基于藻类生长潜力评估调水对藻类生长的影响

为评估水体生态健康,量化和确定供水输入的浮游藻类群落对受水水体浮游藻类生长的影响程度具有重要意义。该研究在不同季节的调水期测定了供、受水水体的理化因子,同时利用藻类生长潜力试验比较和分析了不同比例的供、受水水体混合处理后浮游藻类细胞密度和群落结构变化。结果显示,调水期间受水水库的氮磷营养盐浓度没有显著变化(P>0.05)。不同季节的藻类生长潜力试验显示,夏、冬季处理组的浮游藻类细胞密度峰值时间比对照组提前了4 d,且密度峰值随着混合比例的提高而增大;但夏季培养末期(20 d)处理组的浮游藻类密度均低于对照组,同时夏、秋和冬季处理组的实际藻类密度峰值均低于理论估算值,分别低10%、17%～24%和31%。处理组的群落结构变化表现为夏季受水水库的绝对优势种转变为输入的优势种,秋、冬季绝对优势种的相对丰度随调水比例的提高而增加,明显受到供水优势种生长的影响。供、受水水体的营养盐浓度差异是影响藻类生长的主要因素,持续调水显著影响受水水体浮游藻类的群落结构,但在一定程度上降低了发生藻类水华的风险。     

铈及其配合物对水体富营养化的影响

在静态水体富营养化状态下,分别添加不同浓度的Ce3 溶液和不同浓度的Ce3 -EDTA配合物溶液,在相同自然条件下进行培养,研究其对水体富营养化状态下藻类生长的影响.结果表明:添加浓度为1.00 mg·l-1的Ce3 和Ce3 -EDTA配合物对水体富营养化和藻类生长有抑制作用,添加浓度为0.25mg·l-1和0.50mg·l-1的Ce3 和Ce3 -EDTA配合物对水体富营养化和藻类生长有促进的作用,其中添加浓度为0.50mg·l-1的Ce3 和Ce3 -EDTA配合物溶液的促进作用更明显.相同浓度的Ce3 和Ce3 -EDTA配合物溶液相比,Ce3 -EDTA配合物溶液的作用相对弱一些,即添加EDTA可抑制稀土元素对藻类生长的作用.     

论我国水生态的保护与修复:任务与对策

本文聚焦我国水生态保护与修复工作,结合长期实践,分析当前的形势和任务,指出了当前要着力解决的水生态问题主要是:在大坝上游,河流变湖库,生境变化导致生物物种变化;水库水流流速变缓,水体自净能力降低,导致富营养化及藻类水华。在大坝下游,清水下泄,冲刷下游河道导致局部河道河势变化较大;水库蓄水使坝下游春季水温下降、秋季水温升高,水温变化过程滞后;水库蓄水导致大坝下游的水文过程改变,水的流量、流速、流态发生变化。在河道(航道)整治工程中,裁弯取直,缩短水流在河道中的停留时间,河岸衬砌和硬化,减少水向沿河堤岸的渗透,在大降水和洪水时易造成涝灾和洪灾。在涉湖工程中,阻隔河湖,填湖造地。在明确存在问题和迫切需求的基础上,提出了切实可行的对策建议。当前水生态保护与修复要围绕一条主线,即"人要发展,鱼要生存"的"人鱼线",要采取"调、控、退、通、改、拆"的综合措施,即生态调度,控制水污染,退建还水、退田还湖,河湖连通,对已建涉水工程进行生态化改造,对在保护区、重点风景名胜区、特有鱼类栖息地修建的小型工程要采取坚决措施拆除,恢复原貌。     

富营养化水体磷阈值的动态AGP模拟研究

采用流动原水来培养水体混合藻的动态AGP试验,模拟富营养化条件下藻类的生长过程,并以密云水库为实例,结合MATLAB 7.0数值分析软件,拟合了密云水库富营养化发生的磷阈值.结果表明,该水库达到富营养化的磷阈值随水环境条件和水体生态特征变化;蓝藻(Cyanobacteria)在低质量浓度磷酸盐条件下较绿藻(Chlorophyta)更具有生长竞争力;初始藻密度大小影响藻生长达到最大值的时间.在平均温度为28.8、26.5、25.1℃和初始藻密度为9.2×10~6、10.0×10~6、8.0×10~6个条件下,密云水库发生富营养化的总磷阈值分别为0.053、0.062、0.064mg·L~(-1).     

