• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 7
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Diffraction and microscopy studies of the structure of amorphous solids

Mountjoy, Gavin January 1995 (has links)
No description available.
2

Health risk assessment of heavy metal/metalloid exposure through multiple foods in China and the validation of a novel biomarker for dietary exposure / 中国における複数の食品からの重金属/半金属曝露の健康リスク評価と新たな経口曝露バイオマーカーの妥当性検証

Gong, Yu 24 September 2021 (has links)
要旨ファイルを差し替え(2022-01-24) / 京都大学 / 新制・課程博士 / 博士(工学) / 甲第23492号 / 工博第4904号 / 新制||工||1766(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 高野 裕久, 教授 松井 康人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
3

Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements

Javed, Muhammad Tariq January 2011 (has links)
Toxic elements are present in polluted water from mines, industrial outlets, storm water etc. Wetland plants take up toxic elements and increase the pH of the medium. In this thesis was investigated how the shoots of submerged plants and roots of emergent plants affected the pH of the surrounding water in the presence of free toxic ions. The aim was to clarify the mechanisms by which these plants change the surrounding water pH in the presence of toxic ions. The influence of Elodea canadensis shoots on the pH of the surrounding water was studied in the presence of cadmium (Cd) at low initial pH (4-5). The involvement of photosynthetic activity in the pH changes was investigated in the presence and absence of Cd. The cytosolic, vacuolar and apoplasmic pH changes as well as cytosolic Cd changes in E. canadensis were monitored. The influence of Eriophorum angustifolium roots on the pH of the surrounding water was investigated in the presence of a combination of Cd, copper, lead, zinc and arsenic at low initial pH (3.5). Eriophorum angustifolium root exudates were analyzed for organic acids. Elodea canadensis shoots increased the pH of the surrounding water, an effect more pronounced with increasing Cd levels and/or increasing plant biomass and increased plant Cd uptake. The pH increase in the presence of free Cd ions was not due to photosynthesis or proton uptake across the plasmalemma or tonoplast. Cadmium was initially sequestered in the apoplasm of E. canadensis and caused its acidosis. Eriophorum angustifolium roots increased the surrounding water pH and this effect was enhanced in the presence of arsenic and metals. This pH increase was found to depend partly on the release of oxalic acid, formic acid and succinic acid by the plants. In conclusion, E. canadensis shoots and E. angustifolium roots were found to increase the low initial pH of the surrounding water. The pH modulation by these species was enhanced by low levels of free toxic ions in the surrounding water. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 4: Manuscript.
4

Investigating the potential correlations between metal and metalloid concentrations and soil color : A Minor Field Study on the island province of Marinduque, Philippines / Undersökning av potentiella samband mellan metall- och metalloidkoncentrationer och markfärg : En Minor Field Study på ö-provinsen Marinduque, Filippinerna

