bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptions and Attitudes of Students towards Tourism and Recreation Activities in Kwara State University, Malete, Nigeria
Authors: Bankole B. O. , Ojo O. O. , Shittu A. A. , Joseph S. R.
Published: December 2019

This paper examined perceptions and attitudes of students towards tourism and recreation activities in Kwara State University, Malete, Nigeria. Primary data were collected using structured questionnaire. A sample of 100 students was randomly selected from the 8 colleges purposively selected in the University. The number of respondents that were selected from the colleges depended on the population of each college. Agricultural and Veterinary Sciences, Humanities, Management and Social Sciences, Education, Engineering and Technology, Institute of Education, Information and Communication Technology, Pure and Applied Sciences and Institute of Distance and E-learning were all selected for the study. The researcher was able to retrieve 85 copies of questionnaire from the 100 copies administered. It was revealed that Kwara State University students were willing to engage in tourism and recreation activities. Many of the students were constrained to participate in stressing that their studies give opportunity for them to engage in tourism and recreation activities. It was concluded that the student’s perceptions and attitudes towards tourism and recreation activities is relatively good. Therefore, it was recommended that, the school must create avenue for students to engage and involve more in tourism and recreation activities and this could be done by creating more sport centres and other recreational activities within the campus. The school should create more tourism centres in order to boost student’s involvement in recreation and tourism activities in the school. The school management should ensure that they mandate the students to engage in activities that could help to fresh up their brains.
Cytotoxic Activity of Some Spirooxindole-4H-pyran Derivatives
Authors: Faghih Zeinab , Faghih Zahra , Divar Masoomeh , Khabnadideh Soghra
Published: December 2019

Aims: Isatin is a honored scaffold and one of the most favorable class of heterocyclic systems that possesses many interesting biological activities and well-tolerated in humans. Here a series of fifteen spirooxindole-4H-pyran derivatives containing both isatin and pyran moieties (ICa-ICo) will be examine for their anti-cancer activity.

Study Design: Cytotoxic evaluation of some spirooxindole-4H-pyran derivatives in two cancerous cell lines. 

Place and Duration of Study: Pharmaceutical Science Research Center and Shiraz Institute for Cancer Research, Medical School in Shiraz University of Medical Sciences, Shiraz, Iran, between June 2018 and July 2019.

Methodology: MTT assay was used to evaluate the cytotoxic activities of these compounds. The anticancer properties of the tested compounds were determined using A549 and MCF-7 cell lines.

Results: Among the tested compounds ICc, ICd and ICf showed the best cytotoxic activities  against both cancerous cell lines. Compounds ICh and ICj showed desirable cytotoxic activities against A549 cell line. Compound ICb showed desirable cytotoxic activities against MCF-7 cell line.

Conclusion: We conclude that the isatin-linked pyran analog can serve as a prototype molecule for further development of a new class of anticancer agents.
Novel Spectrophotometric Methods for Simultaneous Determination of Rosuvastatin Calcium, Timolol Maleate and Diclofenac Sodium in Pharmaceutical Ternary Mixture and Spiked Human Plasma
Authors: Hassouna Mohamed E. M. , Salem Hafsa O.
Published: December 2019

Three sensitive, times saving, precise and accurate spectrophotometric techniques have been established and confirmed for the simultaneous determination of ternary admixture of rosuvastatin calcium (ROSCa), timolol maleate (TIM) and diclofenac sodium (DICNa). Method A, first derivative of ratio spectra spectrophotometric (1st DD) which is the most simple simplest one. Using the spectrum of an aliquot of 5 μg/mL of DICNa as a divisor, ROSCa could be determined by measuring 1DD amplitudes at 239.5 and 266.5 nm for ROSCa, while TIM could be similarly determined at 307.7 and 331 nm. DICNa could be determined at 269.7 and 292 nm when 5 μg/mL aliquot of ROSCa was used as a divisor without interference. This method showed limit of detection of 0.556, 0.567 & 0.3 µg/mL and correlation coefficients of 0.9997, 0.9998 and 0.9995 for ROSCa, DICNa and TIM respectively. Method B, depends on subjecting the ratio spectra to mean centering (MCRS). The arithmetical description of this method was explained. The method was performed for the estimation of these drugs together in one run without preseparation in authentic laboratory prepared mixtures, bulk and spiked human plasma. The wave lengths 277.9, 313.1 and 333.12 nm were used for the quantitative estimation of each of the studied drugs with good correlation coefficients (0.9998, 0.997& 0.9999 and LOD of 0.297, 0.150 & 0.24 µg/mL for the studied drugs in the previously mentioned order. Method C, successive-ratio derivative spectra method (SRDS). The mathematical description of the method was explained. By using this method, ROSCa, TIM and DICNa could be determined at 264, 339 and 300 nm, respectively. Correlation coefficients were 0.9998, 0.9999 & 0.9995 and LOD values of 0.374, 0.258 & 0.769 µg/mL in the same order. The three methods were linear in the range 5-25 µg/mL. The obtained results has been statistically compared with those obtained by the published one, showing no significant difference regarding accuracy and precision at p = 0.05. The developed methods do not need sophisticated techniques or instruments, besides being sensitive, selective and eco-friendly.
The Knowledge Framework Approach to Developing Language and Content
Authors: Slater Tammy , Mohan Bernard
Published: December 2019

