Characteristics of fluctuations in salinity and water quality in brackish Lake Obuchi

Fluctuations in the salinity and physicochemical characteristics of water quality were surveyed in brackish Lake Obuchi on the Shimokita Peninsula in Aomori, Japan. The mean salinity in the surface layer in all regions of Lake Obuchi was about 10 psu, whereas in the basin region at depths of greater than 3 m it was 20 psu. Furthermore, all the year round the halocline was formed at depths of 1–4 m. The maximum density gradient along a vertical axis in the center of the lake was observed at depths of 1–2 m in summer and 2–4 m in spring and fall. The depth of the maximum density gradient fluctuated with the seasons. In summer the water in the bottom layer was anoxic, and Fe, Mn, PO₄ ³⁻-P, and NH₄ ⁺-N supplied from the bottom sediment accumulated at high concentrations below the halocline. Thus, it was observed that the transfer of substances between the layers above and below the barrier formed by the halocline is suppressed. Although Lake Obuchi is small and shallow, the inflowing seawater easily resides, and a stable halocline readily forms because of the shape of its basin, which suddenly deepens on the Pacific Ocean side. Received: May 24, 1999 / Accepted: September 25, 1999     

Wastewater treatment at the Houghton Lake wetland: Hydrology and water quality

Lagoon-treated wastewater was discharged to a natural peatland to remove nutrients. For thirty consecutive years, an average of 600,000 m³ of treated water was discharged to the Porter Ranch peatland near the community of Houghton Lake, Michigan. This discharge was seasonal, commencing no sooner than May 1 and ending no later than October 31. During the winter half-year, treated wastewater was stored at the lagoon site. This water contained 3.5 mg/L of total phosphorus, and 7 mg/L of dissolved inorganic nitrogen. Other wastewater quality parameters were CBOD₅ = 15 mg/L, TSS = 34 mg/L, and fecal coliforms at 66 cfu/100 ml. The peatland was large, about 700 ha, but the zone that provided wastewater polishing was approximately 100 ha. Outflows from the larger peatland showed no effects of the discharge, and maintained concentrations of 40 μg/L of phosphorus, and 85 μg/L of ammonia nitrogen. Nutrients were stored in the 100-ha irrigation area, which removed 94% of the phosphorus (53 metric tons) and 95% of the dissolved inorganic nitrogen. All other constituents were also removed in the irrigation area, except for pass-through substances such as chloride. Phosphorus was stored in new biomass, increased soil sorption, and accretion of new soils and sediments, the last being dominant. A simple growth and uptake model described the removal of phosphorus, with an uptake rate coefficient that did not change over time. Thus, rates in this system were stable over time, and the P-removal capacity did not diminish. The irrigation area underwent large changes in ecosystem structure. There was an initial fertilizer response, characterized by much larger standing crops of vegetation. There was also a plant community shift, from the initial sedge-willow cover type to a cattail-dominant cover type. This new cattail patch became a floating mat.     

Application of modified water quality indices as indicators to assess the spatial and temporal trends of water quality in the Dongjiang River

The Dongjiang River plays an important role in southern China, as a source for irrigation and potable water of Hongkong and the other parts of the Pearl River Delta (PRD). The water quality index (WQI) was calculated to assess the spatial and temporal variability and identify the classification of water quality in the river. In order to simplify the procedure and reduce the analytical costs of the water quality evaluation, a modified WQI (defined as WQI_min) was introduced based on Principal Component Analysis (PCA) and correlations analyses of the water parameters detected in dry and wet seasons during 2011–2012. Compared with the previous index, similar spatial changing trend and classification of the water quality were obtained by WQI_min, which was composed of pH, temperature, total suspended solid, NH₄⁺-N, and NO₃⁻-N. The results showed an excellent water quality in the tributary site near the reservoir, a good water quality in the upstream of the river, and medium water quality in the downstream of the river, which suggested that the urban wastewater originated from increasing population size and industry development in the downstream mainly led to the deterioration of water quality along the river. Moreover, WQI_min could more adequately reflect the seasonal changes of water quality which was slightly worse in dry season than wet season. Our results also suggest that continuous monitoring should be conducted to prevent pollution from industry and anthropogenic activities.     

