Water quality of rivers in the drainage basin of Lake Peipsi

Water quality and general regularities that have taken place in the water quality of rivers in the drainage basin of Lake Peipsi have been studied. The lake is located in the basin of the Narva River. Several changes of the water quality of the lake in 1970–1990, caused by increasing human impact, have been observed. The water quality of Lake Peipsi depends on its pollution load whereby the main part of the pollution reaches the lake via rivers. In 1985–1989 an extensive research programme of the lake and its drainage basin was carried out. In this paper a part of these results as well as recent changes in the water quality of the rivers of the Estonian side are studied. In the last years an improvement of the general state of rivers in the drainage basin of Lake Peipsi has taken place; the content of organic substances and nutrients in the inflows of Lake Peipsi and in the Narva River (lake outflow) is decreasing.     

A Study on the Impact of Urban and Industrial Development in the Linggi River Basin,Malaysia. 1. Morphometry and Physical Environment

The Linggi River Basin is one of the most polluted river basins in Malaysia and drains an area of about 1,399km² in the state of Negri Sembilan. An extensive multidisciplinary research was carried out to develop a predictive mathematical model to manage the Linggi River basin effectively. This paper reports only the morphometry and other physical environmental conditions of the Linggi River Basin which was carried out between January, 1983 and January, 1984. Topography, vegetation, landuse pattern, general geology and lithology, population distribution and water usage by the people are discussed. In addition, physical information such as air and water temperatures, precipitation, sunshine, discharge, suspended solids and dissolved solids data collected before and after the study period are discussed in detail.     

A Study on the Impact of Urban and Industrial Development in the Linggi River Basin,Malaysia. 2. Chemical Environment

An investigation of the chemical environment of the Linggi River Basin was carried out at 15 main and 27 supplementary stations between January 1983 and January 1984. Spatial and temporal changes in pH, specific conductivity, alkalinity, chloride, ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, orthophosphate, dissolved oxygen, BOD, and diurnal variations were studied in relation to influence of various kinds of pollutants. The chemical composition of natural water analysed at a few undisturbed forest stream stations in the basin can be considered very good. A drastic change in river water quality was noticed in downstream polluted stations. The pH in the basin varied from 4.05 to 10.5 units, conductivity from 23.0–1,500 umhos/cm, alkalinity from 6.0–1,388 mg/l, chloride from 0.9–160.9 mg/l, orthophosphate from 0.5–5.21 mg/l, ammonia-N from 0.001–53.75 mg/l, nitrite-N from 0.0–8.2 mg/l, nitrate-N from 0.03–6.77 mg/l and BOD₃, from 0.32–384.0 mg/l and COD from 0.02 to 79.2 unit. Among all the rivers, very high values were recorded at Kundor, Simin and Linggi (sensu stricto).     

Abiotic vs. Biotic Factors: Lessons Drawn From Rotifers in the Middle Loire,a Meandering River Monitored From 1995 to 2002, During Low Flow Periods

The numbers of rotifers in large rivers never achieve the abundances observed in eutrophic lakes. The adverse conditions of the current have conduct biologists to establish links between particular geomorphologies and biological processes in the plankton of rivers. Recent attempts to examine specific adaptations of rotifers have shown that among several planktonic forms, the loricate species appeared to be better adapted to the current than soft-bodied or littoral-epibenthic species. The eutrophic Middle Loire provides rotifers with more edible biomass than that necessary for their production so, the aim of this study was to determine which other factors were responsible for the origins, growth and survival of rotifer populations in the river. Samples were taken bi-monthly in the current, from end-June to early-October during 8 years, in two sections of the River Loire situated at 550 and 640 km from the source. Flow rate, temperature, dissolved oxygen, suspended matter, biological oxygen demand and algal densities were examined in parallel, and among the 61 rotifer species collected at each site, the 30 dominant species were retained for the analysis. Planktonic loricate species were dominant in the Middle Loire, followed by epibenthic species, soft-bodied species being least abundant. The densities of rotifers and algae changed in parallel and in relation to temperature; flow was clearly unfavourable to algae, represented by the Chlorophytes and to rotifers, whatever the sites. Co-inertia analysis revealed that the assemblage of species was closely grouped at Dam where the immediate environment was dominated by numerous scattered islands. This analysis also illustrated that the consequence of eutrophication in the water quality was more marked downstream. Lessons drawn from this experience of the Middle Loire, which ranks among the richest rivers in terms of species, allowed to highlight that dominance of the Brachionidae is a rule in numerous rivers and may be explained by the capacity of several species to continue growing in a current of 0.2 m s⁻¹. Trichocercids may be relevant indicators of sandy rivers. The flexibility of rotifers in the face of hydraulic conditions, the question of the rotifers’ origin, the respective roles of downstream transfer and processes, as well as the role of the rotifers in the river food-web are discussed.     

