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Abstract

The geochemical behaviour and the general properties as well as the chemistry of the rare earth elements (also called the lanthanides) has been reviewed with special emphasis on factors which may be of importance in controlling the environmental behaviour of these elements. Under geochemical conditions, the rare earth elements exist exclusively in the trivalent state as the highly ionic rare earth (III) species. The rare earth (II) ions have a strong affinity to clays, Fe/Mn oxides and soil organic matter and they bind easily and strongly to these weathering products, which are present everywhere in nature. At neutral and alkaline pH, the rare earth elements are predominantly immobilized by forming very insoluble hydroxides and carbonates. rare earth (II) ions are capable of forming complexes with naturally occurring ligands; both with the omnipresent inorganic hydroxide and carbonate ions and with members of the soil organic matter, which are polyfunctional ligands preferably containing oxygen donor groups. Artificial chelating agents such as those of the EDTA-family also very easily form complex species with the lanthanides. Some of the rare earth (III) complexes can be neutral or negatively charged, and such species can be potentially mobile and capable of migration.

Additional information

Authors: NILSSON K, RISOE NATIONAL LABORATORY, ROSKILDE (DENMARK);SKYTTE JENSEN B, RISOE NATIONAL LABORATORY, ROSKILDE (DENMARK);CARLSEN L RISOE NATIONAL LABORATORY, ROSKILDE (DENMARK), RISOE NATIONAL LABORATORY, ROSKILDE (DENMARK)
Bibliographic Reference: EUROPEAN APPLIED RESEARCH REPORTS + NUCLEAR SCIENCE AND TECHNOLOGY SECTION, VOL. 7 (1985), NO. 1, PP. 87-147, (EUR 9783 EN).
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