滇池水体磷的时空变化与藻类生长的关系

水体磷的时空变化与藻类生长的关系对研究水体富营养化具有十分重要的作用。采用GPS定位,对滇池海埂、斗南、罗家村、新街、昆阳等5个代表性位点监测断面水体总磷、可溶性磷及叶绿素a含量进行了为期1年（2003年5月至2004年5月）的动态研究,并在滇池海埂位点进行了日变化试验,全面分析了滇池不同区域、不同层次、不同时期水体总磷和可溶性磷的年变化、日变化及水体氮/磷比对藻类生长的影响。结果表明,滇池水体磷与藻类生长呈现显著的年变化和日变化特征,显示了滇池全湖水体总磷与叶绿素a周年变化呈显著正相关,水体可溶性磷与叶绿素a呈正相关趋势;海埂位点水体总磷与叶绿素a日变化呈显著正相关,水体可溶性磷与叶绿素a日变化呈显著的负相关,水体氮磷比与叶绿素a呈显著正相关。表明水体磷负荷对藻类生长影响呈现显著的水体区域性和水层差异性和季节性,藻类生长主要吸收水体中的可溶性磷,暗示了滇池水体磷是藻类生长的主要限制因子之一。     

泥沙沉降对长江水体富营养化相关因素的影响初探

针对三峡库区重庆段蓄水后,泥沙沉降对长江水体富营养化相关因素的影响进行了研究。三峡库区含沙量大,泥沙对水环境的影响不容忽视。为准确预测成库后三峡库区重庆段富营养化的发生,文章通过泥沙沉降对水质影响静态模拟试验,研究了长江原水的泥沙沉降对水体中叶绿素a、透明度、溶解性总磷、溶解性总氮、浊度等指标的影响。结果表明:三峡成库后泥沙更易沉降,引起水体浊度降低、透明度增大,这可能利于藻类的生长,导致叶绿素a的质量浓度增加,同时,泥沙沉降也使水体的溶解性氮磷比增大,对富营养化发生有抑制作用。     

梯级水库群环境风险分析

为提高梯级水库群环境风险管理水平,加强流域生态环境保护,以溪洛渡-向家坝梯级水库为研究对象,基于灾害系统理论和系统动力学,对溪洛渡-向家坝梯级水库环境风险进行了系统梳理,辨识了梯级水库环境风险承载体、风险源、风险诱因,分析了环境风险传递机理,采用贝叶斯理论进行库区水体藻类爆发概率计算。结果表明:溪洛渡-向家坝梯级水库环境风险通过水流、电流、系统动力学流进行传播,并会影响到电站机组和水工建筑物的安全,由于水动力减弱和库区污染物排放,导致库区水体藻类爆发概率为2.42%,死鱼概率为1.21%,在此基础上,绘制环境风险传递拓扑图,并提出相应的环境风险管控措施。     

化感物质的抑藻作用研究、应用及生态安全性评价

水体富营养化日益严重,水华频繁爆发,如何有效控制水华,治理富营养化水体是目前水环境领域的研究热点和前沿。目前湖泊藻类控制技术主要有：物理方法、化学法、生物法,但是这些方法都有其固有的缺点。利用植物化感作用抑制有害藻类生长具有廉价、生态安全等优点近年来备受关注。化感作用就是生物体产生的生物活性物质即化感物质在生物体之间传递信息并导致生物体相互作用。归纳了国内外不同生活型水生植物化感作用研究的主要成果（包括已报道的抑藻水生植物种类、已从水生植物体内和种植水中分离鉴定得到的化感物质）,以及化感物质的联合作用研究,讨论了化感物质的生态安全性。通过化感作用能有效控制引起水体富营养化的各种藻类生长,优化水生生物的组成结构。例如,水体中投放大麦秆可以增加无脊椎动物以及鱼类的数量,从而达到改善水生生态系统的目的。展望了植物化感作用用于水环境治理的发展前景。以期为利用植物化感作用控制水华的发生提供理论基础。     

水动力条件对湖泊水体磷素质量浓度的影响

以环形水槽为研究手段，利用其可控的流速及可模拟的无限长，解决了前人未解决的湖泊水体水动力难以真实模拟的难题，模拟研究了不同流速对湖泊(太湖)水体中磷素质量浓度的影响。研究表明，随着水体流速的变化，湖泊水体中TP质量浓度的变化呈现3个阶段，即下降期、上升期和突增期。从物理化学和泥沙起动理论两方面，结合水流对悬浮物和沉积物的作用，分析了各阶段产生的原因。文章认为下降期的产生是因为在低流速下，一部分磷被悬浮物的絮凝沉淀带走所引起；上升期的产生则是因为流速上升扰动沉积物，使其达到少量动状态所引起；突增期的产生则是因为流速导致了沉积物普遍动而产生的。在研究范围内，溶解性磷质量浓度与水体流速有着明显的正相关关系；而在低流速下，溶解性磷是TP的主要组成成分，其质量浓度的相对比例可高达87％。结合太湖的有关研究，文章认为这是水华现象产生的关键原因。     

饮用水处理中藻类去除方法的研究进展

水体富营养化导致藻类的大量繁殖 ,从而藻类及其分泌物质会影响饮用水质量 .本文对饮用水处理过程中藻类的去除方法进行阐述和比较 ,并对其中影响藻类去除效果的影响因素进行了分析 .参 5 4     

