bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear‐Driven Overturns
Authors: Smyth W.D.
Published: July 2005

Shear‐driven overturns are an important mechanism for mixing in most geophysical and many industrial flows. This article summarizes both the physical processes leading to the turbulent state and the properties of the resulting turbulence. Formulae are provided for estimation of the dominant spatiotemporal scales as well as the turbulent fluxes and diffusivities.
Defluroidation
Authors: Dahi Eli
Published: July 2005

Defluoridation refers to methods of water treatment that reduce the concentration of fluoride in the water, normally in order to make it safe for human consumption. Some water treatments that have the capacity of reducing the fluoride concentration along with most other anions, or anions and cations, in the water are not considered defluoridation methods. Thus, general demineralizing methods like distillation, reverse osmosis, electrodialysis, and resin deanionization, which are able to remove fluoride fully or partly from the water, are not considered defluoridation methods. On the other hand, methods that only remove fluoride without any addition or reduction of other parameters are not yet discovered, which is why the expression “fluoride removal” lacks precision. Defluoridation is used to characterize methods that reduce the fluoride ion specifically, without other

major

changes to the quality of the treated water.
Watershed Modeling
Authors: Wagener Thorsten
Published: July 2005

Models of watershed hydrology are important tools in hydrological investigations for operational and research purposes. Areas of application are the extension of streamflow time‐series in space and time, evaluation of a watershed response to climate and/or land‐use variability and change, calculation of design floods, as load models linked to water quality investigations, real‐time flood forecasting, and the provision of boundary conditions for atmospheric circulation models. This multitude of, often very specific, tasks and circumstances has contributed to the development of a vast number of watershed models starting in the early 1960s (see Todini, for a historical review). These models are usually a mixture of linear and nonlinear functions, combined to represent those processes occurring in the specific watershed and important for the study objectives at hand. Watershed models are also used in water quality studies, but the focus here is simulation of the quantitative response and general features of these models.
Drainage Ditches
Authors: Moore Matthew T. , Cooper Charles M. , Farris Jerry L.
Published: July 2005

Drainage ditches are unique aquatic ecosystems that have gone virtually unnoticed by the scientific community. These systems are often considered nothing more than conduits for water transport from wet or moist areas, when indeed they serve as crucial sites for contaminant transfer and transformation. In many parts of the world, ditches also serve as refuges for endangered species of flora and fauna. Maintenance of drainage ditches is a subject that stirs intense debate between farmers, landowners, scientists, and regulators. Finding a balance between efficient water transport and ditch water quality improvements is a growing field of concern. Various characteristics of drainage ditches are identified, with an emphasis on ditches in agricultural systems. Also included is a brief history of drainage ditches, as well as past and present drainage ditch research, and a brief synopsis of future ditch research directions.
Dyes As Hydrological Tracers
Authors: Mon Jarai , Flury Markus
Published: July 2005

Dyes have been used in hydrological investigations for more than a century. Dye tracers are versatile tools to study flow connections, residence times, hydrodynamic dispersion, flow patterns, and chemical leaching. The major advantage of dyes compared with other tracers is that dyes are readily detected at low concentrations, simple to quantify, and inexpensive. The visualization of dyes is often a powerful tool to demonstrate flow pathways. As most dyes are organic molecules, they tend to sorb to solid surfaces and can be photo‐ and biochemically degraded. For water tracing, dyes should therefore be tested under the specific conditions under which dye tracing is to be conducted. We present a brief overview on the use of dyes as hydrological tracers, and we propose a cost‐effective screening technique for selection of optimal dye tracers. This technique is based on quantitative structure‐activity relationships (QSARs). We conducted a case study on the application of QSAR for screening and selection of dye tracers. The QSAR modeling revealed many hypothetical dyes that show potential to be good tracers.
Water—The Canadian Transporter
Authors:   Environment Canada
Published: July 2005

Water plays an important role in the transformation of the Canadian landscape by moving large amounts of soil, in the form of
sediment
. Sediment is eroded from the landscape, transported by river systems, and eventually deposited in a lake or the sea. For example, the Fraser River carries an average of 20 million tonnes of sediment a year into the marine environment.

The sediment cycle starts with the process of
erosion
, whereby particles or fragments are weathered from rock material. Action by water, wind, glaciers, and plant and animal activities all contribute to the erosion of the earth's surface. Fluvial sediment is the term used to describe the case where water is the key agent for erosion. Natural, or geologic, erosion takes place slowly, over centuries or millennia. Erosion that occurs as a result of human activity may take place much faster. It is important to understand the role of each when studying sediment transport.
The Theory of Alternative Stable States in Shallow Lake Ecosystems
Authors: Williams Adrian E.
Published: July 2005

The concept of alternative stable states within ecosystems was first forwarded in the 1960s. The current view with respect to shallow lakes is that over a range of nutrient concentrations, two alternative stable states can exist. One state comprises of clear water dominated by submerged macrophytes, whereas the other is a turbid phytoplankton‐dominated state. Each of the stable states has a number of buffer systems that maintain that state through top‐down and bottom‐up processes. As many of the buffers and thus forward and reverse switches are well understood, attempts are sometimes made to influence these processes and thus force a change from one state to another, which is especially true during lake restoration projects when it can be desirable to turn a turbid algal‐dominated lake into a clear water macrophyte‐dominated lake.
Fish Passage Facilities
Authors: Tompkins Mark R.
Published: July 2005

A
fish passage facility
provides fish with a watered route around or through a barrier to migration in a fluvial system. Fish passage facilities have been designed for both natural and artificial barriers. Some passage facilities allow fish to propel themselves past the barrier, while others physically transport fish past the barrier. Fish passage facilities must provide passage during periods dictated by migratory requirements without injuring or unduly stressing fish. Fish passage facilities have been designed and constructed in North American, Europe, Russia, Latin American, Africa, Australia, New Zealand, China, and Japan. Depending on the region and type of application, fish passage facilities are also referred to as fishways, fish ladders, fish passes, fish bypasses, fish locks, and fish elevators.
Floods as a Natural Hazard
Authors: Berga Luis
Published: July 2005

The floods constitute the most important disaster among the natural hazards. Floods represent about 30% of the total number of natural disasters and economic damages, and almost 25% of the fatalities produced by the natural disasters (Fig. 4). The extensive and enhanced statistical data show that, in the period 1975–2001, some 95 significant floods per year have been produced, which have caused a mean of some 11,000 fatalities per year, and have affected some 150 M people per year, which signifies that in the last decade of the twentieth century, 25% of the world population has been affected by the floods (6).
Flow‐Duration Curves
Authors: Hordon Robert M.
Published: July 2005

The flow‐duration curve is a cumulative frequency curve that shows the percentage of time that specified stream's discharges were equaled or exceeded during a period of record. It combines in one curve all of the flow characteristics of a stream, ranging from flood flows to drought situations.

In sharp contrast to a hydrograph where time is on thexaxis, chronology is not shown in flow‐duration curves. If the period of record on which the curve is based is sufficiently long, it may be considered a probability curve and therefore, is used to estimate the percentage of time that a specified stream's discharge will be equaled or exceeded in the future.
Ganga River, India
Authors: Jain Sharad K.
Published: July 2005

The Himalayas, the great mountain chain of Asia are the source of three major river systems of the world, the Indus, the Ganga (or the Ganges), and the Brahmputra. The large and fertile plains of the Indus and Ganga in the subcontinent of Northern India have been the cradles of one of the greatest ancient civilization, the Indus Valley Civilization. The River Ganga which occupies nearly one‐third of the geographical area of India is the most important and sacred river of India.

The catchment area of the Ganga falls in four countries, India, Nepal, Tibet (China), and Bangladesh. Many important tributaries of the Ganga originate in the Himalayas in India and Nepal; Bangladesh lies in the deltaic region. The total length of the river is 2525 km which makes it the fifteenth longest river in Asia and the thirtyninth longest in the world. The combined basin of the Ganga, Brahmaputra, and Meghna rivers in India, Nepal, and Bangladesh is also known by the name
Greater Ganga Basin
. The major part of the geographical area of Ganga Basin lies in India.

Though the headwaters region of the Ganga in the Himalayas is dotted by a number of mighty tributaries, the Bhagirathi river that rises from the Gangotri glacier near Gomukh at an elevation of about 7010 m above mean sea level is traditionally considered the source of River Ganga.
Hydrologic Persistence and The Hurst Phenomenon
Authors: Koutsoyiannis Demetris
Published: July 2005

Unlike common random series like those observed, for example, in games of chance, hydrologic (and other geophysical) time series have some structure, that is, consecutive values of hydrologic time series depend on each other. A special kind of dependence observed on large timescales was discovered by Hurst half a century ago and has been known by several names such as long‐range dependence, long‐term persistence, or simply the Hurst phenomenon. Since then, it has been verified that this behavior is almost omnipresent in several processes in nature (e.g., hydrology), technology (e.g., computer networks), and society (e.g., economics). The consequences of this behavior are very significant because it increases dramatically the uncertainty of the related processes. However, even today its importance and its consequences are not widely understood or are ignored, its nature is regarded as difficult to understand, and its reproduction in hydrologic simulation is considered a hard task or not necessary. This article shows that the Hurst phenomenon can have an easy explanation and easy stochastic representation and that simple algorithms can generate time series exhibiting long‐term persistence.
Hydrologic Thresholds
Authors: Sivakumar Bellie
Published: July 2005

Effective and efficient planning and management of our water resources systems largely depend on our ability to model and forecast hydrologic phenomena. “Thresholds” play a crucial role in this regard, because they are (the) indicators of any changes to the system, particularly catastrophic. The purpose of this article is to discuss the role of thresholds in hydrology, with a stronger and broader footing than one that can be found in the literature. Three issues are focused on: (a) relevance of thresholds in hydrology; (b) threshold identification and quantification; and (c) need for interdisciplinary research on thresholds. Within these focus topics, a variety of aspects are covered, including networks and feedbacks, complexity and nonlinearity, chaos and fractals, self‐organization and emergence, reductionism and holism, interpretation and integration of theories, and ongoing interdisciplinary research activities.
Limnology
Authors: Geller Walter , Geller Annette
Published: July 2005

