Determination of Rare Earth Elements, Thorium and Uranium in Seaweed Samples on the Coast in Niigata Prefecture by Inductively Coupled Plasma Mass Spectrometry

The determination of rare earth elements (REEs), thorium (Th), and uranium (U) in seaweeds of various species and in ambient surface seawater were performed by inductively coupled plasma mass spectrometry (ICP-MS). The seaweeds and the seawater samples were collected at 10 different coastal areas of Niigata Prefecture in Japan twice a year (spring and autumn) in 2004 and 2005. Results showed that, concentration of REEs in seaweed species from Niigata Prefecture were about 102-103 times higher than those in seawater；and the enrichment factors of REEs was larger in heavy REE than light REE. A significant concentrations difference of REEs, Th, U was found among species even in the same phylum. The concentration of U in Undaria pinnatifida was the highest. Considering the experimental result that Undaria pinnatifida has low concentration of REEs among typical brown algae, different REEs and U uptake mechanisms were suggested. The concentration of REEs, Th and U did not vary remarkably among sampling points and/or seasons