Monitoring natural organic matter in water with scanning spectrophotometer

This study uses scanning ultraviolet-visible (UV-Vis) spectrophotometer to monitor natural organic matter (NOM) in water. The results showed that the area under the UV-Vis spetra is a good surrogate to monitor the concentrati on of the aqueous NOM. No apparent difference was found between the spectra of the three commercially available humic acids used in this study. The us e of the scanning spectra compensates the potential random error in the abs orbance determined at single wavelength due to the heterogeneous NOM compos itions. The major interference of the proposed method comes from the formaz ine turbidity and nitrate nitrogen (NO3- -N). Although filtration with a 0. 45-mum filter can remove most of the interference from formazine, some inte rference is still present at a wavelength less than 250 nm. Also it is foun d that the presence of the NO3- -N greatly affect the spectra of the NOM. I n order to monitor the NOM in water with minimized interference, it is reco mmended that the area under the spectra between 250 and 350 nm should be us ed as a surrogate for concentration of NOM in water. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.