Spatial variation and source apportionment of water pollution in Qiantang River (China) using statistical techniques

Understanding the spatial distribution and apportioning the sources of water pollution are important in the study and efficient management of water resources. In this work, we considered data for 13 water quality variables collected during the year 2004 at 46 monitoring sites along the Qiantang River (China). Fuzzy comprehensive analysis categorized the data into three major pollution zones (low, moderate, and high) based on national quality standards for surface waters, China. Most sites classified as “low pollution zones” (LP) occurred in the main river channel, whereas those classified as “moderate and high pollution zones” (MP and HP, respectively) occurred in the tributaries. Factor analysis identified two potential pollution sources that explained 67% of the total variance in LP, two potential pollution sources that explained 73% of the total variance in MP, and three potential pollution sources that explained 80% of the total variance in HP. UNMIX was used to estimate contributions from identified pollution sources to each water quality variable and each monitoring site. Most water quality variables were influenced primarily by pollution due to industrial wastewater, agricultural activities and urban runoff. In LP, non-point source pollution such as agricultural runoff and urban runoff dominated; in MP and HP, mixed source pollution dominated. The pollution in the small tributaries was more serious than that in the main channel. These results provide information for developing better pollution control strategies for the Qiantang River.     

Assessment of seasonal and polluting effects on the quality of river water by exploratory data analysis

22 Physico-chemical variables have been analyzed in water samples collected every three months for two and a half years from three sampling stations located along a section of 25 km of a river affected by man-made and seasonal influences. Exploratory analysis of experimental data have been carried out by box plots, ANOVA, display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis) in an attempt to discriminate sources of variation of water quality. PCA has allowed the identification of a reduced number of “latent” factors with a hydrochemical meaning: mineral contents, man-made pollution and water temperature. Spatial (pollution from anthropogenic origin) and temporal (seasonal and climatic) sources of variation affecting quality and hydrochemistry of river water have been differentiated and assigned to polluting sources. An ANOVA of the rotated principal components has demonstrated that (i) mineral contents are seasonal and climate dependent, thus pointing to a natural origin for this polluting form and (ii) pollution by organic matter and nutrients originates from anthropogenic sources, mainly as municipal wastewater. The application of PCA and cluster analysis has achieved a meaningful classification of river water samples based on seasonal and spatial criteria.     

Water quality of the odzi river in the Eastern Highlands of Zimbabwe

For Odzi. the main river originating in the Eastern Highlands of Zimbabwe, the nature, sources and extent of pollution are characterised. Over a span of 9 months, the river water samples collected at six selected sites were analysed for various physical and chemical parameters namely, temperature, conductance, pH, total suspended and dissolved solids, BOD. total phosphate and nitrate levels. The Mutare river carried the seepage from abandoned mine dumps to the Odzi River. Water quality of the Odzi River at different points assessed by the water quality indices (WQI) is compared. According to the quality indices during the study period, water quality in the upper reaches of the river was medium to good. It dwindled in the plains, due to the seepage from abandoned mine dumps and discharges from the farm lands.     

Assessment of the water quality and identification of pollution sources of Kaduna River in Niger State (Nigeria) using exploratory data analysis

Exploratory data analysis such as hierarchical cluster analysis and principal component analysis were applied to water quality dataset of the Kaduna River, obtained during 3 years (2008–2010), monthly monitoring of eight key different sampling sites for 19 parameters to extract correlations and similarities between variables and to classify river sampling sites in groups of similar quality. Hierarchical cluster analysis grouped eight sampling sites into three statistically significant clusters of similar water composition. Six varifactors were obtained after varimax rotation of initial principal components using principal component analysis. These techniques gave an insight into the sources of pollution. Anthropogenic influence (municipal, industrial wastewater and agricultural run‐off) was the major source of river water pollution.     

利用长江水作热泵系统冷热源的技术分析

介绍了江水源热泵系统的形式，分析了长江重庆段的水温和水质情况。研究表明，长江水作为冷热源适于发展水源热泵技术，应优先选择壳管式直接利用热泵系统。此外，针对长江水泥沙含量高、夏季悬浮物和微生物数量多的问题，探讨了江水的净化处理、增强传热和除垢、热泵系统工况分析、取水方式以及江水二次利用等关键技术。     

River health assessment in peri-urban landscapes: an application of multivariate analysis to identify the key variables

An array of river health assessment approaches and water quality variables have been suggested in the past for assessing the level of river health. However, the selection of suitable variables to be monitored for the assessment remains ambiguous and often it is not practical to monitor all the suggested variables. In this study, we employ a multivariate data reduction technique, called Factor Analysis (FA), to identify the key river health variables for a peri-urban river system, viz., the Hawkesbury-Nepean River system in New South Wales, Australia. Out of 40 water quality variables included in the analysis, the FA identified nine key variables, under three varifactors (VFs), explaining 50% of the variance in the river water quality. Variables in the first, second and third VFs revealed anaerobic conditions, microbial quality and effects of eutrophication in the Hawkesbury-Nepean River. Thus, the present work shows a notable reduction in the number of variables and the application of FA for identification of key variables was found promising. The finding of this study has potential application in designing a cost-effective river health monitoring program by reducing the number of variables to be monitored in a peri-urban situation. It can also assist in partitioning variables according to their unique contribution to the total variance.     

Comparison of self-organizing maps classification approach with cluster and principal components analysis for large environmental data sets

Three classification techniques (loading and score projections based on principal components analysis (PCA), cluster analysis (CA) and self-organizing maps (SOM)) were applied to a large environmental data set of chemical indicators of river water quality. The study was carried out by using long-term water quality monitoring data. The advantages of SOM algorithm and its classification and visualization ability for large environmental data sets are stressed. The results obtained allowed detecting natural clusters of monitoring locations with similar water quality type and identifying important discriminant variables responsible for the clustering. SOM clustering allows simultaneous observation of both spatial and temporal changes in water quality. The chemometric approach revealed different patterns of monitoring sites conditionally named "tributary", "urban", "rural" or "background". This objective separation could lead to an optimization of river monitoring nets and to a better tracing natural and anthropogenic changes along the river stream.     

荆门市竹皮河流域水环境综合治理之生态修复工程设计

竹皮河为季节性雨源型城市河流,存在污水直排、底泥淤积、季节性干涸等诸多水环境问题,导致其水质恶化严重,水生态系统受损,自净能力较弱。为恢复竹皮河生态系统多样性,提升水体自净能力,实现水质长效保持,在控源截污的基础上,采用人工湿地、原位微生物修复、生态砾石河床、水生植物恢复等多种生态治理技术集成,实施河道生态补水、生态净化、生态修复三大工程,重建生态系统多样性,实现水质自然净化。通过流域综合治理,竹皮河城区段下游水体水质逐步达到地表Ⅳ类水标准。工程设计为雨源型城市河流的生态治理提供了参考。     

Assessment of water quality using principal component analysis: A case study of the river Ganges

In present study multivariate statistical approaches are used; interpretation of large and complex data matrix obtained during a monitoring of the river Ganges in Varanasi. 16 physicochemical and bacteriological variables have been analyzed in water samples collected every three months for two years from six sampling sites where river affected by man made and seasonal influences. The dataset was treated using Principal Component Analysis (PCA) to extract the parameters that are most important in assessing variation in water quality. Four Principal Factor were identified as responsible for the data structure explaining 90% of the total variance of the dataset, in which nutrient factor (39.2%), sewage and feacal contamination (29.3%), physicochemical sources of variability (6.2%) and waste water pollution from industrial and organic load (5.8%) that represents total variance of water quality in the Ganges River. The present study suggests that PCA techniques are useful tools for identification of important surface water quality parameters.     

The water quality of the River Thame in the Thames Basin of south/south-eastern England

The water quality of the River Thame, a tributary of the River Thames in the Thames basin, is described in relation to point and diffuse contaminant inputs and runoff from permeable and impermeable bedrock geology with their own characteristic water quality. The data is examined to see if the market town of Aylesbury in the upper part of the catchment influences water quality. Previous studies highlighted the influence of Aylesbury sewage treatment works (STW) on soluble reactive phosphorus (SRP) concentrations in the river before and after phosphorus (P) stripping at the STW. Variations in water quality along the river are described and the study indicates that, apart from SRP, water quality determinants seem to be relatively unaffected by Aylesbury. The Thame water quality is compared with other catchment typologies and it is very similar to that of the main stem of the Thames even though the Thames is mainly Chalk groundwater fed. Differences in water quality largely link to the amount of STW effluent within the rivers and to the endmember compositions of the groundwater and near surface water sources.     

