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  • 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.
81

Impact of Phosphorus and Trace Elements on Methane Oxidation in Lakes

Lundqvist, Lexa, Unnerfelt, Saga January 2024 (has links)
Methane (CH4) is a potent greenhouse gas contributing to the warming of Earth's atmosphere. Lakes are a natural source of CH4, where CH4 generally is produced in oxygen depleted sediments. Ebullitive CH4 is regulated naturally in the oxic-anoxic interface of lakes by methane oxidizing bacteria, methanotrophs uses CH4 as a substrate when O2 is present. Lakes in boreal regions are among the largest sources of CH4 emissions, CH4 oxidation can mitigate some of the CH4 emissions from lakes. Gaps in knowledge and data remain regarding net fluxes of CH4, indicating that there are processes unaccounted for. Previous research highlights the variability of CH4 emissions and oxidations rates in lakes, there is lacking knowledge on what drives the variability of oxidation rates and total emissions. It’s been suggested that availability of phosphorus (P) has a positive relationship with increased oxidation rates. Moreover, availability of trace elements has been suggested to affect aerobic CH4 oxidation, but there is a lack of knowledge on these factors in natural lake waters. In this study incubations with lake water from two different lakes, Gårasjön and Kisasjön, were prepared with different treatments of P and/or trace elements. We investigate how this can affect the rate of CH4 oxidation when incubated in specific conditions. Our results indicate that treatments with added P had a greater tendency to exhibit higher rates of methane oxidation in both lakes, while treatments with trace elements and P had varied oxidation rates depending on the lake. This suggests that when there are no limitations of the substrates CH4 and O2, the oxidations rates in lakes might be limited by the availability of P and the specific lake conditions can influence CH4 oxidation.
82

Valorization of Citrus spp. Cultivars cultivated in Sicily for the industrial use of citrus derivatives and in particular for potential alternative uses of essential oils for the enhancement of the island's citrus production

