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Phosphorus Adsorption by an Aluminum‐Peat Complex
Author(s) -
Bloom P. R.
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/sssaj1981.03615995004500020008x
Subject(s) - peat , adsorption , phosphate , organic matter , phosphorus , chemistry , soil water , environmental chemistry , inorganic chemistry , precipitation , soil organic matter , organic chemistry , geology , soil science , ecology , biology , physics , meteorology
Phosphorus adsorption by an organic matter Al complex in acid soils was studied using Al‐peat containing 0.8 equivalents of Al per equivalent of peat carboxyl groups. Phosphate adsorption isotherms were determined with suspensions in 0.005 M CaCl 2 to which either HCl or Ca(OH) 2 was added. The pH ranged from 3.2 to 6.0. Phosphate is strongly adsorbed by Al‐peat. The data suggest that phosphate removal from solution is due both to adsorption of complex Al‐phosphate cations by the peat and to the precipitation of amorphous Al‐hydroxy‐phosphate, likely AlH 2 PO 4 (OH) 2 . For suspensions with similar pH, the strength of phosphate adsorption in Al‐peat is less than that for an Al‐permanent charge resin and greater than that, per gram of organic matter, of an andept soil. As in acid soil and Al‐resin, phosphate adsorption in Al‐peat increased with increasing pH in the pH range studied. It was concluded that the Al‐organic matter complex in acid surface soils is an important source of phosphate adsorption, especially in mineral soils of high organic matter content.