engleski

UV-Vis spectroscopic study of coloured dissolved organic matter (CDOM) in the pristine Krka River estuary (Croatia)

Dissolved organic matter (DOM) is one of the major components of aquatic ecosystems which controls functioning of ecological processes and biogeochemical cycles. For many estuarine systems, riverine discharge is considered as the main source of DOM. However, freshwater systems from karst regions without notable anthropogenic influence, could deviate from this common pattern [1]. The Krka River (and its estuary) is the typical example: in winter period concentration of dissolved organic carbon (DOC) in the Krka River is lower than in the coastal sea waters. Concentration of DOC in the estuary is ~60% higher in the summer, as a consequence of higher biological activity. Increase of DOC is expected to be reflected also on the intensity of a254, however different trends were observed for summer and winter period, avoiding use of this parameter for simple estimation of DOC concentration. Several other relationships and fitting equations were reviewed in order to find the optimal way of relating absorbance and DOC concentration. UV-Vis spectra were additionally treated by using Gaussian decomposition method (combination of exponential and n-gaussian functions), recently suggested by Massicotte and Markager (2016) [2]. [1] Cindrić A.-M., Garnier C., Oursel B., Pižeta I., Omanović D., (2015). Marine pollution bulletin. 94, 199-216 [2] Massicotte, P. and S. Markager (2016). Marine chemistry, 180, 24-32.

Dissolved organic matter ; UV/Vis spectroscopy ; Coastal waters ; Estuary

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