九龙江北溪拟多甲藻水华防治与应急处置

2009年初以来,在福建省九龙江北溪的支流和干流连续发生了拟多甲藻（Peridiniopsis penardii）水华。经检测,拟多甲藻水华没有明显的生物毒性,但其所形成的深褐色水色和轻微藻腥味对该流域的龙岩、漳州和厦门三城市的生产和生活是造成了一定的影响。研究结果表明,在甲藻水华的防治与应急处置过程中,必须进一步加强组织体系建设,明确各职能部门职责,并根据不同水域的实际情况和季节变化,采取相应的物理、化学和生物方法予以防治和应急处置。     

大宁河水华敏感期浮游植物与环境因子关系

以三峡支流大宁河水华敏感期(2008年4～5月)水环境状况的监测数据为基础,运用数理统计分析手段,对浮游植物的分布特征及其与环境因子的关系进行了讨论.结果表明,水温、总氮(TN)、硝酸盐氮(NO3--N)、pH和溶解氧(DO)时空分布差异显著(ANOVA,p<0.05).浮游植物细胞密度时空分布差异显著(ANOVA,p...     

Isolation and algae-lysing characteristics of the algicidal bacterium B5

Water blooms have become a worldwide environmental problem.Recently,algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms.In this study,one strain of algicidal bacterium B5 was isolated from activated sludge.On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence,it was identified as Bacillusfusiformis.Its algae- lysing characteristics on Microcystis aeruginosa,Chlorella and Scenedesmus were tested.The results showed that:(1)the algicidal bacterium B5 is a Gram-negative bacterium.The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B.fusiformis reached 99.86%,so B5 was identified as B.fusiformis;(2)the algal-lysing effects of the algicidal bacterium B5 on M.aeruginosa, Chlorella and Scenedesmus were pronounced.The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-α.The greater the initial bacterial cell density,the faster the degradation of chlorophyll-α.The greater the initial algal cell density,the slower the degradation of chlorophyll-α.When the bacterial cell density was 3.6 x l07 cells/ml,nearly 90% of chlorophyll-αwas removed.When the chlorophyll-αconcentration was less than 550μg/L,about 70% was removed;(3)the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.     

Effects of elevated CO2 on dynamics of microcystin-producing and non-microcystin-producing strains during Microcystis blooms

In an attempt to elucidate the effects of different CO₂ concentrations (270, 380, and 750 μL/L) on the competition of microcystin-producing (MC-producing) and non-MC-producing Microcystis strains during dense cyanobacteria blooms, an in situ simulation experimentwas conducted in the Meiliang Bay of Lake Taihu in the summer of 2012. The abundance of total Microcystis and MC-producing Microcystis genotypes was quantified based on the 16S rDNA and mcyD gene using real-time PCR. The results showed that atmospheric CO₂ elevation would significantly decrease the pH value and increase the dissolved inorganic carbon (DIC) concentration. Changes in CO₂ concentration did not show significant influence on the abundance of total Microcystis population. However, CO₂ concentrations may be an important factor in determining the subpopulation structure of Microcystis. The enhancement of CO₂ concentrations could largely increase the competitive ability of non-MC-producing over MC-producing Microcystis, resulting in a higher proportion of non-MC-producing subpopulation in treatments using high CO₂ concentrations. Concurrently, MC concentration in water declined when CO₂ concentrations were elevated. Therefore, we concluded that the increase of CO₂ concentrations might decrease potential health risks of MC for human and animals in the future.     

Influence of zeta potential on the flocculation of cyanobacteria cells using chitosan modified soil

Using chitosan modified soil to flocculate and sediment algal cells has been considered as a promising strategy to combat cyanobacteria blooms in natural waters. However, the flocculation efficiency often varies with algal cells with different zeta potential (ZP) attributed to different growth phases or water conditions. This article investigated the relationship between ZP of Microcystis aeruginosa and its influence to the flocculation efficiency using chitosan modified soil. Results suggested that the optimal removal efficiency was obtained when the ZP was between − 20.7 and − 6.7 mV with a removal efficiency of more than 80% in 30 min and large floc size of > 350 μm. When the algal cells were more negatively charged than − 20.7 mV, the effect of chitosan modified soil was depressed (< 60%) due to the insufficient charge density of chitosan to neutralize and destabilize the algal suspension. When the algal cells were less negative than − 6.7 mV or even positively charged, a small floc size (< 120 μm) was formed, which may be difficult to sink under natural water conditions. Therefore, manipulation of ZP provided a viable tool to improve the flocculation efficiency of chitosan modified soil and an important guidance for practical engineering of cyanobacteria bloom control.     

基于欧洲航天局“哨兵-2A”卫星的太湖蓝藻遥感监测

欧洲航天局(ESA)2015年6月23日成功发射"哨兵-2A"卫星,该卫星搭载的多光谱成像仪(MSI)在可见光(VIS)至短波红外(SWIR)波长区间配置了多种光谱波段/地面分辨率组合,可以获取大范围、较短重访周期、较高空间分辨率(10 m)的遥感影像。以太湖2016年6月13日MSI数据为例,在完成大气校正的基础上,分析了太湖典型地物类型光谱特征,采用归一化植被指数(NDVI)结合叶绿素反射峰强度(ρchl)构建的综合阈值法对贡湖湾的蓝藻水华信息进行了提取实验。结果表明:"哨兵-2A"卫星MSI影像质量清晰,可精细地反映植被、蓝藻、水体等典型地物类型的光谱特征;ρchl指数对中-高蓝藻聚集区与水生植被、轻度蓝藻聚集区与混合水体具有较好的分离能力;利用综合阈值法提取贡湖湾中-高蓝藻聚集区面积为60.37 km2,主要分布在贡湖北部沿岸、湖心和南部沿岸。"藻-水"混悬体面积为79.49 km2,贡湖湾东部蓝藻水华相对较轻。     

