Solar-induced Degradation of Alkylphenol Ethoxylates (APEO) and APEO Metabolites in Natural Waters (SOLAPIG)
Alkylphenol ethoxylates are industrial surfactants which are fairly well biodegradable. Biodegradation, however, is often incomplete and results in the formation of various metabolites. Alkylphenols (AP) are important metabolites which are formed under anaerobic conditions. AP are more lipophilic and more toxic than the parent APEO, and they have been shown to act as endocrine disrupters (xenoestrogens). APEO, AP, and other metabolites are released into the aquatic environment mainly via sewage treatment plant (STP) effluents. APEO and their metabolites can occur in the microgram-per-liter-range in STP effluents and in rivers with a high input of treated sewage. Chronic exposure to those compounds can result in detrimental estrogenic effects on aquatic biota. With biodegradation being incomplete, other geochemical removal processes become of importance. Solar-induced photochemical degradation is likely to be an important sink in the aquatic environment. Up to date, detailed investigations on the efficiency, environmental factors, reaction pathways, products of photochemical degradation processes under natural conditions and their biological effects have not been carried out. In the current project, the photochemical degradation of APEO and APEO metabolites will be studied in lab-scale experiments using simulated sunlight for irradiation. On the basis of identifcation of the degradation products, possible reaction pathways can be elucidated. The biodegradability, toxicity, and estrogenicity of the degradation products will be investigated using well-established methods.
Keywords: Alkylphenol ethoxylates, solar irradiation, aquatic ecosystems, bioassays, estrogenic effects.