In order to gain a better understanding of the mechanism of As(V) tolerance in rice, a number of hydroponic tolerance tests have been done on the interaction of As(V) with phosphate (PO₄^3-), reduced glutathione (GSH) and O₂ supply.  The PO₄^3—As(V) interaction test revealed that increasing PO₄^3- concentration reduces the toxicity of As(V).  Low PO₄^3- (0.05 mM) showed no protection against As(V) induced root inhibition, but higher PO₄^3- (0.5 and 5 mM) showed marked protection, suggesting PO₄^3- derived tolerance is not due to reduced PO₄^3- transport that has been postulated in other grass species.  The glutathione (GSH)-As(V) interaction test revealed a strong effect of GSH, increasing tolerance in rice.  The O₂ supply test also revealed a significant effect with enhanced tolerance in rice.  Therefore it can be suggested that PO₄^3-, GSH and air bubbling supply all reduces As(V) toxicity in rice by increasing tolerance.  The protection against As(V) provided by GSH and PO₄^3- were not the same for two rice varieties, Azucena (As sensitive) and Bala (As tolerant).  However these tolerance tests cannot explain why Azucena and Bala differ in susceptibility to As(V).  Three green house pot experiments revealed that As(V) treatment reduces growth in dose dependent way.  Total As concentration in the shoots and grain increases with the increasing concentration of the As(V) treatments.  Surprisingly, application of PO₄^3- does not alter As(V) toxicity.  Anaerobic (lowland) soil shows higher shoot As concentration but uptake is lower.  Rice genotypes show significant variation in their plant growth, total shoot As concentration and total As uptake which reveal that tolerant genotypes contain higher shoot As. Results of the hydroponics and pot experiments suggested that tolerance of rice is not derived from competition with As(V) at the PO₄^3- transporters, but rather reflects another, as yet unknown, mechanism.

This is the first study to compare total arsenic (As) and other trace elements in the agricultural soils and grain of Eastern, Western and Southern Libya, North Africa and the Middle East (NA &amp; MIDEA). Soil pot experiments and field experiments were conducted to determine the levels of As within wheat grains in Libya. In the soil pot experiments, wheat genotypes were planted in similar soils and yet differences in grain As concentration were found among the cultivars. The highest As accumulation was found in <i>T. durum; </i>however, in the field data the highest levels were found in <i>T. aestrivum.</i> The levels of As and other trace elements found in agricultural soils from the Eastern Western and Southern regions of Libya are examined. Mean As concentrations in the clay mineral agricultural soils of the Eastern Region were nearly 4.8 and 4.1 times higher than in the southern and western regions, respectively. It is possible that the parent material of that region contains elevated levels of As, which are then exhibited in the overlying soil. Differences in the levels of As and other trace elements found in the irrigated agricultural soil of Southern Libya were compared with non-irrigated soil from the same region.  Concentrations of P, Zn and As in soil were higher in irrigated compared to non-irrigated soils, while the concentration of Cd is nearly the same in all soil samples. A market basket investigation was conducted to determine the total levels of As and Se in rice purchased from supermarkets. The average level of As in rice from NA &amp; MIDEA is 0.22 mg/kg, comparable with average levels in Australia.

