铜绿微囊藻的混凝特性与影响因素研究

以实验室纯培养的铜绿微囊藻为试验材料,用烧杯试验调查铜绿微囊藻的混凝特性。结果显示聚氯化铝(PAC)混凝铜绿微囊藻的效果较好。PAC对水样中铜绿微囊藻的混凝效果与藻的生长期、藻细胞胞外分泌物、温度、pH等有密切关系:铜绿微囊藻处于稳定期以及中性到弱碱性的pH范围有利于PAC混凝;温度对PAC混凝的影响与生长期有关,24-26℃对稳定期藻类的混凝沉淀最有利,对数期和衰亡期藻类需要较高的混凝温度(28-30℃);各个生长期铜绿微囊藻的胞外分泌物均有助于PAC的混凝沉降。天然水体中这些因素的耦合作用使得混凝工艺单元有效控制藻类变得困难。控制某一个或几个因素可以改善铜绿微囊藻混凝效果,其中以调节进水pH最为方便。     

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%。     

不同密度铜锈环棱螺对沉水植物生长和水质的影响EI北大核心CSCD

通过试验研究不同密度铜锈环棱螺(Bellamya aeruginosa)对苦草(Vallisneria natans)和金鱼藻(Ceratophyllum demersum)生长及水质的影响。试验结果表明:铜锈环棱螺的存在显著促进了沉水植物的生长,高密度组苦草和金鱼藻的相对生长率分别是对照组的2.16和1.66倍,高密度组苦草和金鱼藻的相对伸长率分别是对照组的1.18和1.25倍;铜锈环棱螺的存在对水质有一定负面影响,水体电导率随着螺密度的增加而升高,溶解氧浓度随着螺密度的增加而降低,pH值、氧化还原电位和叶绿素浓度随着螺密度的增加没有一致的规律;水体氮的去除率随螺密度的增加呈下降趋势,高密度组苦草和金鱼藻对氮的去除率相对于对照组分别下降了70.0%和64.5%,磷的去除率组间没有显著差异;铜锈环棱螺密度对水体氮浓度变化起主要作用,方差占比为64%,沉水植物不同物种对水体磷浓度变化起主要作用,方差占比为72.54%。     

再生水回用中氮磷对两种典型水华藻类生长影响研究

根据相关标准,试验选取了不同的氮磷浓度值,对蓝藻水华常见的铜绿微囊藻和绿藻水华常见的小球藻分别进行了单独培养以及两者的竞争试验.结果表明,铜绿微囊藻生长的最适氮磷浓度分别为15 mg/L、0.3～0.5 mg/L,小球藻生长的最适氮磷浓度分别为15 mg/L、0.1～0.5 mg/L;在氮磷比为15、30、50、150的试验条件下,竞争试验中的优势藻均为小球藻.建议以再生水为补水水源的景观水体中,再生水的氮磷浓度分别控制为:总氮≥15 mg/L、磷≤0.1 mg/L、氮磷比为150以上,能有效地抑制铜绿微囊藻生长.     

镉胁迫对铜绿微囊藻的抑制作用及营养盐浓度对其的减缓效应

为研究镉胁迫对铜绿微囊藻的生长和生理特征影响,评估氮、磷在减缓镉胁迫中作用,将处于指数生长期的铜绿微囊藻接种于不同的镉胁迫浓度和3种营养盐水平下96 h。结果表明,当镉浓度小于10μmol/L,随着氮、磷浓度增大,藻的生物量、比生长速率、叶绿素a、可溶性蛋白、可溶性糖的浓度和超氧化物歧化酶活性随之增加,然而在镉浓度为10μmol/L时铜绿微囊藻的这些指标含量基本相同,但类胡萝卜素只有在镉浓度为10μmol/L时才会出现明显的降低。     

Detection and variation of microcystin contents of Microcystis blooms in eutrophic Lalla Takerkoust Lake, Morocco

