水动力条件对藻华的影响

水动力条件在湖泊富营养化及藻华爆发的过程中起着决定性的作用.研究了水动力条件对藻类生长的影响,从而找出控制藻类生长的关键因素和相关参数.对于防治藻华具有重要意义.     

九龙河流域水文气象因子演变趋势分析

通过收集整理九龙河流域水文气象监测站点实测监测的气温、降水、蒸发、径流等系列资料,应用数理统计方法分析了流域水文气象因子演变趋势,得出流域气温自20世纪90年代以来持续升高,降水量自1983年以来持续小幅减少,流域为半湿润区,径流量自20世纪80年代以来线性大幅减少等结论。为流域综合治理、经济社会建设、水资源管理提供技术支撑。     

淮北平原基于水文气象多因子的土壤水分动态预测

为研究土壤水分动态变化,利用五道沟水文实验站1989-2015年水文气象和大田土壤水实测资料,采用灰色关联度和线性回归分析,建立了冬小麦各生长阶段不同土层土壤水分预测模型。结果表明:不同土层土壤水分与气象因子的关联度一致;不同生长阶段土壤水分与气温和地下水埋深关联度最强,分别达0. 92和0. 95;分蘖-越冬期,土壤水分与地下水埋深和日照时数关联度最强,其他生长阶段,土壤水分与气温和地下水埋深关联度最强。通过水文气象因子模拟土壤水分拟合度较高,R~2达0. 94。不同生长阶段不同土层,土壤水分计算模型均具有良好的预测能力,R~2达0. 80。成果为实施作物不同生长阶段的灌溉计划提供科学依据。     

环境因子对引黄水库水中水华鱼腥藻生长的影响

以济南引黄水库水中分离出的水华鱼腥藻为对象,研究了不同培养温度、光照、pH条件对其生长的影响;在最佳培养温度和光照强度的基础上设计了L9(34)正交试验模拟研究氮磷物质对水华鱼腥藻生长的影响。结果表明水华鱼腥藻的最适生长温度为30℃,光强为6 000lx;氮磷营养盐对藻类生长影响排序为硝酸盐磷酸盐氨氮亚硝酸盐。研究提示磷可能是引黄水库水华鱼腥藻生长限制因子,在夏、秋季及水库氮、磷浓度大幅变化时应预防鱼腥藻水华的发生。     

某流域水文气象要素变化对水体的影响分析

以水文学研究方法为切入点,利用监测数据及遥感技术.探究塔里木流域气候变化下水体的变化规律.最终得出:塔里木流域地区,随着蒸发降低,年均降雨量升高,水体面积呈现出逐渐增加的趋势.说明降雨量对于水体的控制程度较高.该研究为区域水资源调控方案提供科学的依据.     

温度和光强对4种常见水华藻叶绿素荧光特性的影响

为探寻藻类水华暴发的机理,实现水华的预测预警和防治,深入研究藻类的生理生态学特性十分重要。以4种常见水华藻类(汉斯冠盘藻、小环藻、斜生栅藻和铜绿微囊藻)为研究对象,应用叶绿素荧光技术研究了不同温度梯度和光照强度对4种常见水华藻类叶绿素荧光特性的影响。研究结果显示汉斯冠盘藻对低温有良好的适应性,高温易造成热胁迫,其适宜的生长温度为3~22 ℃;在3~22 ℃条件下,随着光强的增强,其电子传递速率显著增加,表明其具有强的光保护能力和光能利用效率;铜绿微囊藻对高温有着较好的适应性,适宜温度为15~30 ℃,10 ℃以下会受到低温胁迫,光能利用效率随温度上升而升高;小环藻表现出对高温的适应性,3~10 ℃低温导致生长迟滞;相比而言,斜生栅藻对温度的适应范围更广,在22~30 ℃条件下,斜生栅藻具有更高的光能利用效率和光量子产量。研究结果显示了不同藻类生理生态学特性的差异,为水华的预测预警和治理提供参考。     

动力条件对引黄水库藻类的影响

通过维持光照、温度、营养盐等影响因子的一致性,设置不同流速,研究了不同水动力条件对藻类生长的影响。结果表明:在试验条件下,流速小于0.19 m/s时,吸光度随着流速的增大而增大;流速大于0.22 m/s时,吸光度随着流速的增大而减小;流速在0.19~0.22 m/s之间存在临界值。     