The Knowledge Framework (KF) is a heuristic that teachers and researchers working with English language learners can use to make explicit how language, content, thinking skills, and key visuals are connected. Developed in Western Canada to examine discourse in context, particularly educational contexts, the KF offers a theory‐informed tool for planning lessons, projects, and units that brings attention to how language is used functionally across subject areas, thereby helping students with academic language development in content‐based instruction. This entry describes the KF, highlights research that has been done on its use, and summarizes its benefits and challenges.
English as a Medium of Instruction
Authors: Ducker Nathan
Published: December 2019

English as a medium of instruction, or EMI, refers to the teaching and learning of content or academic subjects in the English language in situations where English is not the majority language. This definition covers a range of different situations such as international preschools and kindergartens, immersions schools, university courses in English, and even multilingual situations where English is used as an educational and/or daily lingua franca. Recently, EMI has been growing in popularity, especially in higher education where the decision to implement EMI is often a managerial or political one. This entry discusses the broad scope of EMI, then covers some of the main reasons why institutions and governments may wish to promote the use of EMI, before discussing a wide range of pedagogical issues that need to be resolved when implementing EMI.
Creating a Sustainable Community of Practice for
TESOL
Professionals in the Lower Mekong Region
Authors: Brinton Donna M. , Chilmonik Kimberly , Echelberger Andrea
Published: December 2019

A community of practice (CoP) consists of individuals who ally with one another to pursue topics or goals of common interest. The goal of CoP membership is to deepen one's knowledge and gain additional expertise from the community's more experienced members. In English language teaching, CoPs have typically been implemented with classroom learners. Alternatively, they may also be implemented with teachers for the purpose of ongoing professional development. This entry concerns the latter case, initiated in the five countries in the Lower Mekong region of Southeast Asia as part of a larger US government project. The goal of this project, the Professional Communication Skills for Leaders (PCSL) CoP, was to create transnational alliances among teachers in the region and better prepare them to teach English for professional purposes to local experts in environment, health, infrastructure, energy development, and agriculture. The entry provides information on the implementation of the project and how it is being sustained.
TESOL
Videographers Discuss Their Moviemaking Secrets
Authors: Martinez‐Alba Gilda , Cruzado‐Guerrero Judith
Published: December 2019

There are many opportunities to make video in classrooms, which can be teacher or student created. Thinking through videography as a director of a movie, commercial, news show, or any other event that broadcasts can add an engaging dimension to instruction. Teachers often incorporate video making into their instruction to document interviews with students, have students role‐play parts of a story, or to have students share their own stories. Using various components, teachers can make homemade video look much more professional. To begin with, the goals of the video and instruction should be outlined, which would include the audience. Sound should also be considered, as that can make a video much more interesting to watch. Other areas to consider are angles, rules of third, cuts, and lighting. Creating video that students, teachers, and families enjoy watching or learning from can be a beneficial way to make lasting instruction.
Assessment of Note Quality inTESOL
Authors: Siegel Joseph
Published: December 2019

Assessing the quality of student notes in TESOL can take many forms, including total number of notations, content words, and information units. Such evaluative methods emphasize the quality of student notes and eliminate the complex issue of information transfer from notes to postlistening activities. Measures of note quality provide instructors with valuable information on student ability that can feed into subsequent pedagogy for notetaking as well as offering students a routine for receiving objective feedback on the completeness and efficiency of their notes. The following entry reviews previous research on the topic, summarizes several methods for assessment of note quality in TESOL, and discusses pedagogical implications.
“They Just Don't Know Who We Are”: Rural English Learner Teacher Education
Authors: Coady Maria R.
Published: December 2019

Teacher quality and teacher education are strongly associated with student learning, and teachers of English as an additional language have the added task of supporting both language and content learning of English learners (EL) students. Teachers also play a key role in the social and emotional well‐being of their students, particularly those who are migratory or immigrant, speak languages other than English, or who have faced trauma or educational disruption, an increasing characteristic subsequent to 21st century human migration patterns. Preparing teachers through education and professional development, however, has historically followed a urban‐centric norm, setting out what teachers need to know and do for their EL students. This entry challenges metrocentric norms in teacher education and describes the place‐based needs of rural teacher education for English learner students. It offers suggestions for building place‐based EL teacher education.
Microbial Ecology of Streams
Authors: Leff Laura G.
Published: December 2019

