Water

365 KiB

Open AccessArticle

Evaluating the Measurement of Activated Sludge Foam Potential

by Martin Fryer, Eoghan O’Flaherty and Nicholas F. Gray

Water 2011, 3(1), 424-444; https://doi.org/10.3390/w3010424 - 18 Mar 2011

Cited by 19 | Viewed by 11538

The most widely used technique for assessing the propensity of activated sludge to suffer from biological foaming is to measure foam potential. This involves measuring the amount of foam produced from sludge under conditions of controlled aeration. Two approaches have been adopted: (1) [...] Read more.

The most widely used technique for assessing the propensity of activated sludge to suffer from biological foaming is to measure foam potential. This involves measuring the amount of foam produced from sludge under conditions of controlled aeration. Two approaches have been adopted: (1) Air is passed through specially designed columns from fine porous diffusers at a fixed rate to form uniform sized bubbles or (2) employing Alka-Seltzer^™ tablets which effervesce when added to the sludge. Both tests generate foam formation which can then be quantified. Foam assessment in activated sludge is reviewed. A sintered disc aeration column was compared with the Alka-Seltzer^™ test method and both methods examined under a range of different environmental conditions. Foam potential measured by the sintered disc method displayed better repeatability compared to the Alka-Seltzer test. The use of a wire cage placed over the tablets greatly improved the precision of the Alka-Seltzer test. A positive linear correlation was also found between foam potential and temperature (4–20 °C). Sludge solids concentration was also shown to influence foaming potential making comparisons between reactors problematic. Recommendations on how to improve the repeatability of foam potential measurements are given. Full article

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1170 KiB

Open AccessArticle

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part IV: Quantifying the Chemical Filter Component

by Frank Winde

Water 2011, 3(1), 391-423; https://doi.org/10.3390/w3010391 - 15 Mar 2011

Cited by 4 | Viewed by 7698

Abstract

This is the final part of a paper series on the ability of peat to filter uranium (U) from mining-polluted water. The focus is on the characterization and site-specific quantification of the chemical component of the filter model introduced in Part II. Based [...] Read more.

This is the final part of a paper series on the ability of peat to filter uranium (U) from mining-polluted water. The focus is on the characterization and site-specific quantification of the chemical component of the filter model introduced in Part II. Based on U levels in different sediment-water systems of the study area that were analyzed in this paper, peat generally displays the highest geochemical U enrichment even though absolute U levels are relatively low. Results of batch experiments suggest that peat removes U from local mine waters exceptionally well, reaching a removal efficiency of close to 100%. However, almost all of the initially sorbed U is released again on subsequent contact with clean dolomitic water. A synoptic summary of the findings presented in Parts I to IV concludes the paper series. Full article

(This article belongs to the Special Issue Managing Water Resources and Development in a Changing Climate)

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3591 KiB

Open AccessArticle

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part III: Quantifying the Hydraulic Filter Component

by Frank Winde

Water 2011, 3(1), 356-390; https://doi.org/10.3390/w3010356 - 15 Mar 2011

Cited by 2 | Viewed by 9030

Abstract

As Part III of a four-part series on the filter function of peat for uranium (U), this paper focuses on the hydraulic component of a conceptual filter model introduced in Part II. This includes the quantification of water flow through the wetland as [...] Read more.

As Part III of a four-part series on the filter function of peat for uranium (U), this paper focuses on the hydraulic component of a conceptual filter model introduced in Part II. This includes the quantification of water flow through the wetland as a whole, which was largely unknown and found to be significantly higher that anticipated. Apart from subaquatic artesian springs associated with the underlying karst aquifer the higher flow volumes were also caused by plumes of polluted groundwater moving laterally into the wetland. Real-time, quasi-continuous in situ measurements of porewater in peat and non-peat sediments indicate that rising stream levels (e.g., during flood conditions) lead to the infiltration of stream water into adjacent peat deposits and thus allow for a certain proportion of flood water to be filtered. However, changes in porewater quality triggered by spring rains may promote the remobilization of possibly sorbed U. Full article

(This article belongs to the Special Issue Managing Water in a Changing World: Selected Papers from the 7th Conference of the Commission on Water Sustainability)

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402 KiB

Open AccessArticle

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part II: Examples from Literature and a Conceptual Filter Model

by Frank Winde

Water 2011, 3(1), 323-355; https://doi.org/10.3390/w3010323 - 15 Mar 2011

Cited by 7 | Viewed by 11374

Abstract

As the second part of a series of four, this paper reviews a number of case studies of natural uranium attenuation in peat, as well as underlying chemical mechanisms reported in literature. Based on this review, a generic, conceptual, model for peat to [...] Read more.

As the second part of a series of four, this paper reviews a number of case studies of natural uranium attenuation in peat, as well as underlying chemical mechanisms reported in literature. Based on this review, a generic, conceptual, model for peat to act as filter for dissolved uranium (U) is developed for guiding subsequent field investigations. The model consists of a chemical and an hydraulic component which is derived largely from data reported in literature as well as from limited field observations. For the chemical model component 10 different processes, each controlled by factors relating to water chemistry, have been identified to govern the attenuation of U in peat via a net balance of immobilization and remobilization. For the hydraulic aspect of the filter model, five different principal modes of U polluted water coming in contact with peat are discussed, focusing on the associated peat-water contact time as a crucial parameter controlling chemical U attenuation. Moreover, links between the two model components are discussed and, based on the integrated conceptual model, possible effects of natural and anthropogenic events on U attenuation in peatlands are outlined. Guided by the model, various site-specific field and laboratory investigations are finally designed to verify how far the identified generic factors and processes are indeed applicable to the Gerhard Minnebron Peatland. Full article

(This article belongs to the Special Issue Managing Water in a Changing World: Selected Papers from the 7th Conference of the Commission on Water Sustainability)

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1631 KiB

Open AccessArticle

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part I: Hydrogeological Setting and U Fluxes

by Frank Winde and Ewald Erasmus

Water 2011, 3(1), 291-322; https://doi.org/10.3390/w3010291 - 15 Mar 2011

Cited by 12 | Viewed by 11313

Abstract

Located downstream of goldfields of the Witwatersrand basin, the Gerhard Minnebron (GMB) Eye—as major water source for downstream community of some 300,000 people—may be impacted on by mining-related water pollution especially with uranium (U). Containing up to 5 m-thick deposits of peat that [...] Read more.

Located downstream of goldfields of the Witwatersrand basin, the Gerhard Minnebron (GMB) Eye—as major water source for downstream community of some 300,000 people—may be impacted on by mining-related water pollution especially with uranium (U). Containing up to 5 m-thick deposits of peat that is frequently reported to act as a filter for U and other heavy metals, this paper is the first part of a series that aims to quantify the ability of the GMB peatland to act as buffer against current and future U pollution. In a first step, this paper outlines the geohydrological conditions and discusses how deep–level gold mining impacted on the dolomitic aquifers. Subsequently, the potential influx of U into the wetland is estimated and associated sources and pathways analyzed. Finally, a model is proposed explaining the significant differences in degree and dynamics of U observed within a single groundwater compartment. Full article

(This article belongs to the Special Issue Managing Water in a Changing World: Selected Papers from the 7th Conference of the Commission on Water Sustainability)

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1116 KiB

Open AccessArticle

Integrating Geographical Information Systems, Fuzzy Logic and Analytical Hierarchy Process in Modelling Optimum Sites for Locating Water Reservoirs. A Case Study of the Debub District in Eritrea

by Rodney G. Tsiko and Tesfalem S. Haile

Water 2011, 3(1), 254-290; https://doi.org/10.3390/w3010254 - 3 Mar 2011

Cited by 39 | Viewed by 9711

Abstract

The aim of this study was to model water reservoir site selection for a real world application in the administrative district of Debub, Eritrea. This is a region were scarcity of water is a fundamental problem. Erratic rainfall, drought and unfavourable hydro-geological characteristics [...] Read more.

The aim of this study was to model water reservoir site selection for a real world application in the administrative district of Debub, Eritrea. This is a region were scarcity of water is a fundamental problem. Erratic rainfall, drought and unfavourable hydro-geological characteristics exacerbates the region’s water supply. Consequently, the population of Debub is facing severe water shortages and building reservoirs has been promoted as a possible solution to meet the future demand of water supply. This was the most powerful motivation to identify candidate sites for locating water reservoirs. A number of conflicting qualitative and quantitative criteria exist for evaluating alternative sites. Decisions regarding criteria are often accompanied by ambiguities and vagueness. This makes fuzzy logic a more natural approach to this kind of Multi-criteria Decision Analysis (MCDA) problems. This paper proposes a combined two-stage MCDA methodology. The first stage involved utilizing the most simplistic type of data aggregation techniques known as Boolean Intersection or logical AND to identify areas restricted by environmental and hydrological constraints and therefore excluded from further study. The second stage involved integrating fuzzy logic with the Analytic Hierarchy Process (AHP) to identify optimum and back-up candidate water reservoir sites in the area designated for further study. Full article

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354 KiB

Open AccessReview

Water Radiolysis: Influence of Oxide Surfaces on H₂ Production under Ionizing Radiation

by Sophie Le Caër

Water 2011, 3(1), 235-253; https://doi.org/10.3390/w3010235 - 28 Feb 2011

Cited by 471 | Viewed by 64743

Abstract

The radiolysis of water due to ionizing radiation results in the production of electrons, H^· atoms, ^·OH radicals, H₃O⁺ ions and molecules (dihydrogen H₂ and hydrogen peroxide H₂O₂). A brief history of the [...] Read more.

The radiolysis of water due to ionizing radiation results in the production of electrons, H^· atoms, ^·OH radicals, H₃O⁺ ions and molecules (dihydrogen H₂ and hydrogen peroxide H₂O₂). A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H₂ production. This H₂ production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented. Full article

(This article belongs to the Special Issue Water: Facts without Myths)

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221 KiB

Open AccessArticle

U.S. Midwestern Residents Perceptions of Water Quality

by Zhihua Hu and Lois Wright Morton

Water 2011, 3(1), 217-234; https://doi.org/10.3390/w3010217 - 21 Feb 2011

Cited by 17 | Viewed by 7185

Abstract

The plurality of conservation and environmental viewpoints often challenge community leaders and government agency staff as they seek to engage citizens and build partnerships around watershed planning and management to solve complex water quality issues. The U.S. Midwest Heartland region (covering the states [...] Read more.

The plurality of conservation and environmental viewpoints often challenge community leaders and government agency staff as they seek to engage citizens and build partnerships around watershed planning and management to solve complex water quality issues. The U.S. Midwest Heartland region (covering the states of Missouri, Kansa, Iowa, and Nebraska) is dominated by row crop production and animal agriculture, where an understanding of perceptions held by residents of different locations (urban, rural non-farm, and rural farm) towards water quality and the environment can provide a foundation for public deliberation and decision making. A stratified random sample mail survey of 1,042 Iowa, Kansas, Missouri, and Nebraska residents (54% response rate) reveals many areas of agreement among farm, rural non-farm, and those who live in towns on the importance of water issues including the importance and use of water resources; beliefs about water quality and perceptions of impaired water quality causality; beliefs about protecting local waters; and environmental attitudes. With two ordinal logistic models, we also found that respondents with strong environmental attitudes have the least confidence in ground and surface water quality. The findings about differences and areas of agreement among the residents of different sectors can provide a communication bridge among divergent viewpoints and assist local leaders and agency staff as they seek to engage the public in discussions which lead to negotiating solutions to difficult water issues. Full article

(This article belongs to the Special Issue Non-Point Source Pollution Control and Management)

670 KiB

Open AccessArticle

AnnAGNPS Model Application for Nitrogen Loading Assessment for the Future Midwest Landscape Study

by Yongping Yuan, Megan H. Mehaffey, Ricardo D. Lopez, Ronald L. Bingner, Randy Bruins, Caroline Erickson and Michael A. Jackson

Water 2011, 3(1), 196-216; https://doi.org/10.3390/w3010196 - 17 Feb 2011

Cited by 12 | Viewed by 8631

Abstract

The Future Midwest Landscape (FML) project is part of the US Environmental Protection Agency (EPA)’s new Ecosystem Services Research Program, undertaken to examine the variety of ways in which landscapes that include crop lands, conservation areas, wetlands, lakes, and streams affect human well-being. [...] Read more.

The Future Midwest Landscape (FML) project is part of the US Environmental Protection Agency (EPA)’s new Ecosystem Services Research Program, undertaken to examine the variety of ways in which landscapes that include crop lands, conservation areas, wetlands, lakes, and streams affect human well-being. The goal of the FML project is to quantify current and future ecosystem services across the region and to examine changes expected to occur as a result of the growing demand for biofuels. This study is one of several pilots taking place under the umbrella of the FML research project. In this study, the USDA Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model was applied to the East Fork Kaskaskia River watershed (289.3 km²) located in the Kaskaskia River Basin within the Upper Mississippi River Basin in Illinois. The effect of different spatial resolutions on model performance was investigated by comparing the observed runoff with the AnnAGNPS simulated results. Alternative future scenarios such as meeting future biofuel target were also simulated and analyzed. All delineations of the study area (coarser to finer) produced satisfactory results in simulating monthly and annual runoff. However, the size of the delineation does impact the simulation results. Finer delineations better represented the actual landscape and captured small critical areas that would be homogenized in coarser delineation. Those small critical areas are important to target to achieve maximum environment benefit. Simulations of alternative future scenarios showed that as corn production increases to meet future biofuel needs, total nitrogen loss increases. For this watershed, total N loss would be more than doubled if converting all corn/soybean rotation (15,871.2 ha) to continuous corn comparing with the base year total N loss which is 11.2 kg/ha. Conservation practices are needed to reduce total nitrogen loss from the watershed. This study provides an important foundation for the larger FML region modeling effort by addressing challenging FML landscape modeling issues such as model selection, need for further model development, and spatial resolution. Full article

(This article belongs to the Special Issue Non-Point Source Pollution Control and Management)

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241 KiB

Open AccessArticle

Biosorption Parameter Estimation with Genetic Algorithm

by Khim Hoong Chu, Xiao Feng, Eui Yong Kim and Yung-Tse Hung

Water 2011, 3(1), 177-195; https://doi.org/10.3390/w3010177 - 16 Feb 2011

Cited by 16 | Viewed by 8236

Abstract

In biosorption research, a fairly broad range of mathematical models are used to correlate discrete data points obtained from batch equilibrium, batch kinetic or fixed bed breakthrough experiments. Most of these models are inherently nonlinear in their parameters. Some of the models have [...] Read more.

In biosorption research, a fairly broad range of mathematical models are used to correlate discrete data points obtained from batch equilibrium, batch kinetic or fixed bed breakthrough experiments. Most of these models are inherently nonlinear in their parameters. Some of the models have enjoyed widespread use, largely because they can be linearized to allow the estimation of parameters by least-squares linear regression. Selecting a model for data correlation appears to be dictated by the ease with which it can be linearized and not by other more important criteria such as parameter accuracy or theoretical relevance. As a result, models that cannot be linearized have enjoyed far less recognition because it is necessary to use a search algorithm for parameter estimation. In this study a real-coded genetic algorithm is applied as the search method to estimate equilibrium isotherm and kinetic parameters for batch biosorption as well as breakthrough parameters for fixed bed biosorption. The genetic algorithm is found to be a useful optimization tool, capable of accurately finding optimal parameter estimates. Its performance is compared with that of nonlinear and linear regression methods. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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194 KiB

Open AccessReview

Dye Waste Treatment

by Siew-Teng Ong, Pei-Sin Keng, Weng-Nam Lee, Sie-Tiong Ha and Yung-Tse Hung

Water 2011, 3(1), 157-176; https://doi.org/10.3390/w3010157 - 16 Feb 2011

Cited by 111 | Viewed by 14904

Abstract

Dye wastes represent one of the most problematic groups of pollutants because they can be easily identified by the human eye and are not easily biodegradable. This literature review paper highlights and provides an overview of dye waste treatments performed over the three [...] Read more.

Dye wastes represent one of the most problematic groups of pollutants because they can be easily identified by the human eye and are not easily biodegradable. This literature review paper highlights and provides an overview of dye waste treatments performed over the three years period from 2008–2010. Noteworthy processes for the treatment of dye waste include biological treatment, catalytic oxidation, filtration, sorption process and combination treatments. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

512 KiB

Open AccessArticle

Phosphorus Accumulation Pattern in a Subsurface Constructed Wetland Treating Residential Wastewater

by Agnieszka Karczmarczyk and Gunno Renman

Water 2011, 3(1), 146-156; https://doi.org/10.3390/w3010146 - 27 Jan 2011

Cited by 10 | Viewed by 7478

Abstract

A horizontal subsurface flow constructed wetland was investigated after eight years of residential wastewater discharge (150 person equivalents). Twenty core samples distributed over the entire wetland were taken from the soil matrix. The distribution pattern of phosphorus (P) accumulation in the substrate of [...] Read more.

A horizontal subsurface flow constructed wetland was investigated after eight years of residential wastewater discharge (150 person equivalents). Twenty core samples distributed over the entire wetland were taken from the soil matrix. The distribution pattern of phosphorus (P) accumulation in the substrate of the wetland was determined using kriging technique and P sorption was related to the content of aluminum (Al), calcium (Ca) and iron (Fe). The correlations found between Al, Ca and Fe content and P accumulation in the bed substrate were weak: R²= 0.09, R²= 0.21 and R²= 0.28, respectively. Great heterogeneity was observed in the distribution of Ca, P and organic matter in the superficial and deeper layers of the bed. Hydraulic problems associated with wastewater discharge and conductivity of the bed substrate were suggested to have negative effects on the wetland performance. Full article

(This article belongs to the Special Issue Water Pollution Management by Constructed Wetlands and On Site Filter Technologies)

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853 KiB

Open AccessArticle

Soil Water Surplus in Salado River Basin and Its Variability during the Last Forty Years (Buenos Aires Province, Argentina)

by Olga Eugenia Scarpati, Liliana Beatriz Spescha, Juan Alberto Forte Lay and Alberto Daniel Capriolo

Water 2011, 3(1), 132-145; https://doi.org/10.3390/w3010132 - 18 Jan 2011

Cited by 10 | Viewed by 9064

Abstract

Soil water surplus and deficit occur frequently in Buenos Aires province in Argentina. This paper analyses the soil water surplus in a sub-area, the Salado River basin, in the period 1968–2008. This basin is divided in seven drainage areas, delimitated according to the [...] Read more.

Soil water surplus and deficit occur frequently in Buenos Aires province in Argentina. This paper analyses the soil water surplus in a sub-area, the Salado River basin, in the period 1968–2008. This basin is divided in seven drainage areas, delimitated according to the National Water Resources. The series of soil water surplus data were adjusted by means of the theoretical normal cubic-root probability distribution, and the mean areal soil water surplus value of 300 mm was considered as a threshold above which floods can cause severe damage. An increase in the frequency of extreme events and in their tendency exists during the recent years, coherent with the increase of precipitation recorded in the region. The statistical significance of the results was assessed using the Mann Kendall and MAKESENS tests. The results showed a relevant temporal variability, but did not show significant tendencies. Full article

(This article belongs to the Special Issue Managing Water in a Changing World: Selected Papers from the 7th Conference of the Commission on Water Sustainability)

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1083 KiB

Open AccessArticle

Mapping Irrigated Areas Using MODIS 250 Meter Time-Series Data: A Study on Krishna River Basin (India)

by Murali Krishna Gumma, Prasad S. Thenkabail and Andrew Nelson

Water 2011, 3(1), 113-131; https://doi.org/10.3390/w3010113 - 13 Jan 2011

Cited by 30 | Viewed by 11586

Abstract

Mapping irrigated areas of a river basin is important in terms of assessing water use and food security. This paper describes an innovative remote sensing based vegetation phenological approach to map irrigated areas and then the differentiates the ground water irrigated areas from [...] Read more.