Saric Söderholm, Ivana Pia, Readwin, Erik January 2023 (has links)
This study was carried out as a bachelor's thesis at KTH Royal Institute of Technology during the spring of 2023, investigating the correlation between the color with the concentration of various metal and metalloids (MMs) in the soil of Marinduque, The Philippines. With a history of mineral exploitation, notably copper and gold, the island has faced persistent environmental challenges, exemplified by the catastrophic waste spills in 1993 and 1996 that contaminated the Boac and Mogpog Rivers. These incidents have left lasting consequences on the environment and human health. The research methodology involved an analysis of soil samples collected from Marinduque, using portable equipment such as Olympus Vanta X-Ray Fluorescence (XRF), color scanning using the Nix Pro 2 Color Sensor, followed by data processing through MATLAB version R2023a. The latter involved statistical methods such as Pearson correlation and p-value, which produced correlation coefficients and identified which correlations were statistically significant. The correlations yielded were those between varying MMs concentrations in the soil and CIE L*a*b* soil color parameters across different municipalities in Marinduque. These correlations offer insights into potential causal relationships between arsenic (As), iron (Fe), lead (Pb), manganese (Mn) and zinc (Zn), and soil discoloration. Based on correlations between MMs concentrations and soil color, future studies can encompass a broader range of soil assessment and contamination risks analysis, thus offering valuable guidance to local communities and authorities in devising effective strategies for mitigating MMs pollution in the natural environment. / Denna studie utfördes som en kandidatuppsats vid Kungliga Tekniska högskolan (KTH) under våren 2023 och undersökte korrelationer mellan färg, metalloid- och metallkoncentrationer i marken på Marinduque, Filippinerna. Med en historia av mineralutvinning, särskilt koppar och guld, har ön stått inför pågående miljöutmaningar, såsom katastrofala avfallsutsläpp som förorenat floderna Boac och Mogpog. Dessa händelser har lämnat långvariga konsekvenser för miljön och människors hälsa. Forskningsmetoden omfattade en analys av jordprover från Marinduque, med användning av laboratorieutrustning som röntgenfluorescens (XRF), färgskanning med Nix Pro 2 Color Sensor, följt av databehandling genom MATLAB version R2023a. Den senare involverade statistiska metoder som Pearson-korrelation och p-värde, vilka genererade korrelationskoefficienter och identifierade vilka korrelationer som var statistiskt signifikanta. De erhållna korrelationerna var mellan varierande metallkoncentrationer i jorden och CIE L*a*b* markfärgsparametrar inom olika kommuner på Marinduque. Dessa korrelationer ger insikter i potentiella kausala samband mellan arsenik (As), järn (Fe), bly (Pb), mangan (Mn) och zink (Zn), samt jordfärg. Baserat på korrelationer mellan metalloid- och metallkoncentrationer i mark och markfärg kan framtida studier täcka en bredare räckvidd av risker för markförorening, och därmed erbjuda värdefull vägledning till lokala samhällen och myndigheter för att utveckla effektiva strategier för att minska förorening av tungmetaller i den naturliga miljön.
5

Dinâmica do arsênio no sistema solo - água - arroz na América do Sul: distinções fisiológicas entre cultivares e ocorrência em grãos comerciais / Arsenic dynamics in the system soil - water - rice in South America: physiological distinctions between cultivars and occurrence in commercial grains

