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Author: Suresh Seethapathy Publisher: ISBN: Category : Languages : en Pages : 224
Book Description
Passive air sampling techniques are an attractive alternative to active air sampling because of the lower costs, simple deployment and retrieval methods, minimum training requirements, no need for power sources, etc.. Because of their advantages, passive samplers are now widely used not only for water and indoor, outdoor and workplace air analysis, but also for soil-gas sampling required for various purposes, including vapor intrusion studies, contamination mapping and remediation. A simple and cost effective permeation-type passive sampler, invented in our laboratory, was further developed and validated during this project. The sampler is based on a 1.8 mL crimp-cap gas chromatography autosampler vial equipped with a polydimethylsiloxane (PDMS) membrane and filled with a carbon based adsorbent. Apart from the low material costs of the sampler and ease of fabrication, the design allows for potential automation of the extraction and chromatographic analysis for high-throughput analysis. The use of highly non-polar PDMS reduces water uptake into the sampler and reduces early adsorbent saturation. The thermodynamic properties of PDMS result in moderately low sampling rate effects with temperature variations. Further, the use of PDMS allows for easy estimation of the uptake-rates based on the physicochemical properties of the analytes such as retention indices determined using capillary columns coated with PDMS stationary phase. In the thesis, the theoretical and practical aspects of the new design with regards to uptake kinetics modeling and the dependence of the calibration constants on temperature, humidity, linear flow velocity of air across the sampler surface, sampler geometry, sampling duration, and analyte concentrations are discussed. The permeability of polydimethylsiloxane toward various analytes, as well as thermodynamic parameters such as the energy of activation of permeation through PDMS membranes was determined. Finally, many applications of the passive samplers developed in actual field locations, vital for the field validation and future regulatory acceptance are presented. The areas of application of the samplers include indoor and outdoor air monitoring, horizontal and vertical soil-gas contamination profiling and vapour intrusion studies.
Author: Suresh Seethapathy Publisher: ISBN: Category : Languages : en Pages : 224
Book Description
Passive air sampling techniques are an attractive alternative to active air sampling because of the lower costs, simple deployment and retrieval methods, minimum training requirements, no need for power sources, etc.. Because of their advantages, passive samplers are now widely used not only for water and indoor, outdoor and workplace air analysis, but also for soil-gas sampling required for various purposes, including vapor intrusion studies, contamination mapping and remediation. A simple and cost effective permeation-type passive sampler, invented in our laboratory, was further developed and validated during this project. The sampler is based on a 1.8 mL crimp-cap gas chromatography autosampler vial equipped with a polydimethylsiloxane (PDMS) membrane and filled with a carbon based adsorbent. Apart from the low material costs of the sampler and ease of fabrication, the design allows for potential automation of the extraction and chromatographic analysis for high-throughput analysis. The use of highly non-polar PDMS reduces water uptake into the sampler and reduces early adsorbent saturation. The thermodynamic properties of PDMS result in moderately low sampling rate effects with temperature variations. Further, the use of PDMS allows for easy estimation of the uptake-rates based on the physicochemical properties of the analytes such as retention indices determined using capillary columns coated with PDMS stationary phase. In the thesis, the theoretical and practical aspects of the new design with regards to uptake kinetics modeling and the dependence of the calibration constants on temperature, humidity, linear flow velocity of air across the sampler surface, sampler geometry, sampling duration, and analyte concentrations are discussed. The permeability of polydimethylsiloxane toward various analytes, as well as thermodynamic parameters such as the energy of activation of permeation through PDMS membranes was determined. Finally, many applications of the passive samplers developed in actual field locations, vital for the field validation and future regulatory acceptance are presented. The areas of application of the samplers include indoor and outdoor air monitoring, horizontal and vertical soil-gas contamination profiling and vapour intrusion studies.
