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1
Fishman, Benjamin. "Influence of Environmental Parameters on Mold Sampling Results". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6838.
Testo completoAbstract (sommario):
Mold is a type of fungus present in nearly all environments. Mold thrives under several environmental parameters such as high humidity and an adequate food source. A professional, such as an industrial hygienist, can measure mold in indoor and outdoor environments. Industrial hygienists commonly use a cascade impactor with a culture plate to capture air within a sampling area. While collecting air samples, environmental parameters such as temperature, humidity, and carbon dioxide are recorded. A laboratory then cultures and analyzes the samples, identifying the types and amounts of viable mold found in the sampling area.
In this study, a data analysis method is used to interpret lab results and compare those results to the environmental parameters measured during collection. The study aims to show the relationship between the environmental parameters (temperature, humidity, carbon dioxide) and the types and amounts of mold that were measured in both indoor built environments and their surrounding outdoor areas.
Among all 170 different sampling locations, the outdoor areas had higher counts and concentrations of mold. In addition, both indoor and outdoor areas saw Penicillium, Aspergillus, and Cladosporium as the most prevalent molds, with Cladosporium having the highest counts. Lower temperatures and humidity had a very small influence on mold growth and thus, yielded the lowest counts. Furthermore, the highest concentrations of mold were found within the same temperature and humidity ranges for both indoor and outdoor environments.
2
Eichinski, Philip. "Smart sampling of environmental audio recordings for biodiversity monitoring". Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/123022/1/Philip_Eichinski_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis contributes to the field of acoustic environmental monitoring by developing novel semiautomated methods of processing long audio recordings to conduct species richness surveys efficiently. These methods allow a machine to select rich subset of the recordings though estimations of acoustic variety, which can then be presented to the human listener for species identifications. This work represents a step towards more effective biodiversity monitoring of vocal species that can be performed at a larger scale than is possible with traditional methods.
3
CAMERADA, Maria Teresa. "Environmental Health Indicators. Proposal of a measurement scale for verification of the effectiveness of cleaning/sanitizing processes/disinfection in nosocomial environment". Doctoral thesis, Università degli studi di Ferrara, 2018. http://hdl.handle.net/11392/2488265.
Testo completoAbstract (sommario):
The level of environmental hygiene is often evaluated on olfactory and visual perception, in fact there are not universally recognized standards for measuring the effect of a detergent or the effectiveness of sanitation practices. In addition, when sanitation practices are not properly carried out, the environment may become a reservoir for microorganisms that are able to survive for days on furniture and floor surfaces, increasing the risk of infections. Preventive action plans developed in hospitals are mainly focused on controlling infections. This is of particular relevance due to the strong impact of nosocomial infections on economy and health costs for both health care systems and individuals. Infections often occur during hospital stay or after discharge of the admitted patient, thus leading to prolongation of those stays and in the duration of antibiotic therapy. According to some studies, microorganisms responsible for healthcare-related infections (HAIs) such as Staphylococcus spp., in particular Staphylococcus aureus, Enterobacteriaceae, Pseudomonas spp., Candida spp., Acinetobacter spp., are those ones that frequently survive on multiple surfaces and that can be transmitted to patients as a consequence of direct contact or are conveyed by healthcare staff and visitors. In order to define the levels of acceptability and to verify the effectiveness of the sanitizing procedures in nosocomial stays, a microbiological monitoring was performed in seven Italian hospitals, each one located in different geographical area. The study lasted for a total of 18 months. At these facilities two different sanitizing protocols have been applied; in the initial phase, named phase 1, traditional methods with chemical products were used, while in the following period, phase 2, cleaning was carried out by system that is probiotic-based. The results allowed to evaluate how the effectiveness of the cleaning system may influence the degree of contamination. The data were collected from samplings, performed by Rodac plates containing selective or differential culture media suitable for the growth of those microorganisms who were selected as indicators and were responsible for the onset of the bigger number of infections: Staphylococcus spp., Enterobacteriaceae, Acinetobacter spp., Pseudomonas spp., Clostridium difficile, Candida spp. and Aspergillus spp. The sampling areas were chosen because of their importance and criticality: hospital room floor, hospital room sink and footboard bed side. The values taken after 7 hours by morning cleaning, have been implemented in a database and analyzed in order to observe the reduction and/or biostabilization of microbial load in the short and long term. Data analysis allowed the definition of a sampling protocol and an acceptability index of the contamination level.Il livello di igiene ambientale spesso viene valutato su una percezione visiva e olfattiva, in realtà non sono definiti standard universalmente riconosciuti per misurare l'effetto di un detergente o l'efficacia delle pratiche igienico-sanitarie. Inoltre, qualora le pratiche di sanificazione non vengano eseguite correttamente, l'ambiente può fungere da serbatoio per i microrganismi potenzialmente patogeni, che possono sopravvivere sulle superfici per giorni, aumentando il rischio di acquisizione di infezioni. I piani di azione preventiva sviluppati negli ospedali sono focalizzati principalmente sul controllo delle infezioni. L’importanza attribuita al controllo delle infezioni nosocomiali è dovuto al forte impatto che queste hanno in termini economici sia a carico del sistema sanitario nazionale sia per i privati. Le infezioni spesso possono insorgere durante la degenza in ospedale o dopo la dimissione del paziente ricoverato, prolungando la degenza in ospedale e la durata della terapia antibiotica. Secondo alcuni studi i microrganismi responsabili di infezioni correlate all'assistenza sanitaria (ICA) come Staphylococcus spp, in particolare Staphylococcus aureus, Enterobacteriaceae, Pseudomonas spp., Candida spp., Acinetobacter spp., sono anche quelli che sopravvivono sulle superfici e che possono essere trasmessi ai pazienti come conseguenza di un contatto diretto o trasmessa dai visitatori e dal personale sanitario. Al fine di definire i livelli di accettabilità e verificare l'efficacia delle procedure di sanificazione in degenze nosocomiali, è stato eseguito un monitoraggio microbiologico in 7 ospedali italiani situati in diverse aree geografiche. Lo studio è durato complessivamente 18 mesi ed in ogni struttura sono stati eseguiti campionamenti con cadenza mensile. In questi ospedali sono state applicati due differenti protocolli di sanificazione, in un prima fase, denominata fase 1, sono stati utilizzati metodi tradizionali che hanno previsto l’uso di prodotti chimici, mentre nel periodo successivo, fase 2, le pulizie sono state eseguite con un sistema che impiega detergenti a base di probiotici. I risultati hanno permesso di valutare in che modo l'efficacia del sistema di pulizia può influenzare il grado di contaminazione. I dati sono stati raccolti mediante campionamenti, che sono stati eseguiti con piastre Rodac contenenti terreni di coltura, selettiva o differenziale, per lo sviluppo di microrganismi, responsabili del maggior numero di infezioni ospedaliere, e sono: Staphylococcus spp., Enterobatteriaceae, Acinetobacter spp., Pseudomonas spp., Clostridium difficile, Candida spp. ed Aspergillus spp. Le aree di campionamento sono state scelte per la loro importanza e criticità: pavimento, lavandino e pediera del letto. I valori ottenuti mediante i campionamenti, eseguiti a 7 ore di distanza dalle pulizie mattutine, sono stati implementati in un database ed analizzati per valutare la riduzione e/o biostabilizzazione della carica microbica a breve e lungo termine. L'analisi dei dati ha permesso la definizione di un protocollo di campionamento e di proporre un indice di accettabilità del livello di contaminazione.
