蓝藻水华强度的显著相关环境因素识别模型

为识别蓝藻水华强度的显著相关环境因素,克服现有研究中因变量选择不合理、时间与空间精度较低等问题,构建了以蓝藻水华强度等级为因变量,以水质、水文和气象3类监测指标为自变量的多元线性回归模型,并将该模型应用于太湖蓝藻水华研究.基于水华面积和集聚强度数据,用7级量表生成水华强度等级值,使因变量具有宏观性,避免了仅使用叶绿素a浓度等类似指标表示水华强度所体现出的微观性不足.该数据集的时间精度达到每天采样2次,空间精度则达到太湖湖湾内的某个水域空间范围.因此因变量具有适度宏观性,而自变量的值则与因变量的值在较高的时间和空间精度基础上严格对应.模型的分析结果显示,太湖大贡山水域蓝藻水华强度与气温和硝酸盐浓度呈显著正相关,与风速、湿度和电导率呈显著负相关.上述结论与该研究领域的主流结论一致,验证了该模型的有效性.     

太湖蓝藻的时空变化规律及治理方法

利用2009─2012年丰水期和平水期的生物调查获取的环境和生物数据,研究太湖蓝藻的时空分布规律,分析蓝藻分布与其他物理、化学和生物因子（如温度、酸碱性、有机物和营养盐含量、浮游植物与浮游动物密度等）的相关关系。结果表明：太湖水质基本上超出V类地表水指标,主要的超标因子是总氮。总氮在丰水期和平水期的质量浓度分别为3.05 mg·L-1和1.65 mg·L-1,总氮在丰水期质量浓度降低的主要原因可能是丰水期蓝藻迅速生长,吸收了大量的营养盐。蓝藻仍是太湖浮游植物的优势种。2009─2012年太湖蓝藻的密度随年份无明显变化,但随季节和区域存在显著差异：丰水期蓝藻密度均值为4.87×10^7cell·L-1,明显高于平水期蓝藻密度（1.51×10^6 cell·L-1）;太湖东部采样点蓝藻密度明显低于其他湖区。影响蓝藻的非生物因素包括温度、酸碱度和营养盐,高温、偏碱性和高营养盐含量都会增加蓝藻的密度。蓝藻与其他浮游植物和大型水生植物之间存在竞争关系,蓝藻密度增加促进了枝角类的生长。推荐利用机械打捞和大型水生植物修复方法,因为这2种方法可在降低蓝藻密度的同时去除水体中的有机物和营养盐,可以从根本上降低太湖蓝藻水华的风险。增加其他藻类和枝角类控制蓝藻水华方法可行性较差：1）蓝藻暴发时期其它藻类对能量和营养的竞争能力弱于蓝藻,难以抑制蓝藻的生长;2）在太湖中增加枝角类可能降低现有蓝藻的密度,但建立完整的食物链体系降低富营养化程度,防范生物调控中可能存在的生态风险（如其他藻类水华等）较困难。     