Objective: To compare the knowledge of mothers on food contamination in the home between the towns of Peru and Costa Rica. Methods: It was conducted in a rural area of Peru (San Pablo and Huascar) in San Juan de Lurigancho in Lima, and Costa Rica (San Vicente of Three Rivers). The questions were part of a scale that was validated on an expert opinion. It was developed to measure three components or domains.After validation,the instrument was applied in Costa Rica with a group of mothers or caregivers with children under five. The application was developed in Peru in a population with similar characteristics. Results:The sample consisted of 50 caregivers in Costa Rica and 194 in Peru. There is no significant difference in the domains of contamination utensils at home (p=O.750>0.05) and knowledge of child illness (p=0.060>0.05). Knowledge of agents of contamination was highly significant (p=0.000<0.01). In general there is enough evidence to say that knowledge of food contamination in the home are different in mothers of Peru and Costa Rica, (p=0.013 <0.05). Conclusions: No significant differences on pollution and disease. There is highly significant difference in knowledge about pollutants. Overall knowledge of food contamination in the home were higher in mothers or caretakers of Peru.The scale can contribute to the planning of interventions in the aspect of pollution in the home. / michellelozadau@gmail.com / Objetivo:Compararelconocimiento de las madres sabre Ia contaminaci6n de los alimentos en elhagar entre las poblaciones de Peru y Costa Rica. Metodos:Se llev6 a cabo en una zona rural de Peru (San Pablo y Huascar) en San Juan de Lurigancho en Lima,yen Costa Rica (San Vicente de Tres rfos).Las preguntas formaron parte de una escala que fue validada bajo un juicio de expertos. Se elabor6 para medir tres componentes o dominies. Despues de Ia validaci6n, el instrumento fue aplicado en Costa Rica a un grupo de madres o cuidadoras con nifios menores a cinco anos. La aplicaci6n en Peru fue desarrollada en una poblaci6n con caracteristicas similares. Resultados: La muestra fue de 50 cuidadoras en Costa Rica y 194 en Peru. No existe diferencia significativa en los dominies sabre contaminaci6n por utensilios en el hagar (p=O,750>0,05) y por conocimiento sabre enfermedades del n1no (p=0,060 >0,05). El conocimiento sQbre agentes de contaminaci6n result6 ser altamente significative (p=0,000<0,01). En generalexiste evidencias suficientes para afirmar que el conocimiento de contaminaci6n de los alimentos en el hagar son diferentes en las madres del Peru y Costa Rica, (p=0,013<0,05). Conclusiones: No existen diferencias significativas sabre contaminaci6n y enfermedades. Existe diferencia altamente significativa en el conocimiento sabre agentes contaminantes.En general el conocimiento de contaminaci6n de los alimentos en elhogarfueron mas altas en las madres o cuidadoras del Peru. La escala puede contribuir a Ia planificaci6n de las intervenciones en elaspecto de contaminaci6n en elhagar.

The US-Mexico border divides the communities of Palomas, Chihuahua and Columbus, New Mexico, but they remain intimately linked. Both communities suffer from inadequate social services, poor public infrastructure, high unemployment and high poverty rates. To confront these challenges, Palomas and Columbus work together, sharing resources like hospitals, firefighters, and even schools. Palomas and Columbus also share another vital resource—groundwater. In the parched Chihuahuan desert, the communities depend on this groundwater as their sole water supply source, yet their aquifer is contaminated with arsenic and fluoride. Local governments acknowledged this contamination as early as the 1970s, but it was not until the 2000s that they received the needed reverse osmosis technology and water/wastewater infrastructure to ameliorate household exposure to water contamination. This thesis compares how Columbus and Palomas have addressed water insecurity over a twenty-year period from 1996-2016, using a 1996 study as the baseline (Tanski et al. 1998). New data include a household survey of 152 households, 60 semi-structured interviews, and participant observations of water practices collected during two months of fieldwork in the summer of 2016. The central research questions of this thesis are Q1) What causes household water insecurity on the US-Mexico border? and Q2) How can water policymakers and providers more equitably provide users with access to clean, reliable, and affordable drinking water? From a human development perspective, water security is defined as having an adequate supply of reliable and affordable water for a healthy life. This thesis uses a political ecological lens to more critically examine how water security connects to socio-political processes of water governance and power imbalances. Following Jepson (2014), this thesis argues that water (in)security is produced by problems in water access, water quality, and water affect (or water distress) and unfolds within a complex, hydrosocial landscape. Applying Jepson’s (2014) water security typology to Columbus and Palomas revealed that each local water utility adopted a distinct approach to addressing groundwater contamination, predicated on their financial and social resources, and structured by national and bi-national water policies as well as their institutional parameters. The survey found household water security has improved in terms of water access and reliability. But, centralized water filtration technology increased costs and reduced affordability in Columbus, while decentralized water filtration technology inadequately resolved household water supply contamination in Palomas. Thus, despite the technological improvements, households remain unevenly exposed to water contamination and costs. This raises concern about approaches to water security, which should be more finely attuned to water equity. Water equity means the rights to access clean water are more equitably distributed within the communities, and there is greater recognition/participation of community members in decision making on water management.

