Phosphate Speciation under Organic‐Acid‐Promoted Dissolution of Phosphorus‐Sorbed Ferrihydrite–Boehmite Mixtures: Implications For Soil Phosphorus
| Autor: | Nadia Adam |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
chemistry.chemical_classification
Boehmite Phosphorus Inorganic chemistry Soil Science chemistry.chemical_element 04 agricultural and veterinary sciences 010501 environmental sciences Phosphate 01 natural sciences Bioavailability chemistry.chemical_compound Ferrihydrite chemistry Soil pH 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Dissolution 0105 earth and related environmental sciences Organic acid |
| Zdroj: | Soil Science Society of America Journal. 80:900-910 |
| ISSN: | 1435-0661 0361-5995 |
| Popis: | Organic-acid-promoted dissolution of phosphate is a primary mechanism for enhancing the bioavailability of sorbed, inorganic soil phosphate. Bioavailability of P is, however, dependent on its speciation. Hence, the main objective of this study was to characterize changes in phosphate speciation as a function of pH levels (4–8) during citrate-promoted dissolution of phosphate adsorbed on ferrihydrite–boehmite mixtures using two different sizes of ferrihydrite. A combination of batch dissolution kinetics and P K-X-ray absorption near-edge structure (XANES) spectroscopy was used. Trends in shifts of white-line peak energy and full width at half maximum height of P K-XANES spectra indicated that the phosphate bonding configuration on ferrihydrite–boehmite as single minerals and mineral mixtures was predominantly binuclear–bidentate complexes at pH levels of 4, 6, and 8. When citrate was added to the ferrihydrite–boehmite mixtures with bound phosphate (pH 4 and 6), phosphate was preferentially released from boehmite, resorbed onto ferrihydrite, and precipitated to form noncrystalline FePO₄ minerals. A reverse trend was observed at alkaline pH. These results suggest the potential for excessive P release in P-enriched acidic soils during a redox event due to preferential association of P to Fe(III) phases. |
| Databáze: | OpenAIRE |
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