预氧化对混凝-气浮工艺去除铜绿微囊藻效果的影响

研究了预氧化(高锰酸钾、氯、过氧化氢)对混凝-溶气气浮工艺去除铜绿微囊藻的影响.通过检测出水浊度、藻类浓度以及UV254等指标来评价预氧化对藻类的去除效果.试验结果表明:在氧化剂最佳投量下,经过KMnO4、Cl2和H2O2预氧化后,藻类去除率分别提高了10.81%、11.65%以及9%,其中以氯对藻类去除效果最好,但预氯化过程中引起了藻细胞的破裂使得胞内有机物释放到水中,造成出水中UV254的升高.几种氧化剂对比研究结果表明,采用高锰酸钾预氧化不仅能够节约经济费用,而且不会因藻体内有机物的大量外流而降低出水水质的安全性.     

铜绿微囊藻越冬孢子萌发研究

通过对南湖水体铜绿微囊藻越冬孢子萌发的研究:当营养条件和其它环境条件充分时,温度可以刺激藻类越冬孢子的萌发。孢子萌发规律随温度变化而变化。     

核桃壳对铜绿微囊藻的抑制作用研究

在实验室条件下,以南太湖水华蓝藻铜绿微囊藻为材料,研究了核桃壳对铜绿微囊藻生长的抑制作用。研究结果表明,高温高压灭菌的核桃壳对铜绿微囊藻生长的抑制效果最为明显,0.1%和0.5%高压灭菌核桃壳能有效抑制铜绿微囊藻的生长;在BG-11培养基中添加0.5%和1%的核桃壳提取液后,铜绿微囊藻的生长也被明显抑制;经过次氯酸钙消毒后的新鲜核桃壳对铜绿微囊藻的生长无抑制作用。     

壳聚糖-沸石复合体对铜绿微囊藻的去除效果

研究壳聚糖、沸石单独絮凝除藻以及壳聚糖沸石复合体对铜绿微囊藻去除效果。结果表明：单独使用壳聚糖,质量浓度在0.6～1.1 mg/L时,对铜绿微囊藻的去除率超过90％;单独使用沸石,沸石质量浓度小于500 mg/L时,对铜绿微囊藻的去除率低于40％。经壳聚糖包覆改性后,壳聚糖沸石复合体对铜绿微囊藻絮凝去除能力大幅提高。当壳聚糖质量浓度为0.5 mg/L,沸石质量浓度为6～14 mg/L时,壳聚糖沸石复合体对铜绿微囊藻的去除率达90％以上。壳聚糖沸石复合体适用的pH值范围在5～7之间。     

铜绿微囊藻初始接种量对藻类生长的影响探讨

以铜绿微囊藻为供试藻种进行实验室培养试验,结果表明,蓝藻生长经过延滞期、对数期到稳定期直至衰退期,持续时间很长,符合野外湖库水华的特征;不同接种量对水华产生的影响不大,接种量越小暴发水华的时间相对越短.水华发生机制复杂,充分利用冬季光照强度弱、温度低以及控制碳的供给是防止水华暴发的较好措施.     

丙二酸对铜绿微囊藻的抑制效果

为研究丙二酸对铜绿微囊藻的抑制效果,测定了不同浓度和不同投加方式的丙二酸作用下铜绿微囊藻藻细胞密度和叶绿素a质量浓度的变化;在此基础上,通过丙二酸添加后藻细胞藻胆蛋白含量及超微结构的变化,分析了丙二酸的抑藻机理.结果表明:丙二酸对铜绿微囊藻有较强的抑制效果;当丙二酸质量浓度达到60mg/L时,在试验末期即第12天时对铜...     

淡水藻类生长的环境影响因子分析——以铜绿微囊藻为例

淡水藻类的快速生长易导致水体“水华”.藻类生长受其自身生理特征和外界环境因子共同作用.选取“水华”爆发常见的藻种——铜绿微囊藻为研究对象,通过总结国内外相关实验以及理论研究成果,分析环境因子包括氮、磷营养盐(浓度、形态及氮磷比)、光照(强度和周期)、温度、pH、盐度及水力扰动对其生长的影响.基于上述讨论分析总结藻类生长的适宜环境条件,提出抑制藻类“水华”的必要控制措施和相关技术构想.     