Numerical simulation for impacts of hydrodynamic conditions on algae growth in Chongqing Section of Jialing River, China

Hydrodynamic conditions are important factors for planktonic algae growth, through introducing two parameters which express the optimal velocity and the velocity range for planktonic algae growth, a new velocity factor was put forward for the formula of growth rate. Therefore, the two-dimensional unsteady ecological dynamic model for algae growth was established to analyze the effects of hydrodynamic conditions on algae growth in Chongqing Reach of Jialing River in China. The temporal and spatial distribution of Chlorophyll-a (Chl-a) concentration was simulated numerically for various water levels, under climate conditions in period of high frequency for algae blooms of Three Gorges Reservoir and nutrition status at present in the research reach. The corresponding locations and areas of likely algae blooms were analyzed and forecasted. The results showed that about 0.04 m s⁻¹ was the optimal velocity for algae growth, and the occurrence of algae blooms in large scale is almost impossible because of relatively high water flow velocity for Jialing River.     

Assessment of the effects of a port expansion on algae appearance in a costal bay through mathematical modelling. Application to San Lorenzo Bay (North Spain)

In the last years several episodes of algae appearance affecting bathing areas have been observed in San Lorenzo Bay (north of Spain). The analysis of the collected algae revealed that they might come from near intertidal or shallow subtidal zones due to eutrophication processes or through drift algae movement by the action of marine currents. In the vicinity of this area, the expansion of the Port of Gijón (now under construction) supposes a significant modification of the coastal geometry. The magnitude of such an expansion could cause changes in the patterns of currents in the bay, with the consequent alteration of the observed algal appearance phenomena. A mathematical modelling study to evaluate the risk of generation of eutrophication processes in the San Lorenzo Bay area and the transport of drift algae from near sea bed areas was developed. This study required the use of different hydrodynamic models in order to characterize the currents caused by tides, winds and waves. The eutrophication processes in the bay were analyzed with a depth-averaged two-dimensional eutrophication model which deals with eight water quality variables. Calibration of model parameters with the observed data from a field survey was performed. A reasonable agreement with the field measurements was achieved. Model results showed that the maximum phytoplankton concentrations were below eutrophic conditions. Although, the port expansion has led to an increment of phytoplankton concentrations, chlorophyll a levels were not representative of eutrophic conditions. To analyse the transport of drift algae, a methodology based on the utilization of a two-dimensional model which solves the depth-averaged advection-diffusion equation considering seaweed as a conservative tracer was developed and applied. Numerical modelling allowed the identification of the coastal areas that seems to be the source of the seaweed found on the beach. It was also proven that port expansion does not significantly affect drift algae transport in the area.     

Integration of a fish bioenergetics model into a spatially explicit water quality model: Application to menhaden in Chesapeake Bay

Although fish are usually thought of as victims of water quality degradation, it has been proposed that some planktivorous species may improve water quality through consumption of algae and sequestering of nutrients via growth. Within most numerical water quality models, the highest trophic level modeled explicitly is zooplankton, prohibiting an investigation of the effect a fish species may be having on its environment. Conversely, numerical models of fish consumption do not typically include feedback mechanisms to capture the effects of fish on primary production and nutrient recycling. In the present study, a fish bioenergetics model is incorporated into CE-QUAL-ICM, a spatially explicit eutrophication model. In addition to fish consumption of algae, zooplankton, and detritus, fish biomass accumulation and nutrient recycling to the water column are explicitly accounted for. These developments advance prior modeling efforts of the impact of fish on water quality, many of which are based on integrated estimates over an entire system and which omit the feedback the fish have through nutrient recycling and excretion. To validate the developments, a pilot application was undertaken for Atlantic menhaden (Brevoortia tyrannus) in Chesapeake Bay. The model indicates menhaden may reduce the algal biomass while simultaneously increasing primary productivity.     

Spatial patterns of macroalgal abundance in relation to eutrophication

Based on a large monitoring data set from Danish coastal waters we tested the hypotheses: (1) The vertical pattern of algal abundance is regulated by exposure in shallow water and by light limitation towards deeper water, resulting in a bell-shaped abundance curve, with peak abundance located deeper at more exposed sites, (2) in deeper water, total algal abundance and abundance of perennial algae decrease along a eutrophication gradient while (3) abundance and relative abundance of opportunists increase. The vertical pattern of algal abundance showed a peak at intermediate water depths which was located deeper in more exposed areas and thus confirmed our first hypothesis. For algae growing from depths of peak abundance and deeper, the study demonstrated that total algal abundance and abundance of perennials and opportunists at given depths decreased significantly along a eutrophication gradient and the relationships had high explanatory power (R ² = 0.53–0.73). These results confirmed our second hypothesis. By contrast, the relative abundance of opportunists responded solely to salinity and was largest in the most brackish areas, in contradiction to hypothesis three. The lack of coupling between eutrophication and relative abundance of opportunists arises because both opportunists and the entire algal community were light limited and their ratio therefore relatively insensitive to changing water clarity. The analyses indicated that algal abundance initially responded slowly to increasing eutrophication but showed a more marked response at TN concentrations of 35–40 μM. However, the existence of possible threshold nutrient levels demands further analyses.     