Streams present microorganisms with a unique set of physical and chemical conditions. The most apparent is the unidirectional flow of water. Streams also have strong interconnections to the surrounding landscape and are often exposed to extensive anthropogenic disturbance. This article is divided into three main sections: diversity and composition of microbial communities, biogeochemical functions, and anthropogenic impacts. In terms of diversity, high‐throughput sequencing has transformed microbial ecology; yet, streams and some taxa are relatively understudied. The dynamic nature of streams and large temporal and spatial differences also create challenges for development of generalities. The roles of microbes in organic matter processing and nutrient cycling in streams are clear, and the fate of nutrients has a large impact on downstream processes, such as eutrophication. Humans impact streams in a variety of ways that, in turn, alter the physiochemical conditions and microbial ecology. Often these impacts are combined, such as multiple pollutants in a channelized stream, making it difficult to discern the cause and effect. Overall, microbes are central to function of stream ecosystems biogeochemically. This coupled with the importance of streams to humanity makes the study of stream microbial ecology crucial. Molecular methods are at the heart of microbial ecology, and studies of streams also benefit from this approach.
Fractals in Water and Water‐Related Processes
Authors: Lanza Luca G.
Published: December 2019

Self‐similar and fractal patterns and processes are very common in nature, and water has often a key role in their genesis or dynamics over relevant timescales. They are easily the result of searching for efficient solutions to occupy most of the available volume, connect the most locations on a surface, saving or dissipating energy, etc. After recalling the basic concepts of fractals and self‐similarity theories, this article presents the scaling features associated with the description of turbulence in fluids, as well as the multifractal structure of the rainfall process, and the scaling of natural forms and patterns deriving from the action of water on landscapes. The article also addresses the potential of fractal geometries in technical applications since the development of technological solutions based on fractal concepts is rather promising and constitutes one of the current frontiers of self‐similarity studies and applications in the water sector.
Sustainable Membrane Bioreactor Wastewater Treatment
Authors: Kim Jeonghwan
Published: December 2019

Membrane bioreactor (MBR) has been widely applied for wastewater treatment and reuse. Many efforts have been made to achieve sustainability of the MBR technology with respect to energy reduction and effluent quality improvements. In this article, key aspects to enhance sustainability of the MBR technology in wastewater treatment and reuse applications are discussed. The MBR performance treating wastewaters is mainly limited by membrane fouling which is a long‐standing problem in the MBR operation. Recently, successful attempts have been made to develop fouling mitigation ways at low energy consumptions required. Breakthrough effects have been reported in the field of anaerobic MBR technology to achieve energy‐positive wastewater treatment process with enhancement in membrane permeate flux and recovery of bioenergy. Trace organic contaminants are becoming major concerns, particularly in wastewater reuse applications due to population growth and complexity of wastewater sources. To enhance both permeability quality and energy recovery, there is much attention to be addressed by innovating hybrid MBR systems while their economic feasibility still needs to be proven.
Hydrology of Wetlands
Authors: Brown Hugh J. , Haeft Jessi L.
Published: December 2019

Because wetlands have important functions and values, understanding their hydrology can lead to better management and enhance the success of restoration activities. The hydrogeomorphic classification of wetlands includes assessment of the main water sources and direction of flow for several types of wetlands. Movement of water in and out of wetlands is driven by potential gradients due to gravity, matric forces, and osmotic pressure. A key to wetland hydrology is the development of a water budget that covers inputs, outputs, and storage. Hydrology can be measured with precipitation gauges, monitoring wells, piezometers, gaging stations, and related devices. Hydrology can also be modeled with a variety of computer simulation models such as those that use geographical information systems. Soil and geologic properties influence the location of wetlands on the landscape with concave and convergent areas more likely to be wet. Management of wetlands is strongly influenced by their hydroperiod, which determines the plants that will be best suited for that area.
N
‐Nitrosodimethylamine (
NDMA
) Formation Mechanisms in Drinking Water Systems
Authors: Pham Huong T. , Wahman David G. , Zhang Wen , Fairey Julian L.
Published: December 2019

N
‐nitrosodimethylamine (NDMA) occurrence and formation pathways in drinking water systems are reviewed and NDMA yields are compared on the basis of disinfectant type, water chemistry, and precursor category. While NDMA formation is primarily associated with chloramination, it can form by ozonation, in which it is enhanced by bromide, and during chlorine dioxide disinfection. The reaction pathway for NDMA formation during ozonation involves reactive intermediates such as hydroxylamine, which may also be relevant to NDMA formation with other disinfectant types. In chloramination, despite monochloramine being the predominant species between pH 7 and 9, evidence suggests that dichloramine is the primary species involved in NDMA formation. This is somewhat confounding as NDMA yields are maximal at pH 9, yet at pH 9 dichloramine decays faster than it forms and hence is present at trace levels; additionally, the proposed mechanism involves a spin‐forbidden incorporation of dissolved oxygen as a triplet, which is presumably kinetically slow. This article reveals that kinetic data for NDMA formation is lacking, and its influence on chloramine chemistry has not been carefully considered.
Stable Isotopes in Precipitation
Authors: Hurst Shelby , Krishnamurthy R.V.
Published: December 2019

Application of stable isotopes in hydrological research has a long and well‐developed history almost coincident with the application of stable isotopes in marine‐based paleoclimate research. It would appear logical that isotopes of oxygen and hydrogen would serve as the best tracer in the understanding of the hydrologic cycle since the water molecules are made up of hydrogen and oxygen. Since precipitation is the main source of recharge for all surface and ground waters early focus was toward an understanding of factors that control the isotope ratios in precipitation. This resulted in the development of models that explained these factors very well and also provided a basis for using isotope record of continental deposits such as ice cores in paleoclimate research. Subsequent work generated models that sought to explain isotopic effects in such processes as evaporation and snow formation. All these studies utilized variations in
16
O,
18
O, and
2
H. Recent advances in analytical capabilities have made the determination of
17
O possible, which is rare in terms of abundance and potentially a powerful tool. In addition, advances in remote sensing has opened up new possibilities where it is possible to couple isotope data with atmospheric dynamics.
Basic Principles of Flow and Transport in Porous Media
Authors: Matyjasik Marek , Zaluski Marek Henryk
Published: December 2019

This article provides basic information about flow of water and solute transport in porous medium as it takes place in permeable geologic formations occurring below and above groundwater table. It starts with explanations of principle hydraulic laws and definitions of most essential terms including hydraulic head, Darcy's law, hydraulic conductivity, seepage velocity, heterogeneity and anisotropy of aquifers, confined and unconfined flow, steady and transient flow conditions as well as differences between saturated and unsaturated flow conditions. This knowledge applied together with geological information is useful to appreciate the importance of groundwater resources that are addressed using an example of their occurrence in the United States. A potential impact of industrialization on these resources is then addressed by providing information on advective‐dispersive and reactive fate and transport of solute (contaminant) in groundwater. The article concludes with a concise description and classification of mathematical models that are available to quantify the processes of groundwater flow and solute transport in aquifers.
Water Policy and Management in Chile
Authors: Prieto Manuel , Fragkou María Christina , Calderón Matías
Published: December 2019

The Chilean water model has been described as a textbook example of a successful free water market system that has promoted efficient water rights, allocation, and use. In this article, we seek to provide the reader with a general reference work on the creation, implementation, main features, and impacts of this model. To achieve this, we briefly describe the imposition of Chile's 1981 Water Code. This description provides the historical context for understanding its main characteristics. This makes it both unique and controversial. In continuation, we revise the main arguments for and against the model. Finally, we illustrate how the Chilean water model has operated on the ground by describing four different cases at distinct scales and that illustrate its social, political, and environmental repercussions.
Ecology of Polar Phytoplankton
Authors: Vernet Maria
Published: December 2019

Polar phytoplankton dominate the surface waters of the Arctic and Antarctic. With relatively less bacteria and high productivity, microalgae have adapted to the extreme conditions of freezing temperatures and pronounced seasonality. Transitioning from long summer days to permanent darkness in the winter, polar phytoplankton responds rapidly to small changes in light intensity. Large diatom species are characteristics of these environments although small algae are the most abundant. Living in freezing waters, their growth is optimal in higher than ambient temperatures and they are expected to benefit from rising ocean temperatures.
Geochemistry of Great Salt Lake
Authors: Johnson William P. , Wurtsbaugh Wayne A. , Belovsky Gary E. , Baxter Bonnie K. , Black Frank , Angeroth Cory , Jewell Paul , Yang Shu
Published: December 2019

The Great Salt Lake is terminal, lacking outflow, and is descended from vast Lake Bonneville through evaporation. It is akin to a puddle on the tarmac with a similar surface area to volume ratio. It is an avian wildlife habitat of hemispheric importance, and lies adjacent to a metropolitan population of 2.5 million, with correspondingly increasing water demands and anthropogenic effluents. Engineered partitions spanning the lake generate density‐driven flow among the layered concentrated brines, which show dramatic vertical redox transitions and corresponding contrasts in trace element behaviors, some of which show elevated burdens in the ecosystem. We describe this system in four parts, starting with the geographic and hydrologic framework (Section 1) that determines its limnologic and hydrodynamic characteristics (Section 2) that shape its ecosystem (Section 3), which interacts dynamically with its geochemical characteristics (Section 4).
Groundwater Flow
Authors: Strack Otto D.L.
Published: December 2019

This article presents the fundamental equations for groundwater flow: the constitutive equation (the generalized form of Darcy's law), and the mass balance equation. We restrict this article to isothermal flow of a single fluid, water, through a porous or fractured medium. We consider transient flow with variable density and viscosity through an anisotropic compressible porous medium with variable hydraulic conductivity. When considering compressibility, the approximation is made that the vertical total stress in the porous medium does not vary with time and that horizontal strains in the medium can be neglected. We consider the flow below the water table, called the phreatic surface, to be fully saturated, and above the water table filled by air. Thus, the pores in the soil are assumed to be either filled entirely with water or entirely with air.
The
REE
s in Hydrothermal Systems
Authors: Migdisov Artaches (Artas) , Xu Hongwu , Williams‐Jones Anthony E. , Brugger Joel
Published: December 2019

Extensive use of the rare earth elements (REEs, mostly represented by the lanthanide group from La to Lu) in renewable energy applications and defense‐related technologies triggered high and growing interest to the processes responsible for migration, separation, and concentration of these elements in natural processes. Understanding these processes and the behavior of REEs in them is essential for exploration of new resources of these elements and efficient use of REEs in industrial applications. There is now an almost universal agreement that hot aqueous fluids play a significant and, in some cases, a dominant role in concentration and separation of REEs in nature. This article reviews high‐temperature experimental data collected over the past 15 years on the stability of the REE aqueous species and minerals and discusses the mechanisms responsible for hydrothermal transport and deposition of the REEs.
The Rosgen Stream Classification System
Authors: Rosgen Dave
Published: December 2019

The Rosgen stream classification system utilizes a hierarchical assessment to provide the geomorphic context to link driving processes and response variables at multiple spatial and temporal scales of inquiry. The hierarchy is comprised of four levels of inventory that range from a broad geomorphic characterization of the watershed to reach‐specific evaluations. This article focuses on the classification of stream types associated withLevels I–II(geomorphic characterization and morphological description) without detailed descriptions ofLevels III–IV(assessment and validation). Stream types are a quantitative description of a channel's morphology and reflect the fluvial processes acting to shape their form. The delineative criteria used in the classification consist of directly measurable channel features that describe the stream's vertical containment, shape, pattern, profile, and materials. Stream types, along with fluvial landscape types, are a foundational element used to organize river inventories for numerous management, assessment, and restoration applications.
Water Vapor and Pollutants, Aerosol–Cloud Interactions
Authors: Prabha Thara V. , Khain Alexander
Published: December 2019

Clouds, to a great extent, govern the radiation balance and energy fluxes reaching Earth and have a strong impact on the hydrological cycle and freshwater distribution over the globe. Latent heat release in clouds is the energy source for atmospheric phenomena from cloud scale to global circulation. Changes in cloud microphysical and radiative properties impact weather and climate and contribute in changing climate. All of these determine the vital impact that clouds exert on all forms of life on the planet, human life included. Studies of clouds and cloud‐related phenomena are an integral part of modern meteorology, providing data with direct application in weather forecasting, agriculture, environment control, air traffic control, and many other spheres of human activity. Natural and anthropogenic aerosol particles affect cloud properties and precipitation regimes and continue to be a growing field of research. A significant progress has been achieved in understanding cloud processes and aerosol–cloud interaction during last decade. At the same time some processes, especially those related to ice phase remain uncertain and require further investigation. A review of major processes related to aerosol effects and specially to aerosol–cloud interaction is presented.
Groundwater Impacts from Stormwater Infiltration Practices
Authors: Trojan Michael D. , Gulliver John S. , Fairbairn David J.
Published: December 2019

Stormwater infiltration practices, such as rain gardens and permeable pavement, are a preferred method for managing stormwater runoff in urban landscapes. These practices, when properly designed, constructed, and maintained, mimic predevelopment hydrology and provide benefits for receiving surface waters. Infiltration practices focus large amounts of runoff into underlying soil and eventually to groundwater. The impact of this intentional recharge on groundwater has been a focus of research in recent years. In this article, we provide an overview of stormwater infiltration practices, discuss impacts of these practices on groundwater hydrology and quality, include a short list of research needs, and provide recommendations for appropriate techniques and conditions for stormwater runoff infiltration.
Acid Mine Drainage: Sources and Treatment in the United States
Authors: Skousen Jeffrey G. , Ziemkiewicz Paul F. , McDonald Louis M.
Published: December 2019

Acid mine drainage (AMD) occurs after mining exposes metal sulfides to oxidizing conditions. Leaching of reaction products into surface waters pollute over 20 000 km of streams in the USA alone. The coal mining permitting process requires prediction of AMD potential, most commonly via overburden analysis. Where a potential exists, AMD control measures including spoil handling plans, alkaline amendment and dry covers may be required to stop or hinder AMD generation. Other AMD control technologies include injection of alkaline materials (coal ashes and limestone products) into abandoned underground mines and into buried acid material in mine backfills, remining of abandoned areas, and installation of alkaline recharge trenches. In the event AMD is formed, effluent treatment is required. Treatment chemicals include Ca(OH)2, CaO, NaOH, Na2CO3, and NH3, but chemical treatment is costly, requires expensive equipment and facilities, and often extends for decades. Passive treatment systems may also be employed to treat problem drainages and are effective under certain flow and acidity conditions. Such systems include aerobic and anaerobic wetlands, anoxic limestone drains, vertical flow wetlands, open limestone channels, and alkaline leach beds. This chapter discusses the process of AMD formation, preventative measures, and treatment methods for existing AMD discharges.
Metal–Organic Interactions in Landfill Leachates and Associated Groundwaters
Authors: Gonçalves Mário A.
Published: December 2019

