Perfluoroalkyl acids (PFAAs) are commonly detected in various environmental media and can cause potential risks to the ecological environment and human health. The levels and spatial distribution of 15 types of PFAAs and 3 types of PFAA precursors in the main river water and effluents of three sewage treatment plants (STPs) of Rizhao City were systematically investigated based on methods such as ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), solid phase extraction and enrichment, and hydroxyl radical (·OH) oxidation to explore the pollution characteristics of PFAAs and the contribution of their precursors to environmental pollution in different water bodies of typical tourist cities. The results of this study reveal that 15 types of PFAAs and only perfluorooctane sulfoneamide (FOSA) among the precursors are detectable in most of the water samples. The total concentration of PFAAs (∑PFAAs) in the river water and sewage effluents is 3.79-45.58 ng·L-1 and 54.04-105.64 ng·L-1, respectively. The predominant PFAAs are perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA). The ∑PFAAs value of the river samples is notably lower than that of sewage treatment plant (STP) effluents. An increasing tendency was observed from the upstream to the downstream of the rivers. After hydroxyl radical oxidation treatment, the PFAA concentrations of rivers and STPs increase notably. The increased concentrations of perfluorinated carboxylic acids (PFCAs) with 4-12 perfluoroalkyl carbon chains (∑△PFCAC4~C12) in the STP effluents are much higher than those in the river, which might be induced by the degradation of precursors during the sewage treatment processes. The results of this research provide basic data and technical support for environmental pollution prevention of new emerging pollutants in tourist cities.
Keywords: Rizhao; distribution; perfluoroalkyl acids; precursors; transformation.