基于Sentinel-2遥感影像的巢湖蓝藻水华提取方法研究

Sentinel-2卫星兼具了空间分辨率高、重放周期短、谱段丰富三方面特点,为蓝藻水华爆发阶段及时准确的蓝藻水华提取提供了影像基础,但目前在大型湖泊蓝藻水华提取中的应用报道较少。为此,文章以2018—2020年巢湖的Sentinel-2遥感影像为例,开展包括浮游藻类指数(FAI)在内的多指标蓝藻水华提取方法研究,针对FAI阈值难以确定的典型问题,提出了基于回归分析的FAI阈值确定方法。结果表明,(1)与低分辨率卫星MODIS和GF-1影像的蓝藻水华提取结果相比,Sentinel-2提取到了面积小至100 m2的蓝藻水华区域,提取结果差异主要集中在蓝藻水华区域的边缘部分以及面积较小的零星区域,证明了Sentinel-2遥感影像能够更精确地估算蓝藻水华面积。(2)以NDVI的阈值0为基准,通过回归分析确定FAI的阈值为-1.152(决定系数r2达到0.982 3,显著性检验P<0.001),对2019年6—11月无云雾遮挡的Sentinel-2遥感影像,分别采用归一化植被指数(NDVI)与FAI指标提取蓝藻水华面积,结果表明蓝藻水华的分布情况基本一致,且蓝藻水华面积的相对偏差小于5%,证明了FAI阈值确定方法的有效性。(3)选取云雾遮挡但无大规模蓝藻水华爆发的Sentinel-2遥感影像,分别采用NDVI和FAI指标提取蓝藻水华面积,在无云雾遮挡的区域,两个指标的蓝藻水华分布情况一致,而有云雾遮挡的区域,FAI指标的提取面积仅为NDVI的53.89%,证明FAI指标受云雾影响更小。Sentinel-2遥感影像的高空间分辨率使巢湖蓝藻水华提取更为准确,在未来的水质监测领域将彰显更大的价值。     

太湖水华蓝藻中元素的组成及其环境意义

利用电感耦合等离子质谱仪对2008年7、9和10月采自太湖南泉水域的水华蓝藻样本中19种元素(Na、Mg、K、Ca、Zn、Mn、Fe、Al、Cu、Cr、Co、Ni、As、Se、Mo、Ag、Tl、Cd和Pb)的质量含量(w)及组成变化进行研究。结果表明,在藻华中w较高(1 000μg.g-1,以干质量计)的常量元素或有益元素为Ca、K、Na、Mg、Al、Fe。其中,w(Ca)和w(K)较高(4 000μg.g-1),w(Ca)随月份变化不大,而w(K)、w(Mg)、w(Na)则逐月升高。w(Al)、w(Fe)变化较大,7月最高(1 000μg.g-1),之后迅速降低(400μg.g-1);藻华中w在10~100μg.g-1之间变化的元素为Mn、Zn、Ni、Cu,其中,7月这4种元素w均最高,9~10月则降低。藻华中还检出痕量元素Co、Mo和Se,Tl未检出。藻华中积累的有毒元素中w(As)较高(5~15μg.g-1),而w(Cr)、w(Cd)、w(Pb)、w(Ag)均较低(5μg.g-1)。有毒元素w最高值均出现在7月。基于上述结果,推算出2007—2009年采取物理方法除藻从太湖中移除的元素量约为:K595.89 t、Ca 544.03 t、Mg 181.18 t、Al 83.06 t、Na 63.97 t、Fe 55.45 t、Mn 2.99t、Zn 2.26 t、Ni 1.67 t、Cu 1.11 t、As 0.76 t、Cr 94.5 kg、Cd 82.70 kg、Se 45.01 kg、Pb 37.64 kg、Co 32.27 kg、Mo5.41 kg和Ag 2.46 kg。该研究不仅可为进一步寻找关键元素在蓝藻水华爆发过程中的限制作用及其机制提供基础数据,同时也可为评价利用物理除藻方法去除太湖中有毒元素和降低有可能促进藻华发展的营养元素的负荷量的有效性,从而保护和修复渔业环境提供理论依据。     

