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.     

艾溪湖水华蓝藻多样性探讨

本文首次阐明了艾溪湖水华蓝藻的种类、形态及分类学特征,对艾溪湖水华蓝藻的组成和多样性指数进行了分析,并对艾溪湖水华蓝藻种类在全国的分布特征和产毒能力进行了讨论.艾溪湖水华暴发时蓝藻丰度占据绝对优势并导致藻类多样性急剧下降,严重抑制其它藻类生长.显微镜检后发现优势水华蓝藻7种,分别是惠氏微囊藻、挪氏微囊藻、阿氏浮丝藻、螺旋浮丝藻、拉氏拟浮丝藻、依沙矛丝藻、紧密长孢藻.艾溪湖优势水华蓝藻存在季节演替,春季水华蓝藻优势种是微囊藻,夏季是拉氏拟浮丝藻和螺旋浮丝藻.部分种类能够产生微囊藻毒素、神经毒素等藻毒素,对艾溪湖水生态安全具有重大威胁.     

香溪河水质的平面二维数值模拟

三峡工程建成后改变了三峡库区及长江支流的水动力条件,对水生态环境产生重要影响,导致近年来水华现象频繁发生.该文采用空气动力学数值格式的平面二维水质模型对香溪河的水流水质进行了模拟研究,并采用2007年9月～10月和2008年6月～7月香溪河的水质监测数据对此模型进行了率定和验证.计算结果表明:该模型可以准确地模拟香溪河水流水质时空分布,并验证了流速是诱发香溪河水华发生的重要因素,且0.03 m/s为香溪河水华发生的临界流速;香溪河的营养物质浓度在水华期间处于动态变化中,特别是上游河段的浓度受来流所含营养物质浓度的影响明显,此研究结果可为三峡库区水质管理提供相关科学依据.     

基于水文过程的滨江城市水生态系统修复方法——以浦口区城南河流域为例

正项目从多学科角度对滨江城市水生态修复机理进行全方位总结梳理,提出了从水文、水质、生物、水生态服务功能等方面进行水生态环境现状评价的方法。结合海绵城市理念,构建城南河流域河网水文水质模型和LID水质模型,针对城南河流域干支流水生态现状开展水生态修复的实例研究。提出控源截污、水系连通、生态补水、海绵城市、生态修复等措施,制定水生态修复方案,定量定性分析修复措施模拟效果,确定最佳方案。     

水库潮汐式调度对支流水动力影响研究——以三峡库区支流小江为例

三峡水库蓄水运行后,库区支流在春夏季时有水华暴发,对水质造成了一定影响。大量研究表明,通过水库调度改变库区支流水动力条件,抑制水华发生是可行的。采用Delft3D模型对三峡库区支流小江渠马-双江大桥段进行模拟研究,以探明潮汐式调度对库区支流水动力的影响,为抑制库区支流水华发生进行生态调度提供理论支撑。研究结果表明：三峡水库开展潮汐式调度对小江的水流具有扰动作用,整体趋势表现为水位抬升期回水区中、下游段流速值均有所减小,水位下降时流速值有所增加,基本与河口水位变化的步调保持一致;调度期水位变幅越大,流速的扰动越大;水位抬升期表现为流速减小幅度随调度水位变幅的增加而增加,水位下降期表现为流速增加幅度随调度水位变幅的增加而增加。     

三峡库区水环境模型系统构建

流域水环境受地形、气象、水文和社会经济等诸多方面的因素影响,其模拟分析是当前的研究热点也是一大难点。基于流域水循环机理,通过识别污染物主要来源和迁移途径,对流域及其内部发生的复杂污染过程定量化描述,构建了包含陆地模型、三维水动力模型和水质水生态模型的空-地-水一体化水环境模型体系,实现了大流域尺度水环境系统的高效模拟。通过模型条件节点和应用节点的协调运作,提升了水环境自动监控能力,实现了对全流域水环境状况实时模拟预测的业务化运行和突发事故的快速预警。将系统应用于三峡库区,验证了模型的有效性。研究成果可以为三峡库区的水环境管理提供可靠的技术支撑,对保障三峡库区水环境安全具有十分重要的现实意义。     