洞庭湖底栖动物种类分布及水质生物学评价

1 995年枯水、平水、丰水期对洞庭湖设 6个断面进行采样 ,共采到底栖动物 58种 ;其密度变幅为 78～ 544 .5个 /m2 ;1 0种常见种均成聚集分布。采用综合生物污染指数评价水体质量 ,结果显示洞庭湖整体水质受到轻度污染 ,评价结果与化学污染指数评价结果一致 ;各采样断面综合生物污染指数均明显大于 1 981～ 1 982年的测量结果 ,表明水体质量变差     

A case study on qualitative model evaluation using data about river water quality

Qualitative reasoning has been successfully used for ecological modelling, particularly when numerical data are not available. However, in order to further explore the potential of this modelling approach, it is important to discuss how to incorporate numerical data, if available, and to develop means to evaluate conceptual aspects and model outputs. This paper describes a study on qualitative model evaluation, in which numerical data about water quality are used to define different scenarios in a water basin, so that the outputs of simulations with the model can be compared to the actual system. The model was evaluated by independent experts, concerning its conceptual and operational aspects, and with respect to its predictive capability. The model was considered valid for the intended use, which is to increase the understanding of non-expert water managers.     

Investigation of bathymetry and water quality of Lake Nam Co, the largest lake on the central Tibetan Plateau, China

Comprehensive field investigations have been conducted four times on Nam Co, central Tibet, from September 2005 to September 2008. Here, we present the preliminary results focusing on the bathymetric survey and water quality measurements. The isobathic map shows that Nam Co is a high-altitude, deep lake where a flat and large basin lies in the central part with a water depth of more than 90 m. Water depth data from the northwestern bank areas of Nam Co provide unquestionable evidence of rising water levels in the last 3 decades because of the formation of two small islands that were still peninsulas in the 1970s. Water quality measurements taken at 19 stations during three summer field campaigns (2006, 2007 and 2008) covering almost all of the lake areas showed that the temperature, pH, dissolved oxygen and electric conductivity of surface water are on average 11.43°C, 9.21, 8.90 mg l⁻¹ and 1,851 μS cm⁻¹, respectively. The surface water shows no obvious spatial variability among all the stations. Vertical fluctuations of profiles, however, display some differences in thermocline and related parameters, such as pH and dissolved oxygen. According to the vertical variations of water quality parameters, the water column in relatively deep lake areas of Nam Co could be divided into three layers with distinctly various features: the epilimnion is from the surface to about 18–20 m depth in which the parameters are homogeneous with higher temperature and abundant sunlight; the metalimnion ranged from 20–60 m where a thermocline develops; the deepest layer forms a cold and dark hypolimnion.     

用浮游动物评价巢湖东湖区的水质和营养类型

于2005年6月至2006年6月对巢湖东湖区的浮游动物进行了采样调查,初步研究了巢湖东湖区的浮游动物的种类组成、群落结构特征以及浮游动物物种的多样性,并对巢湖东湖区的水质状况和营养类型作出了评价。研究结果显示浮游动物153种,其中原生动物43属59种,占总种数的38.56%;轮虫类20属48种,占总种数的31.37%;枝角类14属26种,占总种数的16.99%;桡足类20种,占总种数的13.07%。浮游动物的物种多样性随着季节的变化而变化;污生指数法评价结果表明巢湖东湖区的水质状况从2005年6月至2006年6月均处于β-中污带级;用浮游动物数量(ind·L^-1)作为湖泊水体营养程度的生物量指标,其结果显示巢湖东湖区水体从2005年6-9月和2006年3-6月巢湖东湖区水体的营养状况处于富营养状态。     

