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Environmental context Antarctica has several scientific research stations located along its coast, where they discharge often untreated sewage containing organic micropollutants. Although degradation of these pollutants by microorganisms is limited by the cold conditions, other pathways such as photodegradation may be significant. Our results indicate that, during the summer, photolysis is a potentially significant degradation pathway for organic micropollutants in Antarctic surface waters, although the rate of loss would depend on ice cover and water depth. Abstract Knowledge of the environmental fate of organic micropollutants in Antarctica is limited, especially with respect to photolysis. The Antarctic is characterised by extreme light conditions of either continuous sunshine or darkness depending on the season. The photolytic degradation of benzophenone-3 (BP-3), bisphenol A (BPA), 17α-ethinylestradiol (EE2), methyl paraben (mParaben), 4-t-octylphenol (4-t-OP) and triclosan in MilliQ and seawater was investigated over a range of irradiance levels and temperatures. Photodegradation was compound specific. Up to 20% of BPA, BP-3 and EE2 was degraded over a 7-h irradiance period. Triclosan and 4-t-OP degraded to below the limit of detection in all experiments whereas mParaben was not degraded. The degradation of triclosan increased with irradiance in both MilliQ (P=2.2×10–16) and seawater (P=2.2×10–16). The degradation of 4-t-OP increased with irradiance in MilliQ (P=8.5×10–9) and seawater (P=1.1×10–5), and with temperature in MilliQ (P=8.5×10–9) and seawater (P=1.0×10–5). Similar relationships could not be established for BPA, BP-3, EE2 and mParaben due to the limited extent of degradation observed. The photolysis of triclosan was enhanced 4-fold in seawater compared to MilliQ water. Results from this study indicate that micropollutants may persist for extended periods of time in Antarctic coastal waters, particularly with ice cover, above and beyond that exhibited in temperate seawater.

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