Purification Effect Of Dicranopteris Dichotoma To Rare Earth Elements In Rare Earth Elements Mining Area Of Changting County,South China

Ecological restoration and reconstruction of abandoned rare earth mine has been brought into focus in recent year,the restoration of rare earth contaminated soil has also been widely concerned.Phytoremediation technology is an economical and efficient emerging technology,with advantages of large area,good sustainability and will not cause repeated pollution.Compared with the chemical and physical remediation techniques of the environment,phytoremediation is more suitable for remediation of soil pollution in abandoned rare earth mines.This paper takes Dicranopteris dichotoma on rare earth elements mining areas of Changting County,Fujian Province for study.The concentrations of REEs in soil and Dicranopteris dichotoma were determined by ICP-MS.Main results forthis studyare as follows:(1)Dicranopteris dichotoma has strong ability to enrich rare earth elements,the concentration of REEs in Dicranopteris dichotoma is 5 to 7 times of the concentration of REEs in soil.The distributions of rare earth elements in Dicranopteris dichotoma were lamina>rhizome>stem.The light and heavy REEs concentrations in rhizome,stem and lamina of Dicranopteris dichotoma was obviously different,the heavy REEs concentrations in stem and lamina were low,while the light REEs concentration in lamina was high.(2)The transfer and enrichment ability of light REEs in stem and lamina of Dicranopteris dichotoma was higher than that of heavy REEs.The enrichment ability of heavy REEs in rhizome of Dicranpteris dichotoma was higher than that of light REEs.The soils with low concentrations of REEs were more favorable for Dicranopteris dichotoma to transfer and enrich REEs,and the high concentrations of REEs could inhibit Dicranopteris dichotoma to transfer and enrich REEs.The accumulation of REEs in rhizome,stem and lamina of Dicranopteris dichotoma were 0.39?2.38 g/m2?0.01?0.05 g/m2 and 0.87?1.85 g/m2.The accumulation of light REEs in Dicranopteris dichotoma was higher than that of heavy REEs.Especially for the absorption of La?Ce?Pr?Nd?Y was highly obvious.(3)The seasonal concentrations of REEs in Dicranoperis dichotoma is slightly different and the spring and winter concentrations in lamina is higher than that of summer and Autumn(P<0.05).The concentrations of REEs in rhizome and stem of Dicranopteris dichotoma were no difference in seasons.The bioconcentration factors and accumulation of REEs in different parts of Dicranopteris dichotoma were also no difference in seasons.(4)In addition to lamina of Dicranopteris dichotoma,The concentrations of REEs in rhizome and stem in Niushitang(2006)is higher than Xiakeng(2008)and Sanzhoutongba(2011)(P<0.05),while the bioconcentration factors and accumulation of REEs in different parts of Dicranopteris dichotoma are also higher than Xiakeng and Sanzhoutongba(P<0.05).(5)The best time of cut the Dicranopteris dichotoma is winter,the frequency of cutting is once every 2 years.Because the three rare earth mines situations were different,the time needed to reduce pollution are also different.In Niushitang,a moderately polluted area,it takes about 78 years to reduce the concentration of REEs in soil by cutting Dicranopteris dichotoma;and in Xiakeng and Sanzhoutongba,where the soil is slightly polluted.it needs 28 to 48years to reduce soil pollution.