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。     

ES抑藻剂对再生水补给景观水体水华的防治研究

通过实验室使用小球藻对ES抑藻剂进行抑藻测试,主要测试该抑藻剂对藻类抑制效果,同时确定了ES抑藻剂在实验室条件下,水华刚开始爆发时和水华爆发后的最低使用浓度和使用周期。经过测试,发现该抑藻剂对水华的控制有良好的效果,并且水华发生前实施药剂抑藻,药剂投加量少,抑藻效果好。对以再生水为补水的景观河道进行了现场测试,测试时ES抑藻剂使用浓度为实验室确定的使用浓度的5倍。经过测试,该抑藻剂可以有效地防治水华的暴发,保证测试河道的景观功能。同时在有外来含大量藻类的水体进入河道时,及时对含藻水体投加抑藻剂能够有效控制藻类数量,成功治理藻类水华。     

再生水回用于景观水体磷营养盐对叶绿素a和藻密度的影响研究

以北京市某再生水厂出水为研究对象,人工配制各浓度梯度的营养盐,试验研究补给再生水后景观水体水质指标的变化,重点考察磷对叶绿素a和藻密度的影响情况.试验结果表明叶绿素a和藻密度主要受水体中氮磷比和磷酸盐浓度的影响.在磷酸盐保持在1 mg/L以下,氨氮在2 mg/L以下,硝酸盐氮在8 mg/L以下,将再生水一次性补给景观水体是完全可行的,不会产生藻类暴发;当磷酸盐浓度增加至1.5 mg/L,藻密度将显著增加.     

再生水补水水体中氮磷对斜生栅藻生长影响的研究

北京市利用再生水补充景观水体的主要问题是其引发的水华现象,选取富营养化较严重的西护城河作为研究对象,观察水体中藻类群落发现,绿藻中的栅藻为优势种;调整河水中N、P的浓度做藻类增长潜力(AGP)试验,结果表明,河水中氮磷含量及氮磷比与斜生栅藻(Scenedesmus Obliquus)的生长有一定的关系.     

漳泽水库水体富营养化与水华风险趋势分析

通过对漳泽水库2010—2013年水质、藻类细胞密度和水华暴发风险的分析,对水库水体富营养化程度和水华暴发风险现状和趋势有了初步认识。漳泽水库不同区域的水体营养化评价以轻度富营养为主,年际变化不明显。漳泽水库不同区域藻类细胞密度变化并不完全一致,与全国气候相近地区的水库相比,水库藻类细胞密度较大。4 a间漳泽水库在藻类监测月份藻类细胞密度均超过临界标准,处于藻类暴发的临界状态,藻类细胞密度最高的年份是2011年,从2013年开始逐步下降。     

文峪河水库藻类组成及季节变化简析

以《全国藻类试点监测技术规程》为依据,对文峪河水库进行每月一次的藻类监测.了解了水库的藻类密度和种类组成,分析了藻类组成和优势种的季节分布特征.通过对水库富营养化状态评价和水华爆发风险的分析,得出水库虽暂时富营养程度不高,爆发水华的风险不大,但依然存在进一步富营养化的趋势.提出抑制水库富营养化趋势和降低水华爆发风险的具体措施.     

再生水景观功能保障系统的试验研究

以北京北小河污水处理厂二级出水作为观赏性景观水体补水水源,研究了过滤系统在改善再生水景观功能中的作用,同时得出以再生水作为补水水源的景观水体爆发水华时的水质特征和优势藻种。通过试验研究得出相关的工艺参数。研究表明,采用过滤系统作为再生水景观功能的水质保障系统具有处理效果好、运行经济的特点。     

汾河水库藻类监测与评价

以《全国藻类试点监测技术规程》为依据,对汾河水库进行藻类监测。通过对水库水质、富营养化和藻类的分析,了解了藻类密度、组成和优势种的季节变化特征。指出水库虽暂时富营养化程度不高,爆发水华的风险不大,但存在进一步富营养化的趋势,提出防治水库进一步富营养化和降低水华爆发风险的措施。     

再生水回用中氮磷对两种典型水华藻类生长影响研究

根据相关标准,试验选取了不同的氮磷浓度值,对蓝藻水华常见的铜绿微囊藻和绿藻水华常见的小球藻分别进行了单独培养以及两者的竞争试验.结果表明,铜绿微囊藻生长的最适氮磷浓度分别为15 mg/L、0.3～0.5 mg/L,小球藻生长的最适氮磷浓度分别为15 mg/L、0.1～0.5 mg/L;在氮磷比为15、30、50、150的试验条件下,竞争试验中的优势藻均为小球藻.建议以再生水为补水水源的景观水体中,再生水的氮磷浓度分别控制为:总氮≥15 mg/L、磷≤0.1 mg/L、氮磷比为150以上,能有效地抑制铜绿微囊藻生长.     