微囊藻毒素在太湖白鲢体内的累积规律及其影响因素

太湖蓝藻水华及其次级代谢产物微囊藻毒素(MCs)的生物累积对生态系统和人体健康造成严重威胁,已成为最近环境科学研究的热点。本研究从太湖的不同区域(梅梁湖、西部沿岸区、南部沿岸区和湖心区)采集不同体重和体长的白鲢,利用固相萃取方法提取、高效液相色谱-质谱联用仪测定了白鲢不同器官中MCs的3种异构体MC-RR、MC-YR及MC-LR的含量,结合不同湖区的相关水质指标分析了MCs在白鲢体内的累积规律及其影响因素。研究结果表明:白鲢不同器官MCs的含量由高到低为:肠壁肾脏肝脏肌肉心脏,且肠壁累积的MCs显著高于肾脏、肝脏、肌肉和心脏。MC-RR含量是白鲢各器官累积MCs的异构体的主体,约占MCs的60%。梅梁湖鲢鱼的肌肉、肾脏和心脏中MCs均高于西部沿岸区、南部沿岸区和湖心区。生物指标(体重和体长)是影响白鲢肾脏内MCs和MC-RR含量以及肠壁内MCs含量重要因素。太湖水质指标总磷(TP)、藻细胞数量、湖泊营养指数及环节动物数量尤其是TP对白鲢肝脏累积MCs产生明显影响,TP、总氮(TN)、铵态氮(NH4-N)、内梅罗指数和环节动物数量尤其是NH4-N对肠壁累积MCs产生明显影响。     

太湖浮游植物群落结构及其与水质指标间的关系

为了探讨太湖浮游植物群落结构时空分布特征、以及太湖浮游植物群落指标与水质指标间的关系,于2013年1月─2013年12月对太湖7个点位浮游植物群落结构和水质指标（水温、透明度、pH、溶解氧、电导率、总氮、总磷、氨氮、高锰酸盐指数、化学需氧量、氟化物、生化需氧量、硝酸盐氮、亚硝酸盐氮、溶解性磷酸盐和叶绿素a）进行月度调查,研究其浮游植物群落结构和湖泊水质的时空分布;并利用Pearson相关性分析浮游植物密度、浮游植物多样性与水质指标间的关系;找出影响太湖浮游植物群落结构的主要水质指标。结果表明：太湖7个点位共获得124种浮游植物物种,其中蓝藻门（Cyanophyta）30种、绿藻门（Bacillariophyta）47种、硅藻门（Chlorophyta）34种、隐藻门（Cryptophyta）3种、裸藻门（Euglenophyta）6种和甲藻门（Dinoflagellate）4种;其中蓝藻门的微囊藻属（Microcystis spp.）为绝对优势种群,优势度为80.8%;太湖浮游植物总密度与蓝藻门密度呈极显著正相关（r=1.000,P＜0.0001）;绿藻门和硅藻门占浮游植物总密度百分比分别和蓝藻门占浮游植物总密度百分比呈极显著负相关（r=-0.497,P＜0.0001;r=-0.814,P＜0.0001）。太湖7个点位水质首要污染物为总氮,其次是总磷和化学需氧量;西太湖污染物浓度最高。从空间上看,太湖浮游植物总密度最高值出现在贡湖湾（远离其入湖口处）,且贡湖湾浮游植物群落多样性相对低于太湖其他点位,同时贡湖湾微囊藻属密度百分比达90.1%,远高于太湖其他点位;从时间上看,太湖浮游植物总密度最高值出现在12月份、其次是6月份;通过浮游植物群落指标与水质指标相关性分析,水温、透明度、总氮、化学需氧量、叶绿素a是影响太湖浮游植物群落结构的主要水质指标。控制太湖入湖口水质污染物浓度排放和修?     

Rise of toxic cyanobacterial blooms in temperate freshwater lakes: causes,correlations and possible countermeasures

The progressive degradation of surface freshwater quality due to the mass proliferation of toxic cyanobacterial blooms is of growing global concern. The occurrence of cyanobacterial blooms is not a new phenomenon. However, a global increase in the frequency, duration, and distribution of toxic cyanobacterial blooms could be observed in the past decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. The underlying causes and interrelations for this development have not been fully clarified. Nonetheless, all evidence points to the fact that mitigation of toxic cyanobacterial blooms will be a key challenge of the twenty-first century. This review addresses the underlying causes for the increased incidence of toxic cyanobacteria in temperate freshwater lakes and attempts to reveal possible reciprocities between bloom promoting factors. Selected approaches for the prevention of toxic cyanobacterial blooms as well as the mitigation of their potential negative impacts on humans will be presented.     

