bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamentals of the Meteorology of Storm Systems
Authors: Doswell Charles A.
Published: December 2019

A definition for an atmospheric storm system is as a “disturbance” of the weather. In the context of water science, precipitation can occur when air containing water vapor rises in a storm system. Since atmospheric weather systems have diverse spatial and temporal scales, many different physical processes can result in the development of precipitation. Large‐scale storms are the primary means for mitigating the unequal heating of the Earth's surface owing to variations in topographic, latitudinal, and seasonal factors. They export heat from the tropics to the polar regions and from near the surface to upper levels by their airflows, which also transport the water vapor important for precipitation. Moving downscale to the so‐called mesoscale storm systems, these are dynamically diverse because in this scale domain, it is not possible to make many simplifying assumptions. A number of different mesoscale storm systems are described, including processes associated with topography and “free” mesoscale processes tied to different internal dynamics. Finally, small‐scale storm systems are discussed, many of which involve buoyancy effects and are described as convective storm systems – these are mostly individual thunderstorms. Severe convective storms can produce high precipitation rates leading to flash floods, large hailstones, damaging straight‐line winds, and tornadoes.
Quorum Quenching for Biofouling Control in Membrane Bioreactors
Authors: Yavuztürk Gül Bahar , Köse Mutlu Börte , Park Pyung‐Kyu , Lee Chung‐Hak , Koyuncu Ismail
Published: December 2019

In today's World, the recovery, reuse, and recycling of water turn heads more with the continuing water scarcity, and this requires a development of conventional wastewater treatment technologies. Membrane bioreactors (MBRs) can provide many advantages over the conventional activated sludge systems. However, biofouling problem restricts the potential widespread application of MBRs. The main reason for this is the increase in the operating costs. Nowadays, there are much research to elucidate and control the membrane fouling in MBR. In fact, it is difficult to find an effective solution for biofouling problem without heading toward to biological concepts, because the biomass matrix is significantly complex and includes various living microorganisms. Quorum quenching (QQ) mechanism aims to prevent the signaling for communication and group behaviors. For the last five years, the development of antibiofouling strategies based on QQ in MBRs has been a relatively hot topic in biofouling research. QQ is a natural process which is not harmful to the environment. Therefore, unquestionably, studies on QQ in MBR represent a promising alternative for controlling biofouling for future applications. This article explains the quorum sensing (QS) and QQ concepts and presents various and highly successful examples for enzymatic, bacterial, and fungal QQ MBR operations.
Light Transmission Spectroscopy
Authors: Tanner Carol E. , Ruggiero Steven T.
Published: December 2019

Light Transmission Spectroscopy (LTS) is a recently developed technique for measuring the diameter and concentration of nanoparticles in fluid suspension. LTS is based on obtaining the optical extinction of light as a function of wavelength, over the range of ∼220–1100 nm, and using Mie theory to transform extinction information into a particle‐size distribution. This has been made practical with recent developments in compact, high resolution optical spectrometers and “lap‐top” computing. LTS has a particle diameter measurement range of ∼1–3000 nm. LTS has a large dynamic range, with an ultimate concentration range covering several orders of magnitude. The technique is most applicable to relatively dilute samples, with a minimum detection concentration of ∼1000 objects/mL. LTS has evolved from a laser‐based laboratory instrument to a transportable format with a modest bench‐top footprint. The system has proven itself especially useful to biological‐type investigations involving objects ranging in size from proteins to bacteria – and has even been adapted to detect species‐specific environmental DNA. A special feature of the technique is its ability to perform optical subtraction, whereby objects of a given size and concentration in a reference channel can effectively eliminate their optical contribution in a sample‐measurement channel.
Measurement of Chromium Species in Water Samples
Authors: Furdui Vasile I. , Mädler Stefanie
Published: December 2019

While trivalent chromium (Cr(III)) is an essential nutrient, hexavalent chromium (Cr(VI)) is a human carcinogen and genotoxic. In evaluation of the toxicological risks and environmental impacts, the separate analysis of Cr(III) and Cr(VI) in water samples provides more information than the analysis of total Cr. The relatively high instability of the Cr species in natural water samples further complicates the analysis, requiring preservation or other advanced procedures. This article is intended to present the broad range of available separation methods for Cr analysis, discussing the possible interferences, detection limits, and preserving options. The intense color complex formed between dichromate ions and 1,5‐diphenylcarbazide (DPC) is used for Cr(VI) measurement in spectrophotometric, flow injection analysis (FIA), ion chromatography (IC), liquid chromatography (LC), capillary electrophoresis (CE), and electrochemical methods. Atomic spectrometry, molecular spectrometry, and other methods are also discussed. An absolute analysis with accurate measurement of Cr(VI) at the time of sample collection can be achieved with speciated isotope dilution mass spectrometry (SIDMS) by using LC separation coupled to the inductively coupled plasma mass spectrometry (ICP‐MS) or IC separation coupled to electrospray ionization tandem mass spectrometry (ESI‐MS/MS).
Fundamental Hydrologic Equations
Authors: Beckie Roger
Published: December 2019

