Since the relatively recent discovery of elevated concentrations of contaminants such as mercury and persistent organic pollutants in the Arctic, Inuvialuit have been receiving information about the potential impacts of these contaminants on the environment, wildlife, and human health. Almost 20 years of communication efforts have resulted in only a general awareness of contaminant issues, as the focus on perceptions of message content has overlooked the important impact of communication processes (methods, sources) on message reception, understanding, and acceptance. For this research, interviews, focus groups, and informal conversations were used to explore the myriad of contaminant perceptions and associations held by Inuvialuit in Sachs Harbour, NT, as contaminants were used as a case example to investigate perceptions of and recommendations for science communication. Concepts of respect, time, and relationships influenced the inter-related impressions of communication processes and research/researchers (the mediums), which in turn influenced perceptions of contaminants among participants. The medium is thus an important part of the message in scientific communication, and is implicated in the conduct of research and research communication in small, remote Arctic communities.

To attract more customers and compete with other modes of transportation, railway transport needs to ensure safety, punctuality, high comfort, and low cost; wheel–rail adhesion, i.e., the transmitted tangential force in the longitudinal direction during driving and braking, plays an important role in all these aspects. Adhesion needs to be kept at a certain level for railway operation and maintenance. However, wheel−rail contact is an open system contact. Different contaminants can present between the wheel and rail surfaces, forming a third-body layer that affects the adhesion. Prediction of wheel–rail adhesion is important for railway operations and research into vehicle dynamics; however, this prediction is difficult because of the presence of contaminants. This thesis deals with wheel–rail adhesion from a tribological perspective. The five appended papers discuss wheel–rail adhesion in terms of dry conditions, lubricated conditions, leaf contamination, iron oxides, and environmental conditions. The research methodologies used are numerical modelling, scaled laboratory experiments, and field tests. The research objective is to understand the mechanisms of the adhesion loss phenomenon.  A numerical model was developed to predict wheel–rail adhesion based on real measured 3D surfaces. Computer simulation indicates that surface topography has a larger impact on lubricated than on dry contacts. Plastic deformation in asperities is found to be very important in the model. Ball-on-disc tests indicate that water can give an extremely low adhesion coefficient on smooth surfaces, possibly due to surface oxidation. Investigation of lubricated contacts at low speed indicates that oil reduces the adhesion coefficient by carrying a normal load, while adhesion loss due to water depends on the surface topography, water temperature, and surface oxidation. A field investigation indicates that leaves reduce the friction coefficient because of the chemical reaction between leaves and bulk materials. The thickness of the surface oxide layer was found to be an essential factor determining adhesion reduction. Pin-on-disc experiments found a transition in the friction coefficient with regard to the relative humidity, due to a trade-off between the water molecule film and the hematite on the surface. / <p>QC 20131031</p>

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 122-129). Also available on the World Wide Web.

The production of engineered nanoparticles (ENPs) is growing at an incredibly fast rate and will soon become a trillion dollar industry. At this rate of production, there is a great potential for engineered nanomaterials to be released into the environment, both intentionally and unintentionally. TiO2 ENPs are one of the most widely produced nanoparticles with a broad range of applications in paints, inks, sunscreens, cosmetics, astronautics, and air/water purification. TiO2 ENPs have been proposed for their use in agricultural settings as a UV protectant, a defense against harmful bacteria and fungi, or a catalyst for the degradation of pesticides and herbicides. Furthermore, it has been shown to increase several aspects of photosynthesis in spinach including Rubisco and Rubisco activase activity, chlorophyll synthesis, and oxygen evolution. Foliar application of TiO2 ENPs on spinach resulted in a significant increase in plant fresh weight, dry weight, chlorophyll content, net photosynthetic rate, and carboxylase activity of Rubisco. These findings have prompted investigations for the use of TiO2 ENPs as a foliar spray to promote plant growth and yield. The first main objective of this research was to determine if TiO2 ENPs has the capabilities to increase photosynthetic production in Zea mays at concentrations similar to that of the experiments performed with spinach. Secondly, it was examined if the size of the TiO2 was a factor in the increased photosynthetic response by comparing TiO2 ENPs with bulk TiO2. Finally, the determination of whether the boost in photosynthesis resulted in an increased seed quality/quantity. Another aspect of this research was to determine how the interaction of TiO2 ENPs with inorganic contaminants may affect the uptake and accumulation of the contaminants in plants. Cadmium and arsenic are two of the top ten most hazardous substances on the priority list of the Agency for Toxic Substances and Disease Registry. Sources for Cd and As contamination include atmospheric deposition resulting from mining, smelting, and fuel combustion, phosphate fertilizers, and sewage sludge. Both of these contaminants can be taken up by plant roots and translocated to the leaves and fruits, thus entering the food chain. The release of TiO2 ENPs into domestic and industrial wastewaters is expected to represent the largest release of these nanoparticles. There has been data showing that up to 99% of TiO2 ENPs that enter wastewater treatment plants are retained in the sludge. In addition, TiO2 ENPs are being used at some water treatment plants because of their strong adsorption strength for hazardous materials, such as cadmium, arsenic, and copper and also the photocatalytic breakdown of harmful organic compounds. Since sewage sludge from wastewater treatment plants is applied to agricultural lands as a soil conditioner and fertilizer, this has resulted in the introduction of an estimated 120 g kg-3 per year of TiO2 ENPs. With sewer sludge being the common factor for contamination of agricultural fields, there is a high potential for the simultaneous introduction of TiO2 ENPs and heavy metal contaminants. To date, there has been very little research done for ENP and contaminant interactions. Of the research that has been performed on the subject, the majority of it was conducted using aquatic systems involving fish and daphnids. This research has shown that the interaction of TiO2 ENPs and metal contaminants generally increases the concentration of the contaminant in the organism, however it is still unclear whether the contaminant is biologically available or if it is adsorbed to the surface of the TiO2 ENPs. This information gives rise to two alternative hypotheses on how TiO2 ENPs may affect the fate of heavy metal contaminants in a single substrate growth media. The first is that the TiO2 ENPs may sequester the heavy metals in the soil thus decreasing the amount of the heavy metals that can be taken up by the plant. The alternative is that the TiO2 ENPs could act as a carrier of the metals i.e. if the plant is able to take up the intact TiO2 ENP with heavy metals adsorbed to the surface, it could potentially increase the amount of the metals that enter the plants. The main objective of this study was to determine which of these scenarios is true for broccoli plants that were grown in cadmium and arsenate contaminated growth media.