A hydrodynamic and water quality modeling study of spatial and temporal patterns of phytoplankton growth in a stratified lake with buoyant incoming flow

A three-dimensional hydrodynamic and water quality model was applied to Lake Paldang, a lake in South Korea that is stratified by incoming flows. The spatial and temporal patterns of phytoplankton growth in this lake were determined from the model. The model was calibrated and verified using data measured under different hydrological conditions. The model results were in reasonable agreement with the field measurements, in both the calibration and verification phases. The distributions of water quality and residence time in the lake and phytoplankton response to changes in nutrient loads were examined with the model, and the influence of the hydrodynamics on phytoplankton response was analyzed. The simulation results indicated that Lake Paldang is an essentially phosphorus-limited system, but that phytoplankton growth is limited by low water temperature and short residence time during the winter and the summer monsoon period, respectively. The results of sensitivity analyses also suggested that the hydrodynamics within the lake may have an indirect influence on phytoplankton responses to changes in the limiting nutrient loads, and that reducing phosphorus loading from Kyoungan Stream should be a high priority policy for controlling algal blooms during the pre- and post-monsoon periods. From this study, it was concluded that the three-dimensional water quality model incorporating hydrodynamic processes could successfully simulate phytoplankton response to changes in nutrient loads and that it could become a useful tool for identifying the essential factors determining phytoplankton growth and for developing the best management policy for algal blooms in Lake Paldang.     

太湖重污染湖区和水源地水质概况及藻毒素污染环境风险

近年来太湖流域局部水质状况有所改善,但太湖藻型生境条件还未根本改变,水污染防治任务依然艰巨。确保太湖湖体水质稳定达标,尤其是加强对太湖重点湖区和水源地重点污染物的调查研究十分重要。在此背景下,本文调研了太湖重点湖区和水源地水质概况、藻毒素污染时空分布特征、环境影响因子和迁移转化规律,并总结了藻毒素的环境和健康风险研究的最新进展,指出了太湖西部湖区和饮用水源地的主要环境风险,以及未来太湖藻毒素污染相关研究需解决的关键技术问题,以期为促进太湖流域重点污染物的控制和治理,确保太湖饮用水源地安全提供有益借鉴。     

Quantitative characterization of Cu binding potential of dissolved organic matter （DOM） in sediment from Taihu Lake using multiple techniques

Dissolved organic matter （DOM） plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the third largest freshwater and a high eutrophic lake in the downstream of the Yangtze River, China. In the lake, frequent breakout of algae blooms greatly increased the concentration of different organic matters in the lake sediment. In this study, sediment samples were collected from various part of Taihu Lake to explore the spatial difference in the binding potential of DOM with Cu. The titration experiment was adopted to quantitatively characterize the interaction between Cu（II） and DOM extracted from Taihu Lake sediments using ion selective electrode （ISE） and fluorescence quenching technology. The ISE results showed that the exogenous DOM had higher binding ability than endogenous DOM, and DOM derived from aquatic macrophytes had a higher binding ability than that derived from algae. The fluorescence quenching results indicated that humic substances played a key role in the complexation between DOM and Cu（II） in the lake. However, because of the frequent breakout of algae blooms, protein-like matters are also main component like hnmic matters in Taihu Lake. Therefore, the metals bound by protein-like substances should be caused concern as protein-like substances in DOM were unstable and they will release bound metal when decomposed.     

Eutrophication status and control strategy of Taihu Lake

The water quality and eutrophication status of Taihu Lake in recent years are presented and the pollution trends are analyzed. It is shown that because of unreasonable industrial structures, pollution discharge per GDP is high within the Taihu basin, and the pollution discharge from point and non-point sources exceed the basin’s environmental carrying capacity. Especially, excessive pollutants containing nitrogen and phosphorus are being discharged. Moreover, eutrophication may also result from internal pollution sources such as the release of nutrient elements from sediment. All these factors have resulted in the water quality deterioration of Taihu Lake. To solve this environmental problem, possible control strategies are summarized, including the control of internal pollution sources and inflow-river pollution, ecological restoration and reconstruction of the degraded lakeside zone ecosystem, clean water diversion, dredging, and manual algae removal.     