4
Bucciarelli, Mark. "Cluster sampling methods for monitoring route-level transit ridership". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13485.
Testo completo
5
Guevara-Cue, Cristián Angelo. "Endogeneity and Sampling of Alternatives in Spatial Choice Models". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62098.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 147-155).
Addressing the problem of omitted attributes and employing a sampling of alternatives strategy, are two key requirements of practical spatial choice models. The omission of attributes causes endogeneity when the unobserved variables are correlated with the measured variables, precluding the consistent estimation of the model parameters. The consistent estimation while sampling alternatives in non-Logit models has been an open problem for three decades. This dissertation is concerned with both the endogeneity and the sampling of alternatives in non-Logit models, two problems that have hindered the development of suitable modeling tools for urban policy analysis, but have been neglected in spatial choice modeling. For the problem of endogeneity, this research applies, enhances, adapts, and develops efficient and tractable methods to correct and test for it in models of residential location choice, and also develops novel methods to validate the success of the correction. For the problem of sampling of alternatives in non-Logit models, this study develops and demonstrates a novel method to achieve consistency, relative efficiency, and asymptotic normality when the underlying model belongs to the Multivariate Extreme Value class. This development allows for the estimation of spatial choice models with more realistic error structures. Monte Carlo experiments and real data from Lisbon, Portugal, are employed to illustrate the significant benefits of these novel methods in correcting for endogeneity and addressing sampling of alternatives in non-Logit models, with specific reference to urban policy analysis.
by Cristian A. Guevara-Cue.
Ph.D.
6
Squire, Sharon. "Quantifying uncertainty from environmental sampling of spatially and temporally variable systems". Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8412.
Testo completo
7
Lyn, Jennifer A. "Optimising uncertainty from sampling and analysis of foods and environmental samples". Thesis, University of Sussex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270732.
Testo completo
8
Kuntz, Thomas James. "Campylobacter jejuni and Salmonella spp. Detection in Chicken Grow Out Houses by Environmental Sampling Methods". Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/42526.
Testo completoAbstract (sommario):
Campylobacter and Salmonella are foodborne pathogens commonly associated with raw poultry. Although there has been much research done on isolating these pathogens from poultry production environments using cloacal swabs, fecal samples, intestinal tract contents and dissection, research involving environmental sampling has been limited. New and/or improved environmental sampling methods may provide an easy, convenient, and less time-consuming way to collect samples. Coupling these sampling methods with PCR may provide a relatively simple, rapid, and robust means of testing for foodborne pathogens in a chicken house or flock prior to slaughter.
Air, boot and sponge samples were collected from three commercial chicken grow-out houses located in southwestern Virginia when flocks were three, four, and five weeks old. Air samples were collected onto gelatin filters. Fecal/litter samples were collected from disposable booties worn over investigatorâ s protective shoe coverings. Pre-moistened sponges were used to sample house feed pans and water dispensers on drink lines. A PCR method was used to qualitatively detect Campylobacter jejuni and Salmonella spp. Campylobacter jejuni was detected at each farm (house), across all three ages (3, 4, and 5 weeks), and from each sample type. Salmonella was not detected in any of the environmental samples. For all 270 samples, 41% (110/270) were positive for Campylobacter. Collectively, 28% (25/90) of air, 44% (40/90) of sponge, and 50% (45/90) of bootie samples were positive for Campylobacter. The methods used in this study are non-invasive to live animals, relatively rapid and specific, and could enable poultry processing facilities to coordinate scheduled processing of flocks with lower pathogen incidence, as a way to reduce post-slaughter pathogen transmission.Master of Science
9
Li, Qihang 1964. "Sampling error and environmental noises in passive microwave rainfall retrieval from space". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11204.
Testo completo
10
Bazaco, Michael Constantine. "Quantitative Recovery of Listeria monocytogenes and Salmonella enterica from Environmental Sampling Media". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/30833.
Testo completoAbstract (sommario):
Environmental sampling is a pathogen monitoring technique that has become important in the food industry. Many food processing companies have adopted environmental sampling as a way to verify good manufacturing practices and sanitation plans in their facilities. Environmental sampling is helpful because it gives better information on the source of product contamination than end product sampling. Two specific pathogens of concern to the food industry are Listeria monocytogenes and Salmonella enterica. Environmental samples are rarely analyzed immediately, but instead may be batched for later analysis or shipped to an off site testing facility. Multiple media on the market today is used for storage and transport of environmental samples. These various media types, differences in holding temperatures and time create variability in test sample conditions. Select time, temperature and media combinations were tested to determine their effect on Listeria monocytogenes and Salmonella enterica populations during transport and storage of samples. Cocktails of Listeria monocytogenes and Salmonella enterica were added separately to sample tubes containing D/E Neutralizing Broth, Neutralizing Buffer or Copan SRK Solution. Bacterial counts at 0, 12, 24 and 48 hours post inoculation were compared. Neutralizing Buffer and Copan SRK Solution maintained consistent bacterial populations at all temperatures. At 10° and 15°C, D/E Broth supported bacterial growth. This study helps validate the use of D/E Neutralizing Broth, Neutralizing Buffer and Copan SRK Solution for environmental sample transport and storage at proper holding temperatures. At temperatures >10°C Neutralizing Buffer or Copan SRK solution should be used if quantifying microbial recovery.Master of Science
11
Santagata, Maria Caterina. "Simulation of sampling disturbance in soft clays using triaxial element tests". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12124.