Ioppolo, Antonino 17 January 2021 (has links)
[ES] En esta tesis doctoral se discuten una serie de cuestiones científicas relacionadas con a la producción y el procesamiento de algunas especies de cítricos de especial relevancia en Sicilia y en el área mediterránea. Los objetivos se centran en estudiar la trazabilidad y sostenibilidad de la producción de algunas especies de cítricos, así como encontrar nuevas aplicaciones a los subproductos y productos de desecho de la industria, con el fin de mejorar su rentabilidad. Por lo tanto, los temas que se desarrollarán serán los siguientes: caracterización de los compuestos bioactivos presentes en aceites esenciales y en el hidrolato de diferentes especies de cítricos; seguimiento del efecto del estrés hídrico controlado sobre la producción de aceites esenciales en hojas y flores del cv. Sanguinelli de Citrus sinensis y del cv. Clemenules de Citrus reticulata; estudio de los efectos fitotóxicos de los aceites esenciales en cuatro especies arvenses importantes en el área mediterránea, dos monocotiledóneas (Echinochloa crus-galli (L.) P.Beauv. y Avena fatua L.) y dos dicotiledóneas (Amaranthus retroflexus L. y Portulaca oleracea L.) mediante experimentos in vitro e in vivo; estudio del efecto bioestimulantes de las aguas residuales de la industria procesadora de cítricos sobre la comunidad microbiana del suelo; cuantificación de elementos de tierras raras en frutos de limón cultivados en diferentes áreas geográficas, para su posible uso como trazador geoquímico. Los principales resultados obtenidos son la caracterización de diferentes aceites esenciales, de los cuales los producidos por los residuos de la poda podrían ser utilizados como método de extracción de nuevos aceites esenciales con alto rendimiento. También se han encontrado sustancias nutracéuticas y farmacológicas en los hidrolatos industriales de naranja. Por otra parte, el aceite esencial industrial de limón mostró un buen potencial como agente herbicida, siendo, por tanto, de gran interés en la fabricación de herbicidas de origen natural, biodegradables y ecológicos. La aplicación del estrés hídrico controlado después del reposo invernal y, por tanto, en el momento de la brotación incrementó el diámetro final del fruto. La respuesta en el árbol no fue inmediata. La aplicación de hidrolatos de limón, naranja y mandarina al suelo junto al agua de riego, potenció los depósitos de C contribuyendo a aumentar la biomasa y mejoró la actividad microbiana. Estos resultados ponen de manifiesto el papel que los hidrolatos pueden desempeñar en la agricultura sostenible mejorando la fertilidad del suelo. Finalmente, el modelo de elementos de tierras raras podría utilizarse como una herramienta de conexión entre la producción de limón y el suelo del que proviene, contribuyendo, de esta manera, a su caracterización geográfica. En resumen, los resultados obtenidos en esta tesis contribuyen a impulsar el sector cítrico siciliano ya que: proporcionan medios para una agricultura sostenible; aumentan el valor de los subproductos y residuos de la industria; proponen aplicaciones para que el ciclo de producción y transformación sea más rentable y revalorizan los limones sicilianos vinculándolos a su zona de producción. / [CA] En esta tesi doctoral es discutixen una sèrie de qüestions científiques relacionades amb la producció i el processament d'algunes espècies de cítrics d'especial rellevància a Sicília i a l'àrea mediterrània. Els objectius, acordats prèviament amb la indústria de cítrics "EuroFood" i finançats pel projecte d'investigació "PON Industrial Ph.D. - a.a. 2016/2017", es centren en estudiar la traçabilitat i sostenibilitat de la producció d'algunes espècies de cítrics, així com de trobar noves aplicacions als subproductes i productes de rebuig de la indústria, amb el fi de millorar la seua rentabilitat. Per tant, els temes que es desenvoluparan seran els següents: caracterització dels compostos bioactius presents en els olis essencials i en el l'hidrolato de diferents espècies de cítrics; seguiment de l'efecte de l'estrés hídric controlat en la producció d'olis essencials en fulles i flors del cv. Sanguinelli de Citrus sinensis i del cv. Clemenules de Citrus reticulata; estudi dels efectes fitotòxicos dels olis essencials de cítrics en quatre espècies arvenses importants en l'àrea mediterrània, dos monocotiledònies (Echinochloa crus-galli (L.) P.Beauv. i Avena fàtua L.) i dos dicotiledònies (Amaranthus retroflexus L. i Portulaca oleracea L.) per mitjà de diferents experiments in vitro i in vivo; estudi de l'efecte bioestimulant de les aigües residuals de la indústria processadora de cítrics sobre la comunitat microbiana del sòl; quantificació d'elements de terres rares en fruits de llima cultivats en diferents àrees geogràfiques, per al seu possible ús com a traçador geoquímic. Els principals resultats obtinguts són la caracterització de diferents olis essencials, dels quals els produïts pels residus de la poda podrien ser utilitzats com a mètode d'extracció de nous olis essencials amb alt rendiment. També s'han trobat substàncies nutracéutiques i farmacològiques en els hidrolats industrials de taronja. D'altra banda, l'oli essencial industrial de llima va mostrar un bon potencial com a agent herbicida, sent, per tant, de gran interés en la fabricació d'herbicides d'origen natural, biodegradables i ecològics. L'aplicació de l'estrés hídric controlat després del repòs hivernal i, per tant, en el moment de la brotació va incrementar el diàmetre final del fruit. La resposta en l'arbre no va ser immediata. L'aplicació de hidrolats de llima, taronja i mandarina al sòl amb l'aigua de reg, va augmentar els depòsits de carbó (C) contribuint a augmentar la biomassa i va millorar l'activitat microbiana. Aquests resultats posen de manifest el paper dels hidrolats en l'agricultura sostenible millorant, d'aquesta manera, la fertilitat del sòl. Finalment, el model d'elements de terres rares podria utilitzar-se com una ferramenta d'enllaç entre la producció de llima i el sòl del què prové, contribuint, d'esta manera, a la seua caracterització geogràfica. En resum, els resultats obtinguts en esta tesi doctoral contribueixen a impulsar el sector cítric sicilià ja que: - proporcionen mitjans per a una agricultura sostenible; - augmenten el valor dels subproductes i residus de la indústria; - proposen aplicacions perquè el cicle de producció i transformació siga de més rendabilitat; - revaloritzen les llimes d'origen sicilià vinculant-les a la seua zona de producció. / [EN] In this doctoral thesis are discussed a series of scientific issues regarding citrus fruits production and processing, species of particular relevance in Sicily and in the Mediterranean area. Objectives and research activities addressed in this thesis were agreed with the citrus industry "EuroFood" and financed by the research project "PON industrial Ph.D. - a.a. 2016/2017". The research project was targeted to study the traceability and sustainability of citrus production, and to find new applications to the by-products and waste products of citrus industry with the objective of appreciate and enhance the Sicilian citrus industry. The following topics are addressed and developed in this thesis: - Characterization of the bioactive compounds present in essential oils (EOs) and in the hydrolate of different citrus species. - Monitoring of the effect of controlled water stress on the production of EOs in leaves and flowers of Citrus sinensis (L.) Osbeck cv. 'Sanguinelli' and Citrus reticulata Blanco cv. 'Clemenules'; -Test the phytotoxic effects of citrus EOs on four important weed species in the Mediterranean area, two monocotyledon (Echinochloa crus-galli (L.) P.Beauv. and Avena fatua L.) and two dicotyledon (Amaranthus retroflexus L., and Portulaca oleraceaL.) by different experiments in vitro and in greenhouse conditions; -Evaluation of the effect as natural biostimulants of wastewaters from citrus processing industry by its application on soil microbial community; -Quantification of rare earth elements in lemon fruits from different geographical areas for its possible use as geochemical tracers applied to lemon production. Different Citrus EOs have been characterized in this study and it has been verified that the oils produced by the pruning waste could be used for the extraction of EOs with high yields. In addition, nutraceutical and pharmacological substances have been found in the orange industrial hydrolates. Industrial lemon EO showed good potential when testing its herbicidal activity. Lemon EO represents a good basis for the development of herbicides of natural origin, biodegradable and eco-friendly. Thanks to the application of water stress after the winter vegetative restart, a conclusion found was that water stress increased the diameter of the fruit and it was observed that the effects of stress were not immediate on citrus trees, but were evident after some time. The study of the application of lemon, orange and mandarin hydrolates in the soil, as irrigation water provided the effects on stable and labile soil C pools, on biomass and microbial activity and on main microbial groups. Overall, hydrolates can play a role in sustainable agriculture because when added to a soil, they improve soil quality and fertility. The Rare Earth Element model could be used as a tool to connect lemon production to the soil where they were produced, for a possible geographical characterization and a direct link between the production and the territory or soil. The results obtained were very interesting because: - they provided the means for sustainable agriculture; - they increased the value of the by-products and waste products of the citrus industry; - they proposed applications for the citrus production and transformation cycle being more sustainable; - they could valorize the Sicilian lemons by linking them to their production area. These results could have practical repercussions in the production cycle of citrus fruits and give a boost to the Sicilian citrus fruit sector. / Objectives and research activities addressed in this thesis were agreed with the citrus industry "EuroFood" and financed by the research project PON industrial Ph.D. - a.a. 2016/2017 / Ioppolo, A. (2020). Valorization of Citrus spp. Cultivars cultivated in Sicily for the industrial use of citrus derivatives and in particular for potential alternative uses of essential oils for the enhancement of the island's citrus production [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/159385
83