Landfills are important facilities for proper waste disposal in modern societies, but they can also be the potential source of environmental problems. These are mostly due to leachate spilling and releasing through surface and groundwaters. Because organic compounds are the most abundant constituents of these leachates and have a wealth of reactive functional groups, their interaction with metals is of utmost importance to understand the mobility and bioavailability of these metals in the environment. Metal–organic interaction is mostly characterized by complex formation and stability. Predicting metal–organic complex stability is, however, a difficult task, but the electronic configuration of metal cations may provide some insight on that problem based on the classification into hard‐ and soft‐sphere cations. On the other hand, landfill leachates are complex solutions where these interactions are likely to occur with a wide range of organic compounds, rendering individual interactions almost irrelevant. Besides, the number of cations experimentally studied in this particular environment is limited to Cu, Ni, Zn, Cd, Pb, and Cr. What has been shown is that, depending on the cation, they may be predominantly associated with colloidal and/or dissolved organic matter, in particular, forming chelates with the organic compounds, or forming inorganic complexes as well as insoluble solid phases.
Geochemical Modeling – Computer Codes
Authors: Gonçalves Mário A.
Published: December 2019

Geochemical modeling practices are increasingly using a wealth of available computer codes specifically designed for such purposes. Although obtaining the codes is fairly easy nowadays, the uncritical use of these codes should be avoided at all cost. Each of the computer codes presented herein has its own limitations. Users must also critically evaluate the thermodynamic databases available for each program. Among the codes described here, more emphasis is placed on the hydrogeochemical codes developed by the United States Geological Survey (USGS) and United States Environmental Protection Agency (US EPA) mostly because these institutions provide a wide range of codes, an important number of which are regularly updated. Codes available from other institutions are also referred to, a few of which are commercial programs. A note is given about a new class of object‐oriented platform‐independent programs, whose main objective is to provide a framework for building specialized geochemical models. Finally, the future of these codes and their use in modern high‐level interpreted languages such as Python are briefly discussed.
Sediment Yields and Sediment Budgets
Authors: Walling Desmond E.
Published: December 2019

This article aims to provide a broad overview of the topic across spatial scales ranging from small catchments to a global perspective. The two elements of the topic (i.e. sediment yields and sediment budgets) are closely related, with the former treating the catchment or river basin essentially as a black box. The latter looks into the black box to consider the importance of sediment sources, and sediment mobilization, transport, and storage in influencing sediment yields. Attention is directed firstly to the key features of sediment yields, by considering fluvial sediment loads, measurement techniques, the magnitude of sediment yields, and associated global and regional patterns and key controlling factors. Information on spatial variability of sediment yields is complemented by consideration of medium‐ and longer‐term temporal variability in response to natural factors and, more importantly, the impact of anthropogenic activity and climate change. Sediment budgets are introduced by considering the important role of internal storage in influencing the sediment yield from a catchment or river basin and the concepts of the sediment delivery ratio and connectivity, as well the need to take account of the sediment sources involved. Examples of sediment budgets are provided and available techniques for assembling the information necessary to establish a sediment budget are reviewed.
Metal–Clay Interaction: Spectroscopic Characterization
Authors: Gonçalves Mário A.
Published: December 2019

Spectroscopic techniques are a fundamental complement to experimental studies of metal adsorption on clays or even to characterize metal‐loaded natural samples. The information obtained from these techniques help gain insight on the mechanisms of metal adsorption and binding to clay surfaces, which traditionally rely on surface complexation models. Owing to the uncertainty on parameters, such as number and type of surface sites and types of surface complexes, spectroscopic analysis may be fundamental in constraining such variables and provide more robust, predictable, and reliable models for metal dispersion and transport in the natural environment (contaminated or not). This article surveys the more relevant spectroscopic techniques used for the purpose of probing the nature of metal–clay surface interaction such as Fourier‐transform infrared (FTIR) and Raman spectroscopies, X‐ray photoelectron (XPS) and Auger Electron spectroscopies (AESs), and synchrotron‐based X‐ray absorption spectroscopy (XAS).
Cadmium in Groundwater: Chemical Behavior and Treatment
Authors: Jacobs James A.
Published: December 2019