三峡水库支流库湾营养源解析及水体富营养化调控对策研究

支流库湾水体富营养化是三峡水库带来的主要环境问题之一,三峡水库进入常态调度运行后,支流库湾水体富营养化问题日益突出。为厘清易发生水华的支流库湾水体富营养化的驱动力因素,本文以重庆市奉节县梅溪河为典型支流,采用三维水动力与水环境模拟技术解析了支流库湾水动力的驱动机制及营养盐来源及其组成。干-支流水温差导致的密度流是梅溪河支流库湾蓄水期及枯水运行期的主要驱动力,密度流对支流库湾的水动力影响自河口向上游逐渐减弱,干流倒灌输入的N、P营养盐占梅溪河易发生水华的库湾尾部区营养盐收支比重不足20%,而陆域面源输入(70%)成为梅溪河支流库湾水体富营养演化的主要营养来源。因此,在长江干流水质及干支流水温难以有效调控的条件下,遵循"源头控制-过程阻断-末端拦截-水体原位削减-水生态系统修复"的系统治理思路有针对性支流库湾富营养化水体调控对策措施,可为三峡水库水体富营养化程度较重的支流库湾水污染治理及水质目标适应性管理提供参考。     

大型浅水湖泊水动力特性数值分析

准确模拟太湖水流动态变化特性及水动力特征对模拟、预测污染物迁移转化规律以及理解水流运动与污染物相互作用机制具有重要的实用价值。以环境流体力学(EFDC)模型为基础,收集2009年-2010年水文、气象数据及湖区地形数据,并考虑引江济太工程对湖区的影响,建立符合太湖湖区水流特性的水动力模型。模型模拟结果表明最大风向、最大风速的组合方式模拟出来的流场情况最接近真实湖体流场,引江济太工程对湖流的影响微小,模型的水动力模拟效果良好。     

基于水文过程的滨江城市水生态系统修复方法——一浦口区城南河流域为例

项目从多学科角度对滨江城市水生态修复机理进行全放总结梳理,提出了从水文、水质生物、水生态服务功能等方面进行水生态环境现状评价的方法.结合海绵城市理念,构建城南河流域河网水文水质模型和LID水质模型,针对城南海流域干支流水生态现状开展水生态修复的实例研究.     

基于数据同化校正参数的河流磷迁移估计研究

通过磷迁移数学模型合理估计磷在河流中的时空分布,对防治水体富营养化,抑制水华暴发具有重要的科学和工程意义。数据同化方法可以将模型和观测两种研究手段有机地结合起来,将观测数据融入模型,优化模型状态变量,校正模型参数,进而提高数学模型的模拟预报精度,并依托物联网技术将传统数学模型发展为实时数学模型。本文将粒子滤波数据同化算法引入到水动力-泥沙-磷迁移模型中,以实测的断面磷含量作为观测数据,在观测时刻优化磷含量估计结果,同时校正模型参数磷相平衡分配系数Kd,构建了水动力-泥沙-磷迁移模型同化系统。将其应用于长江上游寸滩至坝前河段的计算结果表明,所构建的同化系统在真实的河流中计算效果良好,可以有效地优化更新状态变量各相磷含量浓度,并反演出模型参数Kd随水沙水环境条件变化的动态变化过程,同化之后模型模拟预报磷输移过程的精度显著提升,为水质实时模型打下基础。     

