Phytoplankton of the Karasuk River (West Siberia) as an indicator of water quality

The authors discuss the indicator value of taxonomic structure, abundance, and biomass of phytoplankton and use of the indicators to characterize water quality by example of the Karasuk River, West Siberian Plain.     

Cyanobacteria and cyanotoxins in the source water from Lake Chivero,Harare, Zimbabwe,and the presence of cyanotoxins in drinking water

The phytoplankton community and cyanotoxins in Lake Chivero (formerly Lake McIlwaine) and the presence of cyanotoxins in treated drinking water were investigated between 2003 and 2004. A typical seasonal succession of Cyanobacteria species occurred from January to April, Bacillariophyta from May to July, and Cryptophyta and Chlorophyta from August to December. Microcystis aeruginosa and M. wesenbergii, known producers of the toxin microcystin, and the non-toxic cyanobacterium M. novacekii dominated during summer. The highest concentrations of microcystins and lipopolysaccharide endotoxins occurred when cyanobacterial biomass was highest. Lipopolysaccharide endotoxin concentrations in the lake ranged between 8 and 3 200 Endotoxin Units (EU) ml^?1. Microcystin concentrations in treated water were below the recommended safe limit for drinking water. Lipopolysaccharide endotoxin concentrations in treated water ranged from 0.15 to 11 EU ml^?1. The phytoplankton community comprised non-microcystin-producing species for the greater part of the study period.     

典型亚热带热分层水库秋季细菌群落垂直分布

水库在我国东南沿海地区是重要的饮用水水源地,对地区经济发展和社会稳定起到重要作用。选择亚热带地区典型的热分层水库——福建莆田东圳水库,于2011年秋季稳定分层期,以水体温度的垂直变化特征为依据进行分层采样。应用PCRDGGE和克隆测序的方法研究浮游细菌群落的垂直分布特征,利用多元统计分析揭示细菌群落与热分层水体理化指标之间的关系。结果显示:溶解氧、电导率、叶绿素a、总氮、氨氮及硝氮在上下层水体中的分布有显著差异,下层缺氧区细菌的ShannonWiener指数和DGGE条带数明显高于上层好氧区,表明东圳水库热分层水体中存在明显的物理、化学及生物分层现象。测序结果表明β-变形菌可能是东圳水库中占优势的细菌类群,统计结果提示溶解氧是显著影响细菌群落组成的环境因子。热分层水体的物理化学分层与水体细菌群落结构密切相关,提示水库生态学研究应对水体热分层给予重视。     

Phytoplankton composition and pigment concentrations as indicators of water quality in the Rybinsk reservoir

Long-term changes in phytoplankton (1954–1981) and chlorophyll (1969–1984) and their spatial distribution in summer 1989 were studied in the Rybinsk reservoir (second largest reservoir of the Volga River, North-West Russia). Estimation of trophic status and saprobity of the reservoir was based on phytoplankton biomass and species composition and chlorophyll content. The most eutrophic waters were found to occupy the peripheral areas in littoral zone and river inflows of the reservoir, while the waters in the central part of the basin were less eutrophic. Long-term changes of the phytoplankton biomass, chlorophyll, chlorophyll/biomass-ratio and saprobity index observed in the central part of the reservoir were analyzed by statistical methods. An increase in saprobity and an inverse relationship between chlorophyll/biomass-ratio and water transparency demonstrate progressive eutrophication in the central part of the reservoir. Two distinct periods (1954–1970 and 1971–1984) could be discerned on the basis of annual mean phytoplankton biomass values. For the earlier period a relationship between biomass and climatic factors (solar radiation and wind velocity) could be established, but no such correlation could be found for the latter period. There was no significant increase in the phytoplankton biomass during the monitoring period, but a definite increase in the proportion of small-sized species of centric diatoms, cryptomonads and blue-greens. These forms are considered as r-strategists in the community, and their increase is interpreted as a sign of eutrophication.     

大辽河水系夏季浮游植物群落结构特征及水质评价

作为建立中国水环境生态学基准的基础性工作,于2010年7月,按照相关规范的要求,对大辽河水系浮游植物群落结构和水质状况进行了调查.结果表明:调查期间大辽河水系共检出5门124种或变种,其中以绿藻和硅藻为主,分别占43.55％和31.45％;总细胞密度在2.05×105～1.46×107个·L-1,平均6.35×106个·L-1,绿藻和硅藻占优势;主要优势种是硅藻的颗粒直链藻极狭变种(Melosira granulata var.angustissima);共检出污染指示种44种,其中β-中污带指示种居多,有36种,占所有指示种的81.81％;Shannon多样性指数为1.43 ～2.68,Margalef指数为1.00～1.78,Pielou均匀度指数为0.52 ～0.83;综合水体中浮游植物的密度、优势种类、指示种、生物多样性指数评价表明,大辽河水系处于富营养化状态、中等程度污染水平.     