Spatial Distribution of Water Quality Indexes and Their Response to Land Use Patterns in the Gaotan River Basin

The relationship between water quality and land use is of significance for the protection of the water environment. Here we take the Gaotan River Basin in Liangping District as the research object, and comprehensively use the spatial analysis with geographical information system(GIS), Pearson correlation analysis, and redundancy analysis(RDA) to study the ecological response of four water quality indexes of chemical oxygen demand(COD), biochemical oxygen demand in the 5 th day(BOD5), ammonia nitrogen(NH3-N), and total phosphorus(TP) on land use patterns on a sub-basin scale. The results show that land use patterns of the Gaotan River Basin have an important impact on water quality: wooded land can improve the water environment of the river; dry land, land for urban and rural housing and public facilities, and land for mining and industrial use are the main sources of COD, BOD5, and NH3-N; garden plot, land for building communications, and water areas have a weak impact on pollutants, indicating that agricultural non-point source pollution and domestics pollution in rural areas are the major cause of the deterioration of the water quality of the Gaotan River. The research results are of guiding significance to the treatment of water environment of the Gaotan River Basin.     

A decision support system for water quality issues in the Manzanares River (Madrid, Spain)

The Manzanares River, located in Madrid (Spain), is the main water supplier of a highly populated region, and it also receives wastewater from the same area. The effluents of eight Waste Water Treatment Plants (WWTPs) downstream of the river, which represent 90% of the flow in the middle and lower parts of the river, are the primary sources of water pollution. Although the situation has improved slightly in the last two years, the water in the river is highly polluted, making it uninhabitable for aquatic life. Water quality modelling is typically used to assess the effect of treatment improvements in water bodies. In this work, the GESCAL module of the Aquatool Decision Support System Shell was used to simulate water quality in the Manzanares River. GESCAL is appropriate for modelling in an integrated way water quality for whole water resources systems, including reservoirs and rivers. A model was built that simulates conductivity, phosphorous, carbonaceous organic matter, dissolved oxygen, organic nitrogen, ammonia, and nitrates. The period from October 2006 to September 2008 was selected for calibration due to the many treatment modifications that occurred during this time. An earlier and longer period, from October 2000 to September 2006, was used for validation. In addition, a daily model was used to analyse the robustness of the GESCAL model. Once the GESCAL model was validated, different scenarios were considered and simulated. First, different combinations of nutrient elimination among the different WWTPs were simulated, leading to the conclusion that investments have to focus on three of the proposed WWTPs. Moreover, these treatments will not be sufficient to maintain fish habitat conditions at all times. Additional measures, such as the increment of the flow in the river or oxygen injection, were simulated. Incrementing the flow of the Manzanares River has been shown to be an efficient means of increasing water quality, but this implies an increment in the risk of water scarcity situations in the Madrid water supply system.     

Water quality assessment of the River Kabul at Peshawar, Pakistan: Industrial and urban wastewater impacts

Untreated wastewater discharges may have significant short term and long term effects on the quality of a river system. Present study was undertaken to assess the present status of the water quality of the River Kabul near Peshawar in Pakistan. Seven sites were sampled upstream and downstream in the River Kabul in 2009. Samples were also taken from waste water channel (Budni Drain) that carries waste-water of Peshawar Industrial Estate as well as the domestic sewers to assess the pollution contribution of these sources to the River Kabul. Physico-chemical and microbiological parameters of the samples were analyzed during the study, as well as possible sources of contamination were investigated. The study showed that the pollution level in river is rising from upstream (at city entrance) to downstream (at city exit) due to discharge of domestic waste water effluents, agricultural activities, and solid waste dumping directly into the river.     

A preliminary pressure–impact analysis applied in the Pinios river basin (Thessaly, Central Greece)

Greece has not yet undertaken one of the first and most important tasks required by the Water Framework Directive (WFD: the integrated review of the impact of human activity on the status of surface waters for each river basin – the IMPRESS analysis. Owing to the lack of a national methodology, a preliminary analysis was carried out for the Pinios river basin, applying a combination of different methodologies refined to suit the particularities of the Greek freshwater environment and to accommodate the limited availability of data. Pressures caused by the main pollution sources, point and nonpoint, were quantified in terms of pollution loads with the use of emission factors. The existing limited biological and physicochemical monitoring data were used to assess impacts. Additionally, we identified pressures caused by alterations from land-use data; we carried out a River Habitat Survey (RHS) and estimated the hydromorphological impacts through the calculation of a Habitat Modification Score (HMS). Our results suggest that the probability of the Pinios river basin failing to achieve good ecological quality by 2015 due to pollution is high, and due to hydromorphological pressures is moderate.     

Monitoring of the antioxidant BHT and its metabolite BHT-CHO in German river water and ground water

The behavior of anthropogenic polar organic compounds in ground water during infiltration of river water to ground water was studied at the Oderbruch area on the eastern border of Germany. Additionally, waste water sewage treatment works (STWs) discharging their treated waste water into the Oder River and rain water precipitation from the Oderbruch area were investigated. The study was carried out from March 2000 to July 2001 to investigate seasonal variations of the target analytes. Samples were collected from four sites along the Oder River, from 24 ground water monitoring wells located close to the Oder, from one rain water collection station, from two roof runoffs, and from four STWs upstream of the Oderbruch. Results of the investigations of the antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) and its degradation product 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO) are presented. BHT and BHT-CHO were detected in all samples of the Oder River with mean concentrations of 178 and 102 ngl(-1), respectively. BHT and BHT-CHO were also detected in effluent waste water samples from municipal STWs at mean concentrations of 132 and 70 ngl(-1), respectively. Both compounds are discharged into river water directly via treated waste water. In the rain water sample, 308 ngl(-1) of BHT and 155 ngl(-1) of BHT-CHO were measured. Both compounds were detected in roof runoff with mean concentrations of 92 ngl(-1) for BHT and 138 ngl(-1) for BHT-CHO. The median values of BHT and BHT-CHO in ground water samples were 132 and 84 ngl(-1), respectively. The chemical composition of ground water from parts of the aquifer located less than 4.5 m distant from the river are greatly influenced by bank filtration. However, wet deposition followed by seepage of rain water into the aquifer is also a source of BHT and BHT-CHO in ground water.     

Evaluating river water quality through land use analysis and N budget approaches in livestock farming areas

This study was carried out to evaluate the quality of river water by analysis of land use in drainage basins and by estimating the N budgets. The drainage basins of Shibetsu River (Shibetsu area) and Bekkanbeushi River (Akkeshi area) in eastern Hokkaido, Japan were selected for a case study, and the evaluation of water quality was up-scaled to the regional level in Hokkaido by using the Arcview/GIS and statistical information. Water sampling was carried out in August 2001 and May 2002 in the Shibetsu and Akkeshi areas, respectively. The proportions of major land uses in drainage basins such as upland field, forest, urban area, wetland and wasteland for each sampling site were estimated by using topographic maps scaled at 1:25,000. The linear regression results showed that the correlation between NO3-N concentration and the proportion of upland in the drainage basins was highly and positively significant for both the Shibetsu area (r = 0.84, n = 57) and the Akkeshi area (r = 0.71, n = 73) at < 0.001 significance level. The regression coefficients or impact factors of river water quality were 0.015 and 0.0052 for the Shibetsu and Akkeshi areas, respectively. A comparison of these results with that of the previous study results in Hokkaido indicated that the impact factors were highest for intensive livestock farming areas (0.040), medium for mixed agriculture and livestock farming (0.020-0.030), and the lowest for grassland-based dairy cattle and horse farming areas (0.0052-0.015). The results of a simple regression analysis showed that the impact factors had a significant positive correlation with the cropland surplus N (r = 0.93, P < 0.01), chemical fertilizer N (r = 0.82, P < 0.05), and manure fertilizer N (r = 0.76, P < 0.05), which were estimated by using the N budget approach. Using the best-correlated regression model, impact factors for all cities, towns and villages of the Hokkaido region were estimated. The NO3-N concentrations for all major rivers in Hokkaido were predicted by multiplying the estimated impact factors by the proportion of uplands. The regression analysis indicated that the predicted NO3-N concentrations were significantly correlated (r = 0.62, P < 0.001, n = 203) with the measured NO3-N concentrations, reported previously. It can be concluded that estimating the proportions of upland fields in drainage basins, and calculating cropland surplus N enables us to predict river water quality with respect to NO3-N concentration.     

Proposal of a geo-environmental zoning method based on Ottobasin compartmentalization

This paper proposes a new geo-environmental zoning method based on the hydrographic basin compartmentalization and codification technique known as the Ottobasin Method [Pfafstetter in Classificação de Bacias Hidrográficas—Metodologia de Codificação Rio de Janeiro, RJ. Departamento Nacional de Obras de Saneamento (DNOS), p 19, 1989]. A study was carried out in the Pardo River Basin, São Paulo, Brazil. Ottobasins were characterized based on the rock substratum, unconsolidated materials, slope, drainage and landform. The percentage of each analyzed attribute was calculated and compared between the Ottobasins. A GIS-aided analysis was used to assess which Ottobasin should be subjected to further compartmentalization such that an acceptable level of homogeneity was reached. When an adequate level of compartmentalization is attained, the units are sufficiently homogeneous to allow for their use as geo-environmental units, ie as a tool for planning environmental protection/mitigation.     

Modeling the contribution of point sources and non-point sources to Thachin River water pollution

Major rivers in developing and emerging countries suffer increasingly of severe degradation of water quality. The current study uses a mathematical Material Flow Analysis (MMFA) as a complementary approach to address the degradation of river water quality due to nutrient pollution in the Thachin River Basin in Central Thailand. This paper gives an overview of the origins and flow paths of the various point- and non-point pollution sources in the Thachin River Basin (in terms of nitrogen and phosphorus) and quantifies their relative importance within the system. The key parameters influencing the main nutrient flows are determined and possible mitigation measures discussed.The results show that aquaculture (as a point source) and rice farming (as a non-point source) are the key nutrient sources in the Thachin River Basin. Other point sources such as pig farms, households and industries, which were previously cited as the most relevant pollution sources in terms of organic pollution, play less significant roles in comparison. This order of importance shifts when considering the model results for the provincial level. Crosschecks with secondary data and field studies confirm the plausibility of our simulations. Specific nutrient loads for the pollution sources are derived; these can be used for a first broad quantification of nutrient pollution in comparable river basins. Based on an identification of the sensitive model parameters, possible mitigation scenarios are determined and their potential to reduce the nutrient load evaluated.A comparison of simulated nutrient loads with measured nutrient concentrations shows that nutrient retention in the river system may be significant. Sedimentation in the slow flowing surface water network as well as nitrogen emission to the air from the warm oxygen deficient waters are certainly partly responsible, but also wetlands along the river banks could play an important role as nutrient sinks.     

Microbiological water quality along the Danube River: Integrating data from two whole-river surveys and a transnational monitoring network

The River Danube is with 2780 km the second longest river in Europe. Its catchment area covers 801 500 km², with approximately 81 million inhabitants in 19 countries. River water for anthropogenic use, transportation and recreation is of major importance in all of these countries. Microbiological contamination from faecal pollution by anthropogenic sources is considered to be a crucial problem throughout the Danube River basin. Thus, detailed knowledge on the extent and the origin of microbial pollution is essential for watershed management. The determination of faecal indicator concentrations along the Danube and its major tributaries during two whole-river surveys and 16 permanent stations allowed for the first time to draw a clear picture of the faecal pollution patterns along the whole longitudinal profile of this important international river. By including a variety of environmental variables in statistical analysis, an integrative picture of faecal pollution in the Danube River basin could be evolved. Four hot spots and six stretches of differing faecal pollution were identified, mainly linked with input from large municipalities. Significant decline of microbiological pollution was observed in the upper and lower Danube stretches over the investigation period. In contrast, a significant increase in the middle part was evident. The planned implementation of new wastewater treatment plants and advanced wastewater treatment measures according to the European Union urban wastewater directive will have a great potential to reduce microbial faecal pollution in the Danube and thus improving water quality.