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Plutonium Activities in Soil Solutions and the Stability and Formation of Selected Plutonium Minerals
Author(s) -
Rai Dhanpat,
Serne R. J.
Publication year - 1977
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1977.00472425000600010020x
Subject(s) - plutonium , chemistry , oxidizing agent , sorption , soil water , weathering , composition (language) , nuclear chemistry , geology , adsorption , soil science , linguistics , philosophy , organic chemistry , geomorphology
Selected thermodynamic data was used to develop solid phasesoil solution equilibria diagrams which are used to predict and understand plutonium behavior in terrestrial environments. The plutonium mineral transformations in soils are highly dependent upon the pH, Eh, and the soil solution composition. The predictions of weathering and formation sequences of Pu(OH) 3 , Pu(OH) 4 , PuO 2 (OH), PuO 2 (OH) 2 , PuO 2 , βPu 2 O 3 , PuF 3 , PuF 4 , PuO 2 CO 3 , and Pu(HPO 4 ) 2 at pH values from 3 to 11 at pO 2 from 0.68 to 80, and in an assumed weathering environment are given. The study shows that the PuO 2 is the most stable mineral in the pH and pO 2 ranges found in the terrestrial environments. The nature and activity of ions and ion‐complexes and, hence, the total plutonium in solution is a function of the stable phase, pH, Eh, and complexing anions: for example, (i) in a reducing environment (pO 2 80) at pH 8 and in equilibrium with PuO 2 (s), the predominant solution species are Pu 3+ and its complexes, and (ii) in an oxidizing environment (pO 2 16) at pH 8 and in equilibrium with PuO 2 (s), the predominant solution specie is PuO 2 CO 3 OH − . Empirical predictions regarding the plutonium sorption by soils are outlined and verified by experimental results reported in the literature. The deficiencies in the present thermodynamic data and future research needs are outlined.