Occurrence of saxitoxins and an anatoxin-a(s)-like anticholinesterase in a Brazilian drinking water supply

Blooms of toxic cyanobacteria are very common in Brazilian waterbodies, as a consequence of eutrophication processes. Our investigations were focused on the detection of neurotoxins during a cyanobacterial bloom in Tapacurá reservoir, which serves as a water supply for Recife city in northeastern Brazil. We also investigated the possible presence of neurotoxins in strains of Anabaena spiroides isolated from this environment. Samples were collected from March to May 2002 at the water surface and close to the dam. Limnological parameters (conductivity, pH, inorganic nutrients) and cyanobacterial abundance were measured. The samples were assayed for toxicity by mouse bioassay and acetylcholinesterase-inhibiting activity by a colorimetric method; saxitoxins (paralytic shellfish poisons) were quantified by a HPLC-FLD postcolumn derivatization method. The dominant cyanobacteria during the bloom were found to be A. spiroides, Pseudanabaena sp., Cylindrospermopsis raciborskii and Microcystis aeruginosa. The mouse bioassays showed the presence of neurotoxins during both A. spiroides and C. raciborskii dominance, whereas anticholinesterase activity was only observed during periods of A. spiroides dominance. The A. spiroides strains isolated during the study also exhibited an acetylcholinesterase inhibitor. HPLC-FLD chromatograms of bloom material extracts revealed the presence of saxitoxin, neosaxitoxin and dc-saxitoxin, probably produced by C. raciborskii.     

Shifts in water quality in a drinking water reservoir during and after the removal of cyprinids

Lake ülemiste, the drinking water reservoir of Estonia’s capital city Tallinn, was biomanipulated by manual removal of cyprinids in 2004–2006 and its impact on water quality in the vegetation period was studied. A total biomass of 156 tonnes corresponding to 160 kg ha⁻¹ of fish, predominantly cyprinids, were removed. A decline in the unit catches of fishing was observed. The removed fish biomass versus phosphorus concentration of the lake was considered sufficient to reduce the impact of cyprinids on water quality. The phosphorus removed within fish biomass corresponded to 38 μg l⁻¹ and 21% of the external phosphorus load of the fishing period. The mean total phosphorus concentration dropped from >50 to ≤36 μg l⁻¹. However, the densities of planktivorous young-of-the-year percids remained high and the role of zooplankton grazing in improving water quality was found non-significant or transient. The cladocerans biomass decreased and the small-sized Daphnia cucullata remained almost the only daphnid in Lake ülemiste during and after the manipulation. Predomination of filamentous cyanobacteria was replaced by a more diverse phytoplankton composition and co-domination of micro- and pico-sized colonial cyanobacteria during summer. Mean phytoplankton biomass decreased from 15 to 6 mg l⁻¹ primarily as a result of decreased in-lake TP availability. The Secchi disc transparency increased only in May 2005–2007. The effects of coincidental events, a decline of external loading of phosphorus and a simultaneous flushing induced by heavy rainfall, on lake water quality are discussed with some implications to the future management of the reservoir.     

Phytoplankton seasonal dynamics in a Mediterranean coastal lagoon: emphasis on the picoeukaryote community

The dynamics of the phytoplankton community were investigatedin a marine coastal lagoon (Thau, NW Mediterranean) from February1999 to January 2000. Dilution experiments, chlorophyll a (Chla) size-fractionation and primary production measurements wereconducted monthly. Maximum growth and microzooplankton grazingrates were estimated from Chl a biomass fractions to separatepico- from nano- and microphytoplankton and by flow cytometryto distinguish between picoeukaryotes and picocyanobacteria.In spring, the phytoplankton community was dominated by Chaetocerossp. and Skeletonema costatum, which represented most of biomass(B) and primary production (P). Nano- and microphytoplanktongrowth was controlled by nutrient availability and exceededlosses due to microzooplankton grazing (g). Picoeukaryote andcyanobacteria growth was positively correlated with water temperatureand/or irradiance, reaching maximum values in the summer (2.38and 1.44 day^–1 for picoeukaryotes and cyanobacteria, respectively).Picophytoplankton accounted for 57% of the biomass-specificprimary productivity (P/B). Picophytoplankton was strongly controlledby protist grazers (g = 0.09–1.66 day^–1 for picoeukaryotes,g = 0.25–1.17 day^–1 for cyanobacteria), and microzooplanktonconsumption removed 71% of the daily picoplanktonic growth.Picoeukaryotes, which numerically dominate the picoplanktoncommunity, are an important source of organic carbon for theprotistan community and contribute to the carbon flow to highertrophic levels.     

