Characterization of Dissolved Organic Matter with Intermittent Aeration by Fluorescence

ABSTRACT

This work characterized the fluorescence of dissolved organic matter in water under intermittent aeration and the correlation between the fluorescence and ammonia concentration. The fluorescence spectra allowed determination of proteins using two excitation wavelengths for tyrosine and tryptophan. Fulvic acid was determined using visible and ultraviolet excitation. The fluorescence intensities decreased with aeration but increased in the absence of aeration. However, the fluorescence of fulvic acid increased in aerated and nonaerated samples. The fluorescence of the shorter excitation wavelengths for tyrosine and tryptophan was linear with ammonia concentration under intermittent aeration. When the concentration of dissolved oxygen was 6.5 mg l⁻¹, the correlation coefficients were 0.9863 and 0.9822. This study shows that ammonia may be rapidly determined in water by measurement of the fluorescence at the shorter excitation wavelengths of tyrosine and tryptophan.

KEYWORDS:

• Ammonia nitrogen
• dissolved organic matter
• fluorescence excitation–emission matrix spectroscopy
• fluorescence intensity
• intermittent aeration