bluuebunny/crossref_metadata_2025 huggingface dataset:
Agriculture and Land Use Planning
Authors: Seidl Andy , Freedgood Julia , Hunt Fen C.
Published: July 2005

The American public values agricultural land for many reasons beyond its ability to produce food, fiber, and timber. Public values for agricultural land preservation have translated into public support for establishing agricultural land preservation programs at the local, state, and federal levels. A mixture of both regulatory and incentive‐based approaches have resulted in the permanent protection of nearly 1.5 million acres of agricultural land from conversion to nonagricultural uses and the concentration of millions of more acres in agricultural production through zoning. The failure of land markets to reflect the social value of extensive land uses relative to intensive uses and the irreversibility of land‐use intensification decisions create a particularly fluid and pressing policy environment for lay people, land‐use practitioners, and researchers alike. We provide a brief overview of the issues and resources and ongoing programs directly influencing agricultural land protection and land‐use policy. We pay particular attention to resources and information available on the Internet, recognizing the rapidly changing environment in this policy arena.
Maintaining Salt Balance on Irrigated Land
Authors: Kijne Jacob W.
Published: July 2005

The salt balance compares the movement of dissolved salts into and out of an area over a specified period of time. The ratio of the amount of drainage water, percolating from the root zone of an irrigated field, and the amount of water entering the root zone as irrigation and rainfall is the leaching fraction. For steady‐state conditions, when the salt concentration of the soil solution remains the same, this ratio equals the ratio of the electrical conductivity (EC) of the applied water to that of the drainage water. The EC of a salt solution is a proxy for its salt concentration and easier to measure than its concentration. These measurements can be made with a conductivity meter and for bulk soil in the field by means of electromagnetic induction sensors.

To sustain irrigated production, the root zone's salt concentration must be controlled by leaching of the salts beyond the reach of roots. Excessive irrigation leads to high water tables and the mobilization of natural salt residues of arid and semiarid lands. Irrigation‐induced salt transport contributes to river salinity as illustrated for four rivers.

The salts carried in irrigation water come from salts that are continuously released from rocks and soils by mineral weathering and dissolution. Because of their low rainfall, most arid and semiarid lands are rich in these primary salts. The salts were deposited over time in sedimentary rock layers and are dissolved in the waters of aquifers. Unfavorable salt balances are common in arid lands: The global extent of salt‐affected lands is considerable. It has been estimated that worldwide 100 million ha of irrigated land suffer from salinity, 20% of which is severely affected (2). Annually some 2 to 3 million ha of potentially productive agricultural land are taken out of production because of salinization. How much of this land is reclaimed (to various degrees) and then cultivated again is unknown. Wide divergence in the salinity figures is reported by different institutions, probably because of incomplete data and different definitions of salinity‐affected lands; e.g., estimates for salt‐affected land in India, according to different sources, range from 7 to 26 million ha, or between 17% and 60% of the irrigated land. For Pakistan, the most likely figure is some 40%, Israel 13%, Australia 20%, China 15%, Iraq 50%, and Egypt 35% of the irrigated land (3).
Soil Erosion and Control Practices
Authors: McHugh Marianne , Clarke Michelle , Duzant Julia , Morgan Roy , Rickson Jane
Published: July 2005

Soil erosion involves a two‐phase process of soil detachment and transport, both of which require an energy input. Much of the energy of erosion derives from water or wind flow over the soil surface or is provided by gravity. Although reducing the energy of erosive forces is the most effective way of controlling soil erosion, one consequence of reducing energy may be the deposition of any material already eroded. As eroded sediment is often enriched with nutrients, organic matter, and contaminants preferentially adsorbed onto the sediment surface, sediment deposition may allow contaminant release into the environment. It is necessary, therefore, to reduce erosive energy at the source areas of sediment rather than after the sediment has been detached and transported.
Vacuum Gauge Tensiometer
Authors: Alam Mahbub
Published: July 2005

Soil water plays an important role in providing water for plant growth. The vacuum gauge tensiometer is a soil water measuring device that is sensitive to soil water change. The quantity of soil water that adheres around soil particles determines the energy level at which it is being retained or pulled. In other words, the plant root has to exert energy to pull water out of a soil matrix. This energy is also expressed as tension the roots experience in removing the water. Tensiometer is like a mechanical root but shows the tension in the vacuum gauge attached to it. It is an indirect method to determine soil water status. Direct measure of water content is time‐consuming and labor‐intensive, and the result lags behind the current time. Hence, irrigators depend on indirect methods. Vacuum gauge tensiometer is inexpensive, easy to use, and a preferred measurement method, especially for course‐textured soils.
Water Table Contribution to Crop Evapotranspiration
Authors: Madramootoo Chandra
Published: July 2005

Evapotranspiration (ET) is the transfer of water vapor from the soil root zone to the atmosphere via the process of photosynthesis. Water vapor can also move directly from the ground surface to the atmosphere. The rate of ET depends on several climatic, soil water, and crop factors, including rainfall, relative humidity, wind speed, air temperature, solar radiation, cloud cover, soil moisture, and stage of crop growth. The plant transpires at the potential rate if soil water is not limiting, which depends on the soil water content.

Water is held in the soil root zone in three distinct phases: hygroscopic water, capillary water, and gravitational water. Because of the high tension of the hydroscopic water, it is not available to plants. Both capillary water and gravitational water are available for crop uptake in the ET process.
Vapor Transport in the Unsaturated Zone
Authors: Tillman Fred D. , Smith James A.
Published: July 2005

In this section, we focus our attention primarily on the fate and transport of volatile organic vapors in the unsaturated zone. Organic vapors can arise from soil and groundwater contaminated with fuel hydrocarbons, organic solvents, pesticides, or other organic pollutants. Transport of these vapors occurs primarily by some combination of gas‐phase Fickian diffusion (driven by organic vapor concentration gradients) and advection (driven by air pressure gradients). Other processes such as sorption to soil surfaces and air–water interfaces and biodegradation by soil microorganisms can further influence the fate and transport of organic vapors. We review these processes along with organic vapor sampling methodologies and chamber devices used to quantify organic vapor fluxes from the subsurface to the atmosphere.
Well Design and Construction
Authors: Voutchkov Nikolay
Published: July 2005

Wells are used to collect fresh and saline groundwater and seawater. These intake facilities are relatively simple to build, and the water they collect is pretreated via slow filtration through the geologic formations in the area of source water extraction. Well type, size, and capacity are determined by a hydrogeologic investigation. The key factors that determine if the use of subsurface intake is practical or/and economical are the type of the water source aquifer, the aquifer permeability, the average specific yield of the aquifer, and the thickness of the production aquifer deposits. Intake wells are typically vertical or horizontal water collectors drilled into the source water aquifer. Vertical intake wells are usually less costly than horizontal wells, but their yield is relatively small and therefore, vertical wells are typically used for supplying relatively small quantities of water. Horizontal (Ranney) collector wells consist of a caisson that extends below the ground surface with water well collector screens (laterals) projected horizontally from inside the caisson into the surrounding aquifer. This type of well can collect order of magnitude larger volumes of groundwater than vertical wells. Where conventional vertical and horizontal wells are not practical due to unfavorable hydrogeologic conditions, infiltration galleries and riverbed/seabed filtration intake systems have found wide application for groundwater collection.
Limiting Geochemical Factors in Remediation Using Monitored Natural Attenuation and Enhanced Bioremediation
Authors: Jacobs James A. , Vance David B.
Published: July 2005

In Situ
Monitored Natural Attenuation (MNA) and enhanced bioremediation are affected by a variety of limiting factors, including the availability of a terminal electron acceptor (TEA), macronutrients (nitrogen and phosphate), as well as an energy source (carbon). The TEA for aerobic degradation is limited to oxygen. For anaerobic degradation, TEA processes include denitrification using nitrate (NO
3
−
), manganese reduction using manganese dioxide (MnO
2
), iron reduction using bioavailable iron that includes the hydroxide form (Fe(OH)
3
), sulfate reduction using the sulfate ion (SO
4
2−
), and methanogenesis using carbon dioxide (CO
2
) (1).
The Role of Heat in Groundwater Systems
Authors: Jacobs James A. , Vance David B.
Published: July 2005

The role of heat in the subsurface includes the study of the overall transport of heat in saturated groundwater systems. Once site specific dynamics of heat transport are understood the effects of temperature on physical, chemical, and biological processes that govern the transport and degradation of contaminants in an aquifer can be evaluated.
Source, Mobility, and Remediation of Metals
Authors: Jacobs James A. , Vance David B.
Published: July 2005

Metals and high levels of inorganic Total Dissolved Solids (TDS) are associated with leaks from sanitary, solid waste, and hazardous waste landfills.

Innovation in the area of hydrocarbon remediation has been significant in the last decade. However, metals may only be mobilized or immobilized, unlike hydrocarbons they cannot be degraded to less innocuous components, such as CO
2
and H
2
O, for example. This limited reactivity is one of the reasons that innovative remediation technology has been slow to develop for soils or groundwater contaminated with metals, which will likely change with time, however.
Groundwater and Benzene: Chemical Behavior and Treatment
Authors: Jacobs James A. , Villiers Keith
Published: July 2005

Benzene (C
6
H
6
) is a clear, colorless, highly flammable aromatic hydrocarbon liquid. As an important ingredient for making plastics, rubber, resins, and synthetic fabrics like nylon and polyester, benzene is one of the most commonly used industrial chemicals in the world. It is also used as a solvent in printing, paints, and dry cleaning. It is also a major component of gasoline. The wide ranging industrial applications of benzene make it widely distributed, particularly in the case of petroleum products, of which it is a primary constituent. Benzene is highly toxic to humans and the environment. Because of its severe toxic effects, both in the short and long term, benzene use has been under strict regulations for many years. Nonetheless, widespread contamination of benzene has occurred in the environment, and, therefore, significant regulatory efforts in the United States and other nations are being enacted to limit or eliminate potential impacts.
Groundwater and Vinyl Chloride: Chemical Behavior and Treatment
Authors: Jacobs James A. , Munroe Angela
Published: July 2005

