Study on accumulation mechanism of arsenic and selenium in Pteris vittata L. using synchrotron radiation X-ray fluorescence analysis

Pteris vittata L. is known as an arsenic hyper-accumulator. We investigated the accumulation mechanism of arsenic and selenium in the fern cultivated with the culture solution containing As(V) or Se(VI) by utilizing synchrotron radiation X-ray fluorescence analysis. The chemical speciations of arsenic, selenium, and sulfur in the fern were carried out by X-ray absorption near edge structure (XANES) analyses and the elemental distributions in their tissues were visualized by micro-XRF imaging. Arsenic was highly accumulated in pinna especially in the base of sporangium as As(III). Selenium could be taken in the root and less accumulated in the aerial parts. About 60% of Se in the fern was present as Se(-II) and this indicated the selenium was reduced from Se(VI) during uptake process. The chemical speciation of sulfur revealed that the ratio of S(-II) and S(V) compounds such as glutathione (GSH) and cysteic acid, respectively, increased when the fern was cultivated with As(V) and Se(VI). This result demonstrated that sulfur had a certain function in detoxification process of P. vittata L. (author)