Limnology is the study of inland waters as ecosystems. Hydrological, physical, and chemical factors are integral parts of limnological research. The major part of traditional research and practice was the limnology of lakes. Later, concepts for the limnology of rivers were developed, and they were extended to research and management of catchment areas, including rivers and lakes. Applied research was directed on the impacts of waste water to rivers (saprobization) and to lakes (eutrophication). A major problem in industrial countries was the acidification of surface waters by acid rain. Actual subjects of limnological investigations are the effects of climatic change on hydrological systems, rivers and lakes, and their impacts on the ecosystems.
Combustible Watersheds
Authors: Kulik V.
Published: July 2005

Existing hydrological networks can be used for conflagration prediction. Runoff data allows predicting high fire danger earlier, highlights the most dangerous watersheds, and makes forecasting more foolproof. In some cases, a hydroforecast improves the likelihood of preventing a major disaster. This technique has certain differences from standard meteorological methods: (1) It predicts conflagrations not for an administrative or geographical region, but for a watershed—so, a conflagration can be forecast for the area around water supply reservoirs. (2) It allows forecasting the fire danger earlier and estimates of the amount of time available for active response. (3) It excludes most false alarms. (4) It is more accurate, simply because it uses hydrographic data, which are more representative than meteorological data. (5) It is more foolproof and less dependent on errors in observations. (6) It depends less on the stochastic nature of summer rains and other meteorological elements. (7) It is simpler than any other method.
Free Flowing Water: A Source of Wisdom
Authors: Lee Maggie
Published: July 2005

In his extraordinary, rich, and comprehensive lectures and writings of the early 1960s and into the 1970s, Theodor Schwenk (1910–1986) proposed a new ‘water consciousness,’ a transformative way of thinking about this universal element. He described and illustrated fluid circulation, movement, and rhythms of the earth's water cycle and resulting organic forms. His experiments demonstrated the rhythmical, metamorphic potential hidden within fluid processes. Included here are a few of his insights and discoveries.
Hydropsychology
Authors: Sivakumar Bellie
Published: July 2005

The increasing realization that water conflicts around the world are not just because of sheer lack of water, but also have other facets that are reflections of human behavior, presents the need for studying the transactions between humans and water‐related activities. This article is intended to present possible ways to move forward with research on hydropsychology. The topics covered include acknowledgment and identification of the role of human behavior in water planning, management and conflicts, solving the problem, and dissemination of the outcomes.
Conflict and Water Use in the Middle East
Authors: Lipchin Clive D.
Published: July 2005

Where water is scarce, competition for limited supplies can lead nations to seek access to water as a matter of national security. As recently as the mid‐1980s, U.S. government intelligence services estimated that there were at least 10 places in the world where war could break out over dwindling shared water resources; the majority of these locations are in the Middle East. Jordan, Israel, Cyprus, Malta, and the countries of the Arabian Peninsula are sliding into the perilous zone where all available fresh surface and groundwater supplies will be fully used. In Israel, the Palestinian Authority, and Jordan, a water deficit already exists, and all available water resources are overexploited.
Clean Water Act, Water Quality Criteria/Standards,TMDLs, and Weight‐of‐Evidence Approach for Regulating Water Quality
Authors: Fred Lee G. , Jones‐lee Anne
Published: July 2005

The Clean Water Act (PL 92–500, the 1972 amendments to the Federal Water Pollution Control Act) established a water quality standards‐based approach for regulating water quality. The U.S. EPA was to develop national water quality criteria that would serve as the basis for state water quality standards. Those standards are the legally enforceable limits that evaluate water quality impairment. It was specified in the Clean Water Act that violation of the water quality standards was to lead to the listing of the waterbody as “impaired” and trigger the establishment of a total maximum daily load (TMDL) of the pollutant in violation. Significant problems have developed in the implementation of the Clean Water Act. The most important of these problems is use of the numeric U.S. EPA national criteria and state water quality standards without waterbody‐specific adjustment for characteristics that influence the toxicity/availability of potential pollutants. This problem has led to inappropriate listing of waterbodies as “impaired” and the establishment of TMDLs with inappropriate water‐quality‐standard goals. It is becoming recognized that a “best professional judgment” (BPJ) triad weight‐of‐evidence approach should regulate water quality in the United States. The key component of this approach is the “best professional judgment” evaluation of a triad of key parameters: aquatic life toxicity/bioaccumulation of the contaminant(s); aquatic organism assemblage information in the aquatic system of concern; and chemical kinetic/thermodynamic information pertaining to the contaminant(s) of interest and the aquatic system of concern. This evaluation by consensus of a panel of experts in a public, interactive, peer‐review process is crucial for the technically valid, cost‐effective control of pollutants in aquatic systems.
Ground Water Quality in Areas Adjoining River
Y
amuna at
D
elhi,
I
ndia
Authors: Jain Chakresh K. , Sharma Mukesh K.
Published: July 2005