铁在不同磷源条件下对铜绿微囊藻生长与产毒的影响

针对磷和微量元素铁对藻类生长的共同作用,研究不同磷源下藻细胞生长与产毒过程中磷与铁的共同作用特性。试验选用产毒铜绿微囊藻为藻种,以硝态氮为氮源,分别以磷酸氢二钾(K_2HPO_4)、小分子有机磷甘油磷酸钠(Na Gly)和大分子有机磷卵磷脂(LEC)为磷源,同步考察不同铁离子(Fe~(3+))浓度下藻类的生长与产毒表现。结果表明:K_2HPO_4和NaGly是藻细胞优先利用的磷源,在这两种磷源条件下,藻细胞的生长与产毒均得到促进,藻细胞平均粒径随培养时间保持稳定; LEC不利于藻细胞的生长与产毒,且藻细胞平均粒径波动较大。在对数增长期中,叶绿素a与胞内藻毒素(MC-LR)呈现正相关关系,在培养过程中藻细胞胞内总磷与藻液中总的碱性磷酸酶活性并未显现出相关性。不同磷源下微量元素铁对藻细胞的生长状况影响不同,NaGly与铁的协同作用更有利于藻细胞的生长与产毒。     

穗花狐尾藻种植水对铜绿微囊藻的影响

为了探究营养水平对沉水植物化感抑藻作用的影响,选取室外条件下自然繁殖生长的沉水植物穗花狐尾藻(Myriophyllum spicatum)种植水,研究有害蓝藻铜绿微囊藻(Microcystis aeruginosa)产毒株和非产毒株在两种营养水平下对穗花狐尾藻种植水的生长生理响应。结果表明:穗花狐尾藻种植水显著抑制产毒株和非产毒株的生长(P<0.05),影响生理过程,但低营养水平下的抑制作用更强(P<0.05);营养加富穗花狐尾藻种植水暴露9 d后,对产毒株和非产毒株生长的抑制率分别为23.5%和20.9%,对光合系统Ⅱ实际光合效能的抑制率分别为7.4%和17.6%,丙二醛浓度分别增大5.6%和9.1%;而直接将铜绿微囊藻接种到穗花狐尾藻原种植水中,对产毒株和非产毒株生长的抑制率分别为60.7%和49.3%,对光合系统Ⅱ实际光合效能的抑制率分别为15.4%和23.4%,丙二醛浓度分别增大11.1%和18.2%。     

壳聚糖和聚丙烯酰胺复合对铜绿微囊藻去除效果的研究

利用室内模拟实验,以壳聚糖(Chitosan)和聚丙烯酰胺(PAM)为絮凝剂,采用絮凝法去除铜绿微囊藻。系统研究了壳聚糖和聚丙烯酰胺投加量、p H值以及沉淀时间等因素对絮凝效果的影响。并利用响应面法对铜绿微囊藻絮凝进行优化。根据统计模型发现投加量、p H值、沉淀时间均对铜绿微囊藻的絮凝效果有显著影响。通过响应面法优化得到铜绿微囊藻絮凝的条件在温度为27℃下,壳聚糖的投加量为3.59 g/L,聚丙烯酰胺的最佳投加量为0.26 g/L,沉淀时间为13 min,p H为8.02。在上述的最优条件下,铜绿微囊藻的去除率为98.03%,与模型预测值98.01%相近,表明采用响应面法对铜绿微囊藻絮凝沉淀条件进行优化是合理可行的。     

于桥水库铜绿微囊藻上浮运动规律及其控制

对天津于桥水库中铜绿微囊藻竖向分布及其上浮速度进行了测定,在大约3倍透明度水深处藻类数量最多,向上或向下,藻类数量均减小.在无光条件下,上浮速度≤1 cm/min的铜绿微囊藻占77%,上浮速度1～1.5 cm/min的藻类占10%,上浮速度1.5～2 cm/min的藻类占6%,还有7%的铜绿微囊藻上浮速度大于2 cm/min.当向下的流速达到1.65 cm/min时,基本能阻止铜绿微囊藻的上浮.竖向水力混合能将表层藻类输送到下层,从而抑制藻类的生长.     

Algicidal effect of bacterial isolates of Pedobacter sp. against cyanobacterium Microcystis aeruginosa

The aim of this study was to isolate algicidal bacteria so as to control harmful cyanobacterium Microcystis aeruginosa (M.aeruginosa) blooms using biological methods. Nine bacterial strains were isolated to inhibit the growth of M. aeruginosa, among which the MaI11-5 bacterial strain exhibited remarkable algicidal activity against M. aeruginosa cells during the test. Based on the 16S rDNA analysis, the isolated MaI11-5 was identified as Pedobacter sp. through morphology and homology research. The results of cocultivation of the cyanobacteria with MaI11-5 algicidal isolates showed obvious algicidal activity against cyanobacterial cells. The algicidal effect of MaI11-5 exceeded 50% after two days, exceeded 70% after four days, and reached 80% after seven days. The observation results with a scanning electron microscope showed that the cyanobacterial cells aggregated and produced mucous-like substances when cocultivated with the algicidal bacteria. The results indicated that the MaI11-5 bacterial strain may possess a novel function for controlling harmful blooms and further studies will provide new insights into its role in water environment.     