Testo completo
12
Fotopoulos, Fotios 1976. "Simulation of the sampling properties of the Global Precipitation Measurement Mission". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84816.
Testo completo
13
Reynolds, Hayley. "A spatial sampling scheme for a road network". Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63776.
Testo completoAbstract (sommario):
Rabies has been reported in Tanzania, mainly in the southern highland regions, since 1954. To date, rabies is endemic in all districts in Tanzania and efforts are being made to contain the disease. It was determined that mass vaccination of at least 70% of an animal population is most effective, in terms of profitability and cost, in reducing transmission of rabies. The current approach for vaccination in Tanzanian villages takes some features from the EPI method but is rather basic and unreliable. This mini-dissertation proposes using a sampling technique which incorporates the spatial component of the village data and minimises the walking distance between the sampled houses while ensuring the 70% coverage of the animal population.Mini Dissertation(MSc)--University of Pretoria, 2017.
STATOMET The Centre for Artificial Intelligence Research (CAIR) National Research Foundation of South Africa (NRF CSUR grant number 90315)
Statistics
MSc
Unrestricted
14
Kerr, Kent. "Sampling for Beryllium Surface Contamination using Wet, Dry and Alcohol Wipe Sampling". Washington, D.C. : Oak Ridge, Tenn. : United States. National Nuclear Security Administration ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/837587-M4P95G/native/.
Testo completoAbstract (sommario):
Thesis (M.S.); Submitted to Central Missouri State University, Warrensburg, MO (US); 17 Dec 2004.Published through the Information Bridge: DOE Scientific and Technical Information. Kerr, Kent. NNSA Kansas City Site Office (US) NNSA Kansas City Site Office. 12/17/2004. Report is also available in paper and microfiche from NTIS.
15
Morrow, Michael Thomas. "A Self-Sustaining, Boundary-Layer-Adapted System for Terrain Exploration and Environmental Sampling". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34186.
Testo completoAbstract (sommario):
This thesis describes the preliminary design of a system for remote terrain exploration and environmental sampling on worlds with dense atmospheres. The motivation for the system is to provide a platform for long-term scientific studies of these celestial bodies. The proposed system consists of three main components: a buoyancy-driven glider, designed to operate at low altitude; a tethered energy harvester, extracting wind energy at high altitudes; and a base station to recharge the gliders. This system is self-sustaining, extracting energy from the planetary boundary layer.
A nine degree of freedom vehicle dynamic model has been developed for the buoyancydriven glider. This model was used to illustrate anecdotal evidence of the stability and controllability of the system. A representative system was simulated to examine the energy harvesting concept.
Master of Science
16
Lacorazza, Camila. "Evaluation of environmental samples as a sampling method for detecting pathogens in zebrafish". Thesis, Uppsala universitet, Institutionen för kvinnors och barns hälsa, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385875.
Testo completoAbstract (sommario):
Zebrafish are becoming increasingly popular to use in different kinds of research projects as research animals, replacing rodents in many fields. When using animals for research, it is important to keep track of the animal health in order to get reliable results. The purpose of the study was to investigate whether these pathogens could be found analyzing environmental materials with real-time PCR instead of euthanizing fish and submitting them for histopathology. Also, to see if any material differentiated from the rest regarding accessibility to work with in a routine diagnostic laboratory. This study was performed on environmental samples, such as filters, swabs, detritus and water, from a recirculating water system holding zebrafish. The pathogens analyzed were Mycobacterium chelonae, M. haemophilum, M. abscessus, M. marinum, M. fortuitum and Pseudoloma neurophilia, all common pathogens that can affect zebrafish. All materials tested gave at least one positive result for most of the pathogens tested. Two pathogens were not detected, M. marinum and M. abscessus. Due to poorly working PCR-system for M. fortuitum, the results for that bacteria were deemed inconclusive. The filter materials and the swabs of the filter materials gave the best results in this small study, although all materials gave satisfactory results. In conclusion this study shows that environmental samples can be used to detect pathogens in zebrafish, but larger studies should be performed to better evaluate which material is the best one to use.
17
Lu, Chensheng. "Pesticide biomonitoring : a feasibility study of saliva sampling in rats /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8451.
Testo completo
18
Hart, Cheryl K. "Theory and evaluation of a new physiologic sampling pump /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8459.
Testo completo
19
Di, Bonito Marcello. "Trace elements in soil pore water : a comparison of sampling methods". Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/10123/.
Testo completoAbstract (sommario):
This thesis examined a range of methods for sampling soil pore water to investigate the chemistry of trace elements. In particular, the study assessed whether Rhizon samplers, centrifugation, high pressure squeezing and soil suspensions in simulated pore water can be viable approaches for obtaining representative samples of equilibrated soil pore water. Results for metal solubility and speciation were interpreted in terms of both soil morphological effects on trace metal dynamics and artefacts introduced at various stages during sample preparation and handling. The main soil used in the study was an organic-rich sandy silt from a site which has served as a sewage re-processing facility for almost a century. This soil was chosen because of its importance as a long-term repository for metal-enriched sludge applied to arable land, providing a suitable medium on which to study trace metal behaviour. Pore waters were extracted and analysed for major and trace cations and anions, pH, Dissolved Inorganic Carbon (DIC) and Dissolved Organic Carbon (DOC) at two different temperatures (5 degrees Celsius and 15 degrees Celsius), in order to evaluate the extent of bacterial activity, organic decomposition and their consequences on solute composition, during pore water extractions. Speciation was estimated from analysis of pore water chemistry using two software packages (PHREEQCi and WHAM-VI). Pore waters showed different ranges of concentration between the various methods. Different mechanisms and/or chemical reactions were involved during the different extractions; a range of processes was identified, mainly dominated by metal complexation by humus acids and redox reactions. Results revealed that the soil studied was able to partially buffer the free ion activities of the metal ions in pore water with increasing dilutions, but demonstrated virtually no ability to buffer DOC. Identification of the source (i.e. location of pore space) of water extracted was also investigated using water with different isotopic composition (18O/16O). Evidence showed that centrifugation was not able to differentiate between more and less mobile water at FC conditions, rather enhancing the mixing between the two pools of water (native and labelled) by and apparent process of 'infusion'. By contrast, Rhizon samplers appeared to sample water preferentially from the more accessible pool (extra-aggregate), which proved to have a composition showing incomplete mixing with the native water. The results also suggested that mixing of the two pools was rather fast and that was almost completely attained prior to pore water extraction. The study established that the most important factors affecting pore water chemistry during extraction are the conditions to which the samples are exposed during the extraction process. For these reasons Rhizon samplers should be used as a disposable device, and are only applicable for use in high soil moisture soil contents. In contrast, they present no 'side-effects' (providing enough equilibration time) if M2+ (free ion activity) were needed as opposed to Msol (total metal concentration in pore water), as often required in environmental studies. Centrifugation is optimal for bulk solution studies, or when homogenisation represents a key experimental point; targeted studies are also possible. Soil squeezing is subject to severe limitations in the case of prolonged extractions of biologically active soils, due to the effects of anaerobism. Squeezing should only be used for 'fast' extractions of soils. Finally, batch extractions are well suited to studies on M2+ equilibria, but more studies are needed to clarify the effect of soil: solution ratio on metal and DOC solubility.
