The Marine Geochemistry of the Rare Earth Elements
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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Novel methods were developed for the determination of 12 of the 14 Rare Earth Elements REE in seawater. Initial extractions of the REE by chelating ion exchange chromatography is followed by cation exchange for removal of co-extracted U and remaining traces of major ions. Finally traces of U are removed by anion exchange before irradiation for 8 hours at a flux of 5 x 10 to the 13th power neutrons 1 sq. cm.sec. After post-irradiation separation of 24Na, the gamma spectra are recorded over four different time intervals with a GeLi detector. An internal standard 144Ce is carried all along the procedure for improved precision by avoidance of counting geometry errors. Vertical profiles are reported for three stations in respectively the Northwest Atlantic Ocean, the Eastern Equatorial Pacific Ocean and the Cariaco Trench, an anoxic basin. This data set represents the first detailed profiles of Pr, Tb, Ho, Tm and Lu in seawater, together with profiles of La, Ce, Nd, Sm, Eu, Gd, and Yb. The first observations of positive Ce anomalies in seawater are ascribed to regeneration of Ce under reducing conditions. The first reported positive Gd anomalies are ascribed to the unique chemical properties of the GdIII-cation, which has an exactly half-filled 4f electron shell.
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy