Analysis of long-term and seasonal river water quality changes in Latvia

An analysis of long-term historical records of the concentrations of major ions, TDS and nutrients for 20 river sites in Latvia is reported. Periods of water quality observations ranged from 15 to 43 years. A study of the quarterly adjusted time series showed that characteristic features of the data are non-normal distributions, seasonality, serial correlation and presence of significant trends that are mostly positive. The application of state-of-the-art software, based on non-parametric statistics such as the Seasonal Kendall slope estimator and the Seasonal Hodges-Lehmann estimator, made it possible to investigate these water quality records more accurately than other methods allow.Typical seasonal variations and concentration-discharge relationships were analyzed for different constituents. It was shown that fertilizer application and marsh land reclamation can cause widespread and intensive river water quality changes. Concentration increases of as much as 5–10 times that of background values were detected for NO₃⁻, Cl⁻, Na⁺ + K⁺ and SO₄²⁻. The main water quality changes took place in the 1960s and the early 1970s when fertilizer applications and reclamation works increased. After that, concentration increases for constituents other than NO₃⁻ and SO₄²⁻ were statistically insignficiant. The significant increases for NO₃⁻ and SO₄²⁻ were probably due to the additional impact of increased atmospheric deposition. The results of long-term changes of river loads entering the Baltic Sea and the Gulf of Riga from Latvian territory are examined.     

Analysis of the QUESTOR water quality model using a Fourier amplitude sensitivity test (FAST) for two UK rivers

This paper presents the sensitivity analysis of a well-known in-stream water quality model, QUESTOR (QUality Evaluation and Simulation TOol for River systems) as applied to two rivers of contrasting land-use in the northeast of England: the 'rural' Ouse and the 'urban' Aire. The analysis employed a version of the Fourier Amplitude Sensitivity Test (FAST) that quantifies the contribution of changes in individual parameters and combination of parameters to the variance of the model output (here the Nash-Sutcliffe) in an efficient way. The quantification of the sensitivity of the model output to the parameters led to the identification of the most influential parameters. Differences between the Aire and the Ouse were found, reflecting their different water quality regime. Results highlighted the importance of interactions between two, or more, parameters on the model output. It led to question the one-at-a-time calibration method currently applied with QUESTOR and underlined the importance of including interactions between parameters in sensitivity analyses. Comparison of the relative influence of parameters versus input data showed contrasting results. In the urban system, the inputs from discharges (sewage treatment works and industrial effluents) were highly influential on model outputs and generally more important than the model parameters. For the rural river, the tributary discharges were most influential, but only at a similar or a lower level than the model parameters.     

Determination and speciation of copper and lead in sediments of a Mediterranean river (River Tenes, Catalonia, Spain)

Total concentrations of Cu and Pb and the speciation of these metals in sediments of the River Tenes are studied in order to establish the extent to which they are polluted and their capacity of remobilization. Five samples taken along the river were analyzed, major components of the sediments were studied using XRF and total Pb and Cu content were determined by AAS. In order to test the accuracy of the digestion methods used (triacid attack with nitric, perchloric and hydrofluoric acids or diacic attack with nitric and hydrochloric acids) for the determination of total trace metal, a standard reference material was also analyzed. Triacid attack is proposed to obtain good results. The results show a highly polluted area (1556 mg kg⁻¹ Cu and 1555 mg kg⁻¹ Pb) in the last sampling site analyzed. For metal speciation, the sequential scheme of Tessier et al. was used. From the results obtained, it can be concluded that Cu content in non-residual fraction is bonded mainly to organic matter, whereas non-residual Pb is mainly associated to iron and manganese oxides.     

Changes in phytoplankton composition in a Mediterranean coastal lagoon in the Cullera Estany (Comunitat Valenciana,Spain)

The Cullera Estany is a coastal lagoon located in a highly intensified agriculture and tourist area in Valencia. This coastal lagoon has connections with the sea that produce marine intrusion and generate a freshwater interface. Four sampling campaigns were carried out during 2010 in order to analyse the phytoplankton composition and its relation to nutrient content through a Redundancy Analysis. Temperature, dissolved oxygen, nitrite and salinity are the main factors controlling the dynamics of phytoplankton community. During July and October, there is water column stratification; meanwhile in March, there is a well‐mixed water column. In addition, in May and July campaigns, hypoxia/anoxia conditions are detected at the bottom. The most abundant phytoplankton groups are Diatoms and Cryptophyceae. Diatoms and Cyanophyceae respond positively to temperature while Cryptophyceae, Prasinophyceae and Dinophyceae respond to high salinity and dissolved oxygen values. Furthermore, picoplankton is correlated inversely with nutrient concentrations.     

Cryptosporidium spp. and Giardia duodenalis in two areas of Galicia (NW Spain)

The aim of the present study was to investigate the environmental dispersal of Cryptosporidium spp. and Giardia duodenalis in two distinct areas (coastal and inland) in Galicia (NW Spain). Faecal samples were collected from healthy asymptomatic domestic (cows and sheep) and wild animals (deer and wild boars) in the selected areas. In each of the selected areas, samples of untreated water (influent) and of treated water (final effluent) were collected from each of the 12 drinking water treatments plants (DWTPs) and 12 wastewater treatment plants (WTPs) under study. Analysis of a single sample from each of the 635 (coastal) and 851 (inland) domestic and wild animals selected at random revealed that the prevalences of cryptosporidiosis and giardiosis in coastal area were 9.2% and 15.9% respectively, and in inland area, 13.7% and 26.7% respectively. In the coastal area, Cryptosporidium spp. oocysts were detected in influent and effluent samples from 2/12 (16.6%) DWTPs and 8/12 (66.6%) WTPs, while G. duodenalis cysts were detected in influent and effluent samples from 3/12 (25.0%) DWTPs and 12/12 (100%) WTPs. The concentrations were notably higher in WTPs; the mean parasite concentrations in the final treated effluent were 10 oocysts per litre and 137.8 cysts per litre for Cryptosporidium and Giardia, respectively. The mean concentration of G. duodenalis cysts per litre was significantly higher (P < 0.05) than the mean concentration of Cryptosporidium spp. oocysts per litre in both the influent and the effluent samples from all the treatment plants. In the coastal area, C. parvum, C. hominis and G. duodenalis assemblages A (I and II) and E were most repeatedly detected. In the inland area, C. parvum, C. andersoni and G. duodenalis assemblages A (I and II), B and E were most frequently identified.     

Self-build communities: the rationale and experiences of group-build (Baugruppen) housing development in Germany

Group-build housing developments can bring together the cost and customisation benefits regularly attributed to self-build housing with a communitarian ethos associated with ‘intentional’ communities. This paper presents an initial examination of the rationale, motivations and social experiences of group-build housing from Germany, where over half of all new homes are produced independently from volume-build developers. The paper aims, firstly, to test the hypothesis that group-build delivers general ‘community’ benefits; secondly, to contribute to an understanding of the processes leading to successful schemes; and lastly, to demonstrate that by making individual home building dependent on the success of a larger group, collective interests can prevail over personal pursuit. This research draws attention to the motivations, the social experiences through the development process and the social legacy – aspects of particular interest for policy-makers as well as prospective builders – of group-build housing projects.     

Comparative study of the Cd. Cu and Pb determination by AAS and by ICP-AES in river water : Application to a mediterranean river (Congost river, Catalonia, Spain)

The accuracy, precision, detection limit and rapidity in the determination of Cd, Cu and Pb in river water by AAS determination, previous extraction with APDC-MIBK system, is compared with direct determination method ICP-AES. Both methods show a similar detection limit and an analogous accuracy by the addition standard method. With a calibration curve only ICP-AES presents good accuracy, this technique is advantageous in long term precision and requires minimum sample preparation. The sample stability at different temperature conservation is studied. Finally both methods are applied to the determination of Cd, Cu and Pb in Congost river water.     

Eutrophication of Tamar Lakes (1975–2003): a case study of land-use impacts, potential solutions and fundamental issues for the Water Framework Directive

Tamar Lakes is comprised of two reservoirs, which are located in South West England and in the headwaters of River Tamar at approximately 135 m above ordnance datum. Upper Tamar Lake (UTL) is a direct feed source reservoir of potable water in North Cornwall. Immediately following completion in 1975, UTL was subject to intense blue‐green algal blooms that continue to the present. These blooms create operational problems for water treatment, especially in hot‐dry years. Lower Tamar Lake (LTL) was constructed as a water supply reservoir in 1819 and became obsolete following UTL coming on‐line. Detailed water quality investigations over a period of some 28 years have confirmed the source of nutrient enrichment that fuels the algal blooms to be agriculturally derived, corresponding with a substantial increase in livestock farming. Associated poor land management practices, such as extensive field drainage and inappropriate slurry disposal to land, are linked with substantial elevations in organic contaminants such as ammonia, biochemical oxygen demand (BOD) and suspended solids (SS) during rainfall events. Evidence demonstrates that both reservoirs act as primary treatment lagoons, substantially reducing the worst of these pollutants and providing significant environmental gain. The implications of the Common Agricultural Policy (CAP), the Water Framework Directive (WFD) and regulatory monitoring are discussed in relation to resource management.     

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.     

Toxicity and potential risk assessment of a river polluted by acid mine drainage in the Iberian Pyrite Belt (SW Spain)

Metal contamination from acid mine drainage (AMD) is a serious problem in the southwest of the Iberian Peninsula, where the Iberian Pyrite Belt is located. This zone contains original sulfide reserves of about 1700 Mt distributed among more than 50 massive sulfide deposits. Weathering of these minerals releases to the waters significant quantities of toxic elements, which severely affect the sediments and surface waters of the region. The main goal of this paper is to evaluate the toxicity and the potential risk associated with the mining areas using Microtox test and different factors which assess the degree of contamination of the sediments and waters. For this, a natural stream polluted by AMD-discharge from an abandoned mine has been studied. The results show that elevated concentrations of Cu, As and Zn involve an important potential risk on the aquatic environment, associated both with sediments and waters. Microtox test informs that the sediments are extremely or very toxic, mainly related to concentrations of Fe, As, Cr, Al, Cd, Cu and Zn. Pollution is mainly transferred to the sediments increasing their potential toxicity. A natural creek affected by AMD can store a huge amount of pollution in its sediments while exhibiting a not very low water pH and low water metal concentration.     

High resolution modeling of the effects of alternative fuels use on urban air quality: Introduction of natural gas vehicles in Barcelona and Madrid Greater Areas (Spain)

The mitigation of the effects of on-road traffic emissions on urban air pollution is currently an environmental challenge. Air quality modeling has become a powerful tool to design environment-related strategies. A wide range of options is being proposed; such as the introduction of natural gas vehicles (NGV), biofuels or hydrogen vehicles. The impacts on air quality of introducing specific NGV fleets in Barcelona and Madrid (Spain) are assessed by means of the WRF-ARW/HERMES/CMAQ modeling system with high spatial-temporal resolution (1 km², 1 h). Seven emissions scenarios are defined taking into account the year 2004 vehicle fleet composition of the study areas and groups of vehicles susceptible of change under a realistic perspective. O₃ average concentration rises up to 1.3% in Barcelona and up to 2.5% in Madrid when introducing the emissions scenarios, due to the NO_x reduction in VOC-controlled areas. Nevertheless, NO₂, PM10 and SO₂ average concentrations decrease, up to 6.1%, 1.5% and 6.6% in Barcelona and up to 20.6%, 8.7% and 14.9% in Madrid, respectively. Concerning SO₂ and PM10 reductions the most effective single scenario is the introduction of 50% of NGV instead of the oldest commercial vehicles; it also reduces NO₂ concentrations in Barcelona, however in Madrid lower levels are attained when substituting 10% of the private cars. This work introduces the WRF-ARW/HERMES/CMAQ modeling system as a useful management tool and proves that the air quality improvement plans must be designed considering the local characteristics.     

Geochemical and microfaunal proxies to assess environmental quality conditions during the recovery process of a heavily polluted estuary: the Bilbao estuary case (N. Spain)

This study explores the eventual environmental improvement of the Bilbao estuary (northern Spain), from 1997 to 2006, in order to assess current estuarine restoration being undertaken as part of a Revitalization Strategic Plan. The monitoring programme is based on spatial and temporal variation in the distributions of both benthic foraminiferal assemblages and heavy metals contained in surficial sediments from the polluted intertidal flats. The overall pattern shows a decreasing metal concentration; however, reversals to this trend are noticed in the middle estuary. From 2000 to 2003, a significant decrease in heavy metal concentration was observed which is most likely related to the implementation in 2001-2002 of the biological treatment at a central wastewater treatment plant. Although the metal concentration decreased by 85% for some elements, these values still remain considerably high. No significant change occurred between 2003 and 2006 in metal concentrations. During the monitoring period the estuary channel presented environmental conditions close to azoic in 3/4 of its watercourse. Only in the year 2006, the two lowermost estuarine samples exhibited an increase in microfaunal densities. These samples were dominated by pollution-resistant estuarine species. The fact that estuarine sediments quality is recovering very slowly seems to be caused mainly by the resuspension of accumulated contaminants in the sediments due to dredging and working activities in the estuary. Thus, local authorities should consider also the clean up of the pollutants stored in the sediments, not seeking only the achievement of the water quality standards, as these polluted sediments can act as source of contamination.     

Evaluation of Po River water quality in Torino (Italy): Effects of diffuse and local point loads

The aim of this paper is to examine the Po River water quality in a small stretch in Piedmont (northern Italy). In this stretch a large pollution load, derived from the wastewater treatment plant of Torino area (more than 2 million inhabitants), is discharged and diluted in the water. In this study this load has been quantified and modeled in order to understand the sources, destinations and effects of the emitted pollutants. The objective was to determine the impact produced by the Torino Wastewater Treatment Plant on the quality of the water, based on various hydrological conditions and the possible intervention on the point and diffuse loads.     

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.     

Composition of bacterial and archaeal communities in freshwater sediments with different contamination levels (Lake Geneva, Switzerland)

The aim of this study was to compare the composition of bacterial and archaeal communities in contaminated sediments (Vidy Bay) with uncontaminated sediments (Ouchy area) of Lake Geneva using 16S rRNA clone libraries. Sediments of both sites were analysed for physicochemical characteristics including porewater composition, organic carbon, and heavy metals. Results show high concentrations of contaminants in sediments from Vidy. Particularly, high contents of fresh organic matter and nutrients led to intense mineralisation, which was dominated by sulphate-reduction and methanogenesis. The bacterial diversity in Vidy sediments was significantly different from the communities in the uncontaminated sediments. Phylogenetic analysis revealed a large proportion of Betaproteobacteria clones in Vidy sediments related to Dechloromonas sp., a group of dechlorinating and contaminant degrading bacteria. Deltaproteobacteria, including clones related to sulphate-reducing bacteria and Fe(III)-reducing bacteria (Geobacter sp.) were also more abundant in the contaminated sediments. The archaeal communities consisted essentially of methanogenic Euryarchaeota, mainly found in the contaminated sediments rich in organic matter. Multiple factor analysis revealed that the microbial community composition and the environmental variables were correlated at the two sites, which suggests that in addition to environmental parameters, pollution may be one of the factors affecting microbial community structure.     

Urban reuse of public spaces in ‘central suburbs’. Two districts between two rivers in the city of Cosenza (Italy)

ABSTRACT

The article describes the results of a research on the theme of regeneration of urban public spaces in historical centres. A multidisciplinary methodological approach of cooperation of various knowledge was adopted to define, also through the application of open and inclusive participatory approaches, precise intervention actions. The research uses two areas on the edge of the historical city of Cosenza (Italy) as a case study. The research, therefore, has achieved, among its main results, that of reinforcing the awareness that an urban context unable to maintain relationships loses its meaning and becomes but a museum of itself.     