Cadmium occurs naturally in ores containing other elements such as oxygen (cadmium oxide), sulfur (cadmium sulfate, cadmium sulfide), and chlorine (cadmium chloride) or compounds (cadmium carbonate). Cadmium is usually extracted during the production of other metals such as zinc, lead, and copper. A primary use for cadmium is in rechargeable nickel–cadmium and solar batteries, which are sold worldwide. Cadmium does not corrode easily and is also used in metal plating and coating operations including transportation equipment and various industrial machinery as well as plastics manufacturing. It is used in numerous pigments, in baking enamels, and in photographic processes as well as in television and monitor screen phosphors. Cadmium is released into the environment through industrial waste streams and landfills. Cadmium is relatively mobile in surface and groundwater.
Drinking Water Infrastructure
Authors: Lee Juneseok , Güngör‐Demirci Gamze , Keck Jonathan
Published: December 2019

This article provides an overview of our nation's drinking water infrastructure and discusses a range of critical and emerging concerns for the water sector. After an overview of the major and minor systems responsible for drinking water service, critical emerging concerns based on the authors' experience are then discussed relative to their hydraulic, water quality, and physical integrity linkages and implications. In addition to their direct impact on public health, these aspects also have significant socioeconomic implications. We then go on to consider other drinking water industry perspectives such as bottled water, rainwater harvesting, the water–energy nexus, decentralized water systems, and future directions for water systems management. It is the authors' hope that readers will develop a better understanding of the various issues and challenges that lie ahead for the drinking water sector, while also benefiting from our recommendations regarding future industry directions.
Mineral Surface Charge in Aqueous Solution
Authors: Maurice Patricia A.
Published: December 2019

Mineral surfaces in water have charge properties. Mineral surface charge affects a host of environmental processes ranging from adsorption to bacterial adhesion and biofilm formation to colloid aggregation. This article discusses the sources of mineral surface charge and introduces terminology associated with various points of zero charge.
Pipeline Failure and Deterioration Models
Authors: Kabir Golam , Tesfamariam Solomon , Sadiq Rehan
Published: December 2019

The utility managers and other authorities rely on location‐specific pipeline failure information to develop and implement long‐ and short‐term management plans. The pipeline failure or deterioration depends on multiple pipe dependent, time‐dependent, and pipe and time‐dependent factors. For this, substantial efforts have been made to develop pipeline failure or deterioration prediction models using different statistical models like regression‐based, survival analysis‐based, and Bayesian inference‐based models. The performance of these models depends significantly on the quantity and quality of available data. Most prediction models focus on larger utilities where sufficient amount of pipeline failure and other related information is available. Small and medium‐size utilities often suffer due to technical and financial resource shortages and data scarcity. It is essential to consider model uncertainties for pipeline failure or deterioration prediction model development. In this study, a brief review of existing regression‐based, survival analysis‐based, and Bayesian inference‐based pipeline failure prediction models are presented. To demonstrate the applicability of different pipeline failure and deterioration prediction models, the pipeline failure data of the City of Calgary is considered.
Crop Water Requirements and Irrigation Scheduling
Authors: Todorović Mladen
Published: December 2019

Crop water requirements represent the amount of water to be supplied to a field to recover the losses occurred by evaporation and transpiration. Crop water requirements are used for (i) a day‐to‐day on‐field irrigation scheduling, (ii) determination of seasonal water needs of an existing irrigation scheme (i.e. seasonal irrigation planning), and (iii) estimation of water volumes to be supplied to newly irrigated areas (i.e. during the irrigation project design and definition of irrigation network hydraulic characteristics).

Irrigation scheduling is a process used by irrigation managers to determine the correct frequency and duration of watering, i.e. when to irrigate and how much water to apply. It is usually focusing on a specific crop cultivated in an area with homogeneous (representative) weather, soil, and irrigation system characteristics. Irrigation scheduling aims to optimize use of water, nutrient, and energy, while achieving the maximum economic benefits of agricultural production, reducing environmental impacts, and ensuring the provision of ecosystem services. The soil–water‐balance method for irrigation scheduling is described together with a practical example of irrigation scheduling strategy. Moreover, the application of innovative technological solutions that integrate field data, sensors, and models in smartphone Apps for control and automation of irrigation process is illustrated.
Malaria: Water, Hydrology, and Climate Change
Authors: Madey Gregory R. , Maurice Patricia A.
Published: December 2019

Malaria is a disease caused by a parasite that is transmitted by an infected female
Anopheles
mosquito. The eukaryotic parasite can be one of four species of the
Plasmodium
genus. Malaria results in flu‐like symptoms including fever and chills and if left untreated it can progress to severe symptoms that can result in death. Because mosquitoes use water bodies to breed, malaria is closely tied to water and hydrology. This article describes the life cycles of the mosquito and malaria parasite and how they relate to water, briefly reviews several studies of malaria and hydrology including development of malaria transmission and hydrologic models, and discusses some potential climate change effects on malaria occurrence and distribution.
In Situ
Remediation of Heavy Metals in Groundwater
Authors: Jacobs James A.
Published: December 2019

