Comment on 'Formations of Hydroxyapatite and Inositol Hexakisphosphate in Poultry Litter during the Composting Period: Sequential Fractionation, P K-edge XANES and Solution ~(31)P NMR Investigations'

摘要

Hashimoto et al. used mineral stability plots to support their conclusion of hydroxyapatite formation during 7-day composting of poultry litter. Stability plots are handy tools that are seeing wider use by soil and environment scientists as computerized geochemical models become more user-friendly. Stability plots serve as a powerful tool in the study of geochemical processes and may indicate discrete minerals controlling solution composition. Furthermore, they may indicate the existence of minor or amorphous solids that are not detectable in common mineralogical analyses, but do control solution composition. In complex systems, such as soil or manure extracts, stability-plot construction requires detailed speciation, making the use of computerized geochemical models essential. In these models, the appropriate assumptions must be carefully selected, as overlooking or mishandling the model's default settings may lead to erroneous conclusions. We show here that Hashimoto et al. used incorrect assumptions, and we discuss the implications of the consequent erroneous results.