UV spectroscopic properties of principal inorganic ionic species in natural waters

The UV spectroscopic properties of the principal inorganic ionic species in natural waters were investigated at 25 °C in the wavelength range 195 to 280 nm. All absorbing species were identified and the corresponding molar absorptivities were determined experimentally. No cations were found to influence the UV spectrum. Relatively high molar absorptivities were observed for iodide, bromide and nitrate. The UV spectra of natural waters were calculated using the molar absorptivities and compared with observed signals from synthetic samples. This enabled the dominant components to be determined. Both bromide and nitrate have significant influence on the UV spectrum of natural waters. The study results can be used to predict the UV spectra of ionic solutions and thus evaluate the suitability of UV spectroscopy for given measurement projects.