Mapping irrigated areas of a river basin is important in terms of assessing water use and food security. This paper describes an innovative remote sensing based vegetation phenological approach to map irrigated areas and then the differentiates the ground water irrigated areas from the surface water irrigated areas in the Krishna river basin (26,575,200 hectares) in India using MODIS 250 meter every 8-day near continuous time-series data for 2000–2001. Temporal variations in the Normalized Difference Vegetation Index (NDVI) pattern obtained in irrigated classes enabled demarcation between: (a) irrigated surface water double crop, (b) irrigated surface water continuous crop, and (c) irrigated ground water mixed crops. The NDVI patterns were found to be more consistent in areas irrigated with ground water due to the continuity of water supply. Surface water availability, on the other hand, was dependent on canal water release that affected time of crop sowing and growth stages, which was in turn reflected in the NDVI pattern. Double cropped and light irrigation have relatively late onset of greenness, because they use canal water from reservoirs that drain large catchments and take weeks to fill. Minor irrigation and ground water irrigated areas have early onset of greenness because they drain smaller catchments where aquifers and reservoirs fill more quickly. Vegetation phonologies of 9 distinct classes consisting of Irrigated, rainfed, and other land use classes were also derived using MODIS 250 meter near continuous time-series data that were tested and verified using groundtruth data, Google Earth very high resolution (sub-meter to 4 meter) imagery, and state-level census data. Fuzzy classification accuracies for most classes were around 80% with class mixing mainly between various irrigated classes. The areas estimated from MODIS were highly correlated with census data (R-squared value of 0.86). Full article

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3505 KiB

Open AccessArticle

Modification of Aquifer Pore-Water by Static Diffusion Using Nano-Zero-Valent Metals

by David D. J. Antia

Water 2011, 3(1), 79-112; https://doi.org/10.3390/w3010079 - 11 Jan 2011

Cited by 16 | Viewed by 9663

Abstract

Sixteen static diffusion reactors containing n-ZVM (Fe⁰, Cu⁰, Al⁰) establish a common equilibrium redox (Eh-pH) trajectory which is directly linked to the aquifer pore volume, volume of injected n-ZVM, throughflow rate within the aquifer and time. The [...] Read more.

Sixteen static diffusion reactors containing n-ZVM (Fe⁰, Cu⁰, Al⁰) establish a common equilibrium redox (Eh-pH) trajectory which is directly linked to the aquifer pore volume, volume of injected n-ZVM, throughflow rate within the aquifer and time. The effect of NaCl and Ca-montmorillonite on the trajectory is considered. The trajectory can be directly linked to TDS (EC) and to the equilibrium removal of contaminants. In each example, the progressive oscillation between reduction and oxidation reactions (including Fenton reactions) creates the catalytic nuclei (and redox environment) required for the decomposition of organic pollutants and their reconstruction as simple alkanes and oxygenates. Full article

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474 KiB

Open AccessArticle

Distribution of ³⁶Cl in the Yoro River Basin, Central Japan, and Its Relation to the Residence Time of the Regional Groundwater Flow System

by Yuki Tosaki, Norio Tase, Akihiko Kondoh, Kimikazu Sasa, Tsutomu Takahashi and Yasuo Nagashima

Water 2011, 3(1), 64-78; https://doi.org/10.3390/w3010064 - 6 Jan 2011

Cited by 5 | Viewed by 7898

Abstract

This study investigates the potential of ³⁶Cl in tracing young groundwater with residence times of up to ~50 years. Groundwater samples were obtained from 16 irrigation wells in paddy fields located within an upland–lowland system in the Yoro River basin, Central Japan. [...] Read more.