Handheld X-ray Fluorescence (HHXRF) as a Non-Destructive Method for Trace Element Analysis of Ancient Maya (Pre-Conquest 800 BC - AD950) Teeth from Altun Ha, Belize

Binkowski, Griffon G 01 January 2024 (has links) (PDF)
In anthropology, elemental analysis of bone and teeth can provide significant details about an individual’s life history, such as diet, toxicity exposure, residency, and migration patterns. Intra-individual comparisons can help to gather information about a single individual’s life, while inter-individual comparisons can help illustrate a community’s life history during these periods. However, current methods of elemental analysis commonly involve the destruction of skeletal samples, which can damage a collection’s integrity and be perceived as disrespectful by descendant communities. Preliminary research has validated handheld x-ray fluorescence spectrometry (HHXRF) as an accurate and reliable method of analysis appropriate for determining the elemental composition of archaeological bone and teeth. In this study, teeth from 16 individuals (N=16) from the pre-conquest Classic Period (AD 625-1100) Maya site of Altun Ha, Belize, were analyzed using HHXRF to identify trace elements to gain a better understanding of the lives of the individuals and community. This study expands upon preliminary research by increasing the sample size and utilizes a filter to increase sensitivity to elements of interest. Diet and mobility were assessed using calcium (Ca), strontium (Sr), and bromine (Br) ratios. Net photon counts per element of interest were extracted and converted into ratios. An inter- and intra-individual comparison model was used. Results of calculated Sr/Ca ratios show a general increased reliance on marine subsistence sources within the sample. Shifts that do not align with this trend are present in several individuals, indicating social complexity of Altun Ha. Results of Br/Ca ratios are less clear in regard to diet and warrant further investigation.
84