芜湖市镜湖轮虫群落结构分析及水质的生态学评价

2003年1—12月,对芜湖市镜湖轮虫群落结构的周年动态进行了研究,并分析了轮虫密度与有关生态因子间的关系。经鉴定,共发现轮虫55种,隶属于15科21属。密度优势种为裂痕龟纹轮虫(Anuraeopsis fissa)、暗小异尾轮虫(Trichocerca pusilla)、前额犀轮虫(Rhinoglena frontalis)、红多肢轮虫(Polyarthra remata)、长三肢轮虫(Filinia longise-ta)、广布多肢轮虫(Polyarthra vulgaris)和多须伪前翼轮虫(Proalides tentaculates),而生物量优势种为前节晶囊轮虫(Asplanchna priodonta)、多须伪前翼轮虫和暗小异尾轮虫。全年轮虫的总密度与水温、叶绿素a浓度及小型纤毛虫密度具有显著的相关性;温度对全年轮虫总密度的影响最大,叶绿素a浓度对春、冬季轮虫总密度影响最大,小型纤毛虫密度对夏季轮虫总密度影响最大,而水温是影响秋季轮虫总密度的主要因素。根据污染指示生物、物种多样性指数和Q值并结合水理化性质对治理后的镜湖水质所进行的初步评价表明,经清淤、截流和换水等措施治理后,小湖区应偏属寡污-β中污至β中污型水体,大湖区属于β中污型水体;目前镜湖水体处于中营养后期—富营养化初期阶段。       

Effects of the halocline on water quality and phytoplankton composition in a shallow brackish lake (Lake Obuchi, Japan)

The relationships of the halocline to both water quality and phytoplankton composition in Lake Obuchi, a shallow brackish lake in northern Japan, were investigated from April 2001 to December 2004. The halocline in this lake became stronger in summer (July–September, mean maximum density gradient 4.3–5.8 ρ_tm⁻¹) but weaker in spring, fall, and winter (1.9–3.3 ρ_tm⁻¹). Although the difference in water quality between the upper and lower layers separated by the halocline was high in summer, nutrients (PO₄³⁻-P and NH₄⁺-N) were eluted from the bottom sediment as levels of dissolved oxygen decreased in the bottom layer because of the strong stratification caused by the halocline formed over the long term. Moreover, phytoplankton taxa composition also differed between the upper and lower layers in summer, but was similar in other seasons. The dominant phytoplankton taxa in the upper layer in summer were Skeletonema costatum and Cyclotella spp., whereas in the lower layer, Gymnodinium spp. (Dinophyceae) and Chlorophyceae, which prefer eutrophic and low dissolved oxygen conditions, dominated. This suggests that the halocline was related to differentiations in both water quality and ecosystem components between the upper and lower layers in the brackish lake water.     

太湖五里湖生态修复示范区水质改善效果分析

鱼类清除和沉水植被恢复常是富营养化浅水湖泊生态系统修复的重要手段。为探讨这种生态系统修复方式对亚热带富营养化浅水湖泊太湖五里湖水质的改善效果,论文研究了五里湖生态修复区与未进行任何修复的对照湖区为期6个月(2010年7～12月)的水质监测数据。数据分析结果表明,生态修复区总氮(TN)、总磷(TP)、叶绿素-a(Chl-a)以及悬浮质(TSS)浓度显著降低,分别比对照区低43.4%、48.3%、65.5%和78.9%,透明度则明显升高,约为对照区的3倍。本研究表明以鱼类清除和沉水植被恢复为主要手段的生态系统修复措施能够有效改善亚热带富营养化浅水湖泊水体的水质。     

飞来峡水库水质现状及其向广州供水能力的探讨

水库供水(特别是对城市的供水)已成为缓解全球水资源供给不足的重要途径。于2001年至2003年的丰水期和枯水期调查分析了新建河流型水库-飞来峡水库的水质、浮游植物群落特征和营养状态。结果表明飞来峡水库水质良好,多数水质指标为地表水Ⅱ水质标准,其营养盐浓度、浮游植物的密度均较低,属于贫中营养。从近几年的水质变化来看,建库后,水质改善明显。通过对广州市饮用水源水水质现状及存在问题的分析,从水质和水量两方面探讨了飞来峡水水库作为广州优质水源地的优势。由于来水量大,水库水质净化能力强,飞来峡水库水质和水量均有保证,可作为广州市重要水源地之一。但今后,在流域管理和水土保持工作更应重视和加强。     