Hepatotoxic microcystins produced by cyanobacteria represent a significant health hazard. In Morocco, although blooms of cyanobacteria are known to occur frequently in some water‐bodies, studies on toxicology and toxinology of these potentially harmful algae have been scarcely developed. This paper presents results of the detection of Microcystin‐LR (Mcyst‐LR) and other microcystin variants and their content variations from Microcystis natural blooms and from the isolated strain culture. During the cyanobacteria dynamic study, 11 bloom samples were collected between 1994 and 2000 and were assessed for toxicity and quantification of microcystins, respectively, by mice bioassay and the enzyme‐linked immunosorbent assay. The bloom samples exhibit a high toxicity with mice intraperitoneal injection (i.p.) LD₅₀ < 100 mg/kg and the total microcystin contents were 496–8800 μg/g dry weight with a coefficient of variation of less than 11%. However, the Microcystis isolated strain cultured on Z8 medium under controlled laboratory conditions produced an amount of 707 μg/g dry weight, its toxicity level corresponds to a LD₅₀ i.p mice of 31 mg/kg. The detection of microcystin variants and the identification of Mcyst‐LR from some natural bloom samples collected in 1994, 1996 and 1999 have been carried out by high performance liquid chromatography with a photodiode array detector, which confirmed the identification from each bloom sample of at least four microcystin variants, among which the Mcyst‐LR one represents a relative proportion of 30% to 62% of total microcystin contents. Only one variant of microcystin that was not a Mcyst‐LR has been detected from a Microcystis isolated strain. The toxicity level of the material depended either on the amount of microcystins or the number of these variants and their proportion. According to these results, the survey of cyanobacteria and cyanotoxins monitoring in water used for human consumption is needed to avoid any sanitary risk.     

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.     

Spectral Reflectance Measurements of a Microcystis Bloom in Upper Klamath Lake,Oregon

The objective of this study was to measure the in situ spectral reflectance of lake water that contains a bloom of Microcystis, a species of cyanobacteria. Reflectance spectra (350–2,500 nm) of lake water near a boat dock in Upper Klamath Lake, Oregon, were collected with a portable spectroradiometer on a cloud-free day with sunlight as a source of illumination between 0845 to 0915 hours, Pacific Daylight Time (PDT) on 17 August 2004, at a near-normal angle of observation. The averaged spectrum of the lake water containing the Microcystis bloom exhibits reflectance maxima from 550-590 nm and near 710 nm wavelengths and reflectance minima near 630 nm and 675 nm wavelengths. The reflectance gradually decreases from 810–1,000 nm and has very low reflectance in the 1,000–2,500 nm wavelength region. Our results show that the spectral reflectance of Microcystis at this stage of its bloom remains low for wavelengths longer than 1,000 nm in the near-infrared region of the spectrum. These spectral results have implications in selecting the spectral ratios and refining the algorithms that will be used to estimate phycocyanin content using satellite models. Microcystis is the predominant species of cyanobacteria blooms in Lake Erie, which makes these spectral data as important to the Great Lakes as it is to Upper Klamath Lake. Satellite algorithms have been published that have mapped phycocyanin, a pigment more uniquely associated with cyanobacteria than is chlorophyll a, in Lake Erie with data from LANDSAT TM bands 1, 3, 4, 5, and 7, and the reflectance spectra reported here are the first that cover the entire spectral range of all those LANDSAT TM spectral bands for a Microcystis bloom.     

桶装水中铜绿假单胞菌检验方法的建立

本文依据《食品安全国家标准饮用天然矿泉水检验方法》(GB 8538—2016)方法,分别采用单向负压吸附取液微孔滤膜过滤装置(B)与不锈钢过滤系统(A)检测水样中铜绿假单胞菌,比较两种方法的检测效果.对A组和B组检测计数数据进行相关分析,A组和B组之间的相关系数值为0.997,并且呈现出0.01水平的显著性,结果说明二...     

氮磷比对固氮和非固氮蓝藻种间关系的影响

蓝藻是引起水华暴发的主要藻类之一,氮磷比N∶P是影响水体中固氮蓝藻形成的重要参数。然而在水体不同富营养化程度下,N∶P对固氮和非固氮蓝藻的种间关系影响仍不清晰。通过构建氮磷摩尔比为2、16和64的培养体系,比较固氮蓝藻的水华鱼腥藻(Anabaena flos-aquae)和非固氮蓝藻惠氏微囊藻(Microcystis wesenbergii)在单培养和混合培养条件下的增长速率、最大环境容纳量和竞争系数,研究不同N∶P环境中固氮和非固氮蓝藻功能群的种间关系。结果表明:在三种N∶P条件下,纯培养和混合培养的微囊藻的生长速率和最大环境容纳量均高于鱼腥藻。纯培养中微囊藻在N∶P=16条件下细胞密度可达最大,为818×10~4cells/m L,而纯培养中鱼腥藻在N∶P=2条件下细胞密度最大,为113×10~4cells/m L。在不同N∶P条件下微囊藻在混合培养体系中的最大密度均高于纯培养体系,而鱼腥藻的生长趋势正好相反。这说明固氮和非固氮蓝藻在不同N∶P条件下均呈现偏利于非固氮蓝藻的种间关系。水华鱼腥藻的竞争能力较弱,但在其与微囊藻的混合培养体系中为微囊藻提供新氮,从而促进非固氮蓝藻微囊藻增殖。