浅水富营养化湖泊蓝藻垂向分布特征及其动力机制研究—以太湖为例

蓝藻垂向运动的表征对于理解浅水富营养化湖泊中蓝藻水华的形成过程至关重要.本研究以太湖为研究区,通过野外实验观测,分析蓝藻生物量及颗粒物粒径分布的垂向变化特征,结合一维蓝藻平流运动模型,研究在不同扰动强度和群体粒径下的蓝藻垂向运动规律.结果表明,在低风速条件下（风速小于3 m·s^-1）,太湖水体中蓝藻生物量在垂向上分布不均匀,其垂直分布剖线在水表或水柱某一深度形成峰值.当水华发生时,直径> 75 μm的蓝藻群体主要聚集在水表,其剖线在水下形成不明显的峰值;在水华未发生时,75~175 μm直径范围内的蓝藻群体主要聚集在水深1.2 m处,175~250 μm直径范围内的大粒径蓝藻群体仍聚集在水表.垂向运动模拟表明,直径> 100 μm的蓝藻群体随光照变化在水柱中进行周期性上浮下沉运动,直径< 100 μm的蓝藻群体,由于垂向迁移速度较小,在弱扰动条件下聚集在真光层深度附近.不同粒径蓝藻群体的垂向运动规律不同,导致蓝藻生物量垂直剖线在水表和水下形成两类特征峰.     

春季东海赤潮发生前后营养盐及溶解氧的平面分布特征

依据2010年4月8～26日和5月7～14日对东海赤潮高发区调查所得的数据,分析了该海域赤潮发生前后各生源要素的含量及分布特征,并对其影响因素进行了初步探讨.结果表明,调查海域4月处于赤潮暴发前期,以硅藻为优势藻种;5月赤潮大规模暴发,以甲藻为优势藻种.5月DIN和PO34--P浓度与4月相比大幅降低,DIN平均值由18.04μmol·L-1降至10.80μmol·L-1,下降幅度为40%;PO34--P平均值由0.47μmol·L-1降至0.27μmol·L-1,下降幅度为43%.这表明在赤潮发生过程中赤潮生物对营养盐具有强烈的消耗作用.5月东海赤潮主要藻种为甲藻,甲藻在繁殖过程中不消耗SiO23--Si,加之长江冲淡水的补充,所以SiO23--Si平均值由16.15μmol·L-1略升至16.96μmol·L-1,变化幅度不大.DO平均值由4月的8.76mg·L-1下降至5月的6.09 mg·L-1,这主要是由于5月水温对DO的影响大于浮游植物光合作用的影响,5月水温较4月高,氧气在水中的溶解度随温度的升高而降低,所以5月DO浓度低于赤潮发生前期.     

北方富营养分层型水库藻类季节性暴发机制及其阈值分析

季节性藻类水华严重威胁供水安全,为探明北方富营养分层型水库藻类季节性暴发机制,以李家河水库为例,于2017～2020年开展长期连续高频监测,采用传统藻群和功能藻群分类法,并耦合局部加权回归法和边界分析模型,提炼藻华季节性(春季和夏季)演替规律及暴发环境因子阈值.结果表明：(1)春季和夏季藻华演替规律及响应机制不同,春季以绿藻、硅藻和甲藻为主,而夏季以绿藻、硅藻和蓝藻为主;其中,春季以低温、小型且高比表面积藻为主,而夏季以高温、大型或团状且低比表面积藻为主;藻类生理和形态特征差异是造成季节性藻华的主要内因;(2)春季和夏季藻华主要驱动因子不同,春季藻华主要为水温、混合层深度(Z_mix)和光利用率(Z_eu/Z_mix)控制,而夏季藻华主要受水温、Z_mix、Z_eu/Z_mix和总磷(TP)的共同影响;主驱动因子的变化差异是诱发季节性藻华的主要外因;(3)春季和夏季藻华暴发的水环境阈值不同,春季藻类暴发的水温、Z_mix和Z_eu     

In situ studies on growth,oxidative stress responses,and gene expression of juvenile bighead carp (Hypophthalmichthys nobilis) to eutrophic lake water dominated by cyanobacterial blooms

Cyanobacterial blooms have received increasing attention as a public biohazard for human and animal health. To assess the effect of cyanobacteria-dominant lake water on juvenile fish, we measured the responses of specific growth rate, condition factor, body weight and body length, oxidative stress, and related gene expression of juvenile bighead carp Hypophthalmichthys nobilis exposed to in situ eutrophic lake (Chl a was around 7.0 μg L⁻¹). Results showed in situ cyanobacteria-dominant lake water had no effect on the growth performance, but significantly elevated the contents of malondialdehyde, the expression of heat shock protein 70, and the activity of superoxide dismutase, indicating that oxidative stress occurred. Meanwhile in situ lake water significantly decreased the expression of catalase and glutathione S-transferase genes. We conclude that in situ cyanobacteria-dominated lake water was harmful to juvenile bighead carp based on the oxidative stress and changes in the related gene expression levels.