This study characterizes 21 wastewater samples collected from Al-Amal hospital between the period of 12 April till 8 July 2020. Al Almal is a hospital that provides drug addiction and psychological treatment to patients. Using solid-phase extraction and liquid chromatography with tandem mass spectrometry (LC-MS/MS), chemical contaminants profiles in these wastewater samples were determined in a non-targeted manner. These chemicals were then individually analyzed in an in-silico manner by checking against databases and literature to determine if they were mutagenic. By determining the proportion of mutagenic chemicals against the non-mutagenic ones, we aim to determine if untreated hospital wastewater may potentially negatively impact the downstream municipal biological wastewater treatment process. It was determined that 64% of the identified chemicals were not tested for their mutagenic effect, and hence no prior information is available in the literature and databases. Instead, we further performed in-vitro mutagenicity tests using Ames test to determine if the wastewater sample, with all of its chemical constituents, would be mutagenic. Ames test results showed that majority of the samples were non-mutagenic except for 1 sample that imposed a mutagenic effect on Salmonella enterica serovar Typhimurium TA98 and 3 samples with mutagenic effect on TA100. In addition, 1 sample showed a toxic effect on TA100. However, in all 5 instances, these samples only imposed a mutagenic and toxic effect at high concentrations of > 10x. The findings in this study suggest that a specialty hospital like Al Amal does not contribute substantially to mutagenic wastewater streams to the municipal sewer, and hence unlikely to significantly perturb the downstream biological treatment processes. However, there may still be a need to consider ad-hoc contributions of mutagenic and/or toxic wastewater streams from the hospitals.

<p>Nitrate is one of the most common groundwater contaminants, with levels commonly exceeding established drinking water limits. In areas of high agricultural or industrial nitrate use, nitrate contaminated groundwater poses a potential health risk. In situ denitrification is the microbially mediated reduction of nitrate to innocuous nitrogen gas compounds and is the principal process for nitrate removal in contaminated aquifers. This process is becoming increasingly recognized for its ability to reduce or eliminate nitrate concentrations in groundwater with minimal site disturbance and cost. Predicting the extent to which denitrification occurs in aquifers as well as the rate, therefore, has become the focus of numerous mathematical models. However, the predictive capabilities of numerical models are constrained because knowledge of the biological processes implicated in denitrification is limited.</p> <p>This report examines the microbial processes involved in <i>in situ</i> denitrification, and then applies this knowledge to assess the capability of a two-dimensional numerical model, NBI02D. NBI02D is a variation of a code, SEAM2D, developed by Widdowson (1988,1992).</p> <p>Model development and model application are presented. The model development overview provides insight to the mathematical methods used to simulate the microbial processes. The model application compares model predictions with data received from a USGS research site on Cape Cod, Massachusetts. Data are derived from a natural gradient experiment in which formate was injected into a carbon-limited aquifer in order to stimulate and accelerate denitrification. NBI02D simulations for the Cape Cod site are developed for model verification and model applicability.</p> / Master of Science