This study investigates the potential of ³⁶Cl in tracing young groundwater with residence times of up to ~50 years. Groundwater samples were obtained from 16 irrigation wells in paddy fields located within an upland–lowland system in the Yoro River basin, Central Japan. The ³⁶Cl/Cl ratios were in the range of 17 to 362 × 10⁻¹⁵. Among the samples with higher Cl⁻ concentrations (>10 mg/L), two samples showed high nitrate concentrations as well (>30 mg/L). Except for these samples, the distribution of ³⁶Cl in groundwater was essentially consistent with previous tritium concentration data measured in 1982 and 1994, considering the time that has elapsed since these earlier measurements were performed. ³⁶Cl/Cl values were less than 30 × 10⁻¹⁵ in lowland areas, with higher values in and around upland areas. The results indicate longer residence times in the regional groundwater flow system (>50 years) than those estimated in previous studies, especially in the area west of the Yoro River. The results demonstrate the ability of ³⁶Cl to trace young groundwater flow, particularly because high values of bomb-derived ³⁶Cl/Cl are easily discriminated from pre-bomb water with low ³⁶Cl/Cl values. Because of its very long half-life (3.01 × 10⁵ years), ³⁶Cl remains even after tritium is no longer available. Full article

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3531 KiB

Open AccessArticle

Spatially Explicit Analysis of Water Footprints in the UK

by Kuishuang Feng, Klaus Hubacek, Jan Minx, Yim Ling Siu, Ashok Chapagain, Yang Yu, Dabo Guan and John Barrett

Water 2011, 3(1), 47-63; https://doi.org/10.3390/w3010047 - 30 Dec 2010

Cited by 68 | Viewed by 13443

Abstract

The Water Footprint, as an indicator of water consumption has become increasingly popular for analyzing environmental issues associated with the use of water resources in the global supply chain of consumer goods. This is particularly relevant for countries like the UK, which increasingly [...] Read more.

The Water Footprint, as an indicator of water consumption has become increasingly popular for analyzing environmental issues associated with the use of water resources in the global supply chain of consumer goods. This is particularly relevant for countries like the UK, which increasingly rely on products produced elsewhere in the world and thus impose pressures on foreign water resources. Existing studies calculating water footprints are mostly based on process analysis, and results are mainly available at the national level. The current paper assesses the domestic and foreign water requirements for UK final consumption by applying an environmentally extended multi-regional input-output model in combination with geo-demographic consumer segmentation data. This approach allows us to calculate water footprints (both direct and indirect) for different products as well as different geographies within the UK. We distinguished between production and consumption footprints where the former is the total water consumed from the UK domestic water resources by the production activities in the UK and the latter is the total water consumed from both domestic and global water resources to satisfy the UK domestic final consumption. The results show that the production water footprint is 439 m³/cap/year, 85% of which is for the final consumption in the UK itself. The average consumption water footprint of the UK is more than three times bigger than the UK production water footprint in 2006. About half of the UK consumption water footprints were associated with imports from Non-OECD countries (many of which are water-scarce), while around 19% were from EU-OECD countries, and only 3% from Non-EU-OECD countries. We find that the water footprint differs considerably across sub-national geographies in the UK, and the differences are as big as 273 m³/cap/year for the internal water footprint and 802 m³/cap/year for the external water footprint. Our results suggest that this is mainly explained by differences in the average income level across the UK. We argue that the information provided by our model at different spatial scales can be very useful for informing integrated water supply and demand side management. Full article

(This article belongs to the Special Issue Water Footprint: Usefulness of the Concept from Accounting Framework to Policy Response Options in Water Resources Management)

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248 KiB

Open AccessArticle

The Global Dimension of Water Governance: Why the River Basin Approach Is No Longer Sufficient and Why Cooperative Action at Global Level Is Needed

by Arjen Y. Hoekstra

Water 2011, 3(1), 21-46; https://doi.org/10.3390/w3010021 - 29 Dec 2010

Cited by 112 | Viewed by 17321

Abstract

When water problems extend beyond the borders of local communities, the river basin is generally seen as the most appropriate unit for analysis, planning, and institutional arrangements. In this paper it is argued that addressing water problems at the river basin level is [...] Read more.

