城市水环境PFAAs前驱体污染特征及健康风险

为揭示城市水环境中前驱体对全氟烷基酸（PFAAs）输入特征、分布格局及健康风险的影响，对南京城市污水处理厂出水、河流、湖泊、长江饮用水源地等水体进行了考察.利用HPLC-MS/MS及总可氧化前驱体法（TOP Assay）分析了17种PFAAs与其总可氧化前驱体的污染特征，并通过推演耐受剂量评估了饮水途径的健康风险商（HQ）.结果表明，污水处理厂出水中PFAAs浓度90.6~278ng/L，主要单体PFBS、PFHxA、PFOA占总浓度的63%；总可氧化前驱体浓度239~839pmol/L，PFBA前驱体含量最高.城市地表水中PFAAs浓度61.8~157ng/L，总可氧化前驱体浓度195~572pmol/L，PFBA、PFPeA、PFHxA 3种全氟羧酸的前驱体含量最高，城市河流流经人口密集区后，PFAAs赋存浓度有所上升，但总可氧化前驱体浓度下降.饮用水源地中PFAAs浓度50.9~54.6ng/L，总可氧化前驱体浓度273~372pmol/L，以PFBA、PFPeA和PFHxA 3种全氟羧酸的前驱体为主.相对高风险来源于PFOS的免疫毒性（HQ=0.024）以及PFOA的发育毒性（HQ=0.0073）和生殖毒性（HQ=0.0039），可氧化前驱体转化可能将二者潜在风险提高23%和40%.水环境中广泛赋存的前驱体可能增加PFAAs的环境暴露及健康风险.

Contamination and health risk of precursors of PFAAs in urban aquatic environment

In order to characterize the input, distribution and health risk of precursors of perfluoroalkyl acids (PFAAs) in the urban aquatic environment, the effluents of wastewater treatment plants, rivers, lakes and drinking water sources in the Yangtze River in Nanjing were investigated. HPLC-MS/MS and the total oxidizable precursor assay (TOP Assay) were used to analyze 17PFAAs and their total oxidizable precursors. Their health risk quotient (HQ) was assessed based on the tolerable dose interpretation. The results suggested in the effluents PFAAs concentration was 90.6~278ng/L, and the dominant homologues PFBS, PFHxA, PFOA accounted for 63%. The total oxidizable precursors concentration was 239~839pmol/L, and PFBA predominated among the precursors. PFAAs concentration in urban surface water was 61.8~157ng/L, and the concentration of total oxidizable precursors was 195~572pmol/L. PFBA, PFPeA and PFHxA displayed the highest concentration of precursors. PFAAs level in the urban rivers increased while oxidizable precursors level decreased. PFAAs concentration in drinking water sources was 50.9~54.6ng/L, and the total oxidizable precursors concentration was 273~372pmol/L, predominated by the precursor of PFBA, PFPeA and PFHxA. The relatively high risk was immunotoxicity from PFOS (HQ=0.024) and developmental toxicity (HQ=0.0073) and reproductive toxicity (HQ=0.0039) from PFOA. Transformation of oxidizable precursors could increase their potential risk by 23% and 40%. The widespread presence of precursors in aquatic environments may increase the environmental exposure and health risks of PFAAs.