Contenu total en éléments traces de sols forestiers du Québec méridional

Masse, Jacynthe 06 1900 (has links)
Les sols forestiers constituent un réservoir considérable d’éléments nutritifs disponibles pour soutenir la productivité forestière. Ces sols contiennent aussi une quantité, encore inconnue à ce jour, d’éléments traces biodisponibles provenant de sources anthropiques ou naturelles. Or, plusieurs de ces éléments recèlent un potentiel toxique pour les organismes vivants. Ainsi, la quantification de la concentration et du contenu total en éléments traces des sols forestiers s’avère nécessaire afin d’évaluer les impacts des perturbations sur la qualité des sols. Les objectifs de ce projet de recherche sont: 1) de mesurer le contenu total en éléments traces en phase solide (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) des divers horizons de sols d’écosystèmes forestiers du Québec méridional; 2) d’établir des liens significatifs entre la fraction soluble dans l’eau des éléments traces et les propriétés des horizons de sols et; 3) d’évaluer le rôle de la proximité d’un centre urbain sur les contenus en éléments traces. Pour répondre à ces objectifs, quatre profils de sols situés dans la région de St-Hippolyte et deux situés dans la région de Montréal furent échantillonnés jusqu'à l'atteinte du matériel parental. Les résultats de ce projet de recherche ont révélé que le contenu total en éléments traces présents dans les profils de sols se retrouve en grande partie dans les fragments grossiers du sol. Il a été démontré que la teneur en carbone organique, les complexes organométalliques et les oxydes de fer et d’aluminium dictent la distribution en profil de la majorité des éléments traces étudiés. Finalement, il fut prouvé que la région de Montréal présente des niveaux de contamination en éléments traces (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) supérieurs à ceux rencontrés dans les Laurentides. / Forest soils represent an important stock of nutrients available to sustain forest productivity. They also contain an amount, still unknown, of trace elements inherited from natural or anthropogical sources. Many of these trace elements can be toxic to living organisms. Thereby, quantification of the concentration and the total content of trace elements in forest soils is necessary to asses the impact of these elements on soil quality. The specific objectives of this research project are: 1) to measure the total content of trace elements in solid phase (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) of various soil horizons in two forest ecosystems of southern Quebec, 2) to establish significant correlations between the bioavailable fraction (water-soluble) of trace elements and soil horizons properties and 3) to compare the trace element stock of two Canadian Shield’s forest soil with those of similar soils situated in the Montreal area. To achieve these goals four soil profiles situated in the pristine region of St-Hippolyte and two in the urban area of Montréal, were excavated down to the parent material. The results of this research have established that the trace element’s total stock is mainly concentrated in coarse fragments of the soil. Multivariate statistical analyses revealed significant links between organic carbon, organometallic complexes as well as Fe-Al oxides and the distribution of trace element in soil profiles. Finally, it was proved that Montreal’s soil contained more trace element (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) than Canadian Shield’s soils.
85

Cycle géodynamique du soufre : le rôle des sédiments subduits / Geodynamic cycling of sulphur : the role of subducted sediments

Pelleter, Anne-Aziliz 27 June 2017 (has links)
Dans l’objectif d’évaluer le devenir de sédiments subduits variablement enrichis en soufre dans des conditions P-T (pression – température) correspondant au toit de la plaque sous un arc volcanique, des expériences de fusion et de cristallisation ont été réalisées en conditions hydratées en presse piston-cylindre(3 GPa ; 650 – 1000°C ; ƒO2 ~ NNO) sur des sédiments naturels (pélite et marne), non dopés en éléments en traces et variablement enrichis en soufre (0, 1 et 2 wt% Sin). Lors de la fusion du sédiment pélitique, des liquides trondhjémitiques à granitiques sont produits en équilibre avec un résidu composé de grenat +disthène ± phengite ± quartz + rutile. Lors de la fusion du sédiment marneux, des liquides granodioritiques sont produits en équilibre avec un résidu constitué de grenat ± épidote ± clinopyroxène ± disthène ± quartz +rutile. L’ajout de soufre dans le système pour une ƒO2 ~ NNO conduit à une précipitation de sulfures. La quantité de fer (Fe2+) disponible dans le système diminue fortement (augmentation du Mg#) et impactegrandement les relations de phases : le grenat, l’épidote et la phengite sont déstabilisées au profit des pyroxènes, de la biotite ou encore de l’amphibole. La distribution des éléments en traces dans le liquide silicaté par rapport au sédiment de départ est également très affectée pour les systèmes dopés en soufre(ex : fractionnement des terres rares). Nous proposons, à partir des données obtenues dans des xénolites mantelliques (Grenade, Petites Antilles) et lors de modélisations géochimiques, que la contribution dans lecoin mantellique de 1 à 3 % de liquides trondhjémitiques/granitiques issus de la fusion de sédiments pélitiques modérément enrichis en soufre (≤ 1 wt% Sin) peut expliquer la variabilité de composition des basaltes du sud de l’arc des Petites Antilles (Grenade et Grenadines). / The main issue of this study is to constrain the fate of subducted sediments variably enriched in sulphur for P-T (pressure – temperature) relevant for the slab at sub-arc depth. Using piston-cylinder apparatus, we performed melting and crystallisation experiments (3 GPa; 650 – 1000°C; ƒO2 ~ NNO) on natural, trace elementundoped and volatile-rich sediments (pelite and marlstone). Experiments were conducted with variable water (5 to 10 wt% H2Oin) and sulphur (0, 1 and 2 wt% Sin) contents. Silicate melts produced by the fluid-present melting of pelite range from trondhjemitic to granitic compositions, are broadly peraluminous and coexist with garnet + kyanite ± phengite ± quartz + rutile. Those produced by the fluid-present melting of marlstone are sodic (granodioritic composition), metaluminous to slightly peraluminous and coexist with garnet ± epidote ± clinopyroxene ± kyanite ± quartz + rutile. Sulphur addition at ƒO2 ~ NNO leads to sulphide precipitation. Thus, iron (Fe2+) contents decrease (Mg# increase) in the system and this strongly impacts phase relationships: garnet, epidote and phengite are consumed in favour of pyroxens, biotite and amphibole. Trace-element distribution between silicate melt and starting bulk for S-doped systems is largely impacted (e.g. rare earth elements fractionation). On the basis of data obtained in mantle xenoliths(Grenada, Lesser Antilles) and from geochemical modelisations, we are suggesting that a contribution in the mantle wedge of 1 to 3 % of trondhjemitic/granitic melts derived from pelitic sediments (≤ 1 wt% Sin) mayaccount for the composition of basalts in the southern part of Lesser Antilles (Grenada and Grenadines).
86