Vinyl chloride is a colorless, flammable gas at normal temperatures with a mild, sweet odor. It exists in liquid form if it is kept under high pressure or at low temperatures (less than −13.4°C). Vinyl chloride is also known as chloroethene, chloroethylene, and ethylene monochloride (1). All vinyl chloride is manufactured or results from the breakdown of other manufactured substances, such as trichloroethane (TCA), tetrachloroethylene (PCE), and trichloroethylene (TCE). Vinyl chloride was first produced commercially in the 1920s and is now one of the highest volume chemicals produced in the United States (2). Of the vinyl chloride produced, 96–98% is used to make poly(vinyl chloride) (PVC) with the remaining 2–4% being utilized in the manufacture of specific chlorinated hydrocarbons such as 1,1,1‐TCA, 1,1,2‐TCA, and vinylidene chloride (3). PVC is used to make a variety of plastic products including pipes, wire, cable coatings, and packaging materials. Other uses include furniture and automobile upholstery, wall coverings, housewares, and auto parts. Vinyl chloride has been used in the past as a refrigerant, an extraction solvent for heat‐sensitive materials, and in the production of chloroacetaldehyde and methyl chloroform (4). Also, limited quantities of vinyl chloride were used as an aerosol propellant and as an ingredient in drug and cosmetic products (4). However, these practices were banned by the United States Environmental Protection Agency (U.S. EPA) in 1974.
Acid Mine Drainage: Sources and Treatment in theUnitedStates
Authors: Skousen Jeffrey G.
Published: July 2005

Acid mine drainage (AMD) occurs when metal sulfides are exposed to oxidizing conditions. Leaching of reaction products into surface waters pollute over 20,000 km of streams in the United States alone. Mining companies must predict the potential of creating AMD by using overburden analyses. Where a potential exists, special handling of overburden materials and quick coverage of acid‐producing materials in the backfill should be practiced. The addition of acid‐neutralizing materials can reduce or eliminate AMD problems. Placing acid‐producing materials under dry barriers can isolate these materials from air and water. Other AMD control technologies being researched include injection of alkaline materials (ashes and limestone) into abandoned underground mines and into buried acid material in mine backfills, remining of abandoned areas, and installation of alkaline recharge trenches. Chemicals used for treating AMD are Ca(OH)2, CaO, NaOH, Na2CO3, and NH3, with each having advantages under certain conditions. Under low‐flow situations, all chemicals except Ca(OH)2are cost effective, whereas at high flow, Ca(OH)2and CaO are clearly the most cost effective. Floc, the metal hydroxide material collected after treatment, is disposed of in abandoned deep mines, refuse piles, or left in collection ponds. Wetlands remove metals from AMD through formation of oxyhydroxides and sulfides, exchange and organic complexation reactions, and direct plant uptake. Aerobic wetlands are used when water contains enough alkalinity to promote metal precipitation, and anaerobic wetlands are used when alkalinity must be generated by microbial sulfate reduction and limestone dissolution. Anoxic limestone drains are buried trenches of limestone that intercept AMD underground to generate alkalinity. Under anoxia, limestone should not be coated with Fe+3hydroxides in the drain, which decreases the likelihood of clogging. Vertical flow wetlands pretreat oxygenated AMD with organic matter to remove oxygen and Fe+3, and then the water is introduced into limestone underneath the organic matter. Open limestone channels use limestone in aerobic environments to treat AMD. Coating of limestone occurs, and the reduced limestone dissolution is designed into the treatment system. Alkaline leach beds, containing either limestone or slag, add alkalinity to acid water. At present, most passive systems offer short‐term treatment and are more practical for installation on abandoned sites or watershed restoration projects where effluent limits do not apply and where some removal of acid and metals will benefit a stream.
Ghijben–Herzberg Equilibrium
Authors: Holzbecher Ekkehard
Published: July 2005

Classical papers by Badon Ghijben and Herzberg, dealing with the saltwater–freshwater interface in an unconfined coastal aquifers—are presented in some detail first, including the historical context. What follows is a discussion of the conditions that have to be fulfilled for the Ghijben–Herzberg equilibrium (GHE) to be valid. Moreover, generalized formulations and findings, which have been developed during the century, are presented. It is shown that the GHE can be a useful rule of a thumb for confined aquifers, for general two‐phase fluid situations, for saltwater upconing below wells, and for situations without a sharp interface. The GHE can even be included successfully in computer models. Finally, a precursor of the classical papers is mentioned.
In SituBioremediation of Contaminated Groundwater
Authors: Philp Jim C. , Cunningham Colin C. , Kuyukina Maria S. , Ivshina Irena B.
Published: July 2005

More than any other factor, it is likely that oxygen limitation occurs in groundwaters, and the most rapid biodegradation processes normally involve oxygenase enzymes. The supply of oxygen forin situbioremediation adds considerably to the expense and the technical difficulty. This supply involves the use of either blowers or vacuum pumps to draw air through the system. A measure of the pivotal role of oxygen is in the use of hydrogen peroxide to enhance aeration. That its use has been considered at all is remarkable: concentrations of H2O2above 100 to 200 mg/L are toxic to microorganisms; it can be consumed very quickly, limiting treatment to the regions near the injection well; a groundwater circulation system must be created; and good soil permeability is essential.