A novel method for tracking western Lake Erie Microcystis blooms, 2002–2011

After a period of improvement from the late 1970s through the mid 1990s, western Lake Erie has returned to eutrophic conditions and harmful algal blooms now dominated by the cyanobacterium Microcystis aeruginosa. The detection of long-term trends in Microcystis blooms would benefit from a convenient method for quantifying Microcystis using archived plankton tows. From 2002 to 2011, summer Microcystis blooms in western Lake Erie were quantified using plankton tows (N = 649). A flotation separation method was devised to quantify Microcystis biovolume in the tows, and the method was tested against whole water cell counts. Floating Microcystis biovolume (mL) in preserved tows was highly correlated with total Microcystis cells (R² = 0.84) and biomass (R² = 0.95) in whole water samples. We found that Microcystis annual biovolume was highly variable among years; the 2011 bloom was 2.4 times greater than the second largest bloom (2008) and 29.0 times greater than the smallest bloom (2002). Advantages of the method include use of archived samples, high sampling volume, and low effort and expense. Limitations include specificity for cyanobacterial blooms dominated by large Microcystis colonies and the need for site-specific validation. This study indicates that the flotation method can be used to rapidly assess past and present Microcystis in western Lake Erie and that there was high variability in the timing, duration, and intensity of the annual Microcystis blooms over a 10-year period. The data made possible by this method will aid further investigations into the underlying causal factors of blooms.     

From River to Lake: Phosphorus partitioning and algal community compositional changes in Western Lake Erie

The Maumee River is an important source of phosphorus (P) loading to western Lake Erie and potentially a source of Microcystis seed colonies contributing to the development of harmful algal blooms in the lake. Herein, we quantified P forms and size fractions, and phytoplankton community composition in the river–lake coupled ecosystem before (June), during (August), and after (September) a large Microcystis bloom in 2009. Additionally, we determined the distribution and density of a newly emergent cyanobacterium, Lyngbya wollei, near Maumee Bay to estimate potential P sequestration. In June, dissolved organic phosphorus (DOP) was the most abundant P form whereas particulate P (partP) was most abundant in August and September. Green algae dominated in June (44% and 60% of total chlorophyll in river and lake, respectively) with substantial Microcystis (17%) present only in the river. Conversely, in August, Microcystis declined in the river (3%) but dominated (32%) the lake. Lake phytoplankton sequestered < 6% of water column P even during peak Microcystis blooms; in all lake samples < 112 μm non-algal particles dominated partP. Lyngbya density averaged 19.4 g dry wt/m², with average Lyngbya P content of 15% (to 75% maximum) of water column P. The presence of Microcystis in the river before appearing in the lake indicates that the river is a potential source of Microcystis seed colonies for later lake blooms, that DOP is an important component of early summer total P, and that L. wollei blooms have the potential to increase P retention in nearshore areas.     

Response of Microcystis and Stephanodiscus to Alternative Flow Regimes of the Regulated River Nakdong (South Korea) Quantified By Model Ensembles Based on the Hybrid Evolutionary Algorithm (HEA)

This study demonstrates the use of inferential models for scenario analyses by simulating direct and indirect effects of predictor variables on state variables through model ensembles. Two model ensembles have been designed to predict the response of the cyanobacterium Microcystis aeruginosa and the diatom Stephanodiscus hantzschii to modified flow regimes of the River Nakdong (Korea) by a scenario analysis. Whilst flow‐independent predictor variables of growth of Microcystis and Stephanodiscus such as water temperature and pH remain unchanged during the scenario analysis, flow‐dependent predictor variables such as turbidity, electrical conductivity, phosphate, nitrate, silica and chlorophyll a are forecasted by inferential models. In the course of scenario analysis, flow‐independent and flow‐dependent predictor variables feed into the Microcystis and Stephanodiscus models to make sure that both direct and indirect effects of altered flow regimes are taken into account. The eight inferential models that were incorporated into the model ensembles have been developed by the hybrid evolutionary algorithm based on 19 years of time‐series monitored in the River Nakdong between 1993 and 2012. The models achieved good accuracy in terms of timing and magnitudes reflected by coefficients of determination r² = 0.94 for Microcystis and r² = 0.83 for Stephanodiscus. The scenario analysis revealed that extreme summer blooms of Microcystis as observed between 1994 and 1997, and winter blooms of Stephanodiscus as observed between 1994 and 1997 and in 2004 can be prevented in the River Nakdong by adaptive management of seasonal water release from adjacent dams. Copyright © 2017 John Wiley & Sons, Ltd.     

