Fig. 8. The effect of probe temperature on (a) spectral areas of model P compounds in a synthetic mixture of 1 M NaOH (proportion of the initial spectral area at 19°C) and (b) proportion of the spectra assigned to the various functional P classes in a 0.25 M NaOH and 0.05 M EDTA soil extract (%). The regression lines on Fig. 3b describe the following models: [Proportion of orthophosphate (%)] = 53.49 ± 1.36 - 0.188 ± 0.051[probe temperature (°C)], R² = 0.69, F = 13.6, P = 0.010; [Proportion of orthophosphate monoesters (%)] = 41.08 ± 1.83 + 0.165 ± 0.069[probe temperature (°C)], R² = 0.49, F = 5.78, P = 0.053.

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