再生水回用于景观水体氮营养盐对叶绿素a和藻密度的影响研究

再生水回用于景观水体是否会带来严重的生态风险,尚需广泛而深入的研究。以北京市某再生水厂出水为研究对象,人工配制各浓度梯度的营养盐,试验研究补给再生水后景观水体水质指标的变化,重点考察氮营养盐(氨氮、硝酸盐氮)对叶绿素a和藻密度的影响情况。试验结果表明叶绿素a和藻密度主要受水体中氮磷比和磷酸盐浓度的影响,与单独的硝酸盐氮浓度增加并无直接的关系。当磷酸盐浓度保持在1mg/L以下,氨氮浓度在4mg/L以下,硝酸盐氮浓度在16mg/L以下,将再生水一次性补给景观水体是可行的,不会产生藻类暴发。     

不同再生水占比景观水体水质演变机制实验研究

以永定河(北京段)为研究对象,开展不同再生水占比景观水体连续24d的水质监测实验,监测指标包括化学需氧量、氨氮、溶解氧、pH、电导率及土壤微生物多样性等。结果分析表明:相同实验条件下永定河上游山峡段河岸带土壤微生物多样性明显好于下游沙质断流河岸带土壤,而二者混合形成的沙土有利于丰富土壤微生物多样性;高再生水占比水体对于环境更加敏感,更容易因为外部因素引起水质变化,在高温下水质恶化速率更快;根据实验所监测的多项水质指标与生态效应综合分析,静止景观水体再生水占比在超过75%以后水质持续恶化,推荐永定河实际景观河道再生水占比控制在75%以下。     

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.     

Automatic area estimation of algal blooms in water bodies from UAV images using texture analysis

Algal blooms, the spread of algae on the surface of water bodies, have adverse effects not only on aquatic ecosystems but also on human life. The adverse effects of harmful algal blooms (HABs) necessitate a convenient solution for detection and monitoring. Unmanned aerial vehicles (UAVs) have recently emerged as a tool for algal bloom detection, efficiently providing on-demand images at high spatiotemporal resolutions. This study developed an image processing method for algal bloom area estimation from the aerial images (obtained from the internet) captured using UAVs. As a remote sensing method of HAB detection, analysis, and monitoring, a combination of histogram and texture analyses was used to efficiently estimate the area of HABs. Statistical features like entropy (using the Kullback–Leibler method) were emphasized with the aid of a gray-level co-occurrence matrix. The results showed that the orthogonal images demonstrated fewer errors, and the morphological filter best detected algal blooms in real time, with a precision of 80%. This study provided efficient image processing approaches using on-board UAVs for HAB monitoring.

     

再生水回用于景观水体的富营养化趋势研究

通过对天津市三个利用再生水作为水源的景观水体的调查监测,发现以再生水为水源的景观水体存在较强的富营养化趋势。三个景观水体采用的再生水处理工艺相同,但后续处理措施不同,水体的含盐量不同。研究发现,采用循环净化系统的水体中叶绿素a浓度一般较低,但未采用循环净化系统的水体由于水体较浅、含盐量高等原因,没有出现藻类暴发的现象。研究结果表明,适当的后续补充处理措施及水体深度和外界环境条件对于保持以再生水为水源的景观水体水质有积极作用。     

Inactivation of algal blooms in eutrophic water of drinking water supplies with the photocatalysis of TiO2 thin film on hollow glass beads.

Photocatalytic inactivation of algae, Anabaena, Microcystis, and Melosira, was carried out with TiO2-coated Pyrex hollow glass beads under the illumination of UV light (370 nm wavelength). After being irradiated with UV light in the presence of the TiO2-coated Pyrex glass beads, Anabaena and Microcystis, known as typical cyanobacteria, lost their photosynthetic activity, and the string of Anabaena cells and the colonies of Microcystis cells were completely separated into individual spherical ones. In the case of Melosira, which is a typical diatom, however, somewhat lower photocatalytic inactivation efficiency was obtained, which was believed to be due to the presence of the inorganic siliceous wall surrounding the cells of Melosira. The TiO2-coated hollow glass beads could successfully be employed for the practical application in a eutrophicated river under sunlight. More than 50% of the chlorophyll-a concentration could be reduced by the action of TiO2 photocatalysis.     

Unmanned aerial system based spectroradiometer for monitoring harmful algal blooms: A new paradigm in water quality monitoring

Water quality issues continue to impact recreational and resource use of waterways in the Great Lakes and across smaller inland water bodies in their watersheds. With the advancements in small unmanned aerial systems (sUAS) and in small sensor production, sUAS offer flexibility to overcome several of the shortcomings of satellite and airborne systems, and complement their measurements in this environment. In this study, we deployed two different low-cost, boat launchable sUAS configurations instrumented with Ocean Optics STS hyperspectral Vis-NIR spectroradiometers capable of making measurements over an approximately 2.5 km² area, below the cloud deck in the nearshore and open lake environment. Flights of these systems were conducted at ten locations over Lake Erie and the Maumee River. Measured spectra compared well with at-surface based Analytical Spectral Devices (ASD) Fieldspec measured spectra, and derived parameters were consistent with in-water FluoroProbe measured water quality parameters and field observations. Using flight data, we constructed transect maps of derived CI products which show the variability in algae abundance in open water. These systems provide high quality, low cost, very high spatial resolution (cm to m scale measurements) hyperspectral data in the nearshore environment, can be consistently flown at low altitude (minimizing atmospheric effects) below cloud cover and can be deployed on extremely short notice. With the continued advancement in sensor development, automated flight capabilities, and increased flight duration from vertical take off and landing (VTOL) platforms, water quality observation platforms such as these will soon be a common tool in resource manager's toolboxes.