太原汾河公园水华高发期叶绿素a 与环境因子的关系

利用2012年5月至9月太原市汾河公园蓄水池水华防治专项监测资料,分析了1号蓄水池叶绿素a(Chl-a)的动态变化及与相关环境因子的关系。结果表明,在整个研究期间,Chl-a的波动较大,浓度范围为20.1¹32.0mg/m3,均值为55.553 mg/m3;5月份Chl-a含量总体上低于其它月份;Chl-a含量总体上与水温(WT)、COD、总磷(TP)、氨氮(NH3-N)均呈现极显著的正相关,与溶解氧(DO)、总氮(TN)、透明度(SD)呈极显著负相关,但与pH值关系不显著。不过Chl-a与环境因子的关系在不同时间段的表现有所差异:水体Chl-a含量在5月份受环境因子的影响不显著;6月份则显著受到有机质、总磷(TP)、总氮(TN)的影响;7月份受到有机质、TP、透明度(SD)极显著的影响,8月、9月份受到WT、TP、SD的极显著影响。     

黄河源区水文气象要素变化对生态环境的影响

根据黄河源头地区的降水、蒸发、径流等水文气象要素多年变化资料,并结合20世纪70～90年代的卫星影像资料的分析,认为气候变化和人类活动等因素极大地改变了黄河源头地区生态环境的格局,是影响黄河源头生态环境的主要因素。     

不同形态氮对富营养化水源藻华暴发的潜在影响

富营养水源藻华的暴发是给水厂进行水质处理的一大难题.通过设计正交试验,研究了不同营养水平下的硝酸氮、亚硝酸氮、氨氮随藻类生长的变化情况.结果表明,在设计系列中,当N:P=36时,藻类的生长数目达到最大;藻类在吸收N源时更倾向于吸收有机氮DON而不是无机氮DIN;无机氮的利用中藻类倾向于先吸收氨氮而不是硝态氮.     

北京城区河湖水体水华现象成因的初步分析

由于近年来北京市水资源短缺与水环境污染日益严重,北京市城市河湖富营养化愈趋明显,至2001年,北京城区水域爆发了大面积的水华现象.从水体富营养化发生的内在主因与外部条件分析了城市河湖水华现象形成的原因,对京城水系的富营养化控制与水污染防治具有理论指导意义.     

城市河湖水华防治技术研究

城市河湖的富营养化给城市水环境造成了许多不利因素,改善水质,消除藻类水华是一个不容忽视的重要问题。阐述了应用于富营养化水体中藻类控制的物理、化学和生物技术的内容、存在的问题和不足。指出了各种方法有机结合,进一步研究出高效的控制策略才能更加有效地控制水华现象的发生。     

再生水回用人工景观水体优势藻和水华指示指标的研究

以城市污水处理厂二级出水作为人工景观水体用水,考查了北京5～9月期间藻类的生长情况。研究结果表明,以二级出水作为景观用水的人工水池中,夏季暴发水华的优势藻种类以绿藻为主,主要有小球藻、十字藻、栅藻等,另外还有短时期的裸藻出现,蓝藻一直没有成为优势种属。试验水体的氮磷比为5～15,处于地表水的氮磷比为3～45,可见氮磷比并不是决定水华优势藻的主要因素。对各项指标的监测及分析表明,碳元素的水平才是影响水中优势藻种的关键。试验结果得出水体透明度与藻类生长有明显的相关性,在本试验中当透明度低于0.4m可称已发生水华,可作为水华发生的指示指标。     

膜组合工艺应对藻类暴发的能力研究

藻类暴发严重威胁饮用水水质以及供给。试验采用投加混凝剂、粉末活性炭和高锰酸钾作为微滤膜预处理的膜组合工艺,考察应对藻类暴发的能力。研究表明,藻类暴发会引起有机物含量的增加,主要是小分子(相对分子质量低于1 000)的中性亲水组分的大量增加,这类有机物可通过预处理得到有效的去除,因而没有发现藻类暴发会对膜过滤产生严重的影响,粉末活性炭和高锰酸钾可有效延长膜过滤周期。导致膜不可逆污染的有机物主要为中等分子的强疏水和中小分子的中性亲水组分。     

ECO-HYDRAULICS TECHNIQUES FOR CONTROLLING EUTROPHICATION OF SMALL SCENERY LAKES-A CASE STUDY OF LUDAO LAKE IN SHANGHAI

The Ludao Lake with an area of 0.86 km2 and 50% water surface ratio, was taken as an example to study the eco-hydraulics techniques for preventing lake eutrophication. Besides external water inflow and outflow, the term related to internal local flow circulation was added in the continuity equation of two-dimensional horizontal hydrodynamic model, and further the hydrodynamic model was calibrated by the scenario of no water exchange. The velocity of 0.2 m/s was suggested to be the critical velocity of controlling algal bloom. To achieve the critical velocity in the whole lake, three factors were analyzed, which are wind, artificial external inflow augmentation and internal local flow disturbance by pump circulation. It is found that the role of wind can be disregarded. For the eco-hydraulics technique of external lake water inflow augmentation, the water flowing route should be firstly optimized, further, the lake inflow has a critical value under specified water level due to the narrow inlets, so the whole lake is difficult to reach the critical velocity to prevent algal bloom, and a combination of external inflow augmentation and internal local flowing disturbance should be considered. Simulation results show that the combination of external water inflow augmentation and internal local flow disturbance requires less eco-flow to achieve the global critical velocity than the sole internal local flow disturbance, for the Ludao Lake, the former requires total eco-flow of 25 m3/s, which reduces by 50% than the latter requiring total eco-flow of 52 m3/s.     

