利用陆基高光谱遥感捕捉太湖蓝藻水华日内快速变化过程

受蓝藻自身垂直迁移和频繁风浪扰动影响,太湖蓝藻水华漂浮混合和迁移堆积等变化迅速,在传统的湖面定位和断面监测中总感觉蓝藻水华有些"来无影、去无踪",限制了对其形成过程、驱动机制和防控治理的深入认识.卫星遥感可以实现蓝藻水华空间分布同步观测,但由于观测频次的限制很难捕捉蓝藻水华快速动态变化过程.本文利用与杭州海康威视数字技术股份有限公司联合自主研发的陆基（地基、岸基或者平台、船舶、桩基等能固定安装的均可）高光谱多参数水质遥感监测仪,架设于中国科学院太湖湖泊生态系统研究站（简称太湖站）水上观测场,通过对叶绿素a浓度及其他关键水质参数秒-分钟级的连续观测,有效捕捉了一天内蓝藻水华短期突然和快速变化过程.研究结果显示,在微风和小风条件下蓝藻容易在表层水体漂浮,盛行西北风驱动湖面开敞水域蓝藻水华快速漂浮集聚到太湖站岸边,短短半小时内表层水体叶绿素a浓度可以由10 μg/L快速攀升到100 μg/L以上,一天内会出现多个叶绿素a峰值,清晰展示了蓝藻快速日内动态变化过程.受蓝藻快速日内变化影响,透明度、总氮、总磷和高锰酸盐指数等水质参数也呈现出快速日内变化,叶绿素a浓度与透明度存在极显著负相关,与总氮、总磷和高锰酸盐指数存在极显著正相关,叶绿素a能解释总氮、总磷80%以上的变化,说明蓝藻短期内的漂浮和集聚深刻影响到湖泊水质.     

富营养湖泊中的微囊藻优势：原因—后果—对策

Cyanobacterial dominance in lakes has received much attention in the past because of the great success and frequent bloom formation in lakes of higher trophic levels. In this paper underlying mechanism of cyanobacterial dominance are analyzed and discussed using both original and literature data from various shallow mixed and deep stratifying lakes from temperate and (subtropical regions. Examples include all four ecotypes of cyanobacteria sensu MUR et al. (1993), because their behavior in the water column is entirely different.Colony forming species (Microcystis) are exemplified from the large shallow Lake Taihu, China. Data from a shallow urban lake, Alte Donau in Austria are used to characterize well mixed species (Cylindrospermopsis) while stratifying species (Planktothrix) are analyzed from the deep alpine lake Mondsee. Nitrogen fixing species (Aphanizomenon) are typified from a shallow river-run lake in Germany.Factors causing the dominance of one or the other group are discussed as well as consequences for restoration measures. Existing knowledge on cyanobacterial dominance is summarized.     

用TN-TP-SRSi三角形图解评价藻类组成结构的营养比动力学

To show the relative availability of nitrogen, phosphorus and silica for diatoms as well as non-siliceous algae in phytoplankton communities triangular diagrams are most appropriate. Triangular diagrams for TN-TP-SRSi show the nutrient ratios TN:TP, SRSi:TN and SRSi:TP in proportion to each other at the same time.Comparison of waters, grouped according to their limnological characteristics, indicate that these groups have also different seasonal dynamics of TN, TP and SRSi in proportion to each other. From these groups, which include meso-eutrophic and hypertrophic, shallow and deep, polymictic and dimictic lakes,only the group of "flushed, hypertrophic polymictic lakes" has a high seasonal dynamic of the ratios of all three macronutrients. Moreover the relative availability of TN:TP-ratios changes from > 16:1 in spring to <16:1 in summer. Significant changes in phytoplankton structure are associated with this high dynamic of the nutrient ratios. Considerable changes in the share of cyanobacteria to diatom biomass during summer are synchronised with a powerful modification of the relative availability of TN-TP-SRSi as illustrated by the triangular diagrams.For practical purposes trophic situations are most commonly evaluated from concentrations of a single nutrient or a nutrient ratio, such as N:P. However, a complex assessment would often be more appropriate. In this context triangular diagrams have the benefit of synoptically presenting relative nutrient availability for phytoplankton communities as a whole.     

