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Kinetic Model for Phosphate Transport and Transformation in Calcareous Soils: I. Kinetics of Transformation
Author(s) -
Enfield Carl G.,
Phan T.,
Walters David M.,
Ellis Roscoe
Publication year - 1981
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/sssaj1981.03615995004500060010x
Subject(s) - dissolution , sorption , soil water , phosphate , solubility , chemistry , kinetics , calcareous soils , calcareous , correlation coefficient , mineralogy , soil science , environmental chemistry , thermodynamics , geology , mathematics , adsorption , statistics , paleontology , physics , organic chemistry , quantum mechanics
Phosphorous in concentrations exceeding those generally observed through agricultural activities has been encountered at land application wastewater treatment sites. To predict the environmental impact of these systems, a model was developed to describe the reaction of orthophosphate with mineral soils. The model is based on instantaneous reversible absorption theory plus time‐dependent solubility theory. It was assumed, in the model, that first‐order kinetics would adequately describe the formation or dissolution of phosphate minerals. Statistical regression analyses were performed on batch sorption data for 14 mineral soils where two equilibrium compounds were considered. The two compounds considered were hydroxyapatite (Ca 10 HPO 4 ·2H 2 O) and dicalcium phosphate dihydrate (CaHPO 4 ·2H 2 O). Comparisons of correlation coefficients between this model and previous models using a common data set indicate the current model with a mean correlation coefficient of 0.93 is more accurate in describing phosphate reactions in calcareous soils than earlier models with mean correlation coefficients ranging from 0.75 to 0.91.