Abstract:
Chelators has been known to increase heavy metal absorption and accumulation in some plants, but their efficacy in hemp is very seldom realized. Using pot culture, a local hemp variety Bamahuoma was used as experimental material, and 2000 mg·kg
−1 heavy metal lead (Pb) was added to the commercial peat substrate. The effects of chelators disodium ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) with different concentrations (0, 2, 5, 10 mmol·L
−1 and 15 mmol·L
−1) on Pb activation in the substrate and on the growth, Pb absorption and accumulation of hemp were studied in this paper. The results showed that the content of available Pb in substrate increased with the increase of chelator concentration, and it reached the maximum at 15 mmol·L
−1. The growth of hemp, such as plant height, stem diameter and biomass, increased slightly when 2 mmol·L
−1 EDTA and 2~5 mmol·L
−1 CA was added, respectively, and the growth indexes of hemp decreased in varying degrees in other treatments. Under the treatment of 5 mmol·L
−1 EDTA, Pb contents in hemp root, stem and leaf reached the maximum, showing 428.75, 307.68 and 287.44 mg·kg
−1, respectively, which was significantly higher than that of the control (0 mmol·L
−1). Hemp had the highest Pb transport coefficient under 2 mmol·L
−1 EDTA treatment, 1.79 times of the control. The results suggested that appropriate amount of chelator could effectively activate Pb in the substrate and promote the absorption, accumulation and transport of Pb by hemp; hemp showed the best remediation efficacy, when 5 mmol·L
−1 EDTA or 10 mmol·L
−1 CA was added in Pb contaminated substrate.