Occurrence of a thermocline in two lakes of the semi-arid region in western Rajasthan,India

Water quality samples were obtained monthly or bimonthly 17 times from May 1974 to May 1975 at three stations in Delaware Bay. In addition, two 12-hour cruises were also conducted at one station in February and April 1975. Surface and bottom water samples were taken. Measurements and analyses included temperature, salinity, dissolved oxygen, silicate, nitrate and nitrite, orthophosphate, ammonia, chlorophylls a, b, and c, phaeopigments, and carotenoids. The annual pattern of temperature was typical of an estuary in the mid-Atlantic Bight. Salinity and dissolved oxygen ranged from 22.9 to 29.7‰ and from 4.53 to 8.53 ml/l, respectively. Nutrient and pigment values showed seasonal peaks. Silicate (30.3 μg-at/1) and orthosphate (1.59 μg-at/1) were highest in September. Highest concentrations of ammonia were commonly measured in July (6.80 μg-at/1) and September (5.13 μg-at/1), and peak concentrations of nitrate and nitrite were recorded in January (24.27 μg-at/l), February (18.2 μg-at/1), and May (16.37 μg-at/1). Peak concentrations of chlorophyll a were measured in August (17.2 μg-at/1), October (15.70 μg-at/1), and March (15.33 μg-at/1). In general, the annual pattern for chlorophylls b and c were similar to chlorophyll a. Comparison with other estuaries and bays (Narrangansett Bay, Long Island Sound, Raritan Bay, and Chesapeake Bay) indicated that concentrations of nutrients and pigments in Delaware Bay were generally similar in magnitude and seasonality, These are the first set of seasonal water quality data for lower Delaware Bay.     

Top‐down effects on pelagic heterotrophic nanoflagellates (HNF) in a large river (River Rhine): do losses to the benthos play a role?

1. The abundance, production and control of pelagic heterotrophic nanoflagellates (HNF) in the Lower River Rhine (Germany) were investigated. Field samples (live‐counting technique) were taken at least every 2 weeks at Cologne (km 685) over a period of 20 months. In addition, Lagrangian sampling was carried out 160 km downstream of Cologne (Kalkar–Grieth, km 845) over a period of 12 months. Potential HNF growth rates and loss rates caused by planktonic predators were estimated in the laboratory (size fractionation experiments) and compared with the changes in HNF‐density in a water parcel flowing downstream. 2. Mean abundance (±SD) ranged from 7 ± 6 to 4890 ± 560 individuals mL^–1 and was positively correlated with discharge. Heterotrophic nanoflagellates abundance increased up to 30‐fold during flood events, whereas there were only minor changes in the taxonomic composition. 3. HNF growth rate ranged from 0.16 ± 0.12 to 1.98 ± 0.10 day^–1. Between 0 and 95% (mean: 32%) of the gross production was lost to planktonic predators; a larger portion between 0 and 195% (mean: 64%) of the HNF gross production was lost by other means. 4. There may be an important role for benthic predators in the control of pelagic HNF. First, production of HNF was high and grazing losses to planktonic predators low at times when HNF abundance was low. Secondly, high in situ loss rates (not explicable by planktonic predators), which were positively related to temperature, indicate the importance of biotic interactions. Thirdly, the dependence of HNF abundance on discharge indicated a decrease grazing intensity with rising water levels (increase in water volume/colonised river bed ratio). 5. The impact of discharge on planktonic HNF mediated by the grazing impact of benthic predators was modelled, showing a good fit with the field data.     

Assessment of spring water quality and quantity, and health implications in Tongaren division, Nzoia River catchment, Kenya

Spring water is the common source of public water supply in most rural communities of developing countries such as Kenya. The water quality and quantity may be altered due to catchments degradation. This study was carried out in Tongaren division, Nzoia River catchment. The aim of this study was to investigate and map the occurrence and distribution of springs and to determine their water quality and quantity. This study determined the spring water discharge, conductivity, turbidity, total and thermotolerant (faecal) coliforms to assess suitability and sustainability of spring water for safe drinking. Twenty-eight springs were identified and their locations mapped using Global Positioning System (GPS) geo-reference data. Discharge ranged from 0.1 to 3 l s⁻¹, with some drying up during dry season. Total coliform was innumerable in most of the studied springs while thermotolerant (faecal) coliform counts occurred in eight springs, including four protected springs. This poses high risks of water-borne diseases. The water should be filtered and boiled prior to use for drinking. Facilitation of communities enabled development of seven springs to enhance water yield and quality. This study established high potential in the communities to develop springs and utilize the spring water as alternative source of livelihoods.     