20
Tsai, Yeng-Chieh. "The application of two-dimensional genomic DNA nylon matrix for environmental samples analysis". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 67 p, 2009. http://proquest.umi.com/pqdweb?did=1654501591&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
21
Anderson, Cody Allen. "Permeation Sampling of BTEX and Gasoline". University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1279115371.
Testo completo
22
Schroeder, Matthew William. "Association of Campylobacter spp. Levels between Chicken Grow-Out Environmental Samples and Processed Carcasses". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32169.
Testo completoAbstract (sommario):
Campylobacter spp. have been isolated from live poultry, production environment, processing facility, and raw poultry products. The detection of Campylobacter using both quantitative and qualitative techniques would provide a more accurate assessment of pre- or post harvest contamination. Environmental sampling in a poultry grow-out house, combined with carcass rinse sampling from the same flock may provide a relative assessment of Campylobacter contamination and transmission.
Air samples, fecal/litter samples, and feed pan/drink line samples were collected from four commercial chicken grow-out houses. Birds from the sampled house were the first flock slaughtered the following day, and were sampled by post-chill carcass rinses. Quantitative (direct plating) and qualitative (direct plating after enrichment step) detection methods were used to determine Campylobacter contamination in each environmental sample and carcass rinse. Campylobacter, from post-enrichment samples, was detected from 27% (32/120) of house environmental samples and 37.5% (45/120) of carcass rinse samples. All sample types from each house included at least one positive sample except the house 2 air samples. Samples from house 1 and associated carcass rinses accounted for the highest total of Campylobacter positives (29/60). The fewest number of Campylobacter positives, based on both house environmental (4/30) and carcass rinse samples (8/30) were detected from flock B. Environmental sampling techniques provide a non-invasive and efficient way to test for foodborne pathogens. Correlating qualitative or quantitative Campylobacter levels from house and plant samples may enable the scheduled processing of flocks with lower pathogen incidence or concentrations, as a way to reduce post-slaughter pathogen transmission.Master of Science in Life Sciences
23
McMillan, Lindsay Antonia. "Groundwater quality : representative and appropriate sampling of long-screen wells". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6484/.
Testo completoAbstract (sommario):
Groundwater quality sampling guidance typically requires representative samples to be obtained. Such guidance is not always clear what this means and which sampling methods are most appropriate. The situation is complicated by increasing well screen/open interval length. Uncertainty, resulting particularly from observations of vertical flow in wells has led to calls for the use of long-screen (> 3 m) wells to be abandoned for groundwater quality monitoring. Here, four complementary field and modelling studies at various scales are used to examine appropriate groundwater quality sampling in such wells. Numerical modelling demonstrates that literature reported vertical flows in wells < 10 m in length are sufficient to bias pumped groundwater quality sampling. Bias starts for vertical well flow rates less than 50 % of the pumping rate. Vertical flow measurements explain differences and similarities in historical passive sampling between four boreholes and allow vertical aquifer concentration distributions to be quantified. However, such quantification requires per-borehole flow measurement. New technology (Active Distributed Temperature Sensing) provides a versatile alternative to existing borehole flow characterisation methods under ambient and pumping conditions. Data from contrasting field environments demonstrate that even without comprehensive flow investigation long-screen wells can still provide useful information about groundwater concentrations and trends.
24
Sihabut, Tanasri McDow Stephen R. "Sampling artifacts of particulate organic species and their effects on receptor modeling results /". Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/512.
Testo completo
25
Ernst, Michael Jules 1960. "Modeling multicomponent vacuum flow, transport, and outgassing in a membrane-inlet vapor sampling probe". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36502.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.Vita.
Includes bibliographical references (p. 341-345).
by Michael Jules Ernst.
Ph.D.
26
Persoon, Carolyn Lee. "Spatial and seasonal trends of atmospheric PCBs in urban areas captured by passive sampling". Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/873.
Testo completoAbstract (sommario):
The overall hypothesis of this research is that the use of passive samplers is an effective method to measure spatial and seasonal trends of atmospheric PCBs in an urban environment. In support of this, I extracted, analyzed and quantified congener specific concentrations from over 200 passive samples and over 200 active sampler, or Hi-Vols. I studied best practices for the use of methods to derive R-values and the application of R-values on mass accumulated on passive samplers for both indoor and outdoor air and found that indoor air uptake of PCBs was consistent over time and at different locations. I suggest that depuration compounds be used for outdoor sampling when using passive samplers for the most accurate measurement of effective sampling volume. I then applied these practices to passive samplers deployed in two major cities along the Great Lakes, Cleveland and Chicago. I found that these cities had different concentrations as well as different congener profiles. I compared toxicological equivalencies (TEQ) of the WHO dioxin-like PCBs between the two cities and discovered that although Cleveland had higher total PCB concentrations, it had a lower TEQ. I then compared spatial distributions and temporal trends between Hi-Vols and passive samplers and found that passive samplers were accurate at collecting spatial and seasonal trends when compared to Hi-vols, and were consistent at identifying hot-spots of atmospheric PCBs in Chicago. Finally, I developed an instrumental method to identify and quantify OH-PCBs from environmental samples to be used in future research involving the fate of atmospheric PCBs.
