The Marine Geochemistry of the Rare Earth Elements

• Main Author: DE Baar, H. J. W.
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
• Format: Text
• Language: English
• Published: 1983
• Subjects: Physical and Dynamic Oceanography; Geology; Geochemistry and Mineralogy; *RARE EARTH ELEMENTS; *SEA WATER; EQUATORIAL REGIONS; DISTRIBUTION; DEPTH; CERIUM; PACIFIC OCEAN; GADOLINIUM; NORTH ATLANTIC OCEAN; ION EXCHANGE; CHROMATOGRAPHY; CARIBBEAN SEA; GAMMA RAY SPECTROSCOPY; SUBMARINE TRENCHES; COMPUTER PROGRAMS; ANOMALIES; *CHELATING ION EXCHANGE CHROMATOGRAPHY; CARIACO TRENCH; Pacific; North Atlantic; Northwest Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA145132; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA145132

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 Ge(Li) 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 Gd(III)-cation, which has an exactly half-filled 4f electron shell. Report on the Joint Program in Oceanography and Ocean Engineering. Prepared in Cooperation with Massachusetts Inst. of Tech.