汉江中下游浮游植物群落结构及水质评价

南水北调中线工程调水后,汉江中下游水华频发引起社会关注。为掌握调水后汉江中下游浮游植物的群落结构特征,于2017年11月、2018年2月、4月和8月在汉江中下游的8个断面对浮游植物进行了定量调查。调查结果显示:共鉴定浮游植物163种,群落组成以硅藻门(Bacillariophyta)、绿藻门(Chlorophyta)为主,其次是蓝藻门(Cyanophyta)。浮游植物优势种主要为硅藻门的梅尼小环藻(Cyclotella meneghiniana)、颗粒直链藻最窄变种(Melosira granulata var.)、变异直链藻(Melosira varians)、颗粒直链藻(Melosira granulata),隐藻门的卵形隐藻(Cryptomonas ovata),蓝藻门的弯曲颤藻(Oscillatoria sp.)和伪鱼腥藻(Pseudoanabaena sp.),且都有较高的优势度。浮游植物密度和生物量的季节变化范围分别为0. 33×106cells/L～1. 82×106cells/L和0. 49 mg/L～7. 38 mg/L。基于Shannon-Weaver多样性指数和Pielou均匀度指数以及优势种评价法对汉江中下游的水质进行评价,判断汉江中下游水质整体处于中污状态。     

长诏水库浮游植物群落结构及水质评价

于2010年5月、8月和11月对新昌长诏水库浮游植物群落进行了调查,运用Shannon多样性指数(H)、Simpson多样性指数(D)、Margalef丰富度指数(M)及Pielou均匀度指数(J)分析了浮游植物种群的多样性,并结合水质理化指标对长诏水库的富营养化程度及水质状况进行了综合评价.结果显示:长诏水库浮游植物有6门26属(种),其中,绿藻门10属(种),硅藻门9属(种),蓝藻门4属(种),隐藻门1属,甲藻门1属,黄藻门1属.浮游植物的丰度为5.73×105～7.73×105ind·L-1,平均为(6.71±0.81)×105 ind·L-1;生物量为0.73～1.03 mg·L-1,平均为(0.83±0.12) mg·L-1.在水平分布上,蓝藻门、硅藻门和绿藻门的丰度在各采样点中均较高;在季节分布上,硅藻门、绿藻门、蓝藻门分别在春季、夏季、秋季占绝对优势.总体上,浮游植物丰度和生物量在水库入水口较高,出水口较低.水库浮游植物的多样性较差,水质受到较重污染,且主要为氮、磷污染;富营养化程度为中-富营养化水平.     

Bacterial diversity within the planktonic community of an artesian water supply

Culture and molecular methods were used to describe the planktonic bacterial diversity of an artesian water supply in rural Latah County, Idaho, within the drainage of a small perennial stream, Thorn Creek. The surrounding depth to groundwater at this location is thought to be significant (>100 m), and this transitional zone (basalt-granite) of the Palouse aquifer system is little studied. The water produced by this artesian source is consistent even in years of drought and is of high quality, both mineralogically and microbiologically. A culture-based analysis using 30 media types and four incubation temperatures demonstrated that several metabolic types were present in the water. 16S rRNA gene fragments amplified from the DNA of pooled cultured cells and from the DNA extracted from 1 L of the source water were compared using denaturing gradient gel electrophoresis. The results indicated that the two DNA samples did not have similar 16S rRNA gene compositions and that several uncultured phyla were present in the community DNA sample. These results indicated that large-scale culturing did not accurately represent the structure planktonic community. 16S rRNA gene sequences from 17 different genera were obtained from the community DNA sample; the most abundant were similar to Rhodoferax, Rhodobacter, and Polaromonas species. Sequences related to the Proteo bacteria, Bacteroidetes/Chlorobi, Firmicutes, and Acidobacterium/Fibrobacter divisions were also detected.     