水库水动力对水体富营养化影响

当氮磷浓度达到富营养水平时,水动力条件(流量、流速和水位)可能成为制约因子,抑制水华发生.河道型深层出水的水库相对于湖泊型表层出水的水库,因为较大交换流量,较低营养盐浓度,保证了浮游植物和藻类较低的现存量.进一步研究水文条件(滞留时间、水位变化和水流运动)发现,保持较低的滞留时间、较高的水位和底层较低的流速,都有利于水库水体中营养盐和藻类的稀释,不利于浮游植物和藻类的生长,减缓水体富营养化进程.     

Models for identifying significant environmental factors associated with cyanobacterial bloom occurrence and for predicting cyanobacterial blooms

Compared with microscopic indices such as biomass, inverted satellite images can reflect cyanobacterial blooms from a macroscopic perspective, can provide planar information for blooms, and can more definitely reflect the occurrence of visible cyanobacterial blooms. We therefore adopted inverted images (from MODIS imagery) to judge whether cyanobacterial blooms had occurred in a water area at a given time. We constructed two probit models for identifying significant environmental factors related to cyanobacterial bloom occurrence and for short-term forecasts of bloom occurrence. The models used the index of cyanobacterial bloom occurrence as the dependent variable and the predicted variable, respectively, and used three categories (water quality, hydrology, and weather) of monitoring variables as the independent variables (or predictive variables). We used the Hill Dagong water area of Lake Tai in China as a case study of the new methods. The results produced by the identification model are consistent with the general conclusions in this research field indicating the validity of the model. The mean relative error of the forecast model is 13.5%, which is close to or lower than that of two previous models. Compared with the previous models, our forecast model also has advantages in terms of spatial and temporal precision. The new models have both practical applicability and the ability to be generalized and can, therefore, be easily adapted for the prevention, control, and prediction of cyanobacterial blooms in other bodies of water.     

植物抑藻作用及抑藻物质研究

利用植物体内的化感物质进行有害藻类的控制,是一种新型安全的生物抑藻技术,近年来成为水环境领域的研究热点。笔者综述了国内外植物抑藻作用及抑藻物质研究的主要成果,包括已发现的具有抑藻作用的植物种类、已鉴定出的抑藻物质类型,总结了植物抑藻研究中的常用方法及影响抑藻效果的因素,最后提出了植物抑藻技术应用于实践有待研究的问题。     

Effect of selenium on the growth of some selected green and blue-green algae

An algal assay procedure using microplate technique was carried out to assess the effect of selenium on the growth of some green and blue-green algae. Sodium selenite pentahydrate (Na₂SeO₃.5H₂O) and selendioxide (Se₂O₄) were tested as selenium. The test algae were Selenastrum capricornutum, Scenedesmus obliquus, Chlorella sp., Monoraphidium convolutum, Monoraphidium contortum, Monoraphidium griffithii, Anabaena flos-aquae, Micro-cystis aeruginosa, and Oscillatoria agardhii. The blue-green algae are toxin-producing strains. Cell number and in vivo chlorophyll fluorescence were the growth parameters of green and blue-green algae respectively. Dose-response curves quantify the selenium toxicity in terms of EC₅₀. The lowest selenium concentrations giving no detectable growth (EC₁₀₀) were visually inspected. The test algae showed distinctly different responses to various selenium treatments. Selenium at concentrations < 0.1 mg L⁻¹ stimulates, to varying degrees, the growth of all the green algae with one exception: S. capricornutum was dramatically inhibited at all treatments. O. agardhii, A. flos-aquae and M. aeruginosa showed marginal growth stimulation up to 0.1 mg Se L⁻¹, 1.0 mg Se L⁻¹ and 3.2 mg Se L⁻¹ respectively. In terms of EC₅₀, the compound selendioxide was more toxic to greens than sodium selenite. The reverse was indicated for the blue-greens. In general, the EC₅₀ presented a wide range (0.08–7.2 mg Se L⁻¹), with the lowest values reported for S. obliquus and the highest for M. aeruginosa. All the test algae, except S. obliquus, maintained observable growths at higher selenium levels (EC₁₀₀>1.0<100mg Se L⁻¹).