The groundwater quality in areas adjoining the River Yamuna at Delhi (India) has been assessed to determine the suitability of groundwater for domestic use. Thirty‐eight groundwater samples from shallow and deep aquifers were collected each during pre‐ and postmonsoon seasons in the year 2000 and analyzed for various physicochemical and bacteriological parameters and trace elements. The study indicated concentrations of total dissolved solids, nitrate, sulfate, and sodium higher than water quality standards. The presence of total coliforms indicates bacterial contamination in the groundwater. The grouping of samples according to their hydrochemical facies indicated that the majority of the samples fall into Na‐K‐Cl‐SO
4
followed by Na‐K‐HCO
3
and Ca‐Mg‐Cl‐SO
4
hydrochemical facies. The qualitative analysis of data depicted higher concentrations of various physicochemical and bacteriological parameters on the western side of River Yamuna, even in deep aquifers.
Municipal Solid Waste Landfills—Water Quality Issues
Authors: Fred Lee G. , Jones‐Lee Anne
Published: July 2005

When municipal solid waste (MSW) comes in contact with liquid, leachate is formed. Such leachate contains a myriad of hazardous and otherwise deleterious chemicals, which if introduced into groundwater would impair or destroy the ability to use the groundwater and aquifer. In an attempt to provide some protection of groundwater quality from adverse impacts from MSW landfill leachate, the US EPA (1) adopted a “dry tomb” approach for the landfilling of municipal solid wastes. These “Subtitle D” requirements specify isolation of the wastes within a plastic‐sheeting and compacted clay‐lined tomb, collection of leachate, monitoring of groundwater, collection and management of landfill gas, closure procedures, and provision for funding of maintenance for 30 years after landfill closure. However, the Subtitle D dry tomb concept and prescriptive requirements are inadequate to ensure groundwater protection for as long as the wastes represent a threat to public health and the environment. The wastes in a dry tomb landfill will be a threat to generate leachate for thousands of years. The covering will not keep the wastes dry indefinitely. The plastic sheeting and compacted clay composite liner will eventually fail and allow the leachate generated to pollute groundwater. The groundwater monitoring systems allowed have a low probability of detecting polluted groundwater when it first reaches the point of compliance. The 30 years prescribed for postclosure monitoring and maintenance is a small part of the time that postclosure care and funding will be needed. An urgent need exists to revise the US EPA Subtitle D regulations to provide for true long‐term protection of public health, groundwater resources, and the environment for as long as the MSW will be a threat.
Metallothioneins as Indicators of Trace Metal Pollution
Authors: Schettino Trifone , Lionetto Maria Giulia
Published: July 2005

The importance of metallothionein (MT) in toxicologic responses to heavy metals was early recognized for potential application as a “biomarker” of organism exposure to heavy metals in aquatic environments. A biomarker is a pollutant‐induced variation in cellular or biochemical components or processes, structures, or functions that is measurable in a biological system or sample (13). The biomarker approach in environmental monitoring has been increasingly used in the last 20 years for the ecotoxicological assessment of aquatic ecosystems. Since the harmful effects of pollutants are typically manifested at lower levels of biological organization before disturbances are realized at the population, community, or ecosystem levels (14), the use of biomarkers measured at the cellular level has been proposed as sensitive “early warning” tools for biological effect measurement in environmental quality assessment (15).
Monitoring Lipophilic Contaminants in the Aquatic Environment using the
SPMD
‐
TOX
Paradigm
Authors: Johnson B. Thomas
Published: July 2005

The SPMD‐TOX paradigm was designed to monitor our nation's water resources by identifying the presence of lipophilic contaminants that are bioavailable and potentially harmful to the ecosystem. This microscale technique provides a first look at areas of concern and is an alternate to traditional, complex, and more costly whole animal testing with invertebrates and fish. Case studies illustrate the use of a semipermeable membrane device (SPMD) to collect bioavailable lipophilic samples from rivers and streams and microscale tests to assess their toxicity.
Biomanipulation
Authors: Sagehashi Masaki
Published: July 2005

Biomanipulation is a currently used lake purification method, which modifies a lake ecosystem to an ideal state. The theory of biomanipulation is based on the prediction that increased piscivore abundance will result in decreased planktivore abundance and that increased zooplankton grazing pressure will lead to reductions in phytoplankton abundance and improved water clarity. In most cases of biomanipulation, planktivorous fish are replaced, and/or piscivores are introduced into eutrophicated lakes or ponds. A number of biomanipulations have been done in various water ecosystems around the world. To understand the current status of biomanipulation, the manipulations, lake size, and outcomes of some biomanipulations (35 cases) reported in literature are summarized as a table. From this review, there are 71.4% positive, and 20.0% negative results. This indicates that there are pressing needs to understand lake ecosystems in more depth and to evaluate the long‐term stability resulting from biomanipulation prior to implementing biomanipulation.
Macrophytes as Biomonitors of Trace Metals
Authors: Balanson Shimshon , Mal Tarun K.
Published: July 2005

