N-亚硝胺是一类具有高致癌性和致突变性的含氮有机污染物。在我国中小城镇的主要饮用水水源地,N-亚硝胺的污染水平尚不清楚。此外,关于支流河流中N-亚硝胺及其前体浓度的研究仍然缺乏。在这项研究中,研究了清江中的8种N-亚硝胺及其形成潜力(FPs),这是长江的主要支流。还对污水排放点进行了监测,和环境影响因素,N-亚硝胺引起的致癌和生态风险,并对其前体进行了评估。结果表明,清江水样中检测出6种N-亚硝胺,其中NDMA[(10±15)ng·L-1],NDEA[(9.3±9.3)ng·L-1],NDBA[(14±7.8)ng·L-1]为优势N-亚硝胺,而在氯化水样中检测到7种N-亚硝胺,其中NDMA-FP[(46±21)ng·L-1],NDEA-FP[(26±8.3)ng·L-1],以NDBA-FP[(22±13)ng·L-1]为主的N-亚硝胺FPs。清江中游的N-亚硝胺浓度高于上游和下游。此外,污水排放和支流采样点的N-亚硝胺浓度明显高于其他采样点。在污水直接排放点的监测结果表明,河水中N-亚硝胺的主要来源是含有N-亚硝胺及其前体的污水。此外,包括NDMA在内的三种主要N-亚硝胺的浓度,NDBA,与NDEA呈正相关,主要是因为它们的污水来源相似。饮用水源中的N-亚硝胺对居民的平均致癌风险为2.4×10-5,表明存在潜在的致癌风险。此外,由于清江中高浓度的N-亚硝胺形成潜力,饮用水的致癌风险可能更高。生态风险评价表明,清江流域N-亚硝胺的生态风险商值均低于0.002,可忽略不计。
N-
nitrosamines are a type of nitrogen-containing organic pollutant with high carcinogenicity and mutagenicity. In the main drinking water sources of small and medium-sized towns in
China, the contamination levels of N-
nitrosamines remain unclear. In addition, there is still lack of research on the concentration of N-
nitrosamines and their precursors in tributary rivers. In this study, eight N-nitrosamines and their formation potentials (FPs) were investigated in the Qingjiang River, which is a primary tributary of the Yangtze River. The sewage discharge sites were also monitored, and the environmental influencing factors, carcinogenic and ecological risks caused by N-nitrosamines, and their precursors were evaluated. The results showed that six N-nitrosamines were detected in water samples of the Qingjiang River, among which NDMA [(10 ±15) ng·L-1], NDEA [(9.3 ±9.3) ng·L-1], and NDBA [(14 ±7.8) ng·L-1] were the dominant N-nitrosamines, whereas seven N-nitrosamines were detected in chloraminated water samples, among which NDMA-FP [(46 ±21) ng·L-1], NDEA-FP [(26 ±8.3) ng·L-1], and NDBA-FP [(22 ±13) ng·L-1] were the dominant N-nitrosamine FPs. The concentrations of N-nitrosamines in the middle reaches of the Qingjiang River were higher than those in the upper and lower reaches. Furthermore, the concentrations of N-nitrosamines in the sample sites of sewage discharge and tributaries were significantly higher than those in other sampling sites. The monitoring results at the direct sewage discharge points indicated that the main source of N-nitrosamines in river water was the sewage carrying N-
nitrosamines and their precursors. In addition, the concentrations of the three dominant N-nitrosamines including NDMA, NDBA, and NDEA were positively correlated with each other, mainly because of their similar sewage sources. The average carcinogenic risk to residents due to N-nitrosamine in drinking water sources was 2.4×10-5, indicating a potential carcinogenic risk. Moreover, due to the high concentrations of N-nitrosamine formation potentials in the Qingjiang River, the carcinogenic risk of drinking water may be even higher. The ecological risk assessment showed that the ecological risk quotient values of N-nitrosamines in the Qingjiang River watershed were lower than 0.002, which was negligible.