Optical and Photochemical Characterization of Chromophoric Dissolved Organic Matter from Lakes in Terra Nova Bay, Antarctica. Evidence of Considerable Photoreactivity in an Extreme Environment

Water samples from shallow lakes located in Terra Nova Bay, Antarctica, were taken in the austral summer season and characterized for chemical composition, optical features, fluorescence excitation-emission matrix (EEM) and photoactivity toward the generation of (OH)-O-center dot, O-1(2), and (CDOM)-C-3* (triplet states of chromophoric dissolved organic matter). The optical properties suggested that CDOM would be largely of aquagenic origin and possibly characterized by limited photochemical processing before sampling. Moreover, the studied samples were highly photoactive and the quantum yields for the generation of (CDOM)-C-3* and partially of O-1(2) and (OH)-O-center dot were considerably higher compared to water samples from temperate environments. This finding suggests that water in the studied lakes would have considerable ability to photosensitize the degradation of dissolved compounds during the austral summer, possibly including organic pollutants, also considering that the irradiance conditions of the experiments were not far from those observed on the Antarctic coast during the austral summer.