风场对鄱阳湖丰水期表层蓝藻密度的影响

目前,在风场对蓝藻的影响研究方面,国内针对太湖、滇池、巢湖等浅水湖泊的研究较多,针对鄱阳湖的研究则多集中于蓝藻群落特征及其与营养盐之间的关系。近年来,作为长江流域重要的通江湖泊,处于轻度富营养化状态的鄱阳湖水体蓝藻水华在局部库湾和部分水域出现,风场如何影响鄱阳湖表层蓝藻密度是一个值得探讨的问题。2019-2021年,在鄱阳湖布设13~49个采样点,于平水期、丰水期和枯水期现场采集各个点位表层水样、藻类、风场和流场数据,分析风场对鄱阳湖丰水期表层蓝藻密度的影响。结果表明,2019-2021年鄱阳湖丰水期风速与表层蓝藻密度呈显著正相关性,风场对水体的充分混合及驱动水体形成的风生流是促进蓝藻生长的原因之一。在流速较高(>0.05 m/s)的区域,无论风速高于还是低于临界风速(3~4 m/s),鄱阳湖表层蓝藻密度的空间分布受流场的影响更大;在流速较低(<0.05 m/s)的区域,风速在临界风速以下时,鄱阳湖表层蓝藻密度的空间分布受风场影响更大。2019-2021年鄱阳湖丰水期蓝藻密度超过水华暴发的阈值,但在高风速高流速的共同作用下未能发生大范围的蓝藻水华,仅能在风速适宜(<3~4 m/s)、流速较低(<0.05 m/s)的内湾、尾闾区等区域发生小面积的蓝藻水华。鄱阳湖丰水期水体处于长江顶托的低流速且微风条件下时,发生大面积蓝藻水华的概率可能会明显上升。     

Phosphorus metabolism in anthropogenically transformed lagoon ecosystems: The Comacchio lagoons (Ferrara, Italy)

Inorganic phosphorus dynamics were investigated with the use of ³²P in the hypertrophic Comacchio lagoons (NE Adriatic) during an extremely dense, quasi-permanent bloom of picocyanobacteria. Concentrations of dissolved inorganic phosphate (DIP) in waters of the blooming lagoons were usually near the detection limit (0.01 μmoles·dm⁻³). DIP uptake rates by microplankton at near-ambient concentrations (0.01 to 0.1 μmoles·dm⁻³) were in the range of 9.6 to 16.1 nmoles P·dm⁻³·min⁻¹, and turnover times were 1.5 to 3 min. The turnover time was >40 h in the eutrophic coastal waters of the adjacent Adriatic Sea. The uptake rate of DIP depended on its initial concentration. In water samples artificially enriched with DIP, the uptake rate rose to its maximum of 0.10 to 0.13 μmoles P·dm⁻³·min⁻¹ (or 6 to 7 μmoles·dm⁻³·h⁻¹) when the initial concentration of DIP was elevated to 10 to 20 μmoles·dm⁻³. The potential capacity of microplankton in the water samples to consume and retain DIP was estimated at 25 μmoles·dm⁻³. Specific features are discussed of phosphorus metabolism in the anthropogenically transformed lagoon ecosystem with an anomalous food web with few animals.     

富营养化湖泊典型水华蓝藻的固有光学特性

固有光学特性是水体光学特性的重要内容,掌握富营养化湖泊水体内典型水华蓝藻的固有光学特性,是开展不同水华蓝藻遥感识别的理论基础.利用AC-S吸收衰减仪、BB9后向散射仪,通过实验室纯藻培养,研究微囊藻（Microcystis）、鱼腥藻（Dolichospermum）和束丝藻（Aphanizomenon）3种典型水华蓝藻的固有光学特性,并探讨色素浓度、色素占比以及藻类等效粒径对不同水华蓝藻固有光学特性的影响.结果表明,3种典型水华蓝藻的吸收光谱曲线均具有440、620和675 nm吸收峰,微囊藻620和675 nm的比吸收系数最大,鱼腥藻440 nm处的比吸收系数最大;束丝藻单位色素浓度的散射和后向散射能力最高,鱼腥藻次之,微囊藻最低;固有光学特性影响因子分析表明,色素浓度和藻蓝素占比是影响3种水华蓝藻固有光学特性的主要因素.3种蓝藻的吸收系数、散射系数以及鱼腥藻、束丝藻的后向散射系数均随着色素浓度（叶绿素a或藻蓝素）的增加而增大;当蓝藻中藻蓝素占比增加时,3种蓝藻的单位色素浓度的后向散射系数逐渐下降;而藻细胞粒径与固有光学特性之间并未表现出很好的相关性.因此,3种水华蓝藻单位色素浓度的固有光学特性将为典型水华蓝藻的遥感识别提供重要的理论基础和数据支持.     

Laboratory studies on zooplankton‐cyanobacteria interactions

Laboratory studies on cyanobacteria‐zooplankton interactions have largely focused on the inadequacy of cyanobacteria as a food source. Some features of cyanobacteria can be regarded as anti‐herbivore defences. Large colonies of Aphanizomenon, Anabaena and Microcystis cannot be handled by zooplankton, but do not interfere seriously with the filtering process. Small colonies and filaments, however, may cause severe inhibition of the feeding process by mechanical interference. This reduces zooplankton growth, reproduction, and survival. Copepods, rotifers, and Bosmina are less affected by mechanical disturbance than cladocerans. If ingested, some cyanobacteria may be poorly digested or may not provide essential nutrients. Some cyanobacteria are reported to be toxic to zooplankton. Several strains of Microcystis produce an endotoxin, but the amount of toxin produced differs among strains and with the condition of Microcystis. Zooplankton encountering toxic cells cease feeding. Some evidence of an extra‐cellular herbivore deterrent was found for Anabaena. Thus, cyanobacteria may either be individually protected or may create an environment that is unfavourable for efficient grazers (e.g., Daphnia).     