Recent advances in the knowledge of anaerobic biodegradation microbiology have opened up the prospect of greater acceptance of anaerobic bioremediation where maintaining aerobic conditions is not feasible. The existence of microorganisms capable of coupling the anaerobic reduction of Fe3+to the oxidation of organic compounds shows promise. Virtually our entire knowledge of anaerobic metabolism of hydrocarbons has been gained since around 1990 (for reviews, see References 7 and 8). Several alkylbenzenes, alkanes or alkenes, are anaerobically biodegraded by denitrifying, ferric iron‐reducing or sulfate‐reducing bacteria. Another group of anaerobic hydrocarbon‐degrading bacteria are “proton reducers” that rely on syntrophic associations with methanogens. As some of the most significant groundwater pollutants are chlorinated solvents, then a role for microbial reductive dehalogenation is feasible. Although slow, even the reductive dechlorination of dioxins is possible. A recent discovery has shown that even benzene can be oxidized completely under anaerobic conditions by pure cultures, using nitrate as the electron acceptor. Benzene is a particular problem in groundwater because it is relatively soluble and mobile.
Characterizing Soil Spatial Variability
Authors: Corwin Dennis L. , Lesch Scott M.
Published: July 2005

Soil spatial variability refers to the variation in soil physical, chemical, mineralogical, and biological properties across the landscape and through the soil profile. The significance of soil spatial variability lies in its direct or indirect influence on any landscape‐scale soil‐related issue ranging from solute transport of non‐point source pollution to precision agriculture. A general discussion of the origin, need for characterization, and measurement methods is presented with greatest emphasis placed on the use of apparent soil electrical conductivity (EC
a
) to characterize spatial variability. The characterization of spatial variability with geospatial EC
a
measurements is based on the correlation of EC
a
with various physicochemical properties and the use of EC
a
‐directed soil sampling designs. Edaphic factors influencing EC
a
measurements, mobile EC
a
measurement equipment, EC
a
‐directed sampling designs, guidelines for conducting an EC
a
survey, and limitations and precautions are discussed. The discussion is intended to provide a basic understanding of spatial variability and its characterization with geospatial EC
a
measurements to a general scientific audience.
Reactive Transport in the Saturated Zone: Case Histories for Permeable Reactive Barriers
Authors: Li Len , Benson Craig H.
Published: July 2005

This chapter describes comparisons between predictions made with a reactive transport simulator and geochemical conditions observed in three permeable reactive barriers (PRBs) employing zero valent iron (ZVI) as the reactive medium. The emphasis is on reactions involving common ions in groundwater that form minerals that may block the pore space in a PRB. Two common public‐domain programs, MODFLOW and RT3D, were combined to form the simulator. A geochemical algorithm was developed for RT3D to simulate geochemical reactions occurring in PRBs. Comparisons between model predictions and field data are presented for three PRBs. Good agreement was obtained between predicted and measured pH and common ion concentrations by adjusting the rate coefficients within ranges reported in the literature. However, sensitivity analyses showed that predictions made with the simulator are sensitive to the rate coefficients used as input. The field data sets also were too sparse to determine whether the simulator accurately predicts the rapid changes in geochemistry occurring near the entrance face of PRBs.
Sugarcane Industry Wastewaters Treatment
Authors: Durán‐de‐Bazúa María‐del‐Carmen
Published: July 2005

The sugarcane industry, and particularly one that produces distilled potable products besides sugar (sucrose), generates wastewater with a high content of organic and inorganic compounds that are difficult and costly to remove. Particularly those from ethanol production, known as vinasses (the fermented musts are known as wines, from Latin
vinum
), contain from 60 to 150 g COD/L. Compared with household sewage, that has 400 to 800 mg COD/L, vinasses are about 75 to 375 times more polluted. Vinasses contain important amounts of organic chemical substances from the raw materials used during fermentation, such as undegraded sugars, polyphenols, phenols, inorganic ions such as sulfates, and dead yeast. In Mexico, for example, each liter of fermented and distilled ethyl acohol implies the generation of vinasses that may reach up to 12 liters. Most of these vinasses, to date, are discharged to receiving bodies (soil, surface water sources) without any treatment or only with partial depuration. The use of thermophilic anaerobic systems stabilize and recycle these liquid residues from distillation of fermented musts that produce methane gas and may be used within the plants to generate steam for the distillation towers, is a feasible technology that may be easily adapted to the conditions in distilleries in most tropical countries where sugarcane grows. Then, they may use an aerobic treatment whose microbial biomass can be used in fish feedlots. In tropical countries, a crustacean such as river shrimp can be “cultivated” using fish by‐products, and its cephalothorax can be used to produce chitin, a very high value natural polymer, and a carotenoprotein complex to be added to fish pellets to increase their antioxidant content and the final fish flesh organoleptic quality that gives it a pink salmon color. Wastewaters that contain mainly acid and caustic compounds can be evaporated using solar energy and the resulting salts recycled to the companies that provide these chemicals.
Water Impacts from Construction Sites
Authors: Jacobs James A.
Published: July 2005