The principles of mass, momentum and energy conservation are fundamental to quantitative hydrology. Physically based models in hydrology respect these principles, in contrast to many statistical models, which may not. These conservation principles are most clearly expressed when written as mathematical equations. One may view mathematics as a “grammar” and “language” to communicate the “literature” of physical principles. In this chapter, we shall therefore focus mostly upon the mathematical development of the conservation principles and their manifestation in hydrology. In this way, we hope that our development will give physical meaning to the fundamental hydrologic equations. We will assume that reader has an elementary understanding of multivariate calculus and differential equations.

We first state the fundamental principles and then outline the general ways that mathematical expressions for these principles are formulated. We then develop general mathematical equations for each principle for the specific case of a flowing fluid, which in hydrology is usually water. These general equations are typically then used as the basis for expressions used in hydrology. We conclude the chapter with a sequence of examples from hydrology to show how the principles are manifest in expressions that describe hydrologic processes.
Oil and Gas Produced Water, High‐Salinity Brines, and Associated Cost Modeling
Authors: Sullivan Graham Enid J.
Published: December 2019

Produced water (PW) is a large‐volume waste product from the oil and gas industry. Converting this waste into a resource requires system models to optimize treatment designs, transportation, and storage costs. Five models are presented and evaluated for their capabilities. All the models fall within the AACEI Level 5 standard for preliminary evaluation uses, with cost accuracies of ±30%. Three databases that contain useful geospatial data that could improve model results are presented and described. The USGS PW database is the most comprehensive of the group. Most PW data, for both volume and chemistry, has problems with incompleteness, inaccuracies, and lack of correlation from state to state. Model improvements that are needed include the following:

Application of correct desalination processes to varying ranges of salt content and different PW types.

Use of appropriate organic removal technologies.

Inclusion of up‐to‐date cost indices.

Clear graphical results and flow diagrams; energy usage at each step, pumping parameters, energy recovery opportunities, and water and waste stream flows.

Costs output for each step and for the whole system with improved accuracy.

Indications of the output water quality.

Ability to evaluate toxicity of trace constituents.

Linkages with real data sets and GIS.

Ongoing support/funding for maintenance and upgrades.

Feedback loops to validate results with proven field data.

Common computing platforms for model development and evolution.
Applications of Stable Isotopes to Studies of Paleohydrology and Paleoclimatology
Authors: Xia Zhengyu , Yu Zicheng
Published: December 2019

Stable isotope ratios of hydrogen and oxygen in water vary as a function of hydrological processes and environmental conditions. Water isotopic composition preserved in ice cores, and other geological and biological archives have been used as hydrological tracers and climate proxies to study past climate and hydrological changes. We provide a brief overview on the principles and mechanisms of water isotope proxies and on the major contributions of stable isotope techniques to the studies of paleohydrology and paleoclimatology. In oceans, oxygen isotopes of foraminifera in deep‐sea sediments continuously document long‐term history of global ice volumes and ocean temperature from Cenozoic greenhouse to icehouse and through the Quaternary glacial–interglacial cycles. On continents, isotopic composition of meteoric water is influenced by multiple parameters, including air temperature, precipitation amount, air mass history, and atmospheric circulation pattern. The use of water isotope proxies in various archives reveals multifaceted continental climate changes on orbital, millennial, and centennial scales. In addition, isotope proxies in annual growth layers of corals and other biological archives further resolve past short‐term climate variability. Overall, these studies broaden our understandings of the global climate histories and forcing mechanisms and provide benchmarks to project future environmental changes.
The Food–Water–Energy Nexus in Chile: Agriculture, Water Companies, and Mining
Authors: Arce G. , Gironás J. , Molinos‐Senante M. , Suárez F. , Pastén P. , Meza F. , Donoso G. , Vicuña S. , Vargas I.
Published: December 2019

Water, food, and energy (WFE) are critical resources that are intimately linked, as their production requires the other resources as input and changes impacting one of these resources can affect the others as well. For this reason, the WFE nexus concept was coined in order to represent this inextricable connection. In addition to the demands between these resources, external stressors can exert additional demands. In the Chilean case, urban population growth, mining, agriculture, and climate change emerge as relevant drivers of the WFE nexus status. The effect of these drivers are discussed and illustrated through the analysis of the current and future WFE nexus status in four different Chilean basins (Antofagasta, Copiapó, Maipo, and Maule), which represent a sample of WFE nexus problems. Several challenges imposed by these drivers in the Chilean context are presented, along with opportunities to address them, such as the implementation of alternative technologies, resource management strategies, and methodologies for decision‐making.
Deoxygenation of the Open Oceans and its Consequences
Authors: Kirchman David L.
Published: December 2019

Deoxygenation or loss of dissolved oxygen (O2) from the open oceans is caused by higher temperatures, changes in circulation and stratification, and alteration of biological processes, all ultimately due to increasing atmospheric carbon dioxide (CO2) and other greenhouse gases. Coastal waters are also losing O2because of excess nutrients from terrestrial runoff. Deoxygenation and the spreading of oxygen minimum zones seem to have already caused the geographical range of hypoxia‐tolerant organisms to expand whereas it has curtailed the oceanic regions inhabitable (habitat compression) by other organisms sensitive to even slight decreases in O2concentrations. Benthic organisms and demersal fish are negatively affected by the unprecedented shoaling of deep, low O2waters into shallow coastal areas. Deoxygenation also impinges on critical steps in several biogeochemical cycles, such as the production of two nitrogenous gases, N2and nitrous oxide (N2O), during nitrification, denitrification, and anaerobic ammonium oxidation. Loss of N via the two gases could limit biological production in the oceans, which may lead to less deoxygenation, while release of N2O, a potent greenhouse gas, could lead to more deoxygenation. Along with warming temperatures, increasing dissolved CO2, and higher acidity, deoxygenation is likely to continue in the future with many consequences for oceanic biota and biogeochemistry.
Hybrid Ion Exchange Nanotechnology (HIX‐Nanotech)
Authors: German Michael , SenGupta Arup K.
Published: December 2019

From a physical‐chemical viewpoint, every polymeric ion exchange resin bead is a crosslinked polyelectrolyte that is insoluble in water. Today, tens of ion exchange resin manufacturers around the world produce hundreds of different products. As different as they may appear, these ion exchangers are well defined and the specific interactions are well characterized by five independent composition variables, namely, matrix, functionality, crosslinking, pore structure and physical configuration. In addition to the diverse groups of ion exchangers characterized by these five composition variables, a new class of polymeric‐inorganic ion exchangers has been synthesized. Here, a dispersed phase of metal or metal oxide nanoparticles (MNPs or MONPs) is embedded in the ion exchanger phase; together they offer a synergy not available otherwise. The resulting new materials are heterogeneous, even at the sub‐10 nm scale, and termed “Hybrid Ion Exchangers” or HIX. In such a material, the host (i.e. polymer beads) improves the hydraulic permeability in the flow‐through systems with no apparent influence on the behavior of the metal and metal oxide nanoparticles. This article emphasizes how the choice of the functional groups of the polymeric host materials can be harnessed to alter (enhance or diminish) the intrinsic properties of the nanomaterials.
Application ofShewanellato Water Treatment Issues
Authors: Szeinbaum Nadia , Toporek Yael J. , Shin Hyun‐Dong , DiChristina Thomas J.
Published: December 2019

Shewanella drives a variety of environmentally important processes, including the biogeochemical cycling of carbon, metals, metalloids, and radionuclides. The ability of Shewanella to deliver electrons extracellularly also renders this genus valuable for applications of contaminant remediation and energy generation in water treatment processes. Although the first Shewanella species was isolated and studied as a model metal‐reducing microorganism over thirty years ago, only recently has research focused on employing Shewanella to drive water treatment processes. This article examines current and prospective applications of Shewanella to water treatment issues, highlighting biochemical details associated with each technology. The technologies include the remediation of metal‐contaminated environments, the generation of electricity from wastewater streams, the removal of hazardous contaminants under anaerobic conditions, and precious metal recovery in combination with formation of novel biocatalysts.
Geochemistry of Urban Water Systems
Authors: Lyons W. Berry , Gardner Christopher B.
Published: December 2019

The complex infrastructure and concentrated humasn activities in urban areas greatly affect the distribution of both water and elements in and around urban aquatic environments. Unlike more “natural” systems, the ecological, hydrological, and geochemical footprints of cities are much greater than the area of the city itself. In addition, cities themselves are diverse – a city's age, size, climate, building materials, stage of economic development, legacy of previous land uses, and environmental best management practices all exert influence over water quantity and quality. Within any individual urban area, land use and infrastructure age are heterogeneous, and pollution in the aquatic environment can occur both from point‐sources (e.g., wastewater effluent, construction, spills, long‐term leakage) and nonpoint sources (e.g., stormwater runoff). All of these factors combine to alter hydrologic systems and enhance chemical fluxes in urban areas. Only recently have urban systems become the focus of their own, unified approach to investigation within the environmental sciences. In this article, we discuss some of the issues that confound the understanding of the geochemistry of urban aquatic systems, including the impact of impervious surfaces, the effects of heterogeneity of land cover on water quality, and how urban areas function as “global” water polluters.
Reorienting Watershed Management as a Climate Change Adaptation Strategy
Authors: Ratna Reddy V. , Chiranjeevi T.
Published: December 2019

This article aims to assess what it takes (beyond current measures) to make watershed management (WSM) a mitigation or adaptation strategy to deal with climate change impacts. This article draws on the existing literature on WSM with respect to its design, implementation, and impacts on agriculture and community livelihoods. As WSM has evolved over the years as a livelihood strategy in the developing countries of Asia/Africa, this article is confined mainly to experiences from India with broad implications for countries of Asia and Africa. WSM in its present form is necessary but not sufficient to strengthen the resilience of agroecological systems in the context of climate change. Apart from adopting a more scientific and integrated approach toward designing and implementing, WSM could be transformed into a climate change adaptation strategy by integrating additional farm management methods into its package of practices. These include access to climate information at the village level, sustainable groundwater management, access to appropriate farm machinery, judicious input mix, land use, and cropping patterns. In addition, policy directions are provided for making WSM climate resilient.
Manganese Cycling in the Oceans
Authors: Tebo Bradley M. , Luther George W.
Published: December 2019

Manganese (Mn) is an essential element for life. Although its concentration is at (sub)nanomolar levels throughout the ocean, it affects the oxygen concentration of the ocean because it is central to the photosynthetic formation of dioxygen, O2, in photosystem center II. Mn inputs into the ocean are from atmospheric transport of particles and their dissolution to form dissolved Mn, and from the flux of dissolved Mn from rivers, sediments, and hydrothermal vents. The main removal mechanism is transport of particulate Mn from dust and organic matter to the sediments. The environmental chemistry of manganese centers on its +2, +3, and +4 oxidation states. Most recent data show that Mn(II) is dissolved, that Mn(IV) is particulate MnO2, and that Mn(III) can be particulate or dissolved when bound to organic complexes [denoted as Mn(III)‐L]. Mn(II) is oxidized primarily by microbial processes whereas MnO2is reduced by abiotic and biotic processes. Photochemical processing aids redox cycling in surface waters. In suboxic zones, which are defined as areas where both dissolved O2and H2S concentrations are below 3 μM, both oxidation and reduction processes can occur but usually at different depths. In suboxic zones, dissolved Mn is also released from organic matter during its decomposition and from MnO2reduction.
Horizontal Wells
Authors: Russell David L.
Published: December 2019

The design and operation of horizontal wells are often misunderstood. While well screen is an accepted practice for vertical wells, the well screen has a very large open area and is not suited to the desired flow manipulation in the aquifer. This article attempts to explain an effective technique for designing efficient horizontal wells in collection or remedial situations for uniform collection of fluids (oil and water), uniform injection of fluids into the aquifer, or uniform injection or collection of gases into an aquifer.
Colloid Transport in Environmental Granular Porous Media
Authors: Johnson William P. , Ma Huilian , Rasmuson Anna , VanNess Kurt , Li Ke , Ron Cesar , Erickson Brock
Published: December 2019

Colloids are nano‐ to micro‐sized particles (biological and nonbiological) suspended in water. They are important as contaminants (e.g. pathogens), or carriers of contaminants (e.g. dissolved organic matter or clays) in water, as well as in a multitude of other contexts ranging from subsurface cleanup of hazardous waste (e.g. nano zero valent iron) to drug delivery in biological systems. The above contexts all involve colloid transport in porous media, wherein a complex set of physical and chemical interactions act on colloids. These interactions originate at the nanoscale and propagate to the field scale, leading to complex transport behaviors that are difficult to predict even following several decades of research on this topic. In this article, we provide a conceptual description of these interactions and impacts. The physical transport processes governing colloid transport are reviewed, culminating in predictions of pore‐scale transport behavior that are upscaled to predictions of transport at the field scale. A major impediment to prediction has been the complexity of interactions when colloids and collectors (porous media grains) are both negatively charged, leading to repulsion between them. We review strategies to recognize the nanoscale heterogeneity that allows colloid attachment despite overall repulsion, as well as the influence of nonspherical shape on their transport.
Sonochemical Remediation of Pollutants in Soils and Sediments
Authors: Fagan William P. , Weavers Linda K.
Published: December 2019

Ultrasonic treatment serves as an alternative and/or complementary remediation technology for contaminated soils and sediments in comparison to traditional methods, such as dredging andin situcapping. Ultrasonic waves of alternating rarefaction and compression cycles create cavitation bubbles over the course of microseconds. Cavitational collapse produces enormous temperatures and pressures that initiate thermolysis of water and subsequent radical oxidation. Physical effects of ultrasound increase mass transfer rates, whether it be via desorption/dissolution of contaminants or solute transport in porous media. Both of these processes are integral in remediation. Desorption and dissolution ensure that contaminants are available for reaction in the aqueous phase. Increased solute transport by ultrasound enhances amendment delivery to contaminated sites. The purpose of this article is to describe both the potential for and challenges of utilizing ultrasound as a remediation technology. Much of this knowledge has been laid by the literature exploring the sonochemical effects on pollutants in bench‐scale sediment slurries. Both bench‐scale ultrasonic studies on remediation of contaminated soils and sediments and enhanced oil recovery using ultrasound have provided both mechanistic understandings and insights for pilot‐scale systems. Although challenges exist in scaled‐up systems, ultrasound is a multifunctional treatment technology with unique features compared to other remediation technologies.
Extreme Events and Their Impacts – Managing Environmental Risk
Authors: Russell David L.
Published: December 2019

In the environmental field, we focus on prevention, treatment, and cleanup of residuals, and worker safety but often fail to recognize, nor discuss the subject of risk from our operations, facilities, and practices. This article discusses risk, its presentation, analysis, and methods to identify and quantify both project risk and individual risk from a variety of potential sources. Inherent in any operating facility or ongoing activity is risk: risk from fire, risk from explosion, external risks, internal risks, weather etc. – all of which can be devastating on employees, neighbors, equipment, and the environment. This article also introduces demonstrated risk management techniques that have been successfully used in industry and by NASA.
Fault tree analysis
(FTA) and Risk‐Informed Decision Management (RIDM) techniques can improve operational safety and improve decision‐making. RIDM may be too complex for small projects, FTA can be applied simply and effectively, and this article discusses the principles behind each analytical technique and provides references for further investigation and application.
Sorption of Metal Ions on Soils, Batch Experiments
Authors: Ružičić Stanko
Published: December 2019

The ability of soils to sorb metal ions or heavy metals from aqueous solution has consequences for both agricultural issues, such as soil fertility, and environmental questions, such as remediation of polluted soils and water contamination. Sorption is a major process responsible for accumulation of metal ions or heavy metals. Therefore, the study of sorption processes is of utmost importance for the understanding of how heavy metals are transferred from a liquid mobile phase to the surface of a solid phase. Batch sorption experiments are mainly used for determination of soil sorption parameters. The scope of this article covers the theoretical background on sources of heavy metals, sorption mechanisms, isotherms models, sorbents, and batch experiments. In addition to theoretical background, two examples are provided of sorption batch experiments using metal solutions and soils as sorbents.
Air–Sea–Land Interactions During Tropical Cyclones
Authors: Hsu Shih‐Ang
Published: December 2019

Air–sea–land interaction is a branch of boundary‐layer geophysics including coastal meteorology, physical oceanography, and marine geology. Numerous topics related to the air–sea–land interactions during tropical cyclones (TCs) are discussed. Since most of these topics are related to the general public to save life and property during a TC, simplified formulas are presented for use including the rapid estimations of wind, wave, current, storm surge, wave setup, turbulence intensity (TI), gust factor, shoaling depth, and seabed scouring. In addition, when a storm track is located on the left of a major river such as the Mississippi river during Hurricane Isaac in 2012, it is found that the storm surges can propagate more than 228 river miles or 367 km inland and are approximately related to the square root of the distance upstream.
Analysis of Rare Earth Elements in Water and Sediments
Authors: Li Zheng‐Hua
Published: December 2019

Increasing consumption and demand on rare earth elements (REEs) in high‐tech devices, petroleum refinery, medical MRI, metallurgy, agriculture fertilizer, and REEs mining have inevitably released noticeable REEs to soils, waters, and food chains, raising environment and health concerns. Determination of REEs in water and sediments is primarily needed for tracing source materials, exploring mineral resources, and identifying environmental pollutions. REE concentrations in natural water are extremely low in the range of sub‐micrograms per liter to nanograms per liter level. To determine the trace REEs, a sample pretreatment including REEs preconcentration and matrix removal is often required. A wide variety of methods have been developed to fulfill this task. The coprecipitation and solid‐phase extraction (SPE) are among the most used approaches for preconcentrating REEs. Various instruments have been employed for measuring REEs. Currently, the inductively coupled plasma mass spectrometry (ICP‐MS) is the gold standard for trace REEs analysis. This article presents an overview of the analysis of REEs in natural waters and sediments by laying out a practical pathway covering the field sampling, sample pretreatment, REEs instrumentation, and data reduction.
Cleanup of Oil and Chemical Spills
Authors: Russell David L.
Published: December 2019

Oil and chemical spills have created damage to water environment. There are relatively limited methods for mitigating and cleaning up aquatic spills. The article summarizes some currently available techniques including spill control booming or barrier installation, shore remediation, dispersant application, and recovery techniques, limitations of the respective technologies, and guidance on their applications. The article briefly discusses cleanup of groundwater contaminated by oils and chemicals.
Acid Mine Drainage: Extent and Character
Authors: Rose Arthur W.
Published: December 2019

Acid mine drainage (AMD), also known as acid rock drainage (ARD), is an extensive environmental problem in areas of coal and metal mining. For example, the Appalachian Regional Commission estimated that 5700 miles of streams in eight Appalachian states were seriously polluted by AMD. AMD is also serious near major metal mining districts such as Iron Mountain, CA and Summitville, CO. In streams affected by AMD, fish and stream biota are severely impacted and the waters are not usable for drinking or for many industrial purposes. In addition to deleterious effects of dissolved constituents (H
+
, Fe, Al) on stream life, Fe and Al precipitates can cover the stream bed and inhibit stream life, and suspended precipitates can make the water unusable. In metal mining areas, heavy metals can add toxicity. General references on chemistry of AMD are Rose and Cravotta and Nordstrom and Alpers.
Water Security and Sustainability: Global Threats and Conflicts
Authors: Bozorg‐Haddad Omid , Bahrami Mahdi , Kazemi Mehdi , Abdi Babak , Yari Pouria , Chu Xuefeng , Loáiciga Hugo A.
Published: December 2019

This article reviews the concepts of water security and food security. This is followed by an overview of the global issues concerning the safety of water resources in different regions of the world. Climate threats, social and political conflicts, and methods for dealing with water security issues are reviewed.
Bio‐Based Chemicals and Sustainability
Authors: Philp James
Published: December 2019

The world faces unprecedented threats as a result of what have become known as grand challenges. These include some of the greatest policy issues of the day: food, water and soil security, resource depletion, and climate change. Into this perplexing vista has arrived the bioeconomy concept, which envisages a gradual replacement of fossil‐based feedstocks with bio‐based ones, resulting in bio‐based products, especially bio‐based fuels, chemicals, and materials. While this replacement implies an inherently more sustainable production system, this is not necessarily the case; each feedstock, fuel, chemical, or material must currently be judged on a case‐by‐case basis. There is no unified system for assessing their sustainability, which leads to inefficiencies and a slowing down of the process to arrive at this future, which can be viewed as a historic transition, akin to the wood‐to‐coal and coal‐to‐oil transitions. Both of these transitions took at least decades. The bioeconomy transition cannot wait that long – climate change and other grand challenges are forcing our hand. This article looks at the technologies, the barriers, and some of the policy issues to hasten this sustainable future.
Freshwater Cyanobacterial Blooms
Authors: Rosen Barry H.
Published: December 2019

This article provides an introduction to freshwater cyanobacterial blooms, including a brief discussion of those formed by eukaryotic algae. In freshwater systems, cyanobacteria have ecological strategies such as buoyancy regulation, phosphorus mining, and nitrogen fixation that give them a competitive advantage over eukaryotic algae, and they cause visible blooms more frequently in freshwater ecosystems than other algal types. Many cyanobacterial species also have a competitive advantage at higher water temperatures (above 25 °C). Understanding cyanobacterial bloom dynamics includes information on water quality, with emphasis on nutrients, and physical factors such as water temperature and the amount of mixing in a waterbody. Calm conditions allow these organisms to float to the water surface where prevailing winds aid the development of thick accumulations on shorelines. Human and animal exposure to cyanobacteria at these shorelines is problematic because of the potent toxins some species produce that have the potential to be harmful. A synopsis of the key bloom‐forming organisms with photomicrographs is included in this article.
Hazardous Metallic Ions Removal from Water Using Activated Carbons
Authors: González Pedro G.
Published: December 2019

Lignocellulosics and biomass as precursors of activated carbons have become important materials to produce it. Use of these “wastes” results in many benefits, mainly environmental. Special attention must be given to the relationship between the selected precursor and the final microstructure and properties (surface and textural) of the carbons. From these characteristics depends their performance as adsorbents of heavy metals or other applications. For these reasons, the present article provides a summary of research works outlining the use of lignocellulosic‐based precursors to obtain activated carbons. A brief description of the characterization techniques for both the precursors and activated carbons is presented. An explanation of the adsorption process, in terms of the most common kinetic and adsorption models, is included. Finally, the application of these carbons in adsorption of five hazardous metallic ions, chromium, mercury, lead, copper, and zinc, in aqueous solution is analyzed.
Natural Channel Design for River Restoration
Authors: Rosgen Dave
Published: December 2019

The Natural Channel Design (NCD) approach to river restoration aims to establish a self‐regulating, functioning river system associated with physical, ecological, and chemical components by emulating the natural stable form within the constraints imposed by the larger landscape conditions. The NCD method has evolved over five decades to restore impaired rivers using principles from fluvial geomorphology and ecology to meet clearly defined restoration goals. NCD incorporates analog, empirical, and analytical methods through 10 sequential phases that serve as a designframeworkto guide users through the minimum requirements and specific procedures to successfully implement a restoration design. An appropriate reference reach must be selected to direct the natural channel design and determine the physical and ecological departure of the impaired reach from the stable and functioning reference condition. Designing a multistage river system is also an integral part of NCD based on the appropriate stream type for the fluvial landscape. The NCD approach has successfully offset many of the adverse impacts from land use activities and traditional river works by implementing sustainable designs that are intended to work in harmony with river systems.
Water Pollution from Fish Farms
Authors: Bergheim Asbjorn , Schumann Mark , Brinker Alexander
Published: December 2019

In 2014, global aquacultural production of fish for human consumption surpassed that of fisheries, amounting to c. 50 million tons annually. Freshwater aquaculture dominates, accounting for 87% of this total, with the remaining 6.3 million tons produced in marine systems. Water pollution from fish farms takes a variety of forms, from feed‐derived wastes to therapeutics, pesticides and other chemicals to pathogens/parasites and escaped fish. Recipient water bodies can also be significantly affected by the biomass for farmed fish, for example receiving water with low oxygen and high carbon dioxide levels. Depending on the type and intensity and type of production systems in use and in particular the kind of effluent treatment in place, the waste load per ton of fish production fluctuates strongly. In general, open systems such as floating net cages pose a larger local threat to the environment than land‐based closed systems, but the latter might have higher ecological cost on a global scale. Recirculating (RAS) and integrated (IMTA) aquaculture systems have been developed to minimize water consumption and effluent load, and the large‐scale implementation of such systems in the pond farms of China and other Asian countries, which dominate global aquaculture, reflects a significant effort to reduce negative local impacts on recipient water bodies. The potential for alternative added‐value usage of wastes generated in fish farms, for example as fertilizer or in biogas production is currently underexploited.
Sustainable Wells: Problem Causes, Prevention, and Asset Management for Wells and Well Fields
Authors: Smith Stuart A.
Published: December 2019

Water wells and similar structures such as geotechnical drains that transmit water selectively from the natural to the engineered environment experience clogging and other symptoms that impair performance. These symptoms can include biofouling, biocorrosion, and sand and sediment production. Such problems can be prevented and controlled, and system decline slowed, through preventive maintenance (PM) and intelligent management or sustainable use measures. These include optimal design, PM monitoring for signs of problem, and preventive treatments. They also include understanding the hydrogeologic setting and planning accordingly. Corrosion is largely controlled through understanding the electrochemical environment and matching materials choices to the challenges. PM monitoring data should be recorded, analyzed, and trends established to predict the timing and need for PM measures. PM treatment for prevention is performed before serious performance decline occurs. When chemicals are used, their choices should be made to optimize clog removal while minimizing harm, e.g. leaving essential nutrients behind. As in rehabilitation treatments, effective physical agitation is an essential part of the process. The process of effective design and material selection, PM monitoring, and treatment for wells as part of a facility asset management project has been demonstrated to be cost‐effective, despite the additional effort and investment necessary.
The Plankton Food‐Web Role in the Oceans
Authors: D'Alelio Domenico
Published: December 2019

Plankton are organisms not able to swim against water currents. They live in every aquatic environment and stand at the base of food webs and biogeochemical cycles on our planet. Plankton include prokaryotes (unicellular organisms without a nucleus), protists, and protozoans (unicellular eukaryotes or organisms with a proper nucleus) and metazoans (multicellular eukaryotes). These groups feature a huge biological diversity, which cascades into a myriad of different sizes, forms, behaviors, and, ultimately, roles played in aquatic ecosystems. The interaction of different plankton species produce complex ecological networks encompassing multiple feeding connections, or trophic links. The complexity of interactions among plankton is an emergent property whose investigation is made possible by ecological‐network models. Long‐term ecological research programs aiming at assessing ocean health can profit from these modeling tools to integrate (i) plankton biodiversity explorations and (ii) the search for the role played by the entangled plankton webs in the functioning of our planet's largest environment, i.e. the ocean.
Soil Water
Authors: Rasmussen Todd C.
Published: December 2019

Soil water is found in pores (voids) between and within soil particles that fill with water as soils wet and empty as soil dries. The soil water content is a measure of the quantity of water present within soil, and can vary from fully saturated, in which case the water content equals the soil porosity, to oven‐dry, in which case all free water has been evaporated. Wet soils are characterized as having high water contents, which means that more soil pores are filled with water, whereas dry soils have more pores that are filled with air. Water in saturated soils naturally flows into openings such as wells, mines, and caves because the water has a positive pressure. When pores are not saturated, adhesive and cohesive forces prevent water from draining into openings. Adhesive forces are caused by the attraction of water to soil surfaces, whereas cohesive forces are caused by the attraction of water molecules to each other. The soil water tension is a measure of these attractive forces. Moisture characteristic curves relate the water content to the tension; drier soils have higher tensions than wetter soils because water is more strongly attracted to soil surfaces.
Groundwater, Climate Variability and Change
Authors: Gurdak Jason J. , Wolf Cassandra , Gross Zoé , Carvalho Resende Tales , Leblanc Marc
Published: December 2019