The impact of water quality on the Asian clam,Corbicula fluminea,distribution in Pergau Lake,Kelantan, Malaysia

In the present study described the impact of water quality on the Asian clam, Corbicula fluminea, distribution in man – made Pergau Lake was carried out. Recently, Pergau Lake was gazette as state park and any activities related to fishery and agricultural were not allowed in the park. Subsequently, the nearby lake community was affected as many of them earn a living by carrying fisheries activity in the lake especially harvesting Asian clam. 10 sampling sites were selected in the lake to monitor water quality and Asian clam distribution. Water parameters data were also subjected to cluster analysis by using Ward’s method with squared Euclidean distances as a measure of similarity and a dendrogram was successfully generated. The water quality of the lake is under good condition and suitable to carry fishery activities by referred to Malaysia National Water Quality Standards (NWQS). The dendrogram revealed that the sampling sites can be divided into 2 clusters where Location 1 alone in its own cluster. Another cluster possesses 2 sub-clusters where Location 2 and 3 shared similar sub cluster. Another sub-cluster has two groups namely Location 5, 6 and 8 in one group whereas Location 4, 7, 9 and 10 shared similar group. The findings of the present study showed most of sampled Asian clam in Pergau Lake was semi mature indicating highly exploitation of Asian clam in the Lake. Furthermore, there were no correlation was detected between the population of Asian clam and water quality of the lake. Hence, we suggest that seasonal harvesting Asian clam should be implemented in order to conserve the population of Asian clam in the lake at the mean time the community to continue earn a living through carrying fishery activities in the lake.     

Simulation study on water quality based on sediment release flume experiment in Lake Taihu, China

Sediments have a significant influence on the overlying water, and nutrient release from sediments is an important source for lake eutrophication, particularly in shallow lakes. Sediment resuspension is primarily driven by wind-induced currents. In this research, the correlation between release rate of suspended sediment and flow velocity was studied, and an experiment on hydrodynamic forces was conducted in a rectangle flume using water and sediments collected from three sites in Lake Taihu, a eutrophic lake in China. It was shown that the starting velocities of sediment in Lake Taihu at three different incipient standards gained from the experiment were 15, 30, and 40 cm s⁻¹ and the release rate of suspended sediment could reach up to 643.4, 5377.1, and 13980.5 g m⁻² d⁻¹, respectively. Based on the experiment, a water quantity and quality numerical model of wind-induced current with sediment pollution for Lake Taihu was developed. The model was calibrated and validated by applying it to the study of the water quality of Lake Taihu. The calculated values were generally in good agreement with field observations, which indicated that the developed model could represent the dynamics of sediment resuspension to a certain extent. This study provides a new approach and a practical tool for planning and management policy and operations to protect the water quality and ecosystems of shallow lakes.     

Assessing water scarcity by simultaneously considering environmental flow requirements,water quantity,and water quality

Water scarcity is a widespread problem in many parts of the world. Most previous methods of water scarcity assessment only considered water quantity, and ignored water quality. In addition, the environmental flow requirement (EFR) was commonly not explicitly considered in the assessment. In this study, we developed an approach to assess water scarcity by considering both water quantity and quality, while at the same time explicitly considering EFR. We applied this quantity–quality-EFR (QQE) approach for the Huangqihai River Basin in Inner Mongolia, China. We found that to keep the river ecosystem health at a “good” level (i.e., suitable for swimming, fishing, and aquaculture), 26% of the total blue water resources should be allocated to meet the EFR. When such a “good” level is maintained, the quantity- and quality-based water scarcity indicators were 1.3 and 14.2, respectively; both were above the threshold of 1.0. The QQE water scarcity indicator thus can be expressed as 1.3(26%)|14.2, indicating that the basin was suffering from scarcity problems related to both water quantity and water quality for a given rate of EFR. The current water consumption has resulted in degradation of the basin's river ecosystems, and the EFR cannot be met in 3 months of a year. To reverse this situation, future policies should aim to reduce water use and pollution discharge, meet the EFR for maintaining healthy river ecosystems, and substantially improve pollution treatment.     