27
Clare, Evan. "DECOMPOSING A WATERSHED’S NITRATE SIGNAL USING SPATIAL SAMPLING AND CONTINUOUS SENSOR DATA". UKnowledge, 2019. https://uknowledge.uky.edu/ce_etds/87.
Testo completoAbstract (sommario):
Watershed features, physiographic setting, geology, climate, and hydrologic processes combine to produce a time-variant nutrient concentration signal at the watershed outlet. Anthropogenic influences, such as increased agricultural pressures and urbanization, have increased overall nutrient loadings delivered to the fluvial network. The impact of such increased nutrient loadings on Kentucky’s drinking water remains a potential threat to the region.
By coupling spatial sampling of nitrate concentrations in surface water with contemporary nutrient and water quality sensor technology, a decomposition of the Upper South Elkhorn watershed’s nitrate signal and an estimation of source timing and loading in the watershed was completed. The goal of the project was the decomposition of the integrated nitrate signal observed at the outlet of the Upper South Elkhorn watershed into contributing runoff and groundwater sources from agricultural/pasture and urban/suburban land-uses.
Decomposing the watershed’s nitrate signal yielded new knowledge learned about nitrate source, fate and transport in immature fluviokarst. This thesis discusses how mean, seasonal, and fluctuating nitrate behavior is related to soil processes, groundwater transfer, streambed removal, and event dynamics. It is expected that the decomposition of the nitrate signal will allow for the targeting of both the timing and sources for nutrient reductions in a watershed.
28
Longsmith, Rebecca Johnson. "A BIOLOGICAL MONITORING INTERNSHIP WITH THE OHIO ENVIRONMENTAL PROTECTION AGENCY, DIVISION OF SURFACE WATER". Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1451932666.
Testo completo
29
Chatterjee, Kanistha. "A Novel, Periodic Sampling Method to Assess Airborne Bacteria Populations". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1313564597.
Testo completo
30
Farhadi, Leila. "Estimation of land surface water and energy balance flux components and closure relation using conditional sampling". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70757.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 348-364).
Models of terrestrial water and energy balance include numerical treatment of heat and moisture diffusion in the soil-vegetation-atmosphere continuum. These two diffusion and exchange processes are linked only at a few critical points. The performance and sensitivity of models are highly dependent on the nature of these linkages that are expressed as the closure function between heat and moisture dynamics. Land response to radiative forcing and partitioning of available energy into sensible and latent heat fluxes are dependant on the functional form. Since the function affects the surface fluxes, the influence reaches through the boundary layer and affects the lower atmosphere weather. As important as these closure functions are, they remain essentially empirical and untested across diverse conditions. It is critically important to develop observation-driven estimation procedures for the terrestrial water and energy closure problem, especially at the scale of modeling and with global coverage. In this dissertation a new approach to the estimation of key unknown parameters of water and energy balance equation and their closure relationship is introduced. This approach is based on averaging of heat and moisture diffusion equations conditioned on land surface temperature and moisture states respectively. The method is derived only from statistical stationarity and conservation statements of water and energy and thus it is scale free. The aim of this dissertation is to establish the theoretical basis for the approach and perform a global test using multi-platform remote sensing measurements. The feasibility of this approach is demonstrated at point-scale using synthetic data and flux-tower field site data. The method is applied to the mesoscale region of Gourma (West Africa) using multi-platform remote sensing data. The retrievals were verified against tower-flux field site data and physiographic characteristics of the region. The approach is used to find the functional form of the Evaporative Fraction (ratio of latent heat flux to sum of latent and sensible heat fluxes) dependence on soil moisture. Evaporative Fraction is a key closure function for surface and subsurface heat and moisture dynamics. With remote sensing data the dependence of this function on governing soil and vegetation characteristics is established.
by Leila Farhadi.
Ph.D.
31
Liu, Hanqing M. Eng Massachusetts Institute of Technology. "Analysis of volatile organic compounds (VOCs) in soil via passive sampling : measuring partition and diffusion coefficients". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99606.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 55-57).
Passive sampling has been used as a qualitative and semi-quantitative method in detecting volatile organic compound (VOCs) concentrations in soil vapors or water. Passive sampling for soil vapor takes an absorptive material and places it underground for a period of time to allow the VOCs to diffuse into the absorptive materials. In this report, I use low density polyethylene (PE) as the absorptive material and determine two key parameters for passive sampling: the PE-water partition coefficient (Kpew) and diffusion coefficient in PE (Dpe). These two parameters help passive sampling to transition from a qualitative method to a quantitative method. The report describes the steps used to carry out the experiments, gives the results for several specific VOCs, and makes an attempt to draw more general conclusions on how to estimate these two parameters according to some other well-known properties.
by Hanqing Liu.
M. Eng.
32
Martin, Marie M. "Comparison of three methods of breath sampling for biological monitoring of volatile organic chemicals /". Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/8472.
Testo completo
33
Rana, SM Masud. "Contaminant Spread Forecasting and Sampling Location Identification in a Water Distribution Network". University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1383909255.
Testo completo
34
Hollingsworth, Emily K. "The Spatial Heterogeneity of Periphyton in Eight Southeastern Ohio Streams: How Far Can One Sample Take You?" Ohio : Ohio University, 2007. http://www.ohiolink.edu/etd/view.cgi?ohiou1181835600.
Testo completo
35
Jensen, David G. (David Gannon). "Quantitative analysis of volatile organic compounds (VOCs) in soil via passive sampling : polyethylene sampler design and optimization". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99601.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-55).
The potential for the release of volatile organic compounds (VOCs) to our natural environment is pervasive. However, the ability to accurately measure and predict VOC soil vapor concentrations is still limited. A polyethylene (PE) quantitative passive sampler using performance reference compounds and deployed via a hand driven probe is proposed as a solution. Additionally, a 1D diffusion mass transfer model was developed in MATLAB to predict the mass uptake into the PE sampler over time. The model was then implemented to investigate the effects of PE size and deployment time on the detection limit of BTEX compounds. Preliminary testing of the deployment probe indicates that a design to secure the PE around the outside of a driven rod must include a protective cover over the PE during insertion. A perforated pipe design is suggested. After deployment and recovery, the PE is extracted into water. The extraction water is then analyzed by direct aqueous injection to GC/FID. The minimum concentration detectable in soil vapors, by this PE passive sampling method, was determined to be the product of the target compound's air-water partitioning coefficient and the analytical detection limit. Assuming a 5 ng/mL analytical detection limit, the minimum soil vapor detection limit for toluene was approximately 1.25 mg/m 3. This limit would be similar for all BTEX compound and is above sub-slab vapor intrusion screening levels for the more toxic compounds such as benzene. This indicates that direct aqueous injection provides insufficient sensitivity and that purge and trap concentrations of VOCs is likely needed. It was also determined that a PE sampler, with dimensions as small as 5"x5/8"x0.0005", could theoretically reach 10 mg/m 3 sensitivity within a 1 h deployment time. This result suggests potential applications of the sampler for rapid and accurate site characterization of BTEX compounds.
by David G. Jensen.