Farias, Júlia Gomes 29 February 2016 (has links)
Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Rice is the main source of inorganic arsenic (Asi), a carcinogenic substance, in the human diet. In this sense, there is great interest in reducing the accumulation of As in rice grains. To achive this, field management / rice processing and study of different cultivars have been explored. Globally, many countries that consume rice don t produce it, or even specifics regions of a producer country. As to maintain the rice consumption these regions have to import rice, the identifycation of regions with low As is an important option to ensure food security for the consumers. However, the location of As free areas seems to be an incomplete solution; as there is a large demand for rice and the already considerable number of areas described as contaminated. Thus, it is necessary to use a set of information able to describe As levels in different areas, comparing cultivars, including specific mechanisms of tolerance and low translocation, besides the description of side effects such as levels of other minerals present in the grain and effect of soil management on grain quality. Given the above, this study aimed to evaluate commercial samples of rice in Latin America, as well as samples collected in the field under different managements of water, fertilizer and land use; in addition it was used short-term experiments in greenhouse were performed to evaluate morphophysiological parameters in different cultivars. There is a large discrepancy regarding As concentration among the different regions tested. Although the genetic factor (cultivar) has an effect on As concentration in grain, environmental and management factors are decisive. Apparently the cultivar BR-IRGA 409 presents a large susceptibility to As, also presenting a lower translocation to grains while cultivars described as tolerant had a higher accumulation of this element. The phosphorus use efficiency and the concentration of non-protein thiols appear to be related to tolerance, being highly pronounced in tolerant cultivars. Finally, As has a high potential to genotoxic and oxidative stress, and the main abnormality observed was the presence of micro-nuclei. / O arroz é a principal fonte de arsênio inorgânico (Asi), uma substância cancerígena, na dieta humana. Neste sentido, existe um grande interesse em reduzir o acúmulo do mesmo em grãos. Para tal, a gestão a campo, criação/modificação no processamento de arroz e estudo com diferentes cultivares vêm sendo explorados. A nível global, muitos países que consomem arroz não produzem o mesmo, ou mesmo regiões dentro de um país produtor. Visto que para manter o consumo tais regiões importam arroz, a identificação de regiões com baixa concentração de As é uma importante opção para a salubridade dos consumidores. Entretanto, a localização de pequenas áreas livres ou com baixas concentrações de As não parece ser a solução completa para a contaminação observada em alimentos; visto a grande demanda de arroz e o número já considerável de áreas descritas como contaminadas. Desta forma, faz-se necessário o uso conjunto de informações como a descrição dos níveis de As em diferentes áreas, comparação entre cultivares, incluindo mecanismos específicos de tolerância e baixa translocação, além da descrição de efeitos secundários como nível dos demais minerais presentes no grão e efeito do manejo da cultura na qualidade de grãos. Visto o exposto, o presente estudo teve por objetivos avaliar amostras comerciais de arroz da América Latina, bem como amostras coletadas a campo sob diferentes manejos de água, fertilizantes e uso do solo; além de utilizar experimentos de curta duração em casa de vegetação para avaliar parâmetros morfofisiológicos em diferentes cultivares. Existe uma grande discrepância na concentração de As nas diferentes regiões testadas. Embora o fator genético (cultivar) tenha efeito sobre a concentração de As em grãos, os fatores ambiente e manejo são determinantes. Aparentemente, a cultivar BR-IRGA 409 apresenta uma maior suscetibilidade ao As, apresentando também uma menor translocação para os grãos, enquanto que cultivares com comportamentos tolerantes apresentaram um maior acúmulo deste elemento. A eficiência de uso de fósforo e a concentração de tióis não proteicos parecem estar relacionadas à tolerância ao As, sendo altamente pronunciadas em cultivares tolerantes. Finalmente, o As apresenta alto potencial genotóxico e oxidativo, sendo a principal anormalia observada a presença de micro-núcleos.
6

Transferts des métaux et métalloïdes dans le système sol-plante-atmosphère : mécanismes biogéochimiques et conséquences environnement-santé / Transfers of metals and metalloids in the soil-plant-atmosphere system : biogeochemical mechanisms and environmental-health consequences

