雌二醇 [湖泊沉积物对17β-雌二醇的降解效能]

　　摘 要：沿湖泊沉积物垂直高度取表层（SL，0～2 cm）、中层（ML，14～16 cm）、底层（BL，28～30 cm）3层底泥微生物为对象，研究了湖泊沉积物对17β雌二醇（17βestradiol, E2）的生物降解效能。 结果表明：无论在好氧还是厌氧条件下，E2及其副产物雌激素酮（estrone, E1）的降解行为与沉积物沉积深度和环境温度有密切关系：底泥沉积深度愈深，E2降解速率愈低；在微生物活性温度范围内，环境温度愈高，E2降解速率愈高。好氧条件下，湖泊沉积物中E2降解反应的k值为0.002～0.120 h-1?g-1?L；厌氧条件下，k值为0.002～0.057 h-1?g-1?L。由于诱导驯化及有机物竞争关系减小等原因，向反应体系中再次添加E2后，其k值增大约34%。 湖泊沉积物中硝化细菌的存在对E2降解具有促进作用。
　　关键词：湖泊；沉积物；17β雌二醇；生物降解；降解速率
　　中图分类号：X703.1
　　文献标志码：A
　　文章编号：1674-4764（2012）04-0125-06
　　Efficiency of Biodegradation of 17β-Estradiol by Lake Sediment
　　HE Fang1，LI Fusheng2，AKIRA Yuasa2，WANG Liguo1
　　(1. College of Resources and Environment, University of Jinan, Jinan 250022, P. R. China;
　　2. River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan)
　　Abstract:Batch experiments using sediment mud liquors spiked with 17β-estradiol (E2) were performed. The sediment mud liquors were prepared from the sliced surface (SL, 0～2 cm), middle (ML, 14～16 cm) and bottom (BL, 28～30 cm) layers of sediment cores collected in a lake, respectively. By measuring the concentration profiles of E2 and its biotransformation compound, estrone (E1), the great dependency of E2’s degradation behavior upon the vertical position of the sediment and temperature was clearly demonstrated under both aerobic and anaerobic conditions: the degradation rate decreased with the increase of sediment depth and increased with higher temperature. In addition, by assuming a first-order rate reaction, the disappearance rate constant (k) of E2 under the aerobic condition was estimated to in the range of 0002～0.120 h-1?g-1?L, while under the anaerobic condition in the range of 0.002～0.057 h-1?g-1?L. Because of microorganism domestication and competition reduction of organic compounds, k was increased by about 34% after re-spiking E2. The addition of ammonia to the experiment under aerobic condition seemed to be responsible for promoting disappearance of E2 from solutions.
　　Key words:lake; sediment; 17β-estradiol; biodegradation; degradation rate
　　
　　在诸多天然类固醇雌激素中，17β-雌二醇(E2)被认为是最具潜在影响、作用最强烈且在水环境中普遍存在的一种，其质量浓度低至ng/L级时仍对水生生物繁殖、生态安全乃至人类健康造成极大的潜在威胁［1-2］。生活污水是水环境中E2的重要来源，污水处理厂进水中E2的质量浓度达到13.9～136 ng/L［3-4］，由于不同活性污泥处理工艺和使用年限、曝气池中菌密度、操作方式和运行条件的不同，E2在出水中的浓度差别很大，对受纳水体造成极大的安全隐患［5-8］。但目前关于河流、湖泊等天然受纳水体中E2的研究却鲜有报道［9-10］；且由于E2具有一定的脂溶性特征［11］，易在水体沉积物中蓄积，沉积物中富含硝化菌、反硝化菌、硫酸盐还原菌、甲烷菌等微生物［12］会与E2发生物理的、化学的和生物的相互作用，其作用结果对天然水体水质自然净化起着决定性的作用。
　　以日本境内某湖泊为研究对象，该湖泊兼具饮用、灌溉水源、水产水运、开展旅游和改善生态环境等多种功能，具有非常重要的代表性。以该湖泊沉积物中微生物为菌源，探讨温度、DO、底泥沉积深度等环境因子对E2降解过程的影响，旨在完善现有各污水处理厂的操作、运行工艺参数及实际工程应用于E2污染水体治理，有效提高E2的去除效率。