Photodegradation of bisphenol A (BPA) in coastal aquaculture waters: Influencing factors, products, and pathways

Abstract

Bisphenol A (BPA), an endocrine-disrupting contaminant, is ubiquitous in the environment due to its presence in plastics, wastewater, and agricultural runoff. This study investigated the photodegradation behavior of BPA in coastal aquaculture waters near Qingdao, China. Lower salinity promoted BPA photodegradation, while higher salinity has an inhibitory effect, suggesting slower degradation in seawater compared to ultrapure water. Triplet-excited dissolved organic matter (3DOM*) was identified as the primary mediator of BPA degradation, with additional contributions from hydroxyl radicals (•OH), singlet oxygen (1O2), and halogen radicals (HRS). Alepocephalidae aquaculture water exhibited the fastest degradation rate, likely due to its high DOM and nitrate/nitrite (NO3−/NO2−) content, which are sources of 3DOM* and •OH. A positive correlation existed between NO3−/NO2− concentration and the BPA degradation rate. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis identified the primary BPA photodegradation products, formed mainly through oxidative degradation, hydroxyl substitution, nitration, and chlorination pathways. Elucidating these photodegradation mechanisms provides valuable insights into the environmental fate and potential ecological risks of BPA in aquaculture environments. This knowledge can inform strategies for marine environmental protection and the development of sustainable practices.