巢湖和太湖微囊藻毒素差异性研究

采用固相萃取高效液相色谱法检测巢湖和太湖水体中5种微囊藻毒素(MCs)——MC-RR、MC-YR、MC-LR、MC-LA、MC-LY的含量。结果表明,巢湖水体中的MCs以MC-RR、MC-LA、MC-LY为主,太湖水体主要以MC-RR、MC-LR、MC-LA为主,其中太湖MC-LR的最高质量浓度为2.558μg/L,超过《地表水环境质量标准》(GB 3838—2002)中对集中式生活饮用水地表水源地的限定值(1μg/L)。分析巢湖和太湖水体中MCs与水质指标之间的相关性,发现同种MCs与两湖环境因子的相关性存在明显差异。逐步回归拟合结果表明,氨氮和DO分别能与巢湖MC-LR、MC-LY进行拟合;Chl-a、TOC能与太湖MC-LR回归拟合,TOC能与太湖MC-YR进行拟合。由于多数MCs不能通过水质指标的拟合结果来预测,因此在未来研究中需结合环境因子和MCs的遗传机制来共同分析MCs在水中的分布规律。     

氯灭活地下水源中3种优势真菌的效能与机制

地下水源中真菌大量繁殖会产生嗅味,引发毒性反应以及产生大量肉眼可见的絮状物,严重影响供水水质.以地下水源中3种优势真菌木霉属、青霉属、枝孢属为研究对象,以氯为消毒剂,通过研究真菌孢子胞内物质泄漏,胞外三磷酸腺苷(ATP),脱氧核糖核酸(DNA)和蛋白质增加及孢子形态变化,探明了氯灭活3种真菌孢子的效能与机制.结果表明,氯灭活真菌孢子符合一级动力学,满足Chick模型,3种真菌的耐氯性为:木霉属青霉属枝孢属,真菌孢子尺寸越大,亲水性越强,灭活效果越好.氯灭活后,胞内物质泄漏,胞外特征物质(ATP、DNA、蛋白质)显著增加;氯对细胞表面破坏严重,灭活后真菌孢子凹陷,表面褶皱.综上所述,氯首先作用于孢子表面,降低孢子的可培养性,进一步作用使细胞的通透性屏障受损,导致胞内特征物质释放,以致孢子死亡.     

基于Monte Carlo模拟法对水源水体中微囊藻毒素的健康风险评估

调查水源水体中微囊藻毒素MCs(MC-RR、MC-LR和MC-YR)的污染情况,结合调查情况应用蒙特卡洛法(Monte Carlo)模拟量化人群通过饮水途径摄入微囊藻毒素的风险.在珠江西航道沿线设置5个采样点,在2016年1~6月期间共采集90份水样,根据国标(GB/T 20466-2006)推荐的HPLC方法检测水体中的微囊藻毒素,运用专业风险评估软件@Risk7.0,构建非参数概率评估模型,对通过饮水途径摄入微囊藻毒素(暴露)风险进行概率评估.对随机采集90份水源水体中微囊藻毒素MCs质量浓度检测值进行分布拟合,并运用Chi-Squared、Anderson-Darling、Kolmogorov-Smirnov这3种统计方法进行拟合度检验,根据3种评估拟合结果,确定最佳拟合分布模型.结果表明,在检测的90个水样品中,MC-RR的检出率最高,达到51.11%,质量浓度范围为0.001 7~0.386 3μg·L~(-1);其次为MC-LR和MC-YR,检出率分别是47.78%和21.11%,质量浓度范围分别是0.028 5~0.279 6μg·L~(-1)和0.003 0~0.136 2μg·L~(-1),水源水体中3种微囊藻毒素以MC-RR为主,最大检出质量浓度为0.386 3μg·L~(-1),MC-YR的含量最低.采用软件@Risk7.0分布拟合结果显示,MC-LR质量浓度最适的拟合分布为Ext Value Min模型(0.113 91,0.098 462),MC-RR质量浓度最适的拟合分布为Logistic(0.058 064,0.053 044).健康风险评估表明,MC-LR对人体健康危害的风险高于MC-RR的风险,儿童比成人更易于受到MCs污染的威胁.MC-LR对儿童健康危害的致癌年风险数值大于美国环保署(USEPA)推荐的最大可接受风险水平1×10-4;MC-LR对成人的致癌暴露年风险数值大于国际辐射防护委员会(ICRP)推荐的最大可接受风险水平5×10-5,表明水源水体中的MCs对人体健康存在潜在的危害,有必要加强饮用水源水体的保护与监控,为有效控制水源地水质污染和更好地保障人民健康奠定基础.     

