Seasonal variations in optical attenuation spectra of some urban water bodies

Water samples were taken once a month from several urban water bodies, and using a laboratory setup with two concave mirrors and a fiber optic spectrometer attenuation spectra were obtained in visible and near infrared spectral range. Spectra approximation by a power law gave better fit, indicating the primary influence of scattering by non-algal particles on the total attenuation. Seasonal maximums of attenuation were observed in November and late in summer, attributed to detritus scatterings and algal bloom correspondingly. A negative correlation was found between the spectral slope parameter and the attenuation value at 550 nm, which means that spectra for more turbid samples were spectrally flatter in general.