When water problems extend beyond the borders of local communities, the river basin is generally seen as the most appropriate unit for analysis, planning, and institutional arrangements. In this paper it is argued that addressing water problems at the river basin level is not always sufficient. Many of today’s seemingly local water issues carry a (sub)continental or even global dimension, which urges for a governance approach that comprises institutional arrangements at a level beyond that of the river basin. This paper examines a number of arguments for the thesis that good water governance requires a global approach complementary to the river basin approach. Subsequently, it identifies four major issues to be addressed at global scale: Efficiency, equity, sustainability and security of water supply in a globalised world. Finally, the paper raises the question of what kind of institutional arrangements could be developed to cope with the global dimension of water issues. A few possible directions are explored, ranging from an international protocol on full-cost water pricing and a water label for water-intensive products to the implementation of water footprint quotas and the water-neutral concept. Full article

(This article belongs to the Special Issue Water Footprint: Usefulness of the Concept from Accounting Framework to Policy Response Options in Water Resources Management)

549 KiB

Open AccessReview

Arsenic Contamination of Groundwater in Nepal—An Overview

by Jay Krishna Thakur, Rinku Kumari Thakur, AL Ramanathan, Manish Kumar and Sudhir Kumar Singh

Water 2011, 3(1), 1-20; https://doi.org/10.3390/w3010001 - 29 Dec 2010

Cited by 116 | Viewed by 29047

Abstract

In Nepal, arsenic (As) contamination is a major issue of current drinking water supply systems using groundwater and has recently been one of the major environmental health management issues especially in the plain region, i.e., in the Terai districts, where the population [...] Read more.

In Nepal, arsenic (As) contamination is a major issue of current drinking water supply systems using groundwater and has recently been one of the major environmental health management issues especially in the plain region, i.e., in the Terai districts, where the population density is very high. The Terai inhabitants still use hand tube and dug wells (with hand held pumps that are bored at shallow to medium depth) for their daily water requirements, including drinking water. The National Sanitation Steering Committee (NSSC), with the help of many other organizations, has completed arsenic blanket test in 25 districts of Nepal by analysing 737,009 groundwater samples. Several organizations, including academic institutions, made an effort to determine the levels of arsenic concentrations in groundwater and their consequences in Nepal. The results of the analyses on 25,058 samples tested in 20 districts, published in the status report of arsenic in Nepal (2003), demonstrated that the 23% of the samples were containing 10–50 µg/L of As, and the 8% of the samples were containing more than 50 µg/L of As. Recent status of over 737,009 samples tested, the 7.9% and 2.3% were contaminated by 10–50 µg/L and >50 µg/L, respectively of As. The present paper examines the various techniques available for the reduction of arsenic concentrations in Nepal in combination with the main results achieved, the socio-economic status and the strategies. This paper aims to comprehensively compile all existing data sets and analyze them scientifically, by trying to suggest a common sustainable approach for identifying the As contamination in the nation, that can be easily adopted by local communities for developing a sustainable society. The paper aims also to find probable solutions to quantify and mitigate As problem without any external support. The outcome of this paper will ultimately help to identify various ways for: identify risk areas; develop awareness; adopt the World Health Organization (WHO) guideline; identify alternative safe water sources and assess their sustainability; give priorities to water supply and simple eco-friendly treatment techniques; investigate impacts of arsenic on health and agriculture; strengthen the capability of government, public, Non-governmental Organization (NGO) and research institutions. Full article

(This article belongs to the Special Issue Managing Water in a Changing World: Selected Papers from the 7th Conference of the Commission on Water Sustainability)

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Water, Volume 3, Issue 1 (March 2011) – 19 articles , Pages 1-444

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