Highly toxic and highly soluble metals are contained in numerous waste streams, including those from power, chemical, electronics, and general manufacturing plants, and mining facilities. Metals can create significant health risks to humans. One approach to remediating metals contamination involves
in situ
methods. Chemical and biological reducing methods of remediating metals
in situ
are technically effective in significantly lowering metals concentrations in 1–5 years at reasonable cost. Treatment delivery systems for the chemical reductants and bioenhancements have been developed and used at a variety of sites. The keys to success in most of these projects involve accurate subsurface assessments prior to field remediation, properly designed bench tests to optimize chemistry in the laboratory, realistic regulatory targets for site closure, and a well‐designed remediation delivery system.
Energy‐Efficient and Spectrally‐EfficientMIMO
Authors: da Silva Mário Marques , Dinis Rui , Guerreiro João
Published: December 2019

While enabling energy efficiency and spectral efficiency, MIMO systems are implemented with multiple transmit and receive antennas, which translates in an increase in signal processing. This article provides a description of different MIMO techniques, namely space–time coding, multi‐layer transmission, space division multiple access, and beamforming. Different MIMO receivers are also described in this article. MIMO techniques aim to provide diversity and/or to achieve an improvement of spectral efficiency. This is achieved at the cost of an increased complexity. A reduction of complexity can be obtained with the use of the two proposed algorithms: maximum ratio combiner (MRC) and equal gain combiner (EGC). These algorithms are compared with the zero forcing (ZF). While ZF requires the computation of the pseudo‐inverse of the channel matrix for each frequency component, such processing is not required for MRC/EGC, keeping the complexity requirements at low level, but generating a certain level of interference.
Device‐to‐Device Channels
Authors: He Ruisi , Yang Mi , Ai Bo , Zhong Zhangdui
Published: December 2019

Device‐to‐device (D2D) communications enable devices in a communication system to exchange data directly. Through D2D communication link, terminals communicate through multiplexing system resources, which can reduce the pressure on the core network of the communication systems and greatly improve the spectral efficiency and throughput. Therefore, D2D technology is considered as one of the key technologies of 5G systems. Investigation of channel characteristics is an important prerequisite for subsequent D2D communication research. This article reviews the measurements and models for D2D channels. The challenges that D2D channel measurement and modeling may face in the future are also addressed.
IMT‐2020 Channel Model
Authors: Zhang Jianhua
Published: December 2019

Wireless channel models are the prerequisites of the development of any communication system. They are indispensable and widely used in many aspects, such as radio technique research, equipment development, communication system design, performance evaluation, and network optimization. With the approach of commercial deployment of the fifth‐generation mobile communication system (5G) in 2020, the International Telecommunication Union (ITU) delivered the standard of 5G radio technique evaluation methodology and channel model. Owing to the complexity and the importance of the channel model, this article introduces the main characteristics and simulation method of the ITU IMT‐2020 channel model in the standard comparing with the 4G channel model, including scenario configuration, simulation procedure, and advanced channel components. Hence, a detailed understanding of ITU 5G channel model has been made for the readers, in order to improve the further simulation and evaluation of 5G technology.
Millimeter‐Wave RF Designs
Authors: Yu Chao , Hong Wei
Published: December 2019

In this article, the topic of millimeter wave radio frequency (RF) designs is introduced for the fifth‐generation communication system. State‐of‐the‐art studies in both academia and industry are reviewed, from four perspectives of architecture, radio frequency integrated circuit (RFIC) design, package, and measurement. The base station and user equipment architectures are illustrated in details, and the RFIC design, especially for the phased array, is emphasized with several important components, such as power amplifier and on‐chip antenna. Then, antenna‐in‐package technology is illustrated. Later, the over‐the‐air measurement is discussed to resolve the measurement issues. Finally, the current and future challenges in research and practice are pointed out.
Interference Management
Authors: Liu Junyu , Sheng Min , Li Jiandong
Published: December 2019

The fifth‐generation (5G) mobile system is expected to be compatible with numerous network architectures and communication technologies. Despite the promising potential, reuse of the available spectral resources would inevitably result in complicated and overwhelming interference, which is shown as one of the most limiting factors to the 5G system performance. Therefore, designing and implementing more efficient interference management is of great importance in 5G. On this account we first investigate the impact of interference, which grows with the densification of users and network infrastructures, on the performance of the 5G cellular network in terms of area spectral efficiency (ASE). Then, we provide an overview of the state‐of‐the‐art interference management techniques and discuss the potentials and demerits of application of these techniques. Especially, we have shown that the interference power would always overwhelm the desired signal power when available interference management approaches are applied. Therefore, it is critical to jointly control desired signal power and interference power for better interference management. On this account, we have designed an activation probability–based interference avoidance strategy and verified through simulation that the proposed strategy could notably improve ASE for the 5G cellular network. In particular, the ASE could even increase with the increasing density of base stations in the dense BS regime. Otherwise, the ASE will approach zero when other interference management techniques are applied.