Premium
A Chemical Model of Phosphate Adsorption by Soils: II. Noncalcareous Soils
Author(s) -
Goldberg Sabine,
Sposito Garrison
Publication year - 1984
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1984.03615995004800040016x
Subject(s) - adsorption , phosphate , chemistry , soil water , dissociation constant , protonation , capacitance , inorganic chemistry , dissociation (chemistry) , analytical chemistry (journal) , ion , environmental chemistry , soil science , geology , organic chemistry , electrode , biochemistry , receptor
The Constant Capacitance model provided a quantitative description of o ‐phosphate adsorption by 44 noncalcareous soils whose pH values ranged from 4.9 to 7.6. The intrinsic surface protonation‐dissociation constants, capacitance density, and phosphate packing area parameters required by the model were adopted from model calculations on reference hydrous oxide minerals. The intrinsic phosphate surface complexation constants were calculated through the application of a nonlinear least squares fitting program to the soil o ‐phosphate adsorption data. Two of these intrinsic constants were found to be independent of pH over the range investigated, as required by the model. However, the intrinsic constant for the formation of the neutral o ‐phosphate surface species exhibited a statistically significant dependence on pH. The Constant Capacitance model was best able to describe o ‐phosphate adsorption by noncalcareous soils, including pH effects, if a soil‐specific set of intrinsic phosphate surface complexation constants was employed.