Identifying the sources and fate of anthropogenically impacted dissolved organic matter (DOM) in urbanized rivers

Anthropogenic activities have dramatically changed the loads and compositions of dissolved organic matter (DOM) in urbanized streams. In this study, the spatial and temporal variations of DOM in the anthropogenically impacted Zhujiang River were investigated by analyzing the water samples in an upstream, urbanized area and downstream of the rivers on different days of one year. The results indicated that the levels of dissolved organic carbon (DOC) and total phosphorus (TP) were unaffected by seasonal changes, but the specific UV₂₅₄ absorbance (SUVA) values and the total nitrogen (TN) content were greater in the winter than those in the summer. Parallel factor (PARAFAC) analysis of the excitation emission matrices (EEM) revealed the presence of three anthropogenically derived components [tryptophan-like (C1) and tyrosine-like proteins (C3) and anthropogenic humic substances (C5)] in the urbanized rivers, and they had greater seasonal and spatial variability than the terrestrial and microbial humic substances (C2 and C4). Cluster analysis revealed that treated wastewater was an important source of DOM in the urbanized streams. Photodegradation experiments indicated that the DOM in the populous area of the rivers had greater photodegradation potentials than that in the downstream region or in the natural waters. Interestingly, that the anthropogenic humic substances (C5) were considerably more photoreactive than the other four PARAFAC components, which exhibited a decrease of 80% after exposure to sunlight for 0.5 d. This study suggests that the treated wastewater could be an important input to the DOM in the urbanized rivers and the naturally occurring photodegradation could help in eliminating the anthropogenic DOM during their transport.     

Simultaneous removal of carbon and nutrients from an industrial estate wastewater in a single up-flow aerobic/anoxic sludge bed (UAASB) bioreactor

Simultaneous removal of carbon and nutrients (CNP) in a single bioreactor is highly significant for energy consumption and control of reactor volume. Basically, nutrients removal is dependant to the ratio of biochemical oxygen demand to chemical oxygen demand (BOD₅/COD). Thus, in this study the treatment of an industrial estate wastewater with low BOD₅/COD ratio in an up-flow aerobic/anoxic sludge bed (UAASB) bioreactor, with an intermittent regime in aeration and discharge, was investigated. Hydraulic retention time (HRT) of 12-36 h and aeration time of 40-60 min/h were selected as the operating variables to analyze, optimize and model the process. In order to analyze the process, 13 dependent parameters as the process responses were studied. From the results, it was found, increasing HRT decreases the CNP removal efficiencies. However, by increasing the BOD₅ fraction of the feed, the total COD (TCOD), slowly biodegradable COD (sbCOD), readily biodegradable COD (rbCOD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies were remarkably increased. Population of heterotrophic, nitrifying and denitrifying bacteria showed good agreement with the results obtained for TCOD and TN removal. The optimum conditions were determined as 12-15 h and 40-60 min/h for HRT and aeration time respectively.     

Emissions variation in urban areas resulting from the introduction of natural gas vehicles: Application to Barcelona and Madrid Greater Areas (Spain)

On-road traffic is the major contributor to pollutant emissions in urban areas. Nowadays different emission abatement strategies are being tested in order to improve urban air quality (e.g. the European Commission currently promotes the use of natural gas as an alternative fuel). Several feasible scenarios regarding the introduction of natural gas vehicles (NGV) are studied in the two main cities of Spain (Barcelona and Madrid) by using the HERMES emission model. The most suitable emission factors to NGV are selected among those available in the literature. The account of emissions in the base case scenario estimated for a typical summertime polluted day of the year 2004 reflects that in Barcelona 86% of primary pollutants come from on-road traffic compared to 93% in Madrid, because of the heavier industrial activity in the former. The introduction of NGV in urban zones would have a positive effect on emissions, whose extent largely depends on the substituted fleets and the conurbation characteristics. Maximum reductions in NO_x emissions in Madrid are attributed to the substitution of 10% of the oldest diesel and petrol cars, while in Barcelona the change of 50% of the oldest commercial light vehicles becomes more effective. PM_2.5 and SO₂ emissions can be significatively reduced with the introduction of NGV instead of the oldest commercial light vehicles. The substitution of conventional fuels by natural gas must reach around 4% to achieve significative reductions in traffic emissions (larger than 5%). This work focuses on air quality issues, therefore GHG emissions are not included, nevertheless this kind of associated impact has to be considered by the decision makers. Assessing the efficacy of environmental improvement strategies entails a realistic design of emission scenarios and their evaluation. The detailed emission account provides a fundamental basis for the air quality modelling and its comparison among scenarios.