Clipping strategy to assist phytoremediation by hyperaccumulator Dicranopteris dichotoma at rare earth mines

Abstract

Little is known about the clipping strategy to assist phytoremediation by Dicranopteris dichotoma at rare earth mines. We evaluated the phytoremediation ability of D. dichotoma, designed an appropriate clipping strategy, and obtained the phytoextraction time for rare earth elements (REE) by field investigation, laboratory measurement, and statistical analysis etc. at four rare earth mines in south China. D. dichotoma growth and soil nutrients tended to increase across the ecological restoration chronosequence, the total REE content in aboveground biomass was ≥1,000 mg kg−1, the bioabsorption coefficient and translocation factor were ≥1, and the phytoextraction of light REE was greater than heavy REE. Overall, the REE accumulation did not vary significantly among seasons, the total REE accumulation in the underground biomass accounted for 26.55–64% and the vegetation covers were about 90% two years after clipping. It would take 57.88–168.57 years to reduce soil total REE content, and the soil nutrients and REE accumulations of D. dichotoma at Longjing were the highest. D. dichotoma has potential for REE phytoextraction and phytostabilization simultaneously. D. dichotoma should be clipped in winter once every two years with underground biomass retained. The REE phytoextraction time is long with soil nutrients being important influencing factors.