Author: Faten Salim Publisher: ISBN: Category : Languages : en Pages :
Book Description
Understanding the theory behind passive sampling, as well as factors influencing its accuracy, is crucial for proper planning and application of passive sampling methods. The Waterloo Membrane Sampler (WMS) is a permeation air passive sampler that is used for determining the Time Weighted Average (TWA) concentrations of Volatile Organic Compounds (VOCs) in air and soil gas. Determination of the TWA concentrations has been based on the zero-sink assumption, according to which the adsorbent of the sampler efficiently removes analytes permeating through the membrane leaving negligible concentrations at the barrier-sorbent interface. In this thesis, a dynamic model is presented to simulate the sampling process in the WMS. The model equations were solved numerically using MATLAB. The calculated uptake rates were successfully compared to the experimental data. The model predicted that resistance to mass transfer within the sorbent bed may develop during sampling. This resistance needs to be taken into consideration when significant. Therefore, the applicability of the zero-sink assumption depends on the significance of this resistance and, hence, on the properties of the analyte-adsorbent pair, as well as the concentration level and the sampling time. The model presented in this thesis provides the tool to evaluate this effect in a given sampling scenario, allowing optimization of the sampling method. Alternatively, the TWA concentration of the sampled analyte can be calculated using a method that accounts for this effect, as demonstrated in the thesis. An extension of the model that evaluates the post-sampling/storage period of analytes in the WMS is also presented. It was proven both theoretically and experimentally that the amounts of analytes retained in the PDMS membrane are negligible after sampling; therefore, analyzing the sorbent is sufficient to quantitatively determine the sampled amounts. The experimental evaluation also showed that the amounts of analytes found in the sorbent were stable over up to three-weeks of storage at room temperature. Additionally, the effect of intraparticle resistance to mass transfer within the sorbent bed was evaluated. The aim of this evaluation was to extend the applicability of the model to include the case of adsorbents with porous particles. This evaluation is followed by comprehensive sensitivity analysis using two types of adsorbents with different properties and adsorption strengths. The purpose of this analysis was to detect the influential parameters that have major control over the model output, the uptake rate, and to optimize the model parameters. Finally, the effect of air face velocity on the uptake rate of the WMS was added to the model, so that the resistance to mass transfer in the air boundary layer is taken into consideration. The work presented in this thesis provides better understanding of the sampling process in permeation passive samplers similar to the WMS. This understanding permits correct application of the sampler in environmental analysis.
Author: Richard Greenwood Publisher: Elsevier ISBN: 0080489508 Category : Science Languages : en Pages : 487
Book Description
Monitoring pollutants in air, soil and water is a routine requirement in the workplace, and in the wider environment. Passive samplers can provide a representative picture of levels of pollutants over a period of time from days to months by measuring the average concentrations to which they have been exposed. Air monitors are widely used, for instance to measure the exposure of workers to volatile compounds, but also for monitoring the fate of pollutants in the atmosphere. Passive sampling devices are now becomining increasingly used to monitor pollutants in rivers, coastal waters and ground water where contamination results from sources such as domestic and industrial discharges, and the use of agrochemicals. Passive Sampling Techniques in Environmental Monitoring provides a timely collection of information on a set of techniques that help monitor the quality of air, surface and ground waters. Passive sampling can provide an inexpensive means of obtaining a representative picture of quality over a period of time, even where levels of pollutants fluctuate due to discontinuous discharges or seasonal application of chemicals such as pesticides. Recent changes in legislation have increased the pressure to obtain better information than that provided by classical infrequent spot sampling.Brought together in one source, this book looks at the performance of a range of devices for the passive sampling of metals, and of non-polar and polar organic chemicals in air and in water. The strengths and weaknesses and the range of applicability of the technology are considered.* Comprehensive review of passive sampling - covering air, water and majority of available technologies in one volume* Chapters written by international specialist experts * Covers theory and applications, providing background information and guidelines for use in the field
Author: Tatenda Dalu Publisher: Elsevier ISBN: 0323903150 Category : Science Languages : en Pages : 410
Book Description
Emerging Freshwater Pollutants: Analysis, Fate and Regulations comprises of 20 chapters, all written by leading experts. This book is written in the most practical terms and is easy to understand, with numerous helpful examples and case studies and can be used as a practical guide and important educational tool on issues concerning freshwater emerging pollutants. The organisation of the book exposes the reader in logical succession to the full range of complex scientific and management aspects of emerging freshwater pollutants in the developing world. The book recognises that water chemistry, emerging freshwater pollutants and management are inter-dependent disciplines. The book covers (i) the different monitoring techniques, current analytical approaches and instrumental analyses, (ii) fate and occurrence of emerging pollutants in aquatic systems and (iii) management policies and legislations on emerging pollutants. Thus, subsequent chapters elucidate chemicals with pollution potential, multi-detection approaches to analysis of organic pollutants in water, microplastics effects and photochemical transformation of emerging pollutants in freshwater systems. Whereas, other chapters address oxidation of organic compounds in aquatic systems, biomonitoring systems for detection of toxic levels of water pollutants, and health aspects of water recycling practices. This book melds several different perspectives on the subject of freshwater emerging pollutants and shows the interrelationships between the various professions that deal with water quality issues. Further, within the presentation of each separate chapter is discussion of how the various scientific and management aspects of the subject interrelate. - Includes case studies and practical examples in each chapter - Presents a much-needed interdisciplinary approach, representing the overlap between water chemistry and emerging freshwater pollutants - Provides a thorough introduction to emerging tropical and freshwater pollutants that typically occur in these systems
Author: Gerrit Borchard Publisher: Frontiers Media SA ISBN: 288966256X Category : Science Languages : en Pages : 241
Book Description
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Author: David A. Alvarez Publisher: CreateSpace ISBN: 9781500220174 Category : Technology & Engineering Languages : en Pages : 34
Book Description
The success of an environmental monitoring study using passive samplers, or any sampling method, begins in the office or laboratory. Regardless of the specific methods used, the general steps include the formulation of a sampling plan, training of personnel, performing the field (sampling) work, processing the collected samples to recover chemicals of inter- est, analysis of the enriched extracts, and interpretation of the data. Each of these areas will be discussed in the following sections with emphasis on specific considerations with the use of passive samplers.
