Abstract
Mn hyperaccumulator plants are capable of accumulating at least 10,000mg kg -1 Mn (Dry wt), and currently 11 species are known worldwide. To date, speciation studies have not been carried out to determine the nature of Mn hyperaccumulating plants. Hence the aim of this study was to use Mn X-ray absorption spectroscopy (XAS) to elucidate chemical form(s) of Mn in the leaves of Mn-hyperaccumulating plants. Mn K-edge (6.539 KeV) X-ray absorption near edge structure (XANES) spectroscopy and extended absorption fine structure (EXAFS) spectroscopy were carried out at the Australian National Beamline Facility, located in the Tsukuba photon factory. Superimposed XANES profiles of six Mn hyperaccumulating plant samples correlated well, indicated the predominant speciation of foliar Mn to be 2+. Comparison of the plant EXAFS data with the standards showed there was best agreement between plant EXAFS patterns and those of citrate, succinate and malate standards.