Phytostabilization offers a less expensive alternative to traditional cap and plant methods for containing metalliferous mine tailings to prevent wind erosion and contamination of nearby communities and the environment. However, plant establishment during phytostabilization of pyritic legacy mine tailings in semiarid regions is challenging due to particularly extreme conditions including low pH, low organic carbon, low nutrients, and high toxic metal(loid) concentrations. Microorganisms drive major biogeochemical cycles in soils, however, the roles microorganisms play at the root – soil interface during phytostabilization, particularly in relation to plant health and metal immobilization, are not yet fully understood. The aims of this dissertation are to focus on bacterial communities associated with the roots of buffalo grass used in the phytostabilization of pyritic metalliferous mine tailings to: i) characterize bacterial diversity and communities of rhizosphere and bulk substrate, ii) delineate associations between rhizoplane bacterial colonization patterns and environmental and plant status parameters, and iii) develop an in situ method to visually assess associations between roots, bacteria, and metals. Key findings indicate that after addition of a compost amendment to alleviate the plant-growth inhibiting characteristics of mine tailings, rhizosphere and bulk substrate contain a diverse, plant-growth supporting bacterial community. As substrate re-acidifies due to compost erosion, an emergence of an iron (Fe)- and sulfur (S)-oxidizer and Fe-reducer dominated, less diverse community develops in the bulk and rhizosphere substrate, thus posing a threat to successful plant establishment. However, even at low pH, some plant-growth-promoting bacteria are still evident in the rhizosphere. On the rhizoplane (root surface), the relative abundance of metabolically active bacteria was positively correlated with plant health, verifying the strong association between plant health and bacteria. Furthermore, pH showed a strong association with the relative abundance of Alphaproteobacteria and Gammaproteobacteria on the rhizoplane. In relation to microbe-metal interactions on the root surface, results showed that Actinobacteria and Alphaproteobacteria colocalized with Fe-plaque and arsenic (As) contaminant on the root surface, indicating their potential role in adsorbing or cycling of these metal(loid)s. Developing a more thorough understanding of bacteria-root-metal interactions in relation to plant health and metal immobilization can help to improve phytostabilization efforts and success.

Sawmills which conducted dipping operations is a breach where previously used chemicals mean that you generally can expect to find contaminated areas. To investigate contaminated areas the Swedish environmental protection agency developed a method for investigation of polluted areas (MIFO). The purpose of a MIFO analysis is to provide a unified approach and risk classification system for polluted areas. The aim of this thesis it to perform a soil survey according to MIFO phase 2 (general investigations) at the former sawmill in Lövsele, Västerbotten county. The study is based on assumptions about the presence of dioxins in the area, due to the previous use of the wood preservative Ky-5. Dioxins are dangerous substances and are considered poisonous for both humans and the environment. The field study was conducted 30 September 2016 in 8 selected points where the greatest risk to find dioxins were considers to exist after completion of background investigations. 9 samples were the chosen for analysis by ALS Scandinavia AB. The completed analysis shows that pollution levels above the guideline values of both sensitive land use (KM) and less sensitive land use (MKM) were discovered in 7 out of 9 analyzed samples. The MIFO analysis was conducted to answer questions about the pollution hazards, pollution level, distribution conditions and the sensitivity and protection value in the area. The result of the MIFO-analysis is evaluated as class 1, very high risk to human health and the environment. Further studies should therefore be conducted to determine the pollution situation in the area and to provide data for remediation measures to reduce the risk to human health and the environment.

Healthcare acquired infections (HAIs) are a complex and multi-factorial problem associated with high morbidity, mortality, and cost. Toothbrushes (TBs) may be at risk for contamination with potential pathogenic microorganisms (PPMs) from the patient care environment or autoinnoculation from the patient. We focused on three PPMs: multiply resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus (VRE), and Acinetobacter. Specific aims were to (1) describe environmental factors associated with TB contamination in the ICU; (2) describe the relationship between TB contamination and oral colonization in critically ill adults.

Understanding the impacts of explosive contamination on vegetation is key to understanding explosives behavior in the environment. I quantified shrub growth responses to 1,3,5-trinitroperhydro-1,35-triazine (RDX) soil contamination across three life stages and I hypothesized that RDX would have the greatest impact on seed germination. Morella cerifera seeds were germinated on soils amended with RDX up to 1500 mg RDX kg-1 dry soil. Juvenile and adult individuals were exposed for 6 weeks to soil amended with RDX up to 750 and 1500 mg RDX kg-1 dry soil, respectively. Morphological responses were quantified for juveniles while physiological measurements were quantified for adults. RDX induced a significant response in all age groups and, in accordance with the hypothesis, germination was the most impacted of the three stages. Impacts varied by concentration in addition to life stage, showing that many variables influence plant response to RDX.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.