Size, not morphology, determines hydrodynamic performance of a kelp during peak flow

The morphology and shape of algae can affect their survival in wave-swept environments because of the hydrodynamic drag created by water flow. Studies of morphology and drag are typically conducted at relatively low water velocities, and the influence of algal morphology on drag, over the range of water velocities algae must cope with in their natural environment, remains unclear. Here, we tested the link between morphological variation and hydrodynamic drag for a dominant kelp with complex morphology (Ecklonia radiata), over a range of water velocities representative of conditions on wave-swept reefs. Our results indicated that kelps on subtidal reefs must withstand maximal orbital water velocities in excess of 2–3 m s^?1. Our measurements of drag, resulting from flows ranging from 1 to 3 m s^?1, revealed that shape- and width-related thallus and lamina characters were important to drag at low speed, but that total thallus area (or biomass) was the main determinant of drag at high flow. Drag coefficients converged at increasing speed suggesting that, at high flow, significant thallus reconfiguration (more streamlined shape) decoupled drag from morphology. This implies that, at peak velocities, only size (total area), not morphology, is important to drag and the probability of dislodgment.     

Algal blooms decrease care but increase egg survival in a fish with paternal care

Human-induced eutrophication, resulting in algal blooms and increased water turbidity, is an alarming problem in aquatic systems. Here, we experimentally tested the impact of algal turbidity on parental care, egg fanning, and time in the nest, in the sand goby, Pomatoschistus minutus, a fish with uniparental male care. We allowed males to care for their eggs in either clear water or water made turbid by planktonic algae. In the early brood cycle, males fanned their eggs less in turbid than in clear water, but this difference disappeared later. Despite decreased care, egg survival was higher in turbid conditions, indicating that early fanning may partly be redundant for egg survival and perhaps used more as courtship. Males also spent more time out of their nest in turbid water, perhaps as a means to encounter additional females under conditions of low visibility.     

Wind induced upwelling as a possible explanation for mass occurrences of epiphyticEctocarpus siliculosus (Phaeophyta) in the northern Baltic Proper

The quantity of epiphytic filamentous algae varies considerably in macroalgal vegetation along rocky shores of the northern Baltic Proper. The main species responsible for irregular mass occurrences is the summer annual brown algaEctocarpus siliculosus (Dillw.) Lyngb. In this study, data collected over a 3-yr monitoring period are related to hydrographical parameters. The tideless and brackish Baltic Sea is salinity stratified, and the salinity difference between surface and bottom waters can be used to indicate upwelling events. Mass occurrences developed when the salinity difference was low. These salinity differences explained 87% of the observed increase inE. siliculosus cover. We propose that the slight salinity changes themselves do not affect the growth ofE. siliculosus, but rather they can be used as indicators of short nutrient pulses. These nutrient pulses are not detected in standard water sampling, as they are utilised by both pelagic and benthic organisms within a few hours or days. If the proposed mechanism is true, changes in wind speed and direction have an important effect on the nutrient dynamics of littoral algal communities. A higher frequency of SW winds may cause mass occurrences of filamentous algae, which are often believed to indicate eutrophication of an anthropogenic origin.     

高原深水湖泊程海氮磷形态分布特征及其与叶绿素a的相关性

湖泊水体氮、磷形态分布特征及其与藻类生长的关系是湖泊富营养化研究的重要方面。采用GPS定位,在程海湖设置了3个断面9个采样点,研究了氮、磷形态分布特征,并分析了各形态氮磷与叶绿素a的相关性。结果表明：总氮（TN）质量浓度为0.773 mg.L-1,总磷（TP）质量浓度为0.046 mg.L-1,叶绿素a质量浓度为0.024 mg.L-1。氮素的赋存形态特征是以溶解态总氮（DTN）占大部分,DTN中又以溶解态有机氮（DON）占绝大部分;磷素的存在特点是溶解态无机磷（DIP）含量比重较大。各形态氮、磷都有明显的季节性波动但区域性差异不明显,叶绿素a则有明显的季节节律和时空差异。叶绿素a很好地响应了总氮（TN）、总磷（TP）、溶解态总氮（DTN）、溶解态总磷（DTP）、颗粒态总氮（PTN）、颗粒态总磷（PTP）的变化。程海富营养化受氮和磷共同限制,控制富营养化必须同时削减氮和磷。