Effects of dissolved organic carbon on phosphate retention on two calcareous soils.
To evaluate the effects of dissolved organic carbon (DOC) on phosphate retention (including both sorption and/or precipitation reactions) on soils, experiments were performed by using two typical calcareous soils from southeastern Spain (Calcic Regosol and Luvic Xerosol) and two different types of DOC: (1) extracts from a commercial peat (DOC-PE) and (2) high-purity tannic acid (DOC-TA). The experiments were carried out from a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results obtained show that the presence of both DOC-PE and DOC-TA, over a concentration range of 15 (DOC-15) to 100 (DOC-100) mg L(-1), produces in all cases a decreasing amount of phosphate retained in the soils studied, the decrease observed being higher when DOC-PE is used as source of DOC. The values of the decrease observed when DOC-PE was added ranged between 19.9% (DOC-15) and 15.6% (DOC-100) for the Calcic Regosol and between 17.3% (DOC-70, DOC-100) and 14.6% (DOC-15) for the Luvic Xerosol. The variation observed when DOC-TA was added ranged between 8.5% (DOC-100) and 0.5% (DOC-35) for the Calcic Regosol and between 7.0% (DOC-100) and 1.0% (DOC-15) for the Luvic Xerosol.
Fernández-Pérez
Manuel
M
Department of Inorganic Chemistry, University of Almería, La Cañada de San Urbano s/n, 04120 Almería, Spain.
Flores-Céspedes
Francisco
F
González-Pradas
Emilio
E
Ureña-Amate
María Delores
MD
Villafranca-Sánchez
Matilde
M
Socías-Viciana
María
M
Pérez-García
Susana
S
D000327:Adsorption; D002244:Carbon / Q000494:pharmacology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D010539:Permeability; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D010944:Plants / Q000378:metabolism; D012987:Soil / Q000032:analysis*; D013030:Spain
D010710:Phosphates; D012987:Soil; D002244:Carbon