PHYSICOCHEMICAL VARIATIONS IN DOM-SYNCHRONOUS FLUORESCENCE - IMPLICATIONS FOR MIXING STUDIES

Synchronous fluorescence (SF) spectra of dissolved organic matter (DOM ) show promise for mixing studies and can resolve multiple river input s to large water masses in a single fast measurement. This study exami nes the effects of physicochemical variables on DOM SF; independent of mixing. Our results show that changes in the pH and metal ion concent ration do not affect SF in the alkaline Cuyahoga-Erie system. The effe ct of temperature is small and correctable. Model predictions suggest that photobleaching of DOM SF can limit the use of this method to shor t periods (3-7 d, depending an conditions). SF spectra are sensitive e nough to detect 1% river water mixed in Lake Erie water.