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随着社会形态和经济结构的变革,大量的化学合成物质释放到自然环境中,对自然环境造成了严重的污染,尤其是对生物内分泌系统、生殖系统产生不可逆影响的具有激素作用的环境内分泌干扰物(endocrine disrupting chemicals,EDCs),其也被称为外源性雌激素[1]。当前环境雌激素类物质已被确认的主要有酚类、多氯联苯类、邻苯二甲酸盐(酯)、农药(有机氯农药)和类固醇等,其中烷基酚、双酚A、多氯联苯以及二恶英等主要来源于日用品[2]。
壬基酚(nonylphenols, NP)是一种具有强干扰活性的烷基酚,同时也是最具代表性的内分泌干扰物,广泛存在于海洋、河流、地表水、大气、土壤、食品中,其在水体中含量为0.25~330 μg·L-1、大气中含量为2.2~110 ng·m-3、土壤中含量为0.01~0.98 μg·kg-1、食品中含量为0.49~110 μg·kg-1[3]。再生水中NP的来源之一是污水处理厂壬基酚聚氧乙基醚的厌氧降解产物,壬基酚聚氧乙基醚是合成洗涤剂的主要原料,广泛用于工业清洗、化纤油剂、乳液聚合、农药等工业领域[4]。作为环境激素,NP能够对激素的合成、分泌、转运、结合、生物学效应及清除产生影响,继而引起内分泌失调,改变神经、免疫和生殖发育系统等正常调控功能,对垂体、睾丸、卵巢、甲状腺等内分泌腺体及心血管、消化、神经、免疫等其他多个系统均有严重影响[5]。
NP是带有一个苯环和9碳侧链化合物的总称,工业上使用的NP的90%都是4-nNP,理论上应该有211种同分异构体,如果考虑立体异构现象,同分异构体总数将达到550种[6]。研究表明,不同的同分异构体在生物毒性、降解难易程度均有所不同,链越长,毒性越大[7],β和γ位要比α位雌激素活性大[8];在混合液和单独的异构体中,生物降解能力大小分别为NP93> NP112>NP9>NP2> NP1和NP112> NP93>> NP9>NP1> NP2[9]。
城市污水水质复杂、水量大且稳定,是一类非常规淡水资源[10]。随着污水处理工艺研究的深入,城市污水经过深度处理达到一定的回用水质标准后,可以作为“再生水”在一定范围内重复使用[11]。在北方缺水地区,越来越多的河道通过再生水补给来维持河道水环境和水生态功能。郝瑞霞等[12]基于熵值法对再生水回用河湖时壬基酚对鱼类雌激素作用进行评价,研究结果表明,壬基酚对部分鱼类的性分化危害较大,应采取相应的措施降低这种危害;顾永钢等[13]以典型再生水补给型河道为研究对象,研究河道水质变化和年际变化趋势,研究表明叶绿素a、化学需氧量是影响河道水质的主要指标;YANG等[14]以顺义潮白河段再生水受水区为研究对象,研究再生水补给河道中水质的沿程变化过程;赵立新等[15]针对再生水回用于景观水体时发生的富营养化和水华问题,探讨从物理、化学、生物以及综合措施等方式进行预防和调控。由上述研究可知,关于再生水回用河湖的研究主要集中在再生水补给河湖的环境风险、再生水补给对河湖受水水体水环境的影响、再生水补给对河湖沿程水质的影响以及再生水补给的河湖水华防治等,而对于再生水中典型内分泌干扰物NP在河道内含量及其形态的研究则较少。
关于再生水补给型河流水质评价研究,当前主要采用基于聚类分析、因子分析和相关性分析等多元统计分析方法。汪妮等[16]通过因子分析建立再生水水质评价模型评价再生水水质的变化情况,研究表明基于因子分析的水质评价模型能够获得可观合理的评价结果;王京萌等[17]基于点源污水产生的氨氮、硝氮和有机污染等水质指标,采用因子分析法识别通惠河的污染来源;王健等[18]通过系统聚类分析、因子分析对潮白河再生水受水区水质进行系统分析,研究表明基于多元统计分析的水质评价能够较好地体现水质的变化特征。由上述研究可知,因子分析是一类理论成熟、应用广泛的多元统计方法。本研究通过长期定点监测再生水补给河道水体中NP同分异构体含量,分析NP在再生水补给河道中迁移转化过程,基于因子加权法表征河道中壬基酚各同分异构体的总体情况,为评价再生水补给河道的生态风险提供科学支撑。
Analysis on the variation characteristic of endocrine disrupting chemicals nonylphenol in the reclaimed water supply river
- Received Date: 28/01/2019
- Available Online: 26/07/2019
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Key words:
- nonylphenol /
- isomers /
- reclaimed water /
- river /
- factor weighting analysis
Abstract: In this study, the content and distribution of nonylphenol isomers in the reclaimed water supply river were monitored, then the variations of nonylphenol in the river channel was analyzed and its comprehensive evaluation were conducted. This will provide scientific support for the ecological risk assessment of reclaimed water supply rivers. The results showed that there were differences in the content of NP isomers in reclaimed water. Of which NP10, NP9, NP4 and NP2 had the highest content, and NP10 content was about 6 times NP8, which had the lowest content. The content of nonylphenol isomers fluctuated greatly in the reclaimed water supply river, and nonylphenol presented a distinct degradation in the river channel, while no distinct conversion occurred among its isomers. The change of nonylphenol content in the river showed a weak correlation with the seasons and a strong correlation with the content of nonylphenol in the reclaimed water supply. The concentration of nonylphenol based on the factor weighting method could objectively characterize the harm of nonylphenol in the river channel. The comprehensive evaluation results of nonylphenol in the river section were much lower than directly geometric sum of its isomer values, the latter result inevitably exaggerated the hazards of nonylphenol in the river. The results could provide a reference for the safe reuse of reclaimed water.