Phytoextraction of trace elements from an aged biosolid stockpile by willow (Salix) species after one year

摘要

Seven cultivars of willow (Salix) were planted in aged biosolids contaminated with multiple trace elements. Willow shoots (stems and leaves) were harvested in autumn to remove metal contaminants taken up by the plants. Cultivars of two willow species, S. reichardtii and S. matsudana, grown in biosolids produced up to 3 times more biomass than willows grown in soil. Cultivars with high tissue metal concentrations produced less biomass. Salix reichardtii and S. matsudana had some of the lowest tissues metal concentrations but extracted the most heavy metals by comparison to the other cultivars in a single season. Average heavy metal removals (g·ha <'1>) by S. reichardtii in the first year were: Cd 84, Cr 20, Cu 51, Hg 3, Ni 272 and Zn 7726. Biomass production and heavy metal extraction are expected to increase in the second year.