Problem and its importance: Starter is the "heart" of the cheese making industry. only by proper handling of starter can good quality cheese be made. The economic loss from contaminated starter may prove disastrous to a cheese plant if proper corrective measures are not taken. Milk usually contains a variety of bacteria. Under plant conditions some of these bacteria get into the mother starter or bulk starter unless extreme caution is used. Comparatively little is known about how one organism influences another when grown in milk. This problem is important in the cheese industry. Purpose: The purpose of this research project is to determin the effect of some common contaminants on cheese starters. Some of the off flavors and slow acid production found in cheese making may be due to the results of contaminant organisms growing with the starter organisms. If this be true, more information on this subject will prove valuable. Some organisms have detrimental effects on milk. The question arises: What will two different organisms do when grown together in milk? Streptococcus lactis is important in the cheese industry because it satisfactorily produces the acid necessary in cheese making. If some organism inhibits or stimulates this acid production when grown with Streptococcus lactis, it is important that the cheesemaker know this. Scope: Only those contaminants commonly found in dairy products are considered in this project. Simulated plant conditions are used; that is, the starter being tested is contaminated one evening and the results checked and read the next day. Commercial lactic acid cheese starter from the Hansen's Laboratories and milk from the Utah State Agricultural College Creamery are used to propagate the starter. Different percentages of the contaminant are added to the starter to determine the effects of varying numbers of the contaminant on the starter organisms. A control starter is incubated and tested along with the contaminated starter. After the starters have been incubated at 70°F. Overnight, the following tests are run on each one: activity, acidity, pH, creatine, odor and appearance, and microscopic count. Starter vitality may be determined by the above tests; however, these do not indicate how the contaminant organisms affect cheese when carried on into the cheese making process. Therefore, this project is limited to the effects of contaminants on the starter and not on cheese. This latter problem is reserved for future investigators.

Electronic cigarettes are a recent trend that has spark interest in young adults and teens. Due to the recent growth of electronic cigarette companies and their low manufacturing costs, this has allowed the entry-level price point to be drastically low allowing for teens and adults to become users. These products deliver an addictive dose of nicotine and, in the last years, have caused unexpected pulmonary complications that have often resulted in hospitalization. This project is a three-part study that aims to identify contaminants, nicotine concentration, and the psychological reasoning behind vaping. The first part of the study is a statistical overview of the population of students that do smoke and the psychological reason for them starting. This study focuses on the students at University of Central Florida. The second part is the utilization of analytical methods to determine the nicotine concentration and identify any contaminants found in electronic cigarette liquids. This part utilizes gas chromatography-mass spectrometry (GCMS). Additionally, all chemicals that are identified using the GCMS are thoroughly reviewed to determine its usefulness in the electronic cigarette liquid and its effect on the human body. Acid-base titrations are used by many companies and by avid "DIY" vape users to determine the nicotine concentration in the liquid that has been manufactured. This method is very inaccurate and can only give a rough estimate of the nicotine concentration. The third part uses acid-base titrations to determine the nicotine concentration of the electronic cigarette liquids and compare them to the analytic data found in the previous test that utilizes gas chromatography.

No description available.

Environmental quality and emissions guidelines are implemented due to their expected benefit for human and environmental health. However, implementation of such legislation requires knowledge of the behaviour and fate of the contaminants to be controlled. This thesis contributed to the overall understanding of atmospheric PAH deposition to remote lakes and the role atmospherically deposited contaminants play in site assessments which account for environmental pollution due to industry. In chapter 2, atmospheric PAH deposition derived from regional energy generation or industrial sources was found to be decreasing in recent sediments from Siskiwit Lake, Michigan, U.S.A. Considering that Siskiwit Lake is isolated from traffic and development, this supports recent theories which suggest that regional PAH deposition is being overprinting by local traffic sources in sub-urban or urban areas. This study also contributed to the understanding of perylene production in sediments by conclusively demonstrating increases in sedimentary perylene concentrations over a 20 year period. Moreover, kinetic modeling using 1st and 2nd order rate laws failed to accurately predict the concentration changes observed despite rate constants that were similar. This strongly suggested that perylene does not follow a simple concentration dependant kinetic reaction and is more likely controlled by complex kinetics perhaps involving biology. In chapter 3, the superiority of contaminant profiles in sediment cores over current dredge or grab sampling techniques was demonstrated. This was shown by successfully apportioning the source of contaminants to a northern lake as atmospheric deposition rather than point source release from the adjacent industrial facility. Contaminant profiles are able to constrain concentration changes with time and thus atmospheric deposition and point source contributions can be recognized. This is essential as chapter 3 also demonstrated that atmospheric deposition has the potential to produce sediment concentrations at or above current federal guidelines using standard dredge sampling techniques. Without the use of contaminant profiles these exceedences may be attributed incorrectly to industry which may face remediation costs or other fines associated with environmental contamination. This has implications for redefining sediment quality guidelines or currently accepted sampling methods. Moreover, remediation efforts for atmospherically deposited contaminants must differ from a point source release. Site remediation would be effective for a single release of contaminants however with a continuous source, as is the case with atmospheric deposition, remediation efforts must be focussed on the atmospheric contaminant emissions which can be a large distance from the site. / Thesis / Master of Science (MSc)