M. Eng.
36
Apell, Jennifer Nicole. "Using polyethylene passive sampling to assess transport of polychlorinated biphenyls (PCBs) between contaminated sediments, water, and biota". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113473.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017Cataloged from PDF version of thesis.
Includes bibliographical references.
Polychlorinated biphenyls (PCBs), which were a widely used group of chemicals before their manufacture was banned in 1979 in the United States, still contaminate numerous aquatic systems. Although there are ongoing efforts to remediate these sites, our ability to implement effective remediation strategies has been hindered by a limited understanding of how PCBs are transported in the environment as well as how they bioaccumulate into aquatic animals. Investigations of contaminated sites often rely on sediment measurements since PCB concentrations are highest in the sediment phase. However, previous research has shown that sediment concentrations are a poor predictor of contaminant fate and effects, whereas freely dissolved water concentrations were able to predict the extent of bioaccumulation and the onset of toxicological effects more accurately.
Additionally, the concentration gradient between the porewater (i.e., the interstitial water in sediment beds) and the overlying water is thought to be a major driver in PCB transport from the sediment bed. Passive samplers, which are made of polymers like polyethylene (PE), accumulate PCBs when they are deployed into environmental media, can be used to estimate freely dissolved water concentrations. When used in the laboratory by mixing with sediment samples, they provide a measure of the sediment-water equilibrium porewater concentration. When deployed in the field, they can provide measures of the in situ porewater and overlying water concentrations. In this work, PE samplers were deployed at two Superfund sites contaminated with PCBs to investigate if in situ porewater and sediments were at equilibrium with each other.
In situ porewater concentrations were consistently found to be lower than equilibrium concentrations at both sites, an effect that was likely caused by water flow through the sediment bed. At one of the sites, measurements of a geochemical tracer also showed that the exchange of porewater with overlying water was occurring and that the transport of PCBs from sediments was affected by more than just the concentration gradient. Lastly, the sorptive disequilibria between environmental media and the spatial heterogeneity of contamination were shown to affect the extent of bioaccumulation in aquatic animals at one of the sites.
by Jennifer Nicole Apell.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
37
Silvadasan, Xavier. "Environmental performance of steel grit and specialty sand as abrasives". ScholarWorks@UNO, 2004. http://louisdl.louislibraries.org/u?/NOD,175.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of New Orleans, 2004.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Civil and Environmental Engineering."--Thesis t.p. Vita. Includes bibliographical references.
38
Neal, Emily R. "ESCHERICHIA COLI STRAIN DIVERSITY IN HUMANS: EFFECTS OF SAMPLING EFFORT AND METHODOLOGY". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/984.
Testo completoAbstract (sommario):
Studies investigating Escherichia coli strain diversity and demographics in human hosts are frequently inconsistent regarding sampling effort and methodology while current strain typing methods are often expensive or laborious. To rectify these inconsistencies, sampling effort was investigated by comparing the diversity of 15-isolate collections to 100-isolate collections from 3 human subjects. Temporal variation in E. coli strain diversity was also studied by collecting 15 isolates once every 6 months. Additionally, strain identification and diversity collected by different sampling methods (fecal swabs vs. anal swabs collected at different times around defecation) were compared to identify any inherent biases in sampling method. This study employed pyroprinting, a new inexpensive and simple strain typing method using pyrosequencing, to generate DNA fingerprints (or pyroprints) based on the Intergenic Transcribed Spacer sequences in the ribosomal RNA operon to differentiate E. coli strains. Differences in strain diversity were apparent when comparing sampling efforts. The sampling effort investigation suggested that certain subjects hosted very large and highly diverse E. coli strain populations such that even 100 isolates may not fully represent E. coli strain populations in human hosts. Instead, the sampling effort required to accurately represent strain demographics may depend on strain richness and evenness within each host. The temporal investigation yielded similar or greater strain abundance and diversity compared to other typing methods in the literature suggesting pyroprinting is a similarly discriminating tool. When agglomerated over time or by subject, no significant differences in diversity were observed between subjects or between sampling methods despite visible differences in strain richness and evenness.
39
Dou, Yiping. "Dynamic Bayesian models for modelling environmental space-time fields". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/634.
Testo completoAbstract (sommario):
This thesis addresses spatial interpolation and temporal prediction using air pollution data by several space-time modelling approaches. Firstly, we implement the dynamic linear modelling (DLM) approach in spatial interpolation and find various potential
problems with that approach. We develop software to implement our approach. Secondly, we implement a Bayesian spatial prediction (BSP) approach to model spatio-temporal ground-level ozone fields and compare the accuracy of that approach with that of the DLM. Thirdly, we develop a Bayesian version empirical orthogonal function (EOF) method to incorporate the uncertainties due to temporally varying spatial process, and the spatial variations at broad- and fine-
scale. Finally, we extend the BSP into the DLM framework to develop a unified Bayesian spatio-temporal model for univariate and
multivariate responses. The result generalizes a number of current approaches in this field.
40
Soo, Yu Xiang Jaren. "Benchtop testing of polyethylene passive sampling towards a quantitative analysis of volatile organic compounds (VOCs) in soil vapours". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99631.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 42-43).