微囊藻毒素对水稻根系生长和抗氧化系统的影响

以水稻幼苗为材料,研究了不同质量浓度(1、100、1 000、3 000μg·L-1)微囊藻毒素(MCs)在胁迫期和恢复期对水稻幼苗根系生长、吸收活力、抗氧化系统的影响以及MCs在水稻根部的积累.结果表明,胁迫处理7 d,MCs在水稻根部的积累量与MCs质量浓度呈正相关.1μg·L-1MCs处理促进了根系生长,根系活力上升,过氧化氢酶(CAT)活性上升有效维持H2O2于正常水平;100μg·L-1MCs处理下,根系生长受抑,根系活力下降,CAT无显著变化;在高质量浓度(1 000μg·L-1、3 000μg·L-1)MCs处理下,不仅根系生长受抑、根系活力下降,且CAT活性受抑,H2O2大量积累,膜质过氧化加剧.相比胁迫期,恢复7 d后各处理组水稻根系MCs的积累量均低于胁迫期.100μg·L-1MCs处理组根系各生长指标、根系活力、丙二醛(MDA)、H2O2和CAT的变幅减小,优于胁迫期,显示出一定程度的恢复,而1 000μg·L-1和3 000μg·L-1MCs处理组,根系生长与根系活力均低于胁迫期,氧化胁迫进一步加剧,表明高质量浓度(1 000μg·L-1和3 000μg·L-1)MCs对水稻根系造成的伤害不可逆.     

Factors Influencing Prymnesium parvum Population Dynamics During Bloom Initiation: Results from In-lake Mesocosm Experiments1

Roelke, Daniel L., Leslie Schwierzke, Bryan W. Brooks, James P. Grover, Reagan M. Errera, Theodore W. Valenti, Jr., and James L. Pinckney, 2010. Factors Influencing Prymnesium parvum Population Dynamics During Bloom Initiation: Results from In-Lake Mesocosm Experiments. Journal of the American Water Resources Association (JAWRA) 46(1):76-91. DOI: 10.1111/j.1752-1688.2009.00392.x Abstract: The alga Prymnesium parvum forms large fish-killing blooms in many Texas lakes. In some of these lakes, however, P. parvum occurs but does not develop blooms. In this study, we investigated factors that may influence bloom initiation by conducting a series of in-lake experiments involving mixing of waters from Lake Whitney, which has a history of P. parvum blooms, with waters from Lake Waco where no blooms have occurred. In all experiments, the addition of Lake Waco waters resulted in a poorer performance of P. parvum. Various experimental treatments and field data show that differences in grazing, pathogens, nutrients, and salts between the two lakes were not likely factors that contributed to this observation. Industrial and agricultural contaminants, allelochemicals and algicidal chemicals were not measured as a part of this research. However, anthropogenic contaminants other than nutrients were not observed at levels exceeding water quality standards in Lake Waco in recent years. On the other hand, nuisance cyanobacteria are common in Lake Waco, where Microcystis sp. and Anabaena sp. were abundant during the initiation of our experiments, both taxa are known to produce chemicals with allelopathic properties. In addition, the emergent field of algal-heterotrophic bacteria interactions suggests that chemicals produced by heterotrophic bacteria should not be overlooked. Further research focusing on the chemical interactions between cyanobacteria and P. parvum, as well as the potential role of algicidal bacteria, in the initiation of P. parvum blooms is necessary, as it may be important to the management of these blooms.     

Identification of microcystins from three collection strains of Microcystis aeruginosa

Microcystins (MCs) are toxic cyclic heptapeptides produced by various cyanobacteria genera, especially Microcystis. We identified 10 out of 12 MCs produced by three Microcystis aeruginosa strains from cyanobacteria collections, UTEX 2666, UTEX 2670 and UAM 1303, by using two analytical methods: Matrix-assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF/MS) and HPLC Photodiode Array Detector coupled to a hybrid Quadrupole Time of Flight Mass Spectrometry (HPLC-PDA-QTOF/MS). MALDI-TOF/MS failed to detect non-polar MCs, such as MC-LY and MC-LW. HPLC-QTOF/MS permitted the accurate identification of most MCs present in methanolic extracts. Besides, three new MCs, namely: [D-Glu(OCH₃)⁶, D-Asp³] MC-LAba, MC-YL and MC-YM were detected by HPLC-QTOF/MS.     