Aquatic macrophytes are macroscopic aquatic plants that play an important role in the health of aquatic ecosystems. Not only do macrophytes provide vital structural support in aquatic ecosystems (1), but they also contribute toward food production, nutrient regeneration, and habitat for a wide range of organisms. Because of their roles in aquatic ecosystem health, aquatic macrophytes can be utilized as indicators of stream health (2). In fact, aquatic macrophytes may be indicative of a variety of ecosystem stressors including nutrient runoff, changes in hydrologic regime, and exotic species invasion (3, 4). Therefore, species richness of aquatic macrophytes, their composition, and density have all been incorporated into different macrophyte indicators (5, 6). As such, bioindicators estimate the pollutants affecting the biota in an ecosystem and are purely qualitative in nature.
Development and Application of Sediment Toxicity Test for Regulatory Purposes
Authors: Ángel Del Valls Casillas Thomas
Published: July 2005

Since the mid‐1970s research has focused on the development of sediment toxicity bioassays that could effectively predict potential biological adverse effects and could be used as an effective tool to characterize sediment toxicity. It is widely accepted that there are no chemical measurements that reliably predict sediment toxicity. In addition, sediments are a complex matrix that require complex tests for estimating the actual bioavailability of contaminants (7). Here we review the evaluation process that has been applied in the different initiatives carried out to introduce this new approach in a regulatory context. The design of toxicity tests for the characterization of dredged material in Spain is used as an example.
Fungal Contamination of Drinking Water
Authors: Paterson R. Russell M. , Lima Nelson
Published: July 2005

Fungi are a ubiquitous and diverse group of unique organisms accepted as a fifth kingdom. They are associated intrinsically with water, and so it is not surprising that they can occasionally cause problems. Two areas exist: (a) natural contamination and (b) unnatural contamination. Natural contamination is the equivalent of that which occurs with bacteria. Unnatural, or intentional, contamination is associated predominately with security in a field that has rapidly ascended the agenda. Furthermore, bottled water is a huge and growing commercial market and is susceptible to fungal contamination. A major problem is visual growth, which is what is presented to the consumer. Whereas this may not be apparent to the consumer of tap water, it is obvious in bottled water. However, there are technical difficulties associated with quantification and identification. Other actual issues can be odor and pigmentation. In addition, certain fungi cause allergic reactions and some are animal pathogens, including human pathogens, which are of particular concern to immunocompromised people. Finally, toxic compounds can be produced by fungi, which are referred to as mycotoxins. Aflatoxins have been demonstrated to occur in stored water naturally and other mycotoxins in
in vitro
experimentation. Obviously, it is mycotoxin contamination that is the biggest security threat. Methods are provided in this entry for the isolation and biochemical analysis of fungi and the properties of significance to drinking water. The use of a fungal lipid called ergosterol to quantify fungi is preferred. In conclusion, fungi in drinking water are often ignored but require a great deal more attention, particularly in relation to security threats.
Coagulation and Flocculation in Practice
Authors: Ozkan Alper
Published: July 2005

Process wastewater treatment involves removing suspended particles from suspension. Solid/liquid separation is difficult when treated particles are very fine. Aggregation of these particles facilitates their separation from suspension by sedimentation, filtration, or other methods. Coagulation and flocculation methods are the two major techniques used to aggregate fine particles in solid/liquid separation operations. Coagulation is obtained by neutralizing the electrical charge of the interacting particles. If aggregation is provided by polymer bridging, the process is defined as flocculation.

All waters, particularly surface waters and process wastewaters, contain both dissolved and suspended particles. Very fine particles only a few microns in diameter settle extremely slowly by gravity alone. Therefore, several methods are used to increase the size of solid particles in solid/liquid separation. The processes of coagulation and flocculation are the major techniques used to aggregate particles. Solid particles can be flocculated into relatively large lumps, called flocs, that settle out more rapidly and thus particles are separated more easily from water. Although the terms coagulation and flocculation are often used interchangeably, or the single term “flocculation” is used to describe both, they are two different processes. Fine particles can be aggregated by neutralizing the electrical charge of the interacting particles, which is “coagulation,” and bridging the particles with polymolecules is called “flocculation”.
Column Experiments in Saturated Porous Media Studying Contaminant Transport
Authors: Schuessler Wolfram , Artinger Robert
Published: July 2005

Column experiments are one key technique to investigate transport phenomena of contaminants in water‐bearing porous media. In the following a brief description of the principal setup and main experimental techniques used in column experiments is given. In addition, three examples for column experiments investigating different contaminant transport phenomena are described. The examples deal with the determination of sorption coefficients by column experiments, size exclusion effects of colloids, and Am‐humic colloid dissociation kinetics.
Development Validation and Analysis of Salmonella Mutagenicity Test Methods
Authors: Mukherji Suparna
Published: July 2005