A modified drinking water quality index (DWQI) for assessing drinking source water quality in rural communities of Khuzestan Province,Iran

We reconsidered the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) to achieve an efficient drinking water quality index (DWQI) for assessment of drinking source water quality in rural communities of Khuzestan Province, Iran in 2009–2013. In contribution with a panel of water quality experts, the CCME WQI was mainly modified by four changes: (1 and 2) assigning weight factors for input parameters and index factors, (3) modifying excursion concept for carcinogens and bioaccumulative pollutants and (4) removing effect of unequal measurements of input parameters. The DWQI characterizes the drinking source water quality through comparing the measured values of input parameters with relevant benchmarks. The DWQI score (from 0 to 100) classifies the water quality in five categories as poor (0–54.9), marginal (55.0–69.9), fair (70.0–84.9), good (85.0–94.9) and excellent (95.0–100). Based on the DWQI, the temporal changes of the rural drinking source water quality were not significant; while the spatial variations of the water quality were considerable across the province, so the DWQI scores in the northern counties were higher than that in the southern ones. At the county level, the highest and lowest average scores of the DWQI (±standard deviation: SD) were observed in Izeh and Shadegan to be 90 ± 5 and 69 ± 10, respectively. Based on the DWQI, proportions of the drinking water sources with the excellent, good, fair, marginal and poor qualities were determined to be 6.7, 59.1, 26.2, 7.8 and 0.1%, respectively. Turbidity and Ryznar Index (RI) were introduced respectively as the health-based and esthetic parameters with the most violations (22.7 and 63.2%, respectively). The results of the case study and sensitivity analysis indicated that the DWQI is a simple, flexible, stable and reliable index and could be used as an effective tool to characterize drinking source water quality.     

Microbial diversity and composition of the sediment in the drinking water reservoir Saidenbach (Saxonia, Germany)

Sediments contain a huge number and diversity of microorganisms that are important for the flux of material and are pivotal to all major biogeochemical cycles. Sediments of reservoirs are affected by a wide spectrum of allochthous and autochthonous influences providing versatile environments along the flow of water within the reservoir. Here we report on the microbial diversity in sediments of the mesotrophic drinking water reservoir Saidenbach, Germany, featuring a pronounced longitudinal gradient in sediment composition in the reservoir system. Three sampling sites were selected along the gradient, and the microbial communities in two sediment depths were characterized using catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and a bar-coded pyrosequencing approach. Multivariate statistic was used to reveal relationships between sequence diversity and the environmental conditions. The microbial communities were tremendously diverse with a Shannon index of diversity (H') ranging from 6.7 to 7.1. 18,986 sequences could be classified into 37 phyla including candidate divisions, but the full extent of genetic diversity was not captured. While CARD-FISH gave an overview about the community composition, more detailed information was gained by pyrosequencing. Bacteria were more abundant than Archaea. The dominating phylum in all samples was Proteobacteria, especially Betaproteobacteria and Deltaproteobacteria. Furthermore, sequences of Bacteroidetes, Verrucomicrobia, Acidobacteria, Chlorobi, Nitrospira, Spirochaetes, Gammaproteobacteria, Alphaproteobacteria, Chloroflexi, and Gemmatimonadetes were found. The site ammonium concentration, water content and organic matter content revealed to be strongest environmental predictors explaining the observed significant differences in the community composition between sampling sites.     

Understanding the impacts of intermittent supply on the drinking water microbiome

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汕头港浮游植物组成特征及其与环境的关系

于2009年3月-2010年3月对汕头港生态环境进行连续监测,研究了浮游植物组成及其对环境条件的敏感程度.结果表明:研究区共鉴定出322种浮游植物,包含了234种硅藻,141种淡水和半咸水种以及64种赤潮生物;浮游植物丰度、Shannon指数和均匀度指数分别是3127.6×104cells·m-3、2.53和0.57;中肋骨条藻(Skeletonema costatum)和颤藻( Oscillatoria sp.)是全年优势种,优势度分别是0.066和0.038;浮游生物数量组成结构与温度明显相关(r=0.699,P<0.01).浮游植物与环境因子之间的相关性分析显示,透明度是汕头港浮游植物生长主要限制因子.比较浮游植物数量组成与环境因子间的相关程度发现,上游输入是汕头港污染物的重要来源之一.多维尺度与Pearson相关性分析显示,汕头港浮游植物群落结构变化主要受温度、盐度与pH影响.     