The feasibility of polyethylene (PE) as a passive sampler for quantitative analysis of volatile organic compounds (VOCs) was analysed in this work by means of a benchtop testing. A benchtop physical model was setup, which consisted of a jar of glass beads or sand, containing a known mass of toluene as the compound of concern (COC). A beaker of water was placed in the physical model as a second form of measurement of toluene concentration in the air. The concentration of toluene in the air of the physical model was measured using the PE passive sampler and compared to results found by measurement toluene in water in the beaker. The PE-inferred vapour concentrations were consistent with the measurements in the water. With benzene, toluene, ethylbenzene and o-xylene (BTEX) selected to be quantified in the actual soil, both the PE passive sampler and the water-based measurement showed inconsistency in contrast to previous experiments with glass beads and sand. This inconsistency could probably be due to the presence of biodegradation. Nonetheless, if proved consistent in future, PE passive sampling can also be used to estimate the concentrations of compounds based on molecular weight in absence of known literature values of required parameters.
by Yu Xiang Jaren Soo.
M. Eng.
41
Sobchuk, Catherine Elizabeth. "Evaluating the combined use of three-dimensional hydrodynamic modeling and polyethylene passive sampling in the Lower Duwamish Waterway". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119323.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 122-124).
Polyethylene (PE) passive samplers are capable of measuring in-situ, freely dissolved, time-averaged concentration distributions of contaminants in air, surface water, and sediment bed porewater. This sampling technique can be coupled with a three dimensional (3D) hydrodynamic model of a given surface water body to identify where sources contributing to the measured concentration distribution are most likely located and what mass flux is required to produce the measured concentrations. This evaluation was completed for the Lower Duwamish Waterway (LDW), a salt wedge estuary located in Seattle, Washington. The LDW was selected for its idealized conditions (straight channel with relatively uniform cross-section), established 3D hydrodynamic model (Environmental Fluid Dynamics Code [EFDC]), and availability of measured data. Density-driven circulation in the LDW drives saltwater upstream and freshwater downstream, influencing residence times, mixing times, and the resulting concentration distributions of potential sources. The dependence of simulated, unit strength concentration distributions on source location was evaluated by spatially comparing EFDC-simulated sources introduced at various points in the LDW. This determined how far apart potential sources need to be, referred to as a distinguishable distance, to be "resolved" by measured or modeled concentrations at the LDW centerline. East and west bank sources were generally distinguishable within 0.8 miles of introduction; water surface and sediment bed sources were generally distinguishable throughout the LDW; longitudinally distributed sources were distinguishable for 0.4 to 1.1 miles from the source location. PE passive samplers placed at the centerline of the LDW with spacing at or near the distinguishable distance will likely be able to differentiate between various source locations. Inverse model techniques were applied to measured concentration distributions in the water column using numerous cases of potential source locations with distinguishable, unit strength concentration distributions. The resulting mass fluxes ranged from 0.034 mg/s to 0.072 mg/s (average 0.043 mg/s), an order of magnitude higher than known source fluxes (i.e., sediment diffusive flux and air-water exchange flux). Therefore, one or more "missing sources" were determined to exist; based on this evaluation, it is possible the sources originate from the midstream sediment bed, upstream sediment bed, and upstream water surface.
by Catherine Elizabeth Sobchuk.
M. Eng.
42
Parsons, Robert Lee. "Assessment and optimization of site characterization and monitoring activities using geostatistical methods within a geographic information systems environment". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/32847.
Testo completo
43
Zhang, Liang. "Classification and ranking of environmental recordings to facilitate efficient bird surveys". Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/107097/1/Liang_Zhang_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis contributes novel computer-assisted techniques to facilitating bird species surveys from a large number of environmental audio recordings. These techniques are applicable to both manual and automated recognition of bird species by removing irrelevant audio data and prioritising those relevant data for efficient bird species detection. This work also represents a significant step towards using automated techniques to support experts and the general public to explore and gain a better understanding of vocal species.
44
Simon, Philippe 1964. "Long-term integrated sampling to characterize airborne volatile organic compounds in indoor and outdoor environments". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34455.
Testo completoAbstract (sommario):
Sampling methods used for the assessment of exposure to volatile organic chemicals (VOCs) in the workplace or for environmental studies are now limited to an upper integrative sampling time of 24 hours or less. Generally, these methods lack versatility and are difficult to use. A passive sampler that can extend sampling periods was developed as part of this research. This novel sampler relies on capillary tubes to restrict and control ambient air entry into an evacuated sample container.A mathematical model was derived by modifications to the Hagen-Poiseuille and ideal gas laws. This model defines the relationship between container volume and capillary geometry (length/internal diameter) required to provide selected sampling times. Based on theoretical considerations, simulations were performed to study the effects of dimensional parameters. From these results, capillaries having 0.05 and 0.10 mm internal diameters were selected according to their ability to reduce sampling flow rates and to increase sampling times. Different capillary lengths were tested on various sampler prototypes. It was found that a constant sampling flow rate was delivered when a maximum discharge rate was established under the influence of a pressure gradient between a vacuum and ambient pressure. Experimental flow rates from 0.018 to 2.6 ml/min were obtained and compared with model predictions. From this comparison, empirical relationships between capillary geometry and maximum discharge rate given by the pressure gradient were defined. Essentially, based on these empirical relationships, capillary sampling flow controller specifications can be calculated to offer extended integrated sampling periods. On this basis, sampler prototypes were configured for stationary sampling and personal sampling.
Studies, based on theory, have indicated that factors such as temperature, humidity and longitudinal molecular diffusion are not likely to influence the passive sampling process. Subsequent experiments confirmed that temperature changes should not significantly affect flow rates delivered by controllers, and that molecular diffusion does not have any impact on the representativeness of long-term samples. Recovery tests provided acceptable results demonstrating that selected capillaries do not contribute to adsorption that could seriously affect the validity of this sampling approach.
Field demonstration studies were performed with both stationary and personal sampler prototypes in the indoor and outdoor environments. The performance of the sampler compared favorably, and in some instances, exceeded that of accepted methodology. These novel samplers were more reliable, had greater versatility and principally, allowed sampling periods extending from hours to a month. These inherent qualities will assist industrial hygienists and environmentalists in the study of emission sources, pollutant concentrations, dispersion, migration and control measures. This novel sampler is presently the only device available for the effective study of episodic events of VOC emission.
Selected capillary geometries acting as a restriction to the entry of ambient air into evacuated sample container can provide a simple, versatile and reliable alternative for the collection of VOCs. This approach can contribute to a better understanding of VOC effects on human health and the environment.
45
Smyth, John Charles. "A novel air sampling and analytical method for determination of airborne bronopol". [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001744.
Testo completo
46
Montgomery, Sharlan Renae. "Development of a Chloride Concentration Sampling Protocol for Concrete Bridge Decks". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3981.