Ames Assay is widely used for estimating mutagenicity in water samples that are extracted using columns packed with XAD resin. The test is conducted on plates using genetically engineered strains of
Salmonella typhimurium
, such as TA 98 and TA 100, where each is designed to indicate a specific mutation. Activation with rat liver microsomal fractions (S9‐mix) is required for detecting the indirect acting mutagens. Mutagenicity is reflected by revertant count on test plates exceeding the spontaneous mutation frequency. These revertant counts are characterized by large variances often exceeding the mean. The two‐fold rule commonly used for interpreting mutagenicity may yield a false interpretation depending on the strain‐specific spontaneous reversion frequency. A dose response relationship may be established based on the initial linear region; however, parameter estimation is best performed using software specifically developed for this test. The slope is representative of the combined effect of mutagenicity and toxicity.
UnderstandingEscherichia coliO157:H7 and the Need for Rapid Detection in Water
Authors: Bukhari Zia , Weihe Janice , Lechevallier Mark
Published: July 2005

Escherichia coliis a facultative anaerobe that commonly inhabits the gastrointestinal tracts of humans within hours of birth. This gram‐negative bacillus of the family Enterobactericeae is normally a harmless commensal that helps the host by suppressing pathogenic bacteria (due to competition) and by producing vitamin K and vitamin B complex (1). Individuals who suffer severe immunosuppression (both acquired and due to chemotherapy) or a breached gastrointestinal barrier can experience infection by nonpathogenicE. coli. More likely, however, are instances of infection by pathogenicE. colithat can include urinary tract infections, sepsis/meningitis, or diarrhea. Within the pathogenicE. coliresponsible for diarrheagenic disease, differentiation of the strains has led to development of five classes (virotypes): enteropathogenicE. coli(EPEC), enterohemorrhagicE. coli(EHEC), enterotoxigenicE. coli(ETEC), enteroinvasiveE. coli(EIEC), and enteroaggregativeE. coli(EAEC) (2). Differentiation of pathogenic strains ofE. coliis based on the organism's surface antigen profiles of O (somatic), H (flagellar), and K (capsular). This serological classification was originally proposed by Kauffman in 1944 and a modified form is still in use today. Although this serotyping ofE. coliis a reproducible mechanism for identifyingE. coliassociated with particular clinical disease, the serotypes themselves are not responsible for virulence but are only identifiable chromosomal markers for virulence factors (2).

This article focuses onE. coliO157:H7, a member of the EHEC class of diarrheagenicE. coli, and specifically discusses transmission routes, particularly focused on the waterborne route and the methods that may be employed for detecting contamination.
Acid Mine Drainage—Extent and Character
Authors: Rose Arthur W.
Published: July 2005

Acid mine drainage (AMD), also known as acid rock drainage (ARD), is an extensive environmental problem in areas of coal and metal mining. For example, the Appalachian Regional Commission estimated that 5700 miles of streams in eight Appalachian states were seriously polluted by AMD. AMD is also serious near major metal mining districts such as Iron Mountain, CA and Summitville, CO. In streams affected by AMD, fish and stream biota are severely impacted and the waters are not usable for drinking or for many industrial purposes. In addition to deleterious effects of dissolved constituents (H
+
, Fe, Al) on stream life, Fe and Al precipitates can cover the stream bed and inhibit stream life, and suspended precipitates can make the water unusable. In metal mining areas, heavy metals can add toxicity. General references on chemistry of AMD are Rose and Cravotta and Nordstrom and Alpers.
Microbiological Quality Control in Distribution Systems
Authors: Lehtola Markku J. , Miettinen Ilkka T. , Martikainen Pertti J.
Published: July 2005

Microbial growth in drinking water has many undesirable effects on water quality. Microbial growth may cause esthetic and technical problems and in some cases be a health risk for consumers. Growth of microbes in drinking water is affected by various factors like disinfection, residence time in the distribution network, temperature, and microbial nutrients like organic carbon and phosphorus. Most of the bacteria in drinking water originate from biofilms in pipelines, so that also the pipe material and hydraulics can affect the microbial growth. Chlorination is one effective and widely used method for preventing microbial growth in drinking water. However, chlorine reacts with organic matter, which can lead to formation of harmful disinfection byproducts. Other widely used ways to disinfect drinking water are ozonation and UV‐radiation, but these methods have no residual effects in the distribution system. In the lack of the disinfection residuals, microbial growth is limited by the nutrients. Usually the limiting nutrient in drinking waters is organic carbon, but in some cases, water contains such high amounts of organic carbon that microbial growth is limited by the availability of phosphorus.
Regulatory and Security Requirements for Potable Water
Authors: Du Vall Knorr Suzanne
Published: July 2005

Potable water is drinking water that meets the requirements of the Safe Drinking Water Act (SDWA) or stricter state requirements. Water suppliers must provide an annual water quality report to their customers or a consumer confidence report as required in California. Primary drinking water standards require corrective action and public notification when exceeded. The water system must also notify customers when a secondary drinking water standard is exceeded, although corrective action is optional.