Effect of fluid motion on colony formation in Microcystis aeruginosa

Microcystis aeruginosa, generally occurring in large colonies under natural conditions, mainly exists as single cells in laboratory cultures. The mechanisms involved in colony formation in Microcystis aeruginosa and their roles in algal blooms remain unknown. In this study, based on previous research findings that fluid motion may stimulate the colony formation in green algae, culture experiments were conducted under axenic conditions in a circular water chamber where the flow rate, temperature, light, and nutrients were controlled. The number of cells of Microcystis aeruginosa, the number of cells per colony, and the colonial characteristics in various growth phases were observed and measured. The results indicated that the colony formation in Microcystis aeruginosa, which was not observed under stagnant conditions, was evident when there was fluid motion, with the number of cells per largest colony reaching 120 and the proportion of the number of cells in colonial form to the total number of cells and the mean number of cells per colony reaching their peak values at a flow rate of 35 cm/s. Based on the analysis of colony formation process, fluid motion stimulates the colony formation in Microcystis aeruginosa in the lag growth phase, while flushes and disaggregates the colonies in the exponential growth phase. The stimulation effect in the lag growth phase may be attributable to the involvement of fluid motion in a series of physiological processes, including the uptake of trace elements and the synthesis and secretion of polysaccharides. In addition, the experimental groups exhibiting typical colonial characteristics in the lag growth phase were found to have higher cell biomass in the later phase.     

Initial report on identification and toxicity of Microcystis in King Talal Reservoir, Jordan

The cyanobacteria Microcystis aeruginosa forms extensive summer blooms in the King Talal Reservoir, the largest water body in Jordan. The occurrence of the blooms is a function of the water temperature, light intensity and nutrient concentration, with the nitrogen and phosphorus levels being critical factors. This initial study indicated that the time of the seasonal maximum and intensity of Microcystis blooms in the King Talal Reservoir vary significantly from month to month, with a peak reached in summer. The low nutrient concentrations were observed prior to the summer season. There was a rapid, extensive proliferation of M. aeruginosa during the summer of the same year, especially from 1–30 June to 30 November. The LD₅₀ of microcystin in Balb/c was found to be 50 µL kg^?1. Additional studies will provide further information on various aspects of the identification and toxicity of the selected cyanobacterial species.     

三峡水库泥沙絮凝特征及影响因素分析

以三峡水库奉节河段和庙河河段的现场取样资料为基础,通过现场测量和室内实验分析,发现819个现场取样点中,99.4%的测点存在泥沙絮凝现象,其中83.6%的泥沙絮团直径约为单颗粒直径的3~8倍,表明在条件适合的情况下三峡水库泥沙絮凝具有普遍性,絮凝的临界粒径为0.02 mm。从库区泥沙絮凝的分布来看,主要集中在中上层水体中,并且顺水流方向呈现衰减的趋势,庙河河段的絮凝度明显小于奉节河段。库区泥沙絮凝的临界流速为0.7 m/s,流速小于0.7 m/s有利于泥沙絮凝的形成,但由于库区泥沙颗粒间的相对动能较小,泥沙絮凝难以形成稳定的大絮团,主要表现为弱絮凝。     

长江流域水系连通特征及其影响因素分析

水系的连通性是河流健康评价的一个重要指标,它影响到河道生态需水量、通航水深、湿地保留率等。在健康长江评价体系的14个指标中,水系的连通性作为一个重要指标被首次提出。通过对水系连通性基本概念的探讨,归纳了长江水系连通的基本类型,包括河流与河流连通、河流纵向连通和河湖连通3类;分析了长江流域水系连通基本特征和影响水系连通的原因。从地质历史时期及人类历史时期的时间尺度看,新构造运动、气候变化等自然因素在水系连通的阻碍方面是主导因子,但从100~10 a和年时间尺度上看,特别是近百年来,人类活动对水系的连通在很多地方起着决定性的作用。     

Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anova s demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L^?1 PO₄. A pilot study was then conducted to test the effectiveness of the Blue Pro? water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.