Groundwater is a fundamental component of the hydrologic cycle and vital natural resources. It sustains many rivers, lakes, wetlands, and other groundwater‐dependent ecosystems and is a significant source of freshwater for human consumption. Groundwater is also the foundation for irrigated agroecosystems, food production, ecosystem services, energy‐extraction and production, and other industry. As a result, excessive groundwater extraction, particularly in many of the largest and most important aquifer systems in arid and semiarid regions, has resulted in rapidly declining water levels and substantial loss of storage, often referred to as the global groundwater crisis. Climate variability and change and the associated modifications to the global hydrologic cycle are compounding the concerns about the global groundwater crisis. This article provides a brief overview of the importance of groundwater and recent findings about how anthropogenic climate change and natural climate variability on interannual to multidecadal timescales affect hydrologic processes that influence groundwater resources. The article ends with two case studies. The first is an overview of new statewide regulations called the Sustainable Groundwater Management Act (SGMA) in California, USA, that are designed to more sustainably manage the local groundwater resources considering climate change. The second is about new groundwater governance in the Stampriet Transboundary Aquifer System in southern Africa.
Desert Biocrusts
Authors: Kidron Giora J.
Published: December 2019

Soil biocrusts, also known as biological soil crusts or microbiotic crusts, are composed of different proportions of cyanobacteria, green algae, lichens, mosses, fungi, and bacteria, which commonly occupy the upper 0.1–2 cm of the soil. They are especially abundant between the 100‐ and 300‐mm isohyets, where they may occupy up to 80–90% of the surface. Once covering the surface, they may largely affect the ecosystem. They contribute to surface stability, affect the surface and subsurface hydrology (whether infiltration, runoff, and/or evaporation), the input of organic carbon and nitrogen, increase dust (and subsequently nutrient) entrapment, and affect vascular plant germination and growth. This article will focus on the variable effects of biocrusts on the arid and semiarid ecosystems and the possible factors that determine their establishment and growth. Controversial views regarding their growth and effects as reflected at the current state‐of‐the‐art knowledge will be also discussed.
Water Quality Factors Affecting Fish Growth and Production
Authors: Viadero Roger
Published: December 2019

The health and subsequent growth of fish is directly related to the quality of water in which the fish are raised. Fish growth is affected by a wide range of biological, chemical/biochemical, and physical factors. The species of fish or fishes being reared, the size and maturity of the fish, and the presence of other oxygen consuming organisms in the culture water are key biological factors that affect fish production. Key physical factors of importance include water temperature, water velocity, electrical conductivity, and the concentration of solids in the water column. Likewise, the water pH, alkalinity, hardness, and concentrations of ions (dissolved metals and nutrients) are chemical constituents that can impact fish production. While it is common to consider the impacts of each factor on an individual basis, it is important to recognize that the net effect of these factors on fish growth and production are interrelated. Consequently, it is necessary to approach each case as an integrated, dynamic system, as opposed to the sum of individual parts.
Geochemical Models
Authors: Gonçalves Mário A.
Published: December 2019

Geochemical models are considered an abstract representation of natural processes of a system, usually, but not exclusively, represented by a set of master variables and described by mathematical equations. The output data of these models is a quantitative representation of an outcome that can be either observable in the natural system or subject to experimental confirmation. From this definition, the importance of defining proper boundary conditions and using reliable experimental data on models is discussed. Geochemical models may have distinct components such as chemical reactions (inorganic and/or biological), transport of chemical elements by advection and dispersion, fluid flow, and heat transport. These are the building blocks of geochemical models, which can be divided as speciation‐solubility, reaction‐path, inverse mass balance, and coupled reaction‐transport models. Finally, model validation and usefulness is briefly discussed.
Hydrologic Connectivity of Isolated Wetlands: Episodic Flows
Authors: Deemy James B. , Rasmussen Todd C. , Takagi Kimberly K.
Published: December 2019

Episodic flows are storm‐generated events that last from hours to weeks and range in discharge from few to millions of liters per second. These events are the most readily observed form of hydrologic connectivity between isolated wetlands and nearby perennial waters. Unlike perennial streams that flow year‐round and intermittent streams that flow seasonally, episodic flows occur in response to heavy or persistent rainfall. The frequency and return period of episodic flows are dependent on regional climate, patterns of surface–groundwater interaction, and local geomorphic setting. Episodic flows also create linkages between otherwise isolated aquatic ecosystems by providing connections between wetlands, terrestrial ecosystems, and perennially flowing waters across kilometers of upland landscapes. Connectivity between typically isolated systems can be critical to long‐ and short‐term water quality. Episodic flows provide dissolved and suspended matter (e.g. nutrients, dissolved carbon, sediments, coarse woody debris) as well as energy (e.g. erosion, transport) that stimulate aquatic communities. These inputs from temporary hydrologic connections often have lasting impacts on nearby perennial streams in the form of woody debris or sediment deposition in the channel. Pulses from stormflows alter abiotic features and change limitations on biological components of these ecological communities.