[Occurrence and Ecological Risk of Ultraviolet Absorbents in Water from the Guangzhou Reach of the Pearl River]

Ultraviolet absorbents （UVAs） are common additives in personal care and industrial products. Due to their pseudo-persistence, bioaccumulation, and toxicity, environmental pollution and the risks associated with UVAs have raised widespread concern. However, current understanding of the pollution characteristics and ecological risks of UVAs in urban aquatic environments is still limited. To investigate the occurrence, composition, and spatial distribution characteristics of UVAs in the aquatic environment, eight UVAs in 40 paired water and suspended particulate matter （SPM） samples in the Guangzhou reach of the Pearl River were analyzed, and their potential aquatic ecological risks were further assessed using risk quotients. The results showed that UVAs were widely detected in the aqueous and SPM phases of the Guangzhou reach of the Pearl River, with total concentrations （∑₈UVA, range and mean ± standard deviation，ng·L^-1) of 6.52-85.8 （2.80 ± 6.34） and 5.69-461 （6.57 ± 34.1）, respectively. The concentrations of individual UVAs in the aqueous phase accounted for 16% to 99% of the sum concentrations in the aqueous and SPM phases. Specifically, two UVAs （2-ethylhexyl 4-（dimethylamino）benzoate （ODPABA） and 2-（2-hydroxy-5-methylphenyl）benzotriazole （UV-P）） were almost exclusively （97% and 99% on average, respectively） distributed in the aqueous phase, one UVA （2-（2H-benzotriazol-2-yl）-4-（1,1,3,3-tetramethylbutyl）phenol （UV-329）） was mostly （84% on average） distributed in the SPM, and the remaining UVAs were similarly distributed to the aqueous and SPM phases, with concentrations in the aqueous phase accounting for 42%-74% of the sum concentrations in both phases. Concentrations of UVAs in the downstream were generally higher than those in the upstream. Compared with that in other regions, the pollution of UVAs in the waterbodies from the Guangzhou reach of the Pearl River was at a moderate to high level. UVAs were detected at higher concentrations in waterbodies near recreational sites, industrial areas, and wastewater treatment plants. The personal care additive 2-cyano-3,3-diphenyl acrylic acid-2-ethylhexyl ester （OCR） was the most dominant component in the aqueous and SPM phases, with detection frequencies of 98% and 100%, respectively, and its concentrations accounting for 50% and 60% of the sum concentrations in both phases, respectively. The risk quotients of individual UVAs in the aqueous phase from the Guangzhou reach of the Pearl River ranged from <0.1 to 1.08, indicating low to moderate risk. Three UVAs, i.e., ODPABA, OCR, and 2-（2H-benzotriazol-2-yl）-4,6-di-tert-pentylphenol （UV-328）, were the potential chemicals at risk. Moreover, it is urgent to pay attention to their long-term risk to aquatic organisms.