不同填料载体生物膜对微囊藻毒素的去除效果

利用自行设计的生物膜培养装置,通过对4种不同填料载体进行连续曝气循环培养生物膜,对湖水中的溶解态微囊藻毒素(MCs)的去除作用进行了研究。结果表明,填料载体上生物膜从形成到稳定大约需要3周;生物膜形成后对MCs的去除效率由高到低的顺序是:颗粒活性炭柱>多密孔球型滤料柱>塑料悬浮填料柱>陶瓷滤球柱。在实验水质条件下,当水力停留时间(HRT)=5 h,进水MCs浓度为21.5～47.25μg/L时,颗粒活性炭、多密孔球型滤料柱对MCs的去除率最高可达100%,塑料悬浮填料柱对MC-LR和MC-RR的去除率分别为70%和88%。当HRT=2.5 h时,塑料悬浮填料柱对MC-RR的去除率为MC-LR的2倍。生物膜对MCs的降解效果随温度(5～20℃)和溶解氧的升高而增加。塑料悬浮填料作为合适的生物膜挂膜填料载体对水源水的生物预处理具有良好的应用前景。     

聚糖菌颗粒污泥基于胞内储存物质的同步硝化反硝化

采用特殊运行方式的厌氧-好氧SBR系统(厌氧后排水),以乙酸钠为有机基质成功富集了聚糖菌颗粒污泥.聚糖菌颗粒污泥厌氧-好氧批式实验表明,聚糖菌颗粒污泥具有较强的SND能力,TOC/N分别为5.0,4.0,2.8时,SND效率分别96.4%、95.3%及96.2%,而周期总氮去除效率随着碳氮比降低而降低,分别为66.0%、61.2%及56.3%.通过对周期氨氮、亚硝酸盐氮、硝酸盐氮、TOC以及胞内糖原、PHB变化的测定分析,证明聚糖菌颗粒污泥SND过程中,污泥以厌氧阶段储存于胞内的多聚物PHB作为反硝化碳源,并且反硝化聚糖菌是系统中反硝化能力的来源.与溶解性基质相比,PHB的降解速率相对较低,因此在SND过程中,反硝化可以与硝化保持相近的速率,从而有助于获得良好的SND效果.     

藻毒素复合污染对鱼体的免疫毒性研究

针对水体富营养化问题,通过单一暴露和联合暴露方式研究两种MCs四种暴露剂量（0．1,1,10,100μg／L）下对鱼体的免疫毒效应。结果发现,不同剂量MCLR和MCRR单一暴露都能使鲫鱼淋巴细胞发生死亡,呈现明显的剂量效应和时间效应关系。且MCLR对鱼体的毒性相对McRR要更显著;MCLR和McRR复合暴露对鱼体淋巴细胞的毒性效应表现为协同作用,且随着毒素浓度的增加,其毒性效应差异显著性也随之升高,故而鱼体的免疫系统造成重大的影响,因此应当加强控制藻毒素在水体中的复合污染。     

降解微囊藻毒素菌种的筛选和活性研究

研究了滇池底泥和表层水体中的微生物菌群降解微囊藻毒素(Microcystins, MCs)的能力差异,发现底泥中的微生物菌群对MCs有更强的生物降解能力.采用从滇池水华蓝藻细胞中提取提纯的微囊藻毒素作为微生物生长的唯一碳源和氮源,先后经过液体和固体培养基培养后,通过挑取单克隆菌落,分别从底泥中筛选出了能够降解MC-RR和LR的5种不同微生物菌种.其中筛选的菌种D降解MCs的能力最强,在3 d内可将初始浓度分别为60.1 mg·L^-1和38.7 mg·L^-1的MC-RR和LR全部降解,日均降解MC-RR和LR的速率分别高达20.0 mg·L^-1和12.9 mg·L^-1.