Water displacement by sewer infrastructure and its effect on the water quality in rivers

Water quality is affected by a complex combination of natural and anthropogenic factors. To assess watershed integrity on a larger scale and for an optimal, cost-effective integrated watershed management, defining linkages between upstream watershed land cover and riverine water quality is essential. A correct upstream area calculation is an absolute necessity to reach conclusive results, but remains problematic in human influenced catchments. Especially sewer infrastructures (including wastewater treatment plants) are difficult to incorporate. We developed a method that allows us to integrate the sewer system in the upstream calculations and applied it on the Nete catchment in Belgium. Our results show strong changes in results compared to standard runoff methods. We conclude that if sewer systems are not incorporated in upstream area calculation, the impact of human activities on the water quality at a catchment scale estimates will be severely biased. A thorough understanding of the evaluated catchment and a correct translation of the different hydrological flow paths in the upstream area calculation is absolutely necessary to gain reliable results.     

汤溪水库富营养化特征与水质管理对策

通过2003年对广东省汤溪水库水生态学进行调查,分析了该水库的富营养化特征,并从流域管理和水动力学两个方面对水库水质管理对策进行了探讨。汤溪水库为中度富营养化水体,具有明显时空分布差异,丰水期富营养程度高于枯水期,溪头河流区高于新桥河流区。蓝藻是水库浮游植物的主要优势类群,其中引发水华的铜绿微囊藻(Microcystis aeruginosa)为优势种。水库上游集水流域分布近30万居民,大量的生活排污和农业污染形成了主要的外源污染源,这些外源污染的输入是水库水体营养盐的主要来源;合理处理上游居民生活垃圾、减少生活污染中磷含量、增加流域和库区周围植被覆盖、合理使用农业化肥是降低水库表层水体中营养盐浓度的主要途径。由于该水库的蓝藻和富营养化水平直接与水体的稳定性有关,利用对水库排水的可控制性调节水库水体的稳定性,可作为控制蓝藻水华发生的有效途径。     

The data quality foundation in OMNIITOX information system

Extended Summary Goal and Scope  This paper describes the data quality foundation for the OMNIITOX information system, with regard to data quality requirements and maintenance. Main Features  The data quality concept applied in the OMNIITOX project is based on results that are successfully used in other contexts (Fig. 1). Specific data quality requirements have been developed, which are applied in data acquisition and data review. The data quality requirements and quality maintenance is supported by the OMNIITOX concept model, which supplies a common language for the users from the different disciplines. Results and Discussion  The quality requirements and the concept model have been tested during data acquisition for the information system, and have been found to be a successful framework. The results from practical work demonstrate that it is possible to have a common understanding of the concept model and quality requirements. The user's experience the initial phase of learning the concepts and quality requirements as tedious. Nevertheless, experiences show that the users will benefit from the education during the further work. A considerable amount of data has been acquired based on the data quality foundation. Conclusions  The data quality foundation has been a successful framework for managing data quality in the design and establishment of the OMNIITOX information system. The data quality concept, the concept model, and specific quality requirements are applied as quality management tools to find, acquire, document, and interpret the information. Several quality issues deriving from interdisciplinary differences between the different users have been resolved, which facilitates a common understanding and reduces the risk of misinterpretations and misuse of information. Recommendations and Outlook  An important task for the finalization of the OMNIITOX project is to secure the credibility and long-term stability of the information system. The OMNIITOX information system will somewhat have less potential to support the toxicology related assessments in Europe if any of the involved disciplines chooses to reject or not to apply the concept model and the quality requirements.     

应用原生动物群落评价枯水期白洋淀的水质现状

应用PFU微型生物群落监测方法,对长期处于低水位状态下的白洋淀水质进行了综合评价。结果表明,白洋淀水域受府河污水的影响,淀内的内源性污染,对原生动物群落造成了极大的影响。与20世纪90年代的资料相比,淀内中心区4个采样点原生动物的群集种类数(1d)急剧下降,而丰度上升了1．28倍,表明内源性污染对白洋淀水质的影响加剧。     

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.