[Pollution Characteristics and Ecological Risk Assessment of Biocides in Surface Water of Guangdong Province]

Biocides are commonly used additives in personal care products， agriculture， and industry， and when discharged into aquatic environments， they pose potential risks to aquatic organisms. To investigate the pollution status and ecological risks of biocides in Guangdong Province， surface water samples were collected from 21 cities， and 17 target biocides were analyzed using solid-phase extraction combined with ultra-high-performance liquid chromatography-mass spectrometry. The results indicated that the concentrations of biocides in Guangdong's surface waters ranged from 1.17 to 1 619 ng·L^-1. Carbendazim and DEET had detection rates of 100%， with maximum concentrations of 207 ng·L^-1 and 150 ng·L^-1， respectively. Biocides such as methylparaben， ethylparaben， propylparaben， triclosan， climbazole， icaridin， and 1，2-benzisothiazolin-3-one （BIT） showed significant seasonal concentration differences， with higher levels in the wet season， while others exhibited no clear seasonal trends. Regionally， biocide pollution was higher in certain areas of the Pearl River Delta than in other cities. Ecological risk assessments using the risk quotient （RQ） method identified biocides such as triclocarban， carbendazim， climbazole， and 4，5-dichloro-2-octylisothiazolinone as posing ecological risks， especially in two sections of the Pearl River Delta， where risks were elevated during the wet season. Triclosan and 4，5-dichloro-2-octylisothiazolin-3-one， identified through RQ values and Toxicological Priority Index （ToxPi） scores， emerged as key persistent biocide pollutants in Guangdong's surface waters. These findings provide essential data for managing biocidal pollution risks in Guangdong Province.