A
Cryptosporidium
outbreak in Milwaukee, Wisconsin, led to regulations requiring filtration to remove cysts. Between 1999 and 2000, 28 of 39 waterborne disease outbreaks were from groundwater sources. The federal Environmental Protection Agency (EPA) has proposed disinfection of groundwater. Recent focus on chemical contaminants involves methyl‐
t
‐butyl ether (MTBE) and perchlorate found in drinking water sources. EPA classified MTBE as an unregulated contaminant. The California Department of Health Services (CDHS) established primary and secondary maximum contaminant levels (MCL) for MTBE. EPA and CDHS have established advisory levels only for perchlorate.

Focus on intentional contamination led to two federal laws affecting water systems: the Homeland Security Act and the Public Health Security and Bioterrorism Preparedness and Response Act (Bioterrorism Act). The Homeland Security Act requires reporting potential threats to the Department of Homeland Security. The Bioterrorism Act requires that water systems serving more than 3300 people submit a vulnerability assessment to EPA, prepare an emergency response plan, and implement needed security upgrades.

Drinking water requirements change as science and technology advances and as agencies learn more about the health affects of waterborne contaminants. Ensuring a safe potable water supply requires vigilance. The goal of regulatory agencies and water purveyors is to ensure a safe and reliable drinking water supply.
Activated Carbon—Powdered
Authors: Kazmi Absar A.
Published: July 2005

The most commonly used adsorbent in water and wastewater treatment is activated carbon. Activated carbon is manufactured from carbonaceous material such as wood, coal, or petroleum residues. A char is made by burning the material in the absence of air. The char is oxidized at higher temperatures to create a very porous structure. The “activation” steps provide irregular channels and pores in the solid mass, resulting in a very large surface‐area‐per‐mass ratio. Surface areas ranging from 500 to 1500 m
2
/g have been reported, and all but a small surface area is in the pores. Once formed, activated carbon is pulverized to a very fine powder (Fig. 1). The size is predominantly less than 0.075 mm (200 sieve). Dissolved organic material adsorbs to both exterior and interior surfaces of the carbon.
Water Sampling and Laboratory Safety
Authors: Ryan Timothy J.
Published: July 2005

Water sampling is done for a wide variety of reasons; some of which may place the individual in perilous environments. Because sample collection represents a significant allocation of resources, safeguards for personnel and samples alike are important.

Actual hazards of sampling and analysis depend on the sampling location and type of analysis to be conducted. The field log book is perhaps the important sampling tool, and all information pertinent to the sampling trip is to be recorded in it. The physical security and integrity of water samples is essential to ensuring the accuracy and legal defensibility of results, and precautions to protect samples from contamination and deterioration are therefore essential. Precautions must also be taken in the laboratory. Laboratories must comply with safety regulations, as analysis can involve exposure to corrosive, reactive, and toxic reagents, and personal protective equipment should be used.
Source Water Quality Management
Authors: Phoenix Laurel
Published: July 2005

Water utilities serving water authorities or municipalities can have many levels of control over the quality of their source waters. The more control they have over protecting the water quality of their sources, the less money they have to spend on water treatment, and the lower their risk when dealing with unforeseen emergencies. When they have no control of changing water quantities from drought, flood, or industrial pollution, they must spend more money to access backup supplies. Examples of water utilities with high or low control are described. For high control, the types of land use regulations mandated to prevent water degradation are described and the option some cities have for extraterritorial control. For the more common situation of low or no power, four common problems are when (1) source water is degraded, (2) supply is uncertain, (3) drinking water regulations are tightened, or (4) emergency situations arise. Strategies that water utilities use are securing numerous sources to draw upon in case of drought or a pollution event, instituting conservation to “create” new water, or crafting cooperative interlocal agreements to protect, manage, and provide public water more efficiently and sustainably.
Water Quality Management
Authors: Jain Chakresh K. , Sharma K. D.
Published: July 2005

Water quality problems stem from two factors, the natural hydrology of a river basin and the development and use of land and water resources by human beings. Depending on the interrelation of these two factors, a wide variety of quality problems can result. Each river basin, therefore, is unique, and it must be subjected to individual and intensive water quality assessment to provide a proper basis for judicious management of land and water.

The following points should be considered for proper planning of a water quality monitoring program:

What are the objectives of the program?

From where are samples to be taken?

Which determinants are of interest?

When and how often are samples to be taken?

What is to be done with the results?

These questions will provide a framework for defining measurement programs. The results obtained from such a program should be regularly reviewed to decide if any changes (e.g., determinants or sampling frequency) in the monitoring program are necessary.
Sustainable Management of Natural Resources
Authors: Reijnders Lucas
Published: July 2005

Sustainable is defined here in terms of an economy that maintains an equilibrium relation between human activities and the physical environment. Four types of natural resources are distinguished that differ in requirements for sustainable use. Freshwater usage should not exceed addition to stock and the quality of fresh water stocks should be maintained. Improved water efficiency, water conservation, source reduction of pollutants, and water pricing reflecting full cost can contribute to attaining sustainability.