Mombo, Stéphane 27 October 2016 (has links)
Des pollutions des sols (péri)urbains et urbaines fortement peuplées en métaux et metalloïdes persistants (éco)toxiques sont couramment observées à l’échelle globale. Certains éléments (Se, Cu…) ont des rôles biologiques et par contre d’autres (Pb, Cd…) ont uniquement un impact (éco)toxique qui peut être influencé par leur spéciation et compartimentation qui modifient leurs transferts et biodisponibilité. Dans une optique de gestion des sols et d’alimentation durables, des questions scientifiques pluridisciplinaires sont à creuser concernant : (i) les mécanismes en jeu dans la biodisponibilité et l’impact sur les organismes vivants des éléments inorganiques en lien avec leur spéciation ; (ii) la co-gestion des risques environnement-santé induits par des installations industrielles classées : ICPE en France (ex. usine de recyclage de batteries) avec les riverains qui cultivent des potagers ou les employés. Dans ce contexte, ont été étudiés : (i) le transfert des métaux entre phase solide et solution du sol sous l’influence des vers de terre sur un site ICPE; (ii) le transfert et la bioaccessibilité du Se en conditions contrôlées pour 2 formes chimiques; (iii) le risque sanitaire pour les riverains d’un site ICPE qui jardinent, et les facteurs influant les plombémies des professionnels (étude statistique des données). Une review bibliographique de la qualité du manioc en lien avec les pratiques culturales et culinaires et les caractéristiques de l’environnement a finalement été réalisée pour compléter la démarche « Sciences et Société » de la thèse. L’analyse des différents isotopes du plomb dans les sols aux alentours de l’usine de recyclage a permis de conclure que 84 à 100% du plomb des sols de surface est d’origine anthropique. Un comportement d’évitement des zones les plus polluées en plomb a été observé pour l’espèce de vers de terre A. caliginosa. Le transfert racinaire, la translocation du sélénium vers le maïs et sa bioaccessibilité dans le grain sont plus élevés dans le cas du séléniate (facteur de translocation de 1.1, et bioaccessibilité humaine de 89,3%) par rapport au sélénite (0.13, et bioaccessibilité de 82,7%). L’étude de la qualité des cultures des jardins proches de l’usine (à Bazoches), en relation avec la qualité du sol (faible contamination, pH basique et teneur élevée en matières organiques qui réduisent les transferts) et de l’atmosphère a mis en évidence un transfert atmosphère-plante qui dépend du métal (le Cd est le plus biodisponible) et du végétal. Les concentrations en Pb et Cd suivent respectivement les séquences : [laitue>poireau>céleri>carotte] et [laitue>céleri>carotte>poireau]. Pour réduire l’exposition des populations, un lavage soigneux des productions avant la consommation est préconisé. / Pollution of (peri)urban soils by (eco)toxic metal(loid)s is commonly observed on a global scale. Some elements (Se, Cu ...) have biological roles and other (Pb, Cd ...) only have an (eco)toxic impact influenced by their speciation and compartmentalization that can change their transfers and bioavailability. With the perspective of sustainable management of soil and food, multidisciplinary scientific questions are digging for: (i) the mechanisms involved in the bioavailability and impact on living organisms of inorganic elements related to speciation; (ii) the co-management of environmental-health risks from industrial regulated plants (ICPE in France, such as former battery recycling plant) with residents who grow vegetable gardens or employees. In this context, were studied: (1) the transfer of metals between solid phase and soil solution under the influence of earthworms on a ICPE site; (2) the transfer and bioavailability of Se in controlled conditions for two chemical forms; (3) the health risk for the residents with gardening activities near ICPE plant and factors influencing blood lead of professionals (statistical analysis of data). A literature review of the quality of cassava in connection with the cultivation and culinary practices and characteristics of the environment was finally performed to complete the "Science and Society" process of the thesis. From the analysis of different isotopes of lead in the soil around the recycling plant it was concluded that 84 to 100% of lead in surface soils has anthropogenic origin. Avoidance behavior in the most lead polluted areas was observed for A. caliginosa earthworm species. The selenium root transfer, translocation to corn and its bioavailability in the grain are higher in the case of selenate (translocation factor of 1.1, and human bioavailability of 89.3%) compared to selenite (0.13 and bioaccessibility 82.7%). The study of crops quality in the gardens near the ICPE plant (in Bazoches), in relation to atmosphere and soil quality (low Pb contamination, alkaline pH and high organic content that reduce pollutants transfers) highlighted an atmosphere-plant transfer which depends on the metal (Cd is the most bioavailable) and plant species. Pb and Cd concentrations follow respectively the sequences: [lettuce> Leek> celery> carrot] and [lettuce> celery> carrot> leek]. To reduce population exposure, thorough washing of productions before consumption is recommended.
7

Odstraňování olova i jiných kovů z vody / Removal of lead and other metals from water

Šopíková, Lucie January 2015 (has links)
This work covers the topic of metals and semimetals in water. It is divided into three parts. First, each element is characterized by its properties and behavior in water. Incidence in the environment, utilization and effects of intake on human body are described for each element. Second, means of elimination from water are introduced. Different chemical, mechanical and biological methods are discussed. In greater detail, precipitate method, cementation, electrochemical processes, sorption and biosorption are reviewed. Third, hands-on filtration experiment of polluted water with the help of different filtration materials is included. This experiment was done in a laboratory belonging to the Institute of Municipal Water Management, Faculty of Civil Engineering, Brno University of Technology.

Page generated in 0.0455 seconds