CALFRAC: Programa que quantifica o processo de cristalização fracionada e sua aplicação ao estudo de soleiras da Bacia do Paraná (Estado do Paraná) / CALFRAC: Program to quantify fractional crystallization processes and your application in the study Paraná Basin sills (Paraná).

Galdino, Luciano 06 December 2010 (has links)
Foi desenvolvido um programa computacional escrito na linguagem de programação C++ denominado CALFRAC para quantificar o processo de cristalização fracionada em sistemas ígneos, utilizando para isso as concentrações dos elementos maiores, menores e traços. O algoritmo moderniza, torna mais eficiente e aprimora os programas publicados na literatura e possui a grande vantagem de poder calcular, automaticamente, todas as possíveis combinações de evolução das amostras envolvidas na diferenciação, além de associar aos cálculos os elementos-traço, os quais servem para confirmar os resultados sugeridos pelos ajustes dos elementos maiores e menores. O CALFRAC calcula a fração total subtraída do magma inicial e as frações referentes a cada mineral fracionado através do cálculo do balanço de massa, utilizando as concentrações de elementos maiores e menores, empregando os métodos de estimativa de máxima verossimilhança e dos multiplicadores de Lagrange para a resolução por mínimos quadrados, enquanto para os elementos-traço o programa utiliza a Equação de Rayleigh. Em ambos os casos a média dos erros percentuais relativos é usada como indicação das melhores evoluções. O programa CALFRAC foi aplicado na investigação da possibilidade de diferenciação por cristalização fracionada em amostras de soleiras de diabásio da Bacia do Paraná, que ocorrem nos municípios de Salto do Itararé, Ponta Grossa, Prudentópolis, Rebouças, Irati, Reserva e Jaguariaíva (PR), as quais foram coletadas para essa finalidade. Nas 33 amostras coletadas foram realizadas determinações de elementos maiores, menores e traços, incluindo terras raras, empregando-se os métodos de Fluorescência de Raios X e Ativação Neutrônica. Os resultados fornecidos pelo programa foram insatisfatórios, não sendo possível estabelecer um percurso de diferenciação das rochas mais primitivas para as mais diferenciadas das intrusões, devido ao fato de que provavelmente muitas das amostras analisadas representam a mistura de magmas com porções contendo acumulação de fases minerais causada pelo próprio processo de cristalização fracionada in situ. / CALFRAC is a computer program written in C++ programming language developed to quantify fractional crystallization processes in igneous systems. Major, minor and trace element concentrations are used as input for calculations. The new algorithm enhances and makes the program more efficient than those published in the literature. Besides it is capable to automatically calculating all possible rock sample combinations involving differentiation by fractional crystallization process, using in addition trace element concentrations to corroborate the results obtained by the fitting of major and minor element abundances. CALFRAC calculates the total fraction subtracted from the original magma and the percentage of each fractionated mineral by solving least-squares mass balance equations based on major and minor element concentrations. The methods of maximum likelihood estimate and Lagrange multipliers are used to solve the equations, whereas for the quantification of trace elements the program uses the Rayleigh Equation. In both cases the mean relative percentage errors is used as an indication of the best results. The program CALFRAC was applied to investigate the possibility of differentiation by fractional crystallization of diabase samples from Paraná Basin sills, which outcrop nearby Salto do Itararé, Ponta Grossa, Prudentópolis, Rebouças, Irati, Reserva and Jaguariaíva towns (PR). The 33 collected samples were analyzed for major, minor and trace elements, including rare earths, employing X-Ray Fluorescence and Neutron Activation methods. The program output was not satisfactory, since it was not possible to establish a differentiation sequence from the more primitive to the more differentiated rocks of the intrusions. This is probably due to the fact that many rock samples are the result of mixing of magmatic melts with mineral accumulation zones, which were formed by the in situ fractional crystallization process.
87

