The rapid growth of algae has significantly increased algae-derived organic matter (AOM) in surface water, and AOM has been shown to play an important role in the photosensitized degradation of emerging contaminants under natural sunlight. This study investigated the photosensitized degradation of tetracycline (TC) by different AOM, i.e. extracellular organic matter (EOM) and intracellular organic matter (IOM) obtained from Anabaena sp. and Scenedesmus quadricauda, with the focus on the role of the triplet excited states of AOM (