Influence of ultraviolet radiation on the chromophoric dissolved organic matter in natural waters

Colored or chromophoric dissolved organic matter (CDOM) is by definition that portion of the dissolved organic matter (DOM) capable of absorbing light (i.e. contains chromophores). It represents a dominant absorbing species in natural waters and therefore it plays a critical role in controlling the light distribution in aquatic environments. CDOM shows a featureless absorption spectrum that increases exponentially with decreasing wavelength. Under light exposure CDOM loses its optical properties (photobleaching), altering the aquatic light field. Field and laboratory studies indicate that the CDOM photobleaching can represent a quite significant sink of this material over a short time scale.