Testo completoAbstract (sommario):
As the primary cause of concrete bridge deck deterioration in the United States is corrosion of the steel reinforcement as a result of the application of chloride-based deicing salts, chloride concentration testing is among the most common techniques for evaluating the condition of a concrete bridge deck. The objectives of this research were to 1) compare concrete drilling and powder collection techniques to develop a sampling protocol for accurately measuring chloride concentrations and 2) determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. Laboratory experiments on concrete drilling and powder collection were conducted to compare current concrete powder sampling techniques, including constant and stepwise drilling methods and spoon and vacuum powder collection methods. In addition, three charts were prepared to determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. The number of samples is dependent on reliability, spatial variability in chloride concentration, and an allowable difference between sample and population means. For the experiment on drilling, this research shows that the practice of decreasing the size of the drill bit in a stepwise fashion with increasing sampling depth reduces the possibility of abrading concrete from the sides of the hole above the sampling depth, where the chloride concentrations are higher, during drilling of lower lifts. For the experiment on powder collection, this research demonstrates that representative samples of concrete powder can be collected with either a spoon or a vacuum. Based on the results of this research, the stepwise drilling method and either the spoon or vacuum powder collection method are recommended for application. In addition, the charts developed in this research are recommended for estimating the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. This research will be helpful in effectively assessing the condition of concrete bridge decks with respect to chloride-induced corrosion of the reinforcing steel and prioritizing bridge maintenance and rehabilitation projects.
47
McDonald, Lauren. "Wipe Sampling Methodologies to Assess Exposures to Metals in Urban Canadian Homes: 1 Cadmium, Lead, Yttrium 2 Antimony, Arsenic, Chromium, Copper, Nickel". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28588.
Testo completoAbstract (sommario):
Wipe sampling is a means of monitoring exposures to contaminants which has been used extensively for assessment of lead (Pb) in housedust in the U.S. This thesis reports the first baseline wipe dataset for urban Canadian homes, for Pb and other metal(loid)s including: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and antimony (Sb). The literature review covers sampling methods, health effects, and sources. The digestion procedure ASTM 1644 is the accepted HNO3 hotplate protocol for determination of Pb in wipes. However in this study, HF was added to enhance extraction efficiencies for a wide range of elements. The first paper identifies baseline and elevated subpopulations for Cd and Pb using normality plots, and investigates the use of yttrium(Y) as a soil tracer. The second paper investigates application of the wipe methodology for monitoring As, Cr, Cu, Ni, Sb, and Zn. This is the first multi-element wipe sampling dataset in the literature, and will assist risk assessors and risk managers in providing guidance to Canadians about ways to reduce exposures to metals.
48
Brungard, Colby W. "Alternative Sampling and Analysis Methods for Digital Soil Mapping in Southwestern Utah2". DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/973.
Testo completoAbstract (sommario):
Digital soil mapping (DSM) relies on quantitative relationships between easily measured environmental covariates and field and laboratory data. We applied innovative sampling and inference techniques to predict the distribution of soil properties, soil attributes, taxonomic classes, and dominant vegetation across a 30,000-ha complex Great Basin landscape in southwestern Utah. This arid rangeland was characterized by rugged topography, diverse vegetation, and intricate geology. Environmental covariates calculated from digital elevation models (DEM) and spectral satellite data were used to represent factors controlling soil development and distribution. We investigated optimal sample size and sampled the environmental covariates using conditioned Latin Hypercube Sampling (cLHS). We demonstrated that cLHS, a type of stratified random sampling, closely approximated the full range of variability of environmental covariates in feature and geographic space with small sample sizes. Site and soil data were collected at 300 locations identified by cLHS. Random forests was used to generate spatial predictions and associated probabilities of site and soil characteristics. Balanced random forests and balanced and weighted random forests were investigated for their use in producing an overall soil map. Overall and class errors (referred to as out-of-bag [OOB] error) were within acceptable levels. Quantitative covariate importance was useful in determining what factors were important for soil distribution. Random forest spatial predictions were evaluated based on the conceptual framework developed during field sampling.
49
Ho, Sai Hang. "Analysis of airborne organic compounds using thermal desorption- gas chromatography-mass spectrometry methods /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20HO.
Testo completo
50
Swartz, Carol Dorothea. "Integrating environmental sampling and wildlife biomonitoring in exposure and effects assessment: genotoxins at multiple levels of biological organization". Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/269.
Testo completoAbstract (sommario):
Ecotoxicology studies attempt to evaluate the consequences of exposure to environmental contaminants by defining exposure and effects parameters across multiple levels of biological organization. Genetic markers are well-suited for these studies as they can track both somatic and evolutionary effects. In the studies reported here, connections among contaminant levels in environmental media and biota, in vitro bioassay results, and changes in individual- and population-level biomarkers were explored. Sediment and/or wildlife samples were collected from each of three sites of documented environmental contamination, Sumgayit and Baku in the Republic of Azerbaijan and East Fork Poplar Creek in Tennessee. Sumgayit and Baku are heavily contaminated with petroleum and petrochemical wastes. Sediments from several areas and tissues from turtles inhabiting a contaminated wetland contained high levels of several compounds, including mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. Sediment extracts produced variable responses in the Salmonella/microsome mutagenicity assay and did not necessarily reflect contaminant burden. Micronucleus counts in European pond turtles were not statistically different from counts in the same species from an uncontaminated reference site. The counts were statistically correlated with tissue levels of mercury, heptachlor, DDD, hexachlorobenzene, and trans-nonachlor. These results confirmed that Sumgayit and Baku are heavily contaminated with a complex mixture of pollutants and demonstrated that genotoxic effects from exposure to contaminated sediments appear to be slight. East Fork Poplar Creek is a stream that receives contaminant influx from a former Department of Energy nuclear weapons production facility and several point and non-point sources around the city of Oak Ridge, Tennessee. In this study, coefficient of variation in cellular DNA content and randomly amplified polymorphic DNA markers were examined in central stonerollers and compared to previous studies in which the same markers were evaluated in red-breasted sunfish from the same sites. While assay responses were attenuated in stonerollers compared to the sunfish, there is some evidence of genetic damage in both species at the most contaminated sampling site. A common problem in the wildlife studies was high within sample variability combined with small sample size, which most likely masked potential contaminant-induced differences in markers used in these studies.