基于鱼类栖息地需求的雅鲁藏布江中游环境流量计算

针对水利工程影响下,河道下游天然水文情势改变造成鱼类产卵场面积减小和质量降低等潜在生态问题,通过数值模拟与统计建立拉萨裸裂尻鱼产卵期栖息地适宜度模型,采用栖息地模拟法计算了雅鲁藏布江中游藏木水电站坝下米林—尼洋河汇口处38.9 km河段的环境流量。结果表明:拉萨裸裂尻鱼产卵期适宜水深为0.7～1.0 m,适宜流速为0.4～0.6 m/s;研究河段内拉萨裸裂尻鱼产卵期环境流量为432 m~3/s。     

水文变异下淮河长吻鮠生境变化与适宜流量组合推荐

以淮河干流鱼类长吻鮠为保护目标,建立长吻鮠分时期生态需求与流量之间的概念性模型。对FLOWS法进行改进,加入水文变异前后长吻鮠生态环境对比分析,根据分析结果推荐一组适于长吻鮠生长繁殖的流量组合。结果表明,在环境流量成分的对比分析中,变异前的高脉冲流量历时长、发生时间合适,变异后发生洪水的频率增高,变异前的流量更适于长吻鮠的生长繁殖;在相关水力参数满足程度的对比分析中,在长吻鮠生长繁殖的各个时期,变异前的流量条件均优于变异后。选取变异前的平水年1970年的流量作为基础,推荐适宜流量组合,即产卵期的流量为545~1 212m~3/s,幼鱼索饵期应大于1 750 m~3/s,越冬期应大于等于74 m~3/s。该研究可为保护淮河珍稀物种,为淮河生态调度提供依据。     

自然河道中沉水植物苦草对水流的生理响应

通过野外现场研究苦草生长和生理对水流的响应规律。结果表明:30~40 cm/s的水流速度对苦草的生长形态有影响;与静水区相比,动水区中苦草植株矮小、叶片较窄。在植物生长旺季和生殖生长期间,动水对植物细胞内的蛋白质和可溶性糖含量有促进作用,同时也诱导过氧化氢(H2O2)等活性氧上升,使得超氧化物歧化酶(SOD)、过氧化氢酶(CAT)等抗氧化酶活性相应提高以降低活性氧伤害;30~40 cm/s的流速对苦草生长有一定的影响,但不影响苦草在河道生态修复中的应用。     

Vertical distribution of Microcystis colony size in Lake Taihu: Its role in algal blooms

This study investigated the vertical distributions of Microcystis cell density and colony size in Lake Taihu where algal blooms occur frequently. Measurements were made from April 2011 to January 2012 to gain a seasonal outlook on the role of such distributions in the blooms. It was found that large colonies tended to accumulate on the water surface, but the cell density fluctuated widely. The cell density in the water column increased continuously from spring to summer (i.e., April to October) and decreased after late autumn, showing apparent seasonal variations. The abrupt occurrence and disappearance of Microcystis blooms over short periods of time were not caused by the rapid growth of Microcystis but by the rise and accumulation of large Microcystis colonies at the water surface, both of which are affected by colony size. The ascent velocity of large colonies was higher than that of small ones, which enables large colonies to more readily overcome the stirring effects of water flows, waves and perturbations to rise to the surface. The results of canonical correspondence analysis (CCA) of Microcystis vertical distribution in relation to environmental factors suggested that nutrient concentrations and temperature were the main influencing factors related to bloom formation by Microcystis in Lake Taihu during our investigation.     

