Spectrofluorimetric study of dissolved organic matter in River Salaca (Latvia) basin waters

摘要

Dissolved organic matter (DOM) in surface waters influencesmineral weathering, nutrient cycling, aggregation of particulatematter and photochemical reactions in waters and aquatic communities. Inthis study, the effectiveness of UV and fluorescence measurementsin distinguishing the origin of DOM and processes within the riverbasin were analyzed using the River Salaca basin as an example.The basin of River Salaca is characterized by low anthropogenicpressure, however, the water color during the last few decades hasincreased (an effect known as brownification). As tools to studythe composition of dissolved organic substances in waters of theRiver Salaca and its tributaries the use of UV and fluorescence spectroscopywas evaluated. The use of the fluorescence index (a ratio of theemission intensity at a wavelength of 450?nm to that at 500?nm)allowed us to distinguish sources of aquatic DOM, characterize processesin the water body basin and to follow the changes in organic mattercomposition. Synchronous scan fluorescence spectrometry was moreinformative than excitation emission spectra and, provided informationon the basic structural features of DOM.