Surface water and, to a lesser degree, groundwater are impacted by runoff from construction sites, parking lots, roadways, and other nonpoint sources. Soil particles and dissolved constituents in runoff reduce the beneficial uses of water and have become a major regulatory challenge. Erosion rates at construction sites may be 10 to 20 times greater than for undisturbed lands. Construction sites, including environmental remediation activities and redevelopment, might contain a variety of natural and manmade contaminants that might exceed regulatory levels. Sediment runoff from nonpoint sources is primarily the result of wind and water erosion. Construction sites are locations where special erosion control measures may be needed to prevent storm water runoff and sediment buildup in nearby waterways and groundwater recharge areas.
A Statistical Approach to Critical Storm Period Analysis
Authors: Ruiz F. , Abad M. , Rodríguez‐Ramírez A. , Cáceres L. M. , Rodríguez Vidal J. , Pino R. , Muñoz J. M.
Published: July 2005

An evaluation of critical storm period periodicity may be interesting for managing numerous coastal tourist areas. For this purpose, the treatment of the meteorologic data needs to be rigorous with the application of time series analysis. In this article, we analyze some mathematical procedures for resolving these problems, subsequently applied to studying the interrelationships among some meteorologic–oceanographic data of the Gulf of Cádiz (SW Spain) and the recent storm record of this zone. An interesting correlation was found between southwestern wind periodicity and the number of storm periods; the two most probable levels of periodicity are 6–7 years and 9–10 years.
Ground‐Based
GPS
Meteorology at
FSL
Authors: Gutman Seth I. , Holub Kirk L.
Published: July 2005

Water vapor is one of the most important components of the Earth's atmosphere. It is the source of precipitation, and its latent heat is a critical ingredient in the dynamics of most major weather events. As a greenhouse gas, water vapor also plays a critical role in the global climate system: it absorbs and radiates energy from the sun and affects the formation of clouds and aerosols and the chemistry of the lower atmosphere. Despite its importance in climate and weather prediction, water vapor has been one of the most poorly measured and least understood components of the Earth's atmosphere. Researchers at FSL and elsewhere are utilizing recent technology to reverse this situation.
Rainfall
Authors: Smith James A.
Published: July 2005

The capability to measure rainfall advanced dramatically in the last quarter of the twentieth century. The advances have been paced by remote‐sensing technologies including both ground‐based weather radar and satellite‐borne instruments. The most dramatic developments have centered around the capability to monitor precipitation globally from satellite sensors. This measurement capability provides a variety of avenues for hydroclimatological analysis and forecasting. Advances in ground‐based radar technologies and deployment of dense networks of rain gages has enhanced the ability to measure rainfall at short time scales (less than 1 h) and small spatial scales (less than 1 km). These time and space scales are often most relevant for water management applications. A brief summary of rainfall measurement and analysis capabilities is presented in the following three sections and organized by the three principal measurement technologies: rain gage, radar, and satellite.
Whirlpool
Authors: Meaden Terence
Published: July 2005

Whirlpools are most familiar as vortices in the fast‐fluid flow of rivers, usually in the form of an eddy downstream of some obstruction. Whirlpools can also occur in certain marine conditions, usually near particular coasts.
Package Plants
Authors:   National Drinking Water Clearinghouse
Published: July 2005

Small water treatment systems often find it difficult to comply with the U.S. Environmental Protection Agency (EPA) regulations. Small communities often face financial problems in purchasing and maintaining conventional treatment systems. Their problem is further complicated if they do not have the services of a full‐time, trained operator. The Surface Water Treatment Rule (SWTR) requirements have greatly increased interest in the possible use of package plants in many areas of the country. Package plants can also be applied to treat contaminants such as iron and manganese in groundwater via oxidation and filtration.
Iron and Manganese Removal
Authors:   National Drinking Water Clearinghouse
Published: July 2005

Iron and manganese are common in groundwater supplies used by many small water systems. Exceeding the suggested maximum contaminant levels (MCL) usually results in discolored water, laundry, and plumbing fixtures. This, in turn, results in consumer complaints and a general dissatisfaction with the water utility.

There are secondary standards set for iron and manganese, but these are not health related and are not enforceable. The secondary (aesthetic) MCLs for iron and manganese are 0.3 milligrams per liter (mg/L) and 0.05 mg/L, respectively.