水华蓝藻上浮特征与机理的试验研究

利用柱状反应器和太湖蓝藻水华爆发期含有蓝藻颗粒的水体进行试验,模拟了蓝藻上浮特征,对水华蓝藻上浮过程中相关的物理化学因素进行了研究,探讨了蓝藻上浮与物理化学因素之间的相互作用和相关性。试验结果表明：反应器表层蓝藻上浮率明显大于底部,表层以下上浮率随时间没有明显变化规律,不同时刻上浮率变化特征是晚上22：00〉10：00〉14：00;pH和正磷酸盐呈现相似的变化规律,表层和底层的值均小于中间;对相关性进行分析表明,碳水化合物、氨氮和溶解氧是蓝藻上浮的主要影响因素,10：00时与上浮率相关性较大的指标是碳水化合物（P〈0.01）,14：00是溶解氧（P〈0.01）,22：00是碳水化合物（P〈0.05）与氨氮（P〈0.01）,相关系数分别达到0.896、0.887、0.887、0.860。     

Microbial interactions with the cyanobacterium Microcystis aeruginosa and their dependence on temperature

Associated heterotrophic bacteria alter the microenvironment of cyanobacteria and potentially influence cyanobacterial development. Therefore, we studied interactions of the unicellular freshwater cyanobacterium Microcystis aeruginosa with heterotrophic bacteria. The associated bacterial community was greatly driven by temperature as seen by DNA fingerprinting. However, the associated microbes also closely interacted with the cyanobacteria indicating changing ecological consequence of the associated bacterial community with temperature. Whereas concentration of dissolved organic carbon in cyanobacterial cultures changed in a temperature-dependent manner, its quality greatly varied under the same environmental conditions, but with different associated bacterial communities. Furthermore, temperature affected quantity and quality of cell-bound microcystins, whereby interactions between M. aeruginosa and their associated community often masked this temperature effect. Both macro- and microenvironment of active cyanobacterial strains were characterized by high pH and oxygen values creating a unique habitat that potentially affects microbial diversity and function. For example, archaea including ‘anaerobic’ methanogens contributed to the associated microbial community. This implies so far uncharacterized interactions between Microcystis aeruginosa and its associated prokaryotic community, which has unknown ecological consequences in a climatically changing world.     

The addition of FeOOH binds phosphate in organic matter-rich sediments

Due to climate change and anthropogenic nutrients’ runoff into freshwater or shallow lakes, eutrophication caused by phosphorus (P) can be seen in the frequent occurrence of cyanobacterial blooms and excessive growth of macrophytes. Subsequently, decomposition of cyanobacterial bloom biomass (CBB) and macrophytes leads to massive autochthonous organic matter (OM) and creates hypoxia in bodies of water. In this study, we investigated the effects of OM and iron on phosphorus release from lake sediments under anaerobic conditions. As with CBB, the addition of cellulose also enhanced P release from sediments during microcosm experiments, while total phosphorus (TP) concentration in the overlying water displayed an inverse relationship to cellulose amendment, with high TP concentration (0.41?±?0.07?mg?L^?1) observed in the treatment of less cellulose amendment (1?g of cellulose). In addition, P release from OM-rich sediments was effectively inhibited when amorphous FeOOH was added to the microcosms. P release was inhibited by 66–92% when the weight ratio between total Fe and total P in sediments varied from 18 to 60. Thus, iron treatment was useful to inhibit P release from OM-rich sediments, and could alleviate eutrophication problems.     

