Solubility and Phosphorus-31 Magic Angle Spinning Nuclear Magnetic Resonance of Phosphorus in Sludge-Amended Soils
- Zeina R. Hinedi and
- Andrew C. Chang
The solubility of P in two sludge-amended soils was studied. Solubility and activity ratio diagrams for P in sludge-amended soils were constructed and were compared with those of selected Ca-P, Fe-P, and Al-P minerals. The solid phase controlling P solubility in the sludge-amended soils appeared to be a carbonated apatite formed through coprecipitation. The 31P magic angle spinning nuclear magnetic resonance (31P MAS NMR) examinations confirmed that P in the sludge-amended soils was in form of calcium phosphate. The resonant peak [at isotropic chemical shift (δlso) = 3.1 ppm] is indicative of an apatitic calcium phosphate environment characterized by carbonate substitution. Additionally, pyrophosphate was detected by the presence of a peak at δlso = −9 ppm.
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