Small water plants may choose to either sequestrate or remove iron and manganese. Sequestration only works for combined iron and manganese concentrations up to 1.0 mg/L and only in cases where the treatment is not permanent. Removal is usually achieved through ion exchange or oxidation/filtration. There are a number of chemical oxidants and filtration media available that can be used in various combinations.
Water Quality in Distribution Systems
Authors: Michael Lahlou Z.
Published: July 2005

A drinking water system's water quality may be acceptable when the water leaves a treatment plant. However, a variety of physical, chemical, and biological transformations can happen once the water enters and travels through a distribution system. Water producers need to understand the sources of water quality degradation during the distribution process because, in addition to taste and odor problems that can occur, research also suggests that degraded water quality increases the risk of gastrointestinal illnesses.
Point‐of‐Use/Point‐of‐Entry Systems (
POU
/
POE
)
Authors: Lahlou Zacharia Michael
Published: July 2005

Numerous households use point‐of‐use/point‐of‐entry (POU/POE) systems primarily to deal with aesthetic concerns, such as taste and odor. These treatment devices are installed just as their name implies—at the point where water enters a household or where it is used, such as a faucet. In certain situations, however, using POU/POE systems to provide safe drinking water to a system's customers is not an individual's choice, but that of the water system cooperating with regulatory authorities. Therefore, this “Tech Brief” only discusses POU/POE treatment options that meet Safe Drinking Water Act (SDWA) water quality requirements.
Preventing Well Contamination
Authors: Bhardwaj Vipin
Published: July 2005

Nearly 80% of communities rely on groundwater as their primary drinking water source. Wells extract groundwater for use in homes and businesses. In addition, about 42 million Americans use private wells for drinking water. In light of this information, preventing groundwater contamination is of utmost importance, especially since a number of factors can contribute to groundwater contamination. To prevent well contamination, one of the first steps is to construct it properly. This Tech Brief presents tips about how to site a well and includes information about design issues; material selection and location, such as screens and filter pack; appropriate well sealing methods; and the use of pitless adaptors to prevent contamination.
Repairing Distribution Line Breaks
Authors: Bhardwaj Vipin
Published: July 2005

Occasionally, water systems encounter situations where they must repair distribution system pipes. Corrosion and tuberculation (i.e., buildup of sediment, dirt, or rust) may have caused small leaks in the lines, or worse, a major line break may occur, creating an emergency situation. This Tech Brief discusses ways to manage these situations and outlines steps a utility may take to repair the distribution system.
Key Causes of Drinking Water Quality Failure in a Rural Small Water Supply ofSouthAfrica
Authors: Momba M.N.B. , Makala N. , Zani B. , Brouckaert B.M.
Published: July 2005

Despite recent efforts by the South African government to extend and improve water services in rural and periurban areas of the country, most small treatment plants are still experiencing serious operating problems that jeopardize the quality of the water produced and the health of consumers. In the present study, the operation of Alice Water Treatment Plant (AWTP), a small treatment plant serving the town of Alice in the Eastern Cape Province, was evaluated, and the major causes compromising the effectiveness of the disinfection process were identified. The investigation revealed that the AWTP's major operational problems include: (a) The lack of a proper coagulant dosing control resulting in inadequate turbidity removal in the clarifiers and filters. The most common source of problems in rapid filtration was inadequate backwashing. The filters appeared to go for days without backwashing. (b) The lack of a proper chlorine dosing procedure and monitoring program. These problems are linked to the inadequate training of the plant staff. As a result of inadequate pretreatment, which also resulted in high dissolved organic carbon and biodegradable dissolved organic carbon (BDOC) concentrations and insufficient chlorine residuals, Alice treated water did not meet the minimum safety limits for potable water.
Hydraulic Design of Water Distribution Storage Tanks
Authors: Ahmad Rasheed
Published: July 2005

Water distribution storage ensures the reliability of supply, maintains pressure, equalizes pumping and treatment rates, reduces the size of transmission mains, and improves operational flexibility and efficiency. Numerous decisions must be made in designing a storage tank, including size, location, type, and expected operation. There are several key considerations in the hydraulic design of water storage tanks.

Equalization is the primary purpose for constructing water distribution storage tanks. Water utilities like to operate treatment plants at a relatively constant rate, and wells and pumping stations generally work best when pumped at a steady rate. However, water use in most utilities varies significantly during the course of the day. These variations in use can be met by continuously varying source production, continuously varying pumping rates, or filling and draining storage tanks.
Improving Waterborne Disease Surveillance
Authors: Frost Floyd J. , Calderon Rebecca L. , Craun Gunther F.
Published: July 2005

Public health surveillance has played a key role in controlling the spread of communicable disease and identifying the need for specific public health practices, such as the filtration and chlorination of drinking water supplies. However, the characteristics of waterborne outbreaks since the early 1990s have raised questions about whether current water treatment practices can prevent transmission of some enteric pathogens. It is increasingly accepted that additional information is needed about the occurrence and causes of waterborne disease, both epidemic and endemic. The Centers for Disease Control (CDC) funded “emerging pathogen” surveillance projects in selected state health departments, in part to improve surveillance for several important waterborne agents. In New York City (NYC), the Department of the Environment (DEP), responsible for drinking water treatment and delivery, convened a panel of public health experts in 1994 to evaluate current health department disease surveillance programs. The panel recommended specific waterborne disease surveillance activities and epidemiologic studies to determine endemic waterborne disease risks associated with use of unfiltered surface water sources.
Desalination
Authors: Voutchkov Nikolay
Published: July 2005