Salinity-Temperature Relations and Morphotypes of a Mixed Population of Coccoid Cyanobacteria from a Hot, Hypersaline Pond in Israel

Abstract. A mixed population of unicellular and colonial cyanobacteria was transferred into culture from a hypersaline helio-thermal pond in the vicinity of the Dead Sea. The entire complex of strains, incubated in Dead Sea water of varying salinity and temperature, showed a pronounced shift of the maximal growth from a salinity of 72 g l^-1 at 30 ^oC up to 142 g 1^-1 at 50 ^oC. Over the above range of salinities and temperatures, these cyanobacteria were capable of about four divisions per day, providing that any increase in salinity was coupled with the suitable increase in temperature. The above peculiar adaptation can explain the prominent success of this group of microorganisms in the extreme and unstable ecological conditions of hypersaline habitats. Amounts of slime accumulating in the cultures were proportional to the incubation temperature.     

大连金州湾寒武系毛庄组微生物碳酸盐岩生物丘复合体

寒武纪苗岭世早期的毛庄组沉积时期,华北地台围绕着西北部的古陆分布着两个沉积相带,靠近古陆的是局限潮坪相带,远离古陆的是开阔潮坪相带,前者以海侵体系域的干旱红层或海岸萨布哈沉积与高水位体系域的潮坪相白云岩沉积序列为特征,后者则以海侵体系域的潮坪相砂泥岩与开阔海台地相(潮下坪)灰岩沉积序列为特征;大连金州湾剖面的毛庄组,属于远离古陆的开阔潮坪相带的产物,在其高水位体系域中为一套夹有鲕粒灰岩的叠层石与均一石生物丘灰岩,组成一个特别的生物丘复合体。以下特征表明,这个微生物碳酸盐岩生物丘复合体代表着一个较为罕见的蓝细菌主导的微生物席形成的微生物碳酸盐岩的典型实例:①在生物丘复合体第一个单元的大型柱状和穹隆状砂泥质叠层石中发现孢网菌状组构,说明了这些叠层石属于蓝细菌微生物席的钙化作用产物;②在第二个单元均一石灰岩生物丘中,见到少量丝状蓝细菌鞘化石,表明均一石可能为较厚的蓝细菌微生物席的钙化作用产物;③在小型柱状叠层石组成的顶部单元中,保存较好的蓝细菌泥晶纹层、以及充填在叠层石柱体之间的基质中的蓝细菌团块,较为特征地说明了这些小型柱状叠层石是蓝细菌所主导的微生物席的建造物;④在鲕粒灰岩组成的第三个单...     

PAC改性粘土处理蓝藻水华对水环境的影响

利用改性粘土治理蓝藻水华堆积的湖泊近岸区域以及发生水华的养殖水体成为应急治理蓝藻的重要措施,然而负载有毒藻体的改性粘土沉积水体可能引发的安全性风险尚缺乏研究.选取PAC改性粘土作为研究对象,通过模拟实验,研究改性粘土处理蓝藻水华后沉积水体对负载的藻细胞结构、水体营养盐与藻毒素的释放与削减以及对其他水体功能性细菌(硝化、反硝化细菌)的影响.结果表明,PAC改性粘土的施用对低水华水体蓝藻细胞的去除率为96.04%±0.99%,高水华水体与低水华水体施用的去除率之间差异不显著,PAC改性粘土的施用能够在较长的时间内有效地控制水体中的蓝藻浓度.透射电镜结果表明,PAC改性粘土沉降蓝藻第4 d后,蓝藻细胞膜出现了一定程度的不完整,细胞内规则的类囊体片层结构出现了实质性损伤.随着粘土负载蓝藻细胞的损伤,水体中的总可溶性氮浓度迅速上升,但总可溶性磷浓度仍可在较长一段时间内维持在较低水平.PAC改性粘土施用后,水体的总细菌数与空白对照组趋于一致,但硝化、反硝化细菌数却呈显著下降趋势.PAC改性粘土施用下的藻毒素释放风险主要集中在高水华水体.高水华水体中,PAC改性粘土施用导致藻毒素MC-LR和MC-RR加速释放,其最高峰值分别达到空白对照组的1.69±0.09和2.04±0.09倍,但水体MC-LR浓度达到安全限(1μg/L)的时间明显比空白对照组早8 d.此外,PAC改性粘土的施用并没有导致水体中Al~(3+)和Cl~-浓度超标.