白鱀豚饲养池水质状况的研究

白鱀豚是我国特有的稀珍水生哺乳动物。仅分布于长江的中、下游干流之中。关于如何饲养白鱀豚没有可借鉴的资料。在没有水净化装置和流水系统的条件下,为了既能节省人力和财力,又能保证豚体的健康,我们对白鱀豚饲养池的理化和微生物因子进行了系统、全面的测定和研究。     

Colonization of artificial substrates by benthos in a second-order high altitude river in Kenya

An investigation on the colonization of artificial substrate baskets by benthos was carried out in the Naro Moru River, a second-order high altitude river in Kenya, from November, 1986 to October, 1987. Simuliidae dominated the colonizing benthos. The mean (±95% CL) maximum colonization time was achieved after 9.63±1.57 days. The highest mean diversity (H) occurred after 6 days of exposure whilst the highest mean H_maximum, evenness (J) and species richness (s) were achieved after 10, 8 and 10 days respectively.The benthos arrival rate (AR) declined exponentially with time. The changes in benthos departure rate (DR) with time was insignificant. Equilibrial state (AR:DR=1.0) was not achieved in the present study.     

香溪河流域水体环境因子研究

基于香溪河及其三大支流古夫河、高岚河与九冲河的8年监测数据,对该流域水体的环境因子及其时空动态进行了比较分析。结果显示,香溪河流域的水体呈中性偏弱碱性,属于中等硬度水,水体溶解氧丰富,还原性物质以及氯化物水平不高,具有较强的缓冲能力。多数环境因子具有明显的季节变化,而年际变化规律不显著。香溪河流域水体的主要营养元素氮含量较高,并以有城镇影响的古夫河为最;高岚河由于受到生活污水与农业活动的影响,水质相对较差;香溪河的磷污染严重;森林覆盖率较高的九冲河的水质最佳。在香溪河流域,氮主要以面源污染的方式进入河道,而香溪河的磷则主要以点源污染的方式进入河道。水土流失是香溪河流域面源污染的主要途径,磷矿和磷化工厂的排污则是磷点源污染的主要途径。从保护三峡水库香溪河库湾的生态学角度考虑,应重点控制香溪河磷的点源污染。     

Qualité des eaux en milieu estuarien: Suivi annuel de critères physiques et chimiques dans les eaux de l'estuaire de la Loire

Chemical composition and physical parameters of waters from the Loire estuary were examined in 1981–1982 in order to assess water quality. It appears that riverflow is of first importance on suspended matter load, dissolved nutrient concentrations and oxygenation. The annual hydrological cycle is made of two periods. During the first one low riverflow, low nutrient concentrations, high suspended matter load and oxygen depletion are noticed. During the second one higher riverflows occur accompanied with increasing nutrient concentrations, decreasing turbidity and restoration of dissolved oxygen. Results indicate that annual inputs of dissolved nutrients attain 60 000 t a^–1 for nitrogen, 2 400 t a^–1 for phosphorus and 100 000 t a^–1 for silica. It is suggested that the high suspended matter loading (¹ million t a^–1) is a significant factor disturbing oxygenation and by the way limiting water quality within the estuary.

     

生态修复工程条件下污染河流水质模拟和应用

生态工程是改善河流水质的重要手段,利用数学模型可以有效模拟水环境治理和预测生态修复工程效益.本文根据实际河流资料,应用WASP水质模型进行建模和验证,模拟和评估了河流的主要化学参数,进而研究了人工湿地和曝气复氧对河流水质的生态改善作用.结果表明: WASP水质模拟结果与实测水质数据拟合良好,可以对不同生态修复情景方案进行预测分析.合理减排、人工湿地、曝气复氧均可以降低河流水体中的污染物浓度、有效改善水质.在人工湿地系统中增加曝气复氧装置,将进一步提升河流水体的生态修复效率.以吉林省伊通河曝气条件下的人工湿地工程为例,分析了其生态修复效率.结果表明: 夏季的污染物去除效果最好,可能的原因为夏季气温较高,水体中的微生物活性较强.本研究对于污染河流环境的生态修复工程设计和运行具有指导意义.     

Main characteristics of the phytoplankton of the Southern Hungarian section of the River Danube

The Danube is a large eutrophic river and may be one of the best studied rivers in the world. This paper presents a short characterization of the biological water quality based on data from the 1986–1992 period, collected in the Southern Hungarian section at 1480.2 river km. Variations in the hydrological features (including discharge and turbulence) are the most important factors determining the total phytoplankton biomass in the River Danube. A good correlation has been found between chlorophyll a content and discharge, from early spring to autumn, whereas the suspended matter appeared weakly related to discharge. In addition, some taxonomic notes refer to the most common members of the phytoplankton, as well as to several rare taxa.