Contenu total en éléments traces de sols forestiers du Québec méridional

Masse, Jacynthe 06 1900 (has links)
Les sols forestiers constituent un réservoir considérable d’éléments nutritifs disponibles pour soutenir la productivité forestière. Ces sols contiennent aussi une quantité, encore inconnue à ce jour, d’éléments traces biodisponibles provenant de sources anthropiques ou naturelles. Or, plusieurs de ces éléments recèlent un potentiel toxique pour les organismes vivants. Ainsi, la quantification de la concentration et du contenu total en éléments traces des sols forestiers s’avère nécessaire afin d’évaluer les impacts des perturbations sur la qualité des sols. Les objectifs de ce projet de recherche sont: 1) de mesurer le contenu total en éléments traces en phase solide (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) des divers horizons de sols d’écosystèmes forestiers du Québec méridional; 2) d’établir des liens significatifs entre la fraction soluble dans l’eau des éléments traces et les propriétés des horizons de sols et; 3) d’évaluer le rôle de la proximité d’un centre urbain sur les contenus en éléments traces. Pour répondre à ces objectifs, quatre profils de sols situés dans la région de St-Hippolyte et deux situés dans la région de Montréal furent échantillonnés jusqu'à l'atteinte du matériel parental. Les résultats de ce projet de recherche ont révélé que le contenu total en éléments traces présents dans les profils de sols se retrouve en grande partie dans les fragments grossiers du sol. Il a été démontré que la teneur en carbone organique, les complexes organométalliques et les oxydes de fer et d’aluminium dictent la distribution en profil de la majorité des éléments traces étudiés. Finalement, il fut prouvé que la région de Montréal présente des niveaux de contamination en éléments traces (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) supérieurs à ceux rencontrés dans les Laurentides. / Forest soils represent an important stock of nutrients available to sustain forest productivity. They also contain an amount, still unknown, of trace elements inherited from natural or anthropogical sources. Many of these trace elements can be toxic to living organisms. Thereby, quantification of the concentration and the total content of trace elements in forest soils is necessary to asses the impact of these elements on soil quality. The specific objectives of this research project are: 1) to measure the total content of trace elements in solid phase (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) of various soil horizons in two forest ecosystems of southern Quebec, 2) to establish significant correlations between the bioavailable fraction (water-soluble) of trace elements and soil horizons properties and 3) to compare the trace element stock of two Canadian Shield’s forest soil with those of similar soils situated in the Montreal area. To achieve these goals four soil profiles situated in the pristine region of St-Hippolyte and two in the urban area of Montréal, were excavated down to the parent material. The results of this research have established that the trace element’s total stock is mainly concentrated in coarse fragments of the soil. Multivariate statistical analyses revealed significant links between organic carbon, organometallic complexes as well as Fe-Al oxides and the distribution of trace element in soil profiles. Finally, it was proved that Montreal’s soil contained more trace element (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) than Canadian Shield’s soils.
88

ペリドタイト部分溶融における粒界濃集元素の挙動

鈴木, 和博, 諏訪, 兼位, 榎並, 正樹 03 1900 (has links)
科学研究費補助金 研究種目:一般研究(B) 課題番号:63460053 研究代表者:日比野 倫夫 研究期間:1988-1989年度
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Trace Metal Composition Of Particulate Matter In The Water Column And Sediments Of The Black Sea And Regional Rivers

