Photodegradation of bisphenol A and identification of photoproducts in artificial snow under UVA radiation

Bisphenol A (BPA) is an organic micropollutant detected in various environments, from urban to remote areas, including Arctic snow. As a known endocrine disruptor, it is essential to investigate its environmental fate and potential impact on ecosystems. Previous studies have explored BPA photodegradation and its transformation products in different aqueous environments (freshwater, seawater, and ice), by using photosensitizers to trigger specific reactions. However, there is still a significant gap in understanding the photodegradation processes in snow, which, although similar to ice, has distinct chemical and physical characteristics. In this work, we investigated the direct and indirect photodegradation of BPA in artificial snow and identified its degradation products through HPLC-HRMS. Nitrite and benzophenone-4-carboxylate, the latter used as a surrogate of chromophoric dissolved organic matter, induced significant BPA photodegradation under UVA irradiation. The photoproducts found in snow were partly similar to those previously observed in liquid water and ice. Their toxicity towards aquatic organisms was predicted with ECOSAR software as well. Finally, BPA photolysis and formation of photoproducts were investigated in two Alpine snow samples collected above and below the tree line, with a different organic matter content. Oxidation and nitration products of BPA were detected in these samples, suggesting that BPA photodegradation may indeed occur in natural snow. It was also noted that the aquatic toxicity of several identified photoproducts would be similar to that of BPA, but others may be even more toxic than the parent contaminant.