Fishery catches should not exceed addition to stock and population structure should be maintained. To attain this goal, a variety of approaches has been tried, some on a voluntary basis such as the Marine Stewardship Council, and others based on government intervention. Governmental efforts aimed at sustainable management of fish stocks have met with varying success.

Sustainable management of ecosystems should focus on maintaining the area allocated to nature, maintaining proper abiotic conditions, and conserving species diversity. A major problem in this respect is that many ecosystem services do not have a price.
Flood of Portals on Water
Authors: Jong Dick De , Bryce Marta
Published: July 2005

A flood of gateways and portals is emerging in recent years. This is contributing to confusion rather than helping Internet users who search the web on water issues. Part of this confusion is the result of definition problems of what makes a “portal” and what not. Here, we give some recent examples, try to create more clarity by providing definitions and types, discuss key lessons learned, and raise key issues for further discussion and research. This is based on various Internet searches and an annotated selection of various gateways/portals by IRC.

For each of them a short description of content, topic, date of establishment, and page views are provided. The majority of the gateways/portals described here focus on the broadest possible water topic: water resources and management.

The huge difference in the percentage of the population of Internet users in the North and the South needs to be addressed. Global access in 2002 was around 9%. In The Netherlands and Denmark it was around 61%. In Colombia it was about 2.8%, in Bolivia 0.9%, in India 0.7%, in Nepal 0.23%, in Mozambique and Bangladesh 0.1%, and in Ethiopia 0.03%.

A good example from the reality of the developing world will be described as well: the Virtual Library on Environmental Health (VLEH) of the Pan American Information Network on Environmental Health, REPIDISCA, which has been operating since 1982 in 21 countries of Latin America and the Caribbean with 370 Cooperating Centres. The Pan American Center for Sanitary Engineering and Environmental Sciences, CEPIS/PAHO, of the Pan American Health Organization, PAHO/WHO, is in charge of the regional coordination.
Fuzzy Criteria for Water Resources Systems Performance Evaluation
Authors: Simonovic Slobodan P.
Published: July 2005

One of the main goals of engineering design is to ensure that a system performs satisfactorily under a wide range of possible future conditions. This premise is particularly true of large and complex water resources systems. Water resources systems usually include conveyance facilities such as pipes and pumps, treatment facilities such as sedimentation tanks and filters, and storage facilities such as reservoirs and tanks. These elements are interconnected in complicated networks serving broad geographical regions. Each element is vulnerable to temporary disruption in service due to natural hazards or human error whether unintentional, as in the case of operational errors and mistakes, or due to intentional causes such as a terrorist act. Most of the hazards cannot be controlled or predicted with an acceptable degree of accuracy. Uncontrollable external factors also affect the capacity and the performance of water resource systems. The determination of the load pattern presents unique challenges. Ang and Tang (1) point out that there is uncertainty in all engineering‐based systems because these systems rely on the modeling of physical phenomena that are either inherently random or difficult to model with a high degree of accuracy.
Photocatalytic Membrane Reactors in Water Purification
Authors: Molinari Raffaele , Palmisano L.
Published: July 2005

Potable water, industrial water, and wastewater are often polluted by toxic organic species. New methods, such as those involving heterogeneous photocatalytic reactions, allow in many cases a complete degradation of organic pollutants to small and non‐noxious species, without using chemicals, avoiding sludge production and its disposal. When combined with membrane separation processes, photocatalytic membrane reactors (PMRs) are obtained. These have some advantages compared to conventional photoreactors. Indeed, confining of the photocatalyst in the reaction environment as a result of the presence of the membrane (separation at molecular level) enables operation with high amounts of catalyst, control of the residence time of the molecules in the reactor, and realization of a continuous process with simultaneous product(s) separation from the reaction environment.

The influence of various operating parameters on the photodegradation rate of various pollutants present in aqueous effluents by means of discontinuous and continuous photocatalytic processes are described. The hybrid continuous photoreactor, where a nanofiltration membrane is used, can give a simplification of clean‐up or purification of various types of waters (for industrial, municipal/domestic, and agricultural uses) and no sludge production as well as a saving in chemicals usage. It is expected that these hybrid processes will be considered when plant upgrade is planned and, especially, if sunlight energy can be used for irradiation.
Problems Encountered During Pipe Repair and Renewal
Authors: Gokhale Sanjiv
Published: July 2005

The major problem encountered during sliplining of an existing sewer is improper preparation of the interior of the sewer prior to inserting the sliplining pipe.

Obstructions such as roots, large joint offsets, extended laterals, rocks, or other debris that would prevent the passage of or the damage to the liner pipe sections must be removed or repaired prior to the installation of the new liner pipe.