Desalination is the production of fresh potable water from a saline water source (seawater or brackish water) via membrane separation or evaporation. Desalination plants operate in more than 120 countries worldwide, and some desert states, such as Saudi Arabia and the United Arab Emirates, rely on desalinated water for more than 70% of their water supply. Sea or brackish waters are typically desalinated using two general types of water treatment technologies—thermal evaporation (distillation) and membrane separation. All thermal desalination technologies use distillation (heating of source water) to produce water vapor that is then condensed into low‐salinity potable water. The thermal desalination technologies most widely used today are multistage flash distillation (MSF), multiple effect distillation (MED), and vapor compression (VC). Membrane desalination is a process of separating minerals from source water using semipermeable membranes. Two general types of technologies are currently used in membrane desalination—reverse osmosis (RO) and electrodialysis (ED). Reverse osmosis desalination is the most widely used membrane separation process today. Currently, there are more than 2000 RO membrane seawater desalination plants worldwide whose total production capacity is in excess of 3 million cubic meters per day (800 MGD).
The Economics of Water Resources Allocation
Authors: Bond Patrick
Published: July 2005

No one would doubt “the principle that water is a scarce good with dimensions of economic efficiency, social equity, and environmental sustainability.” Yet as articulated in the World Bank's (1)
African Water Resources
document, the principle disguises two polar‐opposite positions about pricing water.

On the one hand,
The Economist
magazine's (2; pp. 1–5) survey on water declared the central dilemma: “Throughout history, and especially over the past century, it has been ill‐governed and, above all, collossally underpriced.” Identifying this problem, naturally begets this solution: “The best way to deal with water is to price it more sensibly,” for “although water is special, both its provision and its use will respond to market signals.” In rural areas where there is competition among farmers for irrigation water, “The best solution is water trading.” As for the problem of allocating and delivering water to the poor, “The best way of solving it is to treat water pretty much as a business like any other.” We can call this the “neoliberal” position.
Extraterritorial Land Use Control to Protect Water Supplies
Authors: Phoenix Laurel
Published: July 2005

Cities continually need water to grow. If they are located near a river, lake, or groundwater source, they will use these closest sources first. Some cities, however, have needed to search for water far beyond their boundaries, typically looking for rivers, large lakes, or valleys suitable for damming to create reservoirs. Because these distant areas are in different political jurisdictions that may fight a city in its quest for water, a state may step in and give a city the power it needs to expropriate and subsequently control lands outside its municipal boundaries. A city needing water from a new source may need extraterritorial control over land in that area in order to (1) establish the source, (2) maintain access to the source, and (3) maintain quality of the source. Brief descriptions are given of how Boston, New York City, and Syracuse exert their extraterritorial control to protect their source water supplies.
Air–Sea Interaction
Authors: Hsu S. A.
Published: July 2005

Air–sea interaction (ASI) is the exchange of energy and mass across the air–water interface. ASI encompasses vast variations in spatial and temporal scales, so a list of recent literature regarding these fields is provided. This article summarizes several basic and applied topics in ASI. They include but are not limited to the parameterization of stability and roughness lengths, determination of friction velocity, parameterization of latent heat flux and evaporation, and estimation of wind–wave interaction and shoaling depth during hurricanes. It is shown that the stability and roughness parameters, Bowen ratio, and evaporation can be estimated directly using measurements of wind, wave, and air and water temperatures from offshore buoys. The data from these buoys are reported hourly by the U.S. National Data Buoy Center (NDBC) at its website (www.ndbc.noaa.gov). Because of the extensive impact caused by hurricanes, formulas are also provided to determine the maximum sustained wind speed, maximum significant wave height, storm surge, and shoaling depth using the minimum sea‐level (central) pressure as the only input.
Trace Element Pollution
Authors: Presley Bobby J.
Published: July 2005

Unlike pesticides and other synthetically produced substances, trace elements occur naturally in the environment. Their concentration in rocks, soil, water, tissue and other substances can be determined using sensitive instruments. At least two dozen trace elements are known to be essential to the health of humans and other organisms. However, several trace elements are very toxic, even in low concentrations, and some essential trace elements are toxic at elevated concentrations. Many human activities, such as mining, manufacturing, transportation and agriculture, can mobilize trace elements and add them to the environment. If the additions are too great, they cause pollution which has adverse effects on human and ecosystem health. For this reason, industrialized nations regulate trace element additions to the environment. In the United States, most parts of the environment are less polluted with trace elements than they were before environmental regulations took effect in the 1970s.
Renewable Energies from the Ocean
Authors: Jalihal Purnima
Published: July 2005

This chapter discusses wave, tidal, and ocean thermal energy. The principles involved in these various types of renewable ocean energy forms are discussed. Some earlier efforts toward harnessing these energy forms are also discussed. Two Indian case studies are presented, one of which is a wave‐powered desalination system and the other is the design and installation of a 1‐MW floating OTEC plant. It is concluded that harnessing ocean energies is challenging and needs several engineering and technological innovations.
Food Chain/Foodweb/Food Cycle
Authors: Juhl Andrew
Published: July 2005