Author: National Research Council Publisher: National Academies Press ISBN: 0309086256 Category : Technology & Engineering Languages : en Pages : 433
Book Description
Bioavailability refers to the extent to which humans and ecological receptors are exposed to contaminants in soil or sediment. The concept of bioavailability has recently piqued the interest of the hazardous waste industry as an important consideration in deciding how much waste to clean up. The rationale is that if contaminants in soil and sediment are not bioavailable, then more contaminant mass can be left in place without creating additional risk. A new NRC report notes that the potential for the consideration of bioavailability to influence decision-making is greatest where certain chemical, environmental, and regulatory factors align. The current use of bioavailability in risk assessment and hazardous waste cleanup regulations is demystified, and acceptable tools and models for bioavailability assessment are discussed and ranked according to seven criteria. Finally, the intimate link between bioavailability and bioremediation is explored. The report concludes with suggestions for moving bioavailability forward in the regulatory arena for both soil and sediment cleanup.
Author: Hans de Kroon Publisher: Springer Science & Business Media ISBN: 9783540001850 Category : Science Languages : en Pages : 424
Book Description
In the course of evolution, a great variety of root systems have learned to overcome the many physical, biochemical and biological problems brought about by soil. This development has made them a fascinating object of scientific study. This volume gives an overview of how roots have adapted to the soil environment and which roles they play in the soil ecosystem. The text describes the form and function of roots, their temporal and spatial distribution, and their turnover rate in various ecosystems. Subsequently, a physiological background is provided for basic functions, such as carbon acquisition, water and solute movement, and for their responses to three major abiotic stresses, i.e. hard soil structure, drought and flooding. The volume concludes with the interactions of roots with other organisms of the complex soil ecosystem, including symbiosis, competition, and the function of roots as a food source.
Author: National Academies of Sciences, Engineering, and Medicine Publisher: National Academies Press ISBN: 0309470501 Category : Science Languages : en Pages : 251
Book Description
Understanding, quantifying, and tracking atmospheric methane and emissions is essential for addressing concerns and informing decisions that affect the climate, economy, and human health and safety. Atmospheric methane is a potent greenhouse gas (GHG) that contributes to global warming. While carbon dioxide is by far the dominant cause of the rise in global average temperatures, methane also plays a significant role because it absorbs more energy per unit mass than carbon dioxide does, giving it a disproportionately large effect on global radiative forcing. In addition to contributing to climate change, methane also affects human health as a precursor to ozone pollution in the lower atmosphere. Improving Characterization of Anthropogenic Methane Emissions in the United States summarizes the current state of understanding of methane emissions sources and the measurement approaches and evaluates opportunities for methodological and inventory development improvements. This report will inform future research agendas of various U.S. agencies, including NOAA, the EPA, the DOE, NASA, the U.S. Department of Agriculture (USDA), and the National Science Foundation (NSF).
Author: National Research Council Publisher: National Academies Press ISBN: Category : Medical Languages : en Pages : 553
Book Description
Discusses pollution from tobacco smoke, radon and radon progeny, asbestos and other fibers, formaldehyde, indoor combustion, aeropathogens and allergens, consumer products, moisture, microwave radiation, ultraviolet radiation, odors, radioactivity, and dirt and discusses means of controlling or eliminating them.
Author: Suresh Seethapathy
Author: Suresh Seethapathy
Author: Faten Salim
Author: Richard Greenwood
Author: Tatenda Dalu
Author: Gerrit Borchard
Author: David A. Alvarez
Author: National Research Council
Author: Hans de Kroon
Author: National Academies of Sciences, Engineering, and Medicine
Author: National Research Council