| Summary: | Antarctica is an extreme climatic region and its terrestrial ecosystems are among the most uncontaminated on Earth. Antarctic lake waters have been less extensively studied than other matrices, such as seawater or snow. Most available data on Antarctic lake waters derive from the McMurdo Dry Valleys area in southern Victoria Land. In this work the photoproduction of excited triplet states of chromophoric dissolved organic matter (CDOM) and singlet oxygen were assessed upon irradiation of water samples, taken from shallow lakes and ponds located in the Terra Nova Bay area, Northern Victoria Land (Antarctica). Absorption spectral features, fluorescence emission and the chemical composition of samples were investigated, too. The fluorescence spectra suggested the absence of organic material such as humic and fulvic substances, usually correlated with highly photoactive waters. On the other hand, CDOM optical features and Total Organic Carbon (TOC) concentrations measured in the studied samples revealed the presence of relatively small organic compounds, probably due to marked photobleaching of CDOM as a consequence of intense UV irradiation. All the samples showed an unexpectedly high photoreactivity, especially for the photoproduction of triplet states of chromophoric dissolved organic matter, despite the negligible presence of humic/fulvic acids that we have previously observed as the main photoreactive species in Alpine lakes.
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