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Sorption and Fractionation of Dissolved Organic Matter and Associated Phosphorus in Agricultural Soil
Author(s) -
Gjettermann B.,
Styczen M.,
Hansen S.,
Borggaard O. K.,
Hansen H. C. B.
Publication year - 2007
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/jeq2006.0081
Subject(s) - sorption , dissolved organic carbon , desorption , chemistry , environmental chemistry , fractionation , organic matter , soil water , leaching (pedology) , phosphorus , soil organic matter , adsorption , chromatography , soil science , environmental science , organic chemistry
Mobility of dissolved organic matter (DOM) strongly affects the export of nitrogen (N) and phosphorus (P) from soils to surface waters. To study the sorption and mobility of dissolved organic C and P (DOC, DOP) in soil, the pH‐dependent sorption of DOM to samples from Ap, EB, and Bt horizons from a Danish agricultural Humic Hapludult was investigated and a kinetic model applicable in field‐scale models tested. Sorption experiments of 1 to 72 h duration were conducted at two pH levels (pH 5.0 and 7.0) and six initial DOC concentrations (0–4.7 mmol L −1 ). Most sorption/desorption occurred during the first few hours. Dissolved organic carbon and DOP sorption decreased strongly with increased pH and desorption dominated at pH 7, especially for DOC. Due to fractionation during DOM sorption/desorption at DOC concentrations up to 2 mmol L −1 , the solution fraction of DOM was enriched in P indicating preferred leaching of DOP. The kinetics of sorption was expressed as a function of how far the solution DOC or DOP concentrations deviate from “equilibrium.” The model was able to simulate the kinetics of DOC and DOP sorption/desorption at all concentrations investigated and at both pH levels making it useful for incorporation in field‐scale models for quantifying DOC and DOP dynamics.