Assessment of water quality in groundwater resources of Iran using a modified drinking water quality index (DWQI)

An innovative drinking water quality index (DWQI) based on the Canadian DWQI was developed as “modified DWQI” and applied for assessing the water quality in all of the groundwater resources that are used as the source of drinking water in urban areas of Iran in 2011. Assignment of weight factors for input parameters was the modification carried out in the DWQI. In development of the modified DWQI, twenty-three water quality parameters and relevant Iranian standards for drinking water quality were selected as input parameters and benchmarks, respectively. The modified DWQI is calculated for each sampling station over one year using three factors: the number of parameters that excurse benchmarks, the number of measurements in a dataset that excurse benchmarks and the magnitude of excursion from benchmarks in the violator measurements. The modified DWQI contains two sub-indices: health-based index as “modified HWQI” and acceptability index as “modified AWQI”. The modified DWQI and its sub-indices scores range from 0 to 100 and classify water quality in five categories as poor, marginal, fair, good and excellent, respectively. The results of the case study revealed that the nationwide average scores of the modified DWQI, HWQI and AWQI in the groundwater resources were 85, 79 and 91, respectively and overall situation of water quality in the groundwater resources was described as good. According to the modified DWQI value, about 95% of the groundwater flowrates were in the good condition, also in 3 and 2% of the groundwater flowrates, water quality was determined to be fair and marginal, respectively. This study indicated that the modified DWQI and its sub-indices could describe the overall water quality of water bodies easily, reliably and correctly and have the potential suitability for extensive application all over the world.     

Relationship of drinking water quality (hardness-softness) to cardiovascular mortality in Newfoundland

The profile of mortality in Newfoundland was analysed for all deaths occurring in 1969 of persons 35 to 69 years of age, of whom the total was 1036. An exceptionally high cardiovascular mortality (793 deaths/100,000) was noted for St. John''s, the capital city of Newfoundland, a city which has an extremely soft drinking-water supply. This high rate corresponds to that observed in the “high mortality belt” reported for the east coast of the United States, and in conjunction with data from mainland Canada, extends the belt across the entire eastern aspect of North America. The proportion of cardiovascular deaths of men occurring outside the hospital was less within hard drinking-water areas in Newfoundland than in the soft water areas of the province. Thus, the statistics reported here of cardiovascular mortality confirm evidence reported elsewhere on “macro-geographic” variations in this disease(s) as well as “micro-geographic” regional variations which may be dependent upon local environmental factors.     

Case study of complaints on drinking water quality

Several families of Talca city, Chile complained to health authorities for what they attributed to consumption of copper (Cu)-contaminated drinking water. We assessed the situation 6–12 mo after the initiation of complaints by characterizing the symptoms reported, the chemistry of drinking water, and the Cu concentration in stagnant drinking water. After completing a census, 1778 households accepted participation and were categorized as follows: category 1, Cu plumbing for tap water and dwellers reporting health complaints (HC); category 2, Cu plumbing for tap water and dwellers reporting no HC; category 3, plastic plumbing for tap water and dwellers reporting no HC. Questionnaires recorded characteristics of households and symptoms presented by each member of the family in the last 3 mo. The Cu concentration in drinking water was measured in a subsample of 80 homes with Cu pipes. In category 1, participants presented significantly more abdominal pain, diarrhea, and/or vomiting (gastrointestinal [GI] symptoms) in comparison to category 3 and to categories 2 plus 3. The stagnant Cu concentrations measured in drinking water in all houses studied were below the US Environmental Protection Agency guideline value (<1.3 mg Cu/L). In summary, data obtained by interviews suggested that individuals in some areas of Talca city were suffering more GI symptoms potentially related to Cu excess, but measurement of Cu concentration in stagnant tap waters ruled out the association between Cu exposure and GI symptom reports at the time of this study. The dose-response curves for GI symptoms and Cu exposure now available were crucial in the analyses of results.     

Bacteriological examinations of drinking water in the district of Melut (Upper Nile Province) South Sudan

In October and November 1983 bacteriological examinations of drinking water were done in the district of Melut/Upper Nile Province/South Sudan. The samples were taken from the middle of the White Nile, from handpumps along the river-bank, from the bank of the river and from drinking water bowls in the village of Melut and other surrounding villages within about 100 kilometers. All together 213 water samples were bacteriologically examined. The examinations of the samples taken from the river-bank and from the drinking water bowls showed very high plate counts (10(4)-10(7) colonies/ml) and a very high identification rate of Escherichia coli (11.1-31.5%) and of coliforms (82.1-92.8%). The water from the middle of the White Nile and from the handpumps, which are pumping water from a distance of 25 meters from the river-bank, had a better bacteriological quality. The plate counts were about 10(3)-10(4) colonies/ml. Escherichia coli could only be identified in one sample from the handpumps (4.4%) and coliforms were found in 40% of the samples of the middle of the Nile and in 48.8% of the samples from the handpumps. The trial to get qualitative better water with handpumps from regions far away from the river-bank, can be viewed as successful.