A representation of the feeding relationships within an ecosystem is given. Energy flow through the system is shown by diagrammatically linking predators with their prey. The three terms “food chain”, “foodweb”, and “food cycle” are nearly interchangeable, although food chains are usually simpler representations, lacking omnivory and other complications of real systems. Oversimplification is a common criticism of food chains, but also of foodwebs and food cycles. As models of one of the ways that organisms within an ecosystem interact, they always lack some complexities found in real ecosystems. The degree of naturally occurring complexity that is represented in any given foodweb depends largely on the purpose for which the model is constructed. It may be acceptable for some purposes to show only the most important energy paths, with many species lumped together into functional groups. Other needs may require greater detail or may require making aspects of the foodweb quantitative. Regardless of the simplicity or complexity, foodwebs are a powerful tool for studying ecosystems. Foodwebs from different types of ecosystems share certain basic characteristics. The search for properties that are general to all foodwebs is an interesting area of ecological research.
Histopathology in Biomonitoring Marine Invertebrates
Authors: Martín‐Díaz M.L. , Jiménez‐Tenorio N. , Sarasquete C. , González de Canales M.L. , DelValls T.A.
Published: July 2005

The use of the histopathological alterations as a biomarker of effect in marine invertebrates has been widely included in the assessment of the quality of the marine environment. This biomarker may link the bioavailability of different compounds with the effect at target tissues and it has been successfully included in major national monitoring programmes. Nevertheless, this biomarker is still under a experimental stage.

The present work critically reviews the advantages and limitations of the use of this biomarker: the methodology for its determination and its inclusion as a complementary tool for the marine pollution assessment in a Weight of Evidence (WOE) approach.
Solubility of Hydrocarbons and Sulfur Compounds in Water
Authors: Yaws Carl L. , Narasimhan Prasad K. , Lou Helen H. , Pike Ralph W.
Published: July 2005

Correlations are presented for the solubility of hydrocarbons and organic sulfur compounds in water. A wide variety of compounds are covered—alkanes, olefins, diolefins, acetylenes, cyclopentanes, cyclohexanes, benzenes, mercaptans, thiophenes, and sulfides. The new correlation provides reliable solubility values down to very low concentrations (parts per million range). The correlation is based on the boiling point of the compound. Correlation and experimental data are in favorable agreement. The results are useful in process engineering for wastewater minimization.
Dissolved Gases
Authors: Boström M. , Ninham B. W.
Published: July 2005

Gases dissolved in water play an important role in solution chemistry and in biological processes in solutions. The story that we will present of dissolved gases in water is in some sense twofold. We begin with the more conventional description and a general discussion of gases dissolved in groundwater, in seawater, and in blood, and decompression sickness. We then give a short introduction to a new and rapidly developing scientific field within colloid and solution chemistry that has demonstrated a profound role for dissolved gas in, for example, colloidal interactions, hydrophobic interactions, conductance, surface tension, and bubble fusion. We argue strongly that different scientific disciplines that consider dissolved gases in very different ways can benefit tremendously from better knowledge of work in other disciplines.
Acid Rain and Society
Authors: Middleton Paulette
Published: July 2005

The relationships between chemical emissions into the atmosphere and the effects of the chemicals on various ecosystems, human health, and materials are highly complex. Many harmful chemicals (i.e., air pollutants) chemically interact to form other pollutants, which are perhaps even more harmful than the originally emitted chemicals. The most prominent examples of these dangerous chemical products are acid rain, ozone, and aerosols. In addition, many air pollutants are thought to interact in a synergistic fashion to cause even more harm as a group rather than individually. An example of the possible synergism is the hypothesized impact of acid rain and ozone on forest ecosystems. Understanding the causes and effects of acid rain and related air quality issues has become an important mission of atmospheric scientists around the globe.
Mechanisms of Water Adsorption on Carbons
Authors: Gauden Piotr A. , Terzyk Artur P. , Rychlicki Gerhard , Furmaniak Sylwester , WesoŁowski RadosŁaw P. , Wiśniewski Marek , Kowalczyk Piotr
Published: July 2005

The properties of water are of importance in many scientific disciplines such as chemistry, biology, geology, nanotechnology, and materials technology. Moreover, the adsorption of water on activated carbon (AC) is an important topic in many different areas of science and technology because water is the most common solvent in nature. The adsorption and phase behavior of polar fluids in carbon pores has been studied extensively, but our understanding of the adsorption of water on carbonaceous materials is still incomplete (1, 2, 3, 4).

In recent years, a number of experimental and simulation studies of adsorption of water in pores have appeared in the literature. Some studies have assumed that the adsorption behavior of water in graphite pores is hydrophobic. Although principally hydrophobic adsorbents may contain significant numbers of adsorption centers that can interact with water, it is generally believed that the combination of weak carbon–water dispersive attractions and strong water–water associative interactions are responsible for the complex behavior of water confined in carbonaceous pores.