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The effect of non‐instantaneous exchange on the self‐diffusion of phosphate in soil
Author(s) -
STAUNTON S.,
NYE P. H.
Publication year - 1989
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1989.tb01315.x
Subject(s) - diffusion , chemistry , suspension (topology) , kinetics , isotope , ion exchange , isotopes of calcium , phosphate , analytical chemistry (journal) , environmental chemistry , thermodynamics , ion , calcium , organic chemistry , physics , mathematics , quantum mechanics , homotopy , pure mathematics
SUMMARY The kinetics of isotopic exchange of phosphate in a soil were studied using three techniques: (a) in shaken suspension, (b) in a system where solution circulated through a thin disc of soil, and (c) in moist soil from which solution was extracted by centrifugation with a dense immiscible liquid. The exchange kinetics of isotope diffusing in moist soil were inferred from the concentration profile of the isotope after diffusion periods of 10‐60 days. The proportion of the exchange that is effectively instantaneous in this diffusion system was much lower than in systems in which isotope is uniformly applied to the soil. It is postulated that the difference arises because exchange of diffusing isotope is limited by access to exchange sites and not, during the period considered, by slow exchange at the solid‐liquid interface.