Environmental behaviors and ecological risks of organophosphate esters in a metropolitan river system of the Pearl River Basin, South China.

Organophosphate esters (OPEs) are ubiquitous endocrine-disrupting chemicals that have been frequently detected in metropolitan river systems. However, the distinctions in OPE sources and water-sediment dynamics between urban and suburban rivers remain poorly understood. In this study, the occurrence of 5 alkyl organophosphate esters (alkyl-OPEs), 4 aryl organophosphate esters (aryl-OPEs), 3 chlorinated organophosphate esters (Cl-OPEs), and 2 oligomeric organophosphate esters (oligomeric-OPEs) was investigated in water and sediments of 4 urban rivers and 2 suburban rivers in the Pearl River Basin, South China. All these compounds were found in both types of rivers. In the water phase, OPE occurrence was primarily influenced by dissolved oxygen and chemical oxygen demand, while in the sediment phase, it was mainly associated with total organic carbon. Sediment density was another dominating factor in only suburban rivers. Additionally, log Kow largely governed the OPE partitioning behaviors in both rivers. The source attribution analysis revealed domestic emissions as the primary source for urban rivers and industrial emissions for suburban rivers. Furthermore, triphenyl phosphate (TPHP), tris(chloro-2-propyl)phosphate (TCIPP), and tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) had high ecological risks in sediments of certain sites, highlighting the necessity of OPE management in sediments. These results will deepen our understanding of the OPE contamination in metropolitan river systems.