应用物种敏感性分布法分析太湖及天目湖水体的生态风险

采用物种敏感性分布法(SSDs法),应用水生生物急性和慢性毒性数据计算了31种污染物在水中和其中疏水物质在沉积物中的预测无效应浓度(PNECwater和PNECsed),通过收集以往报道的16种污染物在太湖和天目湖的环境浓度,用商值法求得物质的风险商并进行排序.结果发现:蒽、菲、萘、荧蒽、阿特拉津和马拉硫磷在太湖的梅梁湾和五里湖具有很大的生态风险;毒死蜱、三丁基锡氧化物和环己锡虽无环境浓度报道但很有可能具有风险.     

Seven years from the first application of polyaluminium chloride in the Czech Republic – effects on phytoplankton communities in three water bodies

This study determines the efficiency of polyaluminium chloride application on phytoplankton species as a consequence of five reservoir restorations in the Czech Republic during the years 2005 and 2008, including the first ever large-scale application. Although polyaluminium chloride has been used in water treatment plants across the world, information about its application toward cyanobacterial blooms in nature is poor. Although the application of polyaluminium chloride did not cause any fundamental long-term changes in the composition of phytoplankton species or phosphorus load, instead causing fast and acute removal of the phytoplankton community, it may act as an algicidal compound with fast removal efficiency. All treated water bodies described in our study remained unaffected by cyanobacterial blooms and the hygienic limit for the purposes of recreation was not exceeded in any particular season. This article should serve as notice of the advantages and disadvantages of polyaluminium chloride application, and also warn against the uniform usage of this chemical as a method of reducing phytoplankton species in all types of water bodies where cyanobacteria are present. Moreover, data about the effects on non-target (invertebrates) species and microcystin release from cyanobacterial cells are also mentioned.     

Annual cycles of phytoplankton community-structure and bloom dynamics in the Neuse River Estuary, North Carolina

The spatiotemporal distributions of major phytoplankton taxa were quantified to estimate the relative contribution of different microalgal groups to biomass and bloom dynamics in the eutrophic Neuse River Estuary, North Carolina, USA. Biweekly water samples and ambient physical and chemical data were examined at sites along a salinity gradient from January 1994 through December 1996. Chemosystematic photopigments (chlorophylls and carotenoids) were identified and quantified using high-performance liquid chromatography (HPLC). A recently-developed factor-analysis procedure (CHEMTAX) was used to partition the algal group-specific chlorophyll a (chl a) concentrations based on photopigment concentrations. Results were spatially and temporally integrated to determine the ecosystem-level dynamics of phytoplankton community-constituents. Seasonal patterns of phytoplankton community-composition changes were observed over the 3 yr. Dinoflagellates reached maximum abundance in the late winter to early spring (January to March), followed by a spring diatom bloom (May to July). Cyanobacteria were more prevalent during summer months and made a large contribution to phytoplankton biomass, possibly in response to nutrient-enriched freshwater discharge. Cryptomonad blooms were not associated with a particular season, and varied from year to year. Chlorophyte abundance was low, but occasional blooms occurred during spring and summer. Over the 3 yr period, the total contribution of each algal group, in terms of chl a, was evenly balanced, with each contributing nearly 20% of the total chl a. Cryptomonad, chlorophyte, and cyanobacterial dynamics did not exhibit regular seasonal bloom patterns. High dissolved inorganic-nitrogen loading during the summer months promoted major blooms of cryptomonads, chlorophytes, and cyanobacteria. Received: 12 September 1997 / Accepted: 12 December 1997     

无锡市水环境变化及其引发的地质灾害问题与对策

随着经济的快速发展，无锡市水环境质量发生了很大的变化。由于在太湖、五里湖等湖泊周围大规模围湖造田，水域生态环境和原有水系格局被破坏，五里湖、梅梁湖水质恶化，每10年下降一个等级，太湖水质总体上呈现富营养化状态。水环境变化在一定程度上导致了地面沉降的发生，有的地区地下水位呈加速下降的趋势，有的地区已出现多个地下水位降落漏斗，后者面积达220km^2。应该加快区域供水建设步伐，调整工业结构，加强对水资源的管理和调控。