Yigiterhan, Oguz - 01 July 2005 (has links) (PDF)
The Black Sea, with its oxic, suboxic and anoxic layers, provides a unique environment for studying how biological and geochemical processes affect the composition of particulate matter. The elemental composition of particles in the Black Sea is controlled by their origin and sources. Particles from rivers are dominated by aluminosilicate material that has compositions similar to the earth&rsquo / s crust. In general this material is relatively unreactive. Biological processes in the upper oxic and suboxic layers of the water column result in enrichments of elements which used as nutrients. Cu, Ba and Mo have been proposed as tracers for planktonic material and new production. Geochemical processes like manganese and iron recycling between oxidized and reduced forms, metal sulfide formation, and biogenic matter decomposition can have a large impact on the composition of particles in the suboxic and anoxic zones. The aim of this thesis was to study the composition of particles suspended in the water column of the Black Sea, in regional rivers draining into the Black Sea, and of particles deposited in these rivers and Black Sea sediments. The objectives were to determine the chemical composition and distribution of particles supplied by rivers and produced in the Black Sea, and compare with those particles buried in the sediments. The chemical distributions can help us to understand the biogeochemical processes taking place. The ultimate goal is to understand if there is a chemical signature that characterizes sediments deposited in anoxic basins that can be used to determine if ancient sedimentary rocks were deposited under such conditions. Water column filter samples were collected from the central western basin and along transects to the SW shelf regions during several research cruises of R/V Bilim and R/V Knorr in the Black Sea. Samples were taken by using both in situ large volume filtration systems and on deck vacuum filtration of discrete samples. River samples were collected by hand from the bank of four Turkish rivers and the Danube River. Sediment samples were obtained from 0 - 25 cm interval of a box core from the deep western basin. All samples were digested and analyzed by inductively coupled plasma - mass spectrometry and combination of atomic absorption (flame &amp / graphite furnace) instruments. The elements analyzed included Al, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Mo, Ag, Cd, Ba, Pb, and U. Great care was taken to avoid contamination and to obtain the highest level of precision and accuracy. The precision was typically about 5% for most elements. The accuracy, determined using standard reference materials, was also usually better than 5%. Another goal of this research was to determine the metal concentrations and best digestion methods using different types of filter materials. Blank filters were digested and analyzed and the analyses of various filter blanks are presented in the thesis. The analyses showed that the particulate matter data from Turkish Rivers were very similar to the composition of global average riverine particulate material and global average crust. The Danube River had elevated concentrations for some elements that were probably due to anthropogenic contamination. The Turkish river samples were closer to (but still higher than) the averages for the world&rsquo / s rivers but many elements in the Danube were much higher. These high values determined for major elements in the Danube samples strongly suggest considerable contamination of the Danube as compared to the Turkish Rivers. The Danube River samples were especially enriched in Pb, Zn, Ag, Cu, Cd, and Mn and slightly enriched with Cr and Ni. The first five elements, in particular, are well known indicators of pollution. The particulate matter in the water column of the Black Sea was influenced by lithogenic input from rivers, biological processes and geochemical processes. In order to examine the biogeochemical processes extensively, all the data were plotted as Metal/Al (Me/Al) ratios and compared with the ratios of the average crust and Turkish Rivers. Deviations were used to examine the anomalies due to biological and geochemical processes. In addition, the Al content of individual sample and the Me/Al ratio of crust or rivers were used to subtract the lithogenic component from the total composition. Enrichments due to biological processes were observed for Ba &gt / Fe &gt / Cr &gt / Mn &gt / Zn &gt / Ni &gt / Cu &gt / Mo &gt / V &gt / Co &gt / Cd &gt / U for the overall biogenic composition. Enrichments due to biology are most evident for Ba, Fe, Cr and Mn. This is a unique data set as there have been few previous analyses of biological enrichment for most of these elements. The results of particulate matter analyses showed that some elements including U, V, Cr, Ni, Cu, Co, Zn, Ba and Mo were enriched in the set of samples from the euphotic zone. Redox cycling in the suboxic zone was observed, as expected, for Mn and Fe, whose oxides play an important role in scavenging processes. The redox dependent processes in the suboxic &ndash / anoxic interface influence the vertical distribution of U, Ni, Co, Cu, Zn, Ba and possibly Mo, Cr and V. Elements influenced by sulfide formation in the anoxic layer are Fe, Cr, Ni, Co, Mo, and presumably Ag. The sediment data were also examined based on the same approaches. The elements Zn, Pb, U and Cd decreased with sediment depth over the top 5 cm suggesting that they were remobilized out of the sediments. In general the sediments from the Black Sea have Me/Al ratios very similar to local Turkish Rivers and average crust. There is no unique sediment signature (except possibly for Mo) indicating that these sediments were deposited under sulphidic conditions. This study does not support the hypothesis that the composition of ancient rocks can be used to characterize the environment of deposition.
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Spårämnestillsatsers påverkan på biogasproduktionen vid anaerob rötning av avloppsslam : Behovet av spårämnen vid slamrötning på Karlstads reningsverk / The influence of trace element addition on the biogas production from anaerobic digestion of sewage sludge : The need for trace elements in the digestion of sewage sludge at Karlstads wastewater treatment plant

Fokkema, Maaike January 2018 (has links)
Sverige har som mål att endast använda fossilfria bränslen inom fordonsflottan till år 2030. Ett av dessa fossilfria bränslen är biogas som bland annat produceras på Karlstads reningsverk, Sjöstadsverket. Sjöstadsverket planerar att bygga ut sin slammottagningsstation för att kunna ta emot mer slam. I samband med detta finns det ett intresse av att undersöka effektiviseringsmöjligheter inom biogasproduktionen. Ett vanligt förekommande sätt att öka biogasproduktionen är genom tillsatser av olika spårämnen. I detta arbete har därför tillsatser av spårämnena järn, kobolt, nickel och magnesium undersökts genom termofila småskaliga rötningsförsök i satsreaktorer. Tillsatserna har även undersökts i kombination med det komplexbildande ämnet EDTA för att undersöka om den biologiska tillgängligheten påverkar vid rötning av avloppsslam. Förutom rötningsförsök har även en korrelationsanalys genomförts där olika faktorer som kan påverka biogasproduktionen undersökts för år 2017. Resultaten av rötningsförsöken visar att inga tillsatser av järn, magnesium, nickel eller kobolt kommer öka biogasproduktionen vid Sjöstadsverket. Istället har biogasproduktionen hämmats vid två av tre rötningsförsök. Dessa resultat indikerar att organismerna i rötningsanläggningen på Sjöstadsverket inte har någon brist på spårämnen. Inte heller tillsatser av EDTA ökade biogasproduktionen vilket visar att det inte heller finns brist på biologiskt tillgängliga spårämnen. Resultaten från rötningsförsöken styrks av korrelationsanalysen eftersom det inte heller finns några tecken på korrelation mellan biogasproduktion och de nämnda spårämnena. Resultaten av korrelationsanalysen visar att pH ut ur rötningsanläggningen kan ha en negativ inverkan på biogasproduktionen vid Sjöstadsverket. Resultaten indikerar att pH blir för högt i anläggningen, något som även påvisats vid rötningsförsöken. Ett högre flöde in i anläggningen kan sänka pH-värdet enligt vidare korrelationsstudier. Detta har även kunnat påvisas vid rötningsförsöken där pH blev lägre vid en kortare uppehållstid. Eftersom Sjöstadsverket baserar sin uppehållstid på en stabil volym i rötkamrarna bör det alltså vara möjligt att öka biogasproduktionen genom att öka flödet in i rötningsanläggningen, vilket kommer ske när den nya slammottagningsstationen sätts i bruk. Eftersom dessa slutsatser främst är baserade på korrelationer rekommenderas vidare studier där pH-värdets och uppehållstidens inverkan på biogasproduktionen vid Sjöstadsverket undersöks närmare. / The Swedish government has set a national goal to have no vehicles running on fossil fuels in year 2030. One of the fuels that can replace the fossil fuels of today is biogas. The biggest wastewater treatment plant in Karlstad, called Sjöstadsverket, is already producing biogas and is expanding to receive more sludge in the future. Because of this, Sjöstadsverket wants to investigate the possibility of a more effective biogas production. A common way to improve biogas production is trace element additives. Therefor the addition of cobalt, nickel, iron and magnesium has been investigated through small scale thermophilic anaerobic digestion trials in batch reactors. The trace elements have also been added in combination with EDTA to investigate the bioavailability of the trace elements. In addition to these experiments a correlation analysis was performed where different factors that might influence the biogas production were investigated for year 2017. The results from the digestion trials prove that no addition of iron, magnesium, cobalt or nickel will increase the biogas production. Instead, the biogas production was inhibited during two out of three experiments. These results indicate that the organisms in the digester at Sjöstadsverket already have a sufficient amount of trace elements. The addition of EDTA did not increase the biogas production either which indicates that the trace elements also are bioavailable to a sufficient extent. The results from the digestion trials are validated by the correlation analysis because no correlation could be found between the biogas production and the investigated trace elements. The results from the correlation analysis show that the pH-level affects the biogas production negatively. The results indicate that the pH-level is to high, something that was also observed during the digestion trials. A higher flow rate into the digesters could lower the pH-levels according to further correlation studies. This has also been observed during the digestion trials where a shorter retention time lowered the pH-levels. Because Sjöstadsverket bases their retention time on a stable volume in the digesters, it could be possible for them to increase the biogas production by increasing the flow rates, which will happen when they start receiving more sludge. Because these conclusions are mainly based on correlations, further studies of the influence of pH-levels and retention times on the biogas production at Sjöstadsverket are recommended.

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