Status,causes and controls of cyanobacterial blooms in Lake Erie

The Laurentian Great Lakes are among the most prominent sources of fresh water in the world. Lake Erie's infamous cyanobacterial blooms have, however, threatened the health of this valuable freshwater resource for decades. Toxic blooms dominated by the cyanobacterium Microcystis aeruginosa have most recently been one of primary ecological concerns for the lake. These toxic blooms impact the availability of potable water, as well as public health and revenues from the tourism and fishery industries. The socioeconomic effects of these blooms have spurred research efforts to pinpoint factors that drive bloom events. Despite decades of research and mitigation efforts, these blooms have expanded both in size and duration in recent years. However, through continued joint efforts between the Canadian and United States governments, scientists, and environmental managers, identification of the factors that drive bloom events is within reach. This review provides a summary of historical and contemporary research efforts in the realm of Lake Erie's harmful cyanobacterial blooms, both in terms of experimental and management achievements and insufficiencies, as well as future directions on the horizon for the lake's research community.     

The good,the bad,and the algae: Perceiving ecosystem services and disservices generated by zebra and quagga mussels

Dreissenid (zebra and quagga) mussels are widely recognized as having strong, adverse ecological and economic impacts, e.g., biofouling and loss of water column primary production. We assessed perceptions and values associated with two less often considered ecological outcomes of dreissenid mussel influences on coastal ecosystems along Lake Ontario and the western St. Lawrence River in New York State. One, the generation of water clarity through filtration, we define as an ecosystem service; the other, the production of large amounts of nuisance algae (e.g., Cladophora and Microcystis) is defined as an ecosystem disservice. Surveys of business owners and homeowners quantified their preferences and the formation of values regarding these products of zebra mussel influence. Water clarity increased greatly, particularly in the eastern portion of Lake Ontario, and algal problems increased throughout. Businesses attributed increases and decreases in revenues associated with water clarity and algae; homeowners reported analogous changes in property values. Water clarity was positively associated, and algae negatively associated, with changes in revenues and property values. Threshold responses of costs as functions of filamentous algae were evident. Given the likely continued influx of invasive species due to human activities, further development of the ecosystem service concept should consider potential “goods” and “bads” of invasives and their influence on ecosystem and social system resiliency.     

不同生物联合对滇池草海水质的净化作用

为了解不同沉水植物种植密度、不同沉水植物组合、沉水植物和鲫组合对滇池草海富营养化水体的净化效果,于2017年9—12月在滇池草海东风坝试验平台,选取4种滇池现存土著沉水植物(篦齿眼子菜(Stuckenia pectinata)、轮叶黑藻(Hydrilla verticillata)、穗花狐尾藻(Myriophyllum spicatum)、马来眼子菜(Potamogeton wrightii))、1种鱼(鲫(Carassius auratus))进行不同组合模拟试验。结果表明:种植密度为(0.63±0.06)g/L的篦齿眼子菜和轮叶黑藻对于TP的去除效果明显优于(0.33±0.05)g/L的种植密度;不同沉水植物组合均能够提高水体中的氮磷比,对草海富营养化水体的TN、TP、Chl-a具有明显的去除效果,试验组TN、TP、Chl-a的平均去除率分别提高了49.67%、9.06%、39.41%;鲫对于轮叶黑藻和篦齿眼子菜的生长具有明显的促进作用,加入鲫的穗花狐尾藻和马来眼子菜组合TN去除率提高了87.48%,且试验结束后,水体TN、TP去除效果稳定;沉水植物组合中,穗花狐尾藻和轮叶黑藻在高营养盐水体中生长状况最好,同时能有效控制水体中的TN、TP和Chl-a的质量浓度;鲫+穗花狐尾藻+马来眼子菜组合对草海富营养化水体的SS、TN、TP、Chl-a都具有较高的去除能力。