decreased by 8.9% in the rhizosphere soils, indicating that NTA addition recruited some microorganisms to maintain rhizosphere functions in Pb-contaminated soils, while inhibited others with low tolerance to Pb. Results suggest that lower pH, more DOC exudation and higher soil enzyme activities after NTA application contributed to the increase of Pb accumulation in A. wardii. This study gave some preliminary evidence for NTA-assisted Pb remediation by A. wardii by modifying rhizosphere characteristics.