Seawater carbonate chemistry and biological processes of zooplankton Amphiascoides atopus and Schizopera knabeni during experiments, 2010

Increased atmospheric CO2 concentrations are causing greater dissolution of CO2 into seawater, and are ultimately responsible for today's ongoing ocean acidification. We manipulated seawater acidity by addition of HCl and by increasing CO2 concentration and observed that two coastal harpacticoid copepods, Amphiascoides atopus and Schizopera knabeni were both more sensitive to increased acidity when generated by CO2. The present study indicates that copepods living in environments more prone to hypercapnia, such as mudflats where S. knabeni lives, may be less sensitive to future acidification. Ocean acidification is also expected to alter the toxicity of waterborne metals by influencing their speciation in seawater. CO2 enrichment did not affect the free-ion concentration of Cd but did increase the free-ion concentration of Cu. Antagonistic toxicities were observed between CO2 with Cd, Cu and Cu free-ion in A. atopus. This interaction could be due to a competition for H+ and metals for binding sites.

XDX, Mg/Ca, and delta18O analyses of core top sediments

Mg/Ca and d18O data for four species of planktic foraminifera (G. ruber (white), G. sacculifer (without sac), N. dutertrei, and P. obliquiloculata) from core top sediments from the tropical Pacific, Atlantic, and western Indian Ocean. Deepwater calcite saturation values (Delta[CO3**2-]) at the sites range from 55 to -23 µmol/kg.

Seawater carbonate chemistry and conditions of Mytilus edulis extracellular body fluids and shell composition in a pH-treatment experiment: Acid-base status, trace elements and delta11B, 2012

Mytilus edulis were cultured for 3 months under six different seawater pCO2 levels ranging from 380 to 4000 µatm. Specimen were taken from Kiel Fjord (Western Baltic Sea, Germany) which is a habitat with high and variable seawater pCO2 and related shifts in carbonate system speciation (e.g., low pH and low CaCO3 saturation state). Hemolymph (HL) and extrapallial fluid (EPF) samples were analyzed for pH and total dissolved inorganic carbon (CT) to calculate pCO2 and [HCO3]. A second experiment was conducted for 2 months with three different pCO2 levels (380, 1400 and 4000 µatm). Boron isotopes (delta11B) were investigated by LA-MC-ICP-MS (Laser Ablation-Multicollector-Inductively Coupled Plasma-Mass Spectrometry) in shell portions precipitated during experimental treatment time. Additionally, elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF of specimen from the second experiment were measured via ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry). Extracellular pH was not significantly different in HL and EPF but systematically lower than ambient water pH. This is due to high extracellular pCO2 values, a prerequisite for metabolic CO2 excretion. No accumulation of extracellular [HCO3] was measured. Elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF increased slightly with pH which is in accordance with increasing growth and calcification rates at higher seawater pH values. Boron isotope ratios were highly variable between different individuals but also within single shells. This corresponds to a high individual variability in fluid B/Ca ratios and may be due to high boron concentrations in the organic parts of the shell. The mean delta11B value shows no trend with pH but appears to represent internal pH (EPF) rather than ambient water pH.

(Table 2) Location, age of accompanied sediments, chemical and Sr isotopic compositions of manganese nodules in DSDP/ODP cores

Strontium isotopic compositions of acetic acid (HOAc) leachate fractions of eight manganese oxide deposits from the modern seafloor, and of twenty-one buried manganese nodules from Cretaceous to Recent sediments in DSDP/ODP cores were measured. ratios of HOAc leachates in all modern seafloor manganese oxides of various origins are identical with present seawater. The ratios of the HOAc leachates of buried nodules from DSDP/ODP cores are significantly lower than those of nodules from the modern seafloor and are mostly identical with coeval seawater values estimated from the age of associated sediments. It is suggested that the buried nodules in DSDP/ODP cores are not artifacts transported from the present seafloor during the drilling process, but are in situ fossil deposits from the past deep-sea floor during Cretaceous to Quaternary periods. The formation of deep-sea fossil nodules prior to the formation of Antarctic Bottom Water (AABW) indicates that the circulation of oxygenated deep seawaters have activately deposited manganese oxides since the Eocene Epoch, or earlier.

Geochemical analysis at ODP Site 207-1261 from the Demerara Rise in the western equatorial Atlantic

A high-resolution geochemical record of a 120 cm black shale interval deposited during the Coniacian-Santonian Oceanic Anoxic Event 3 (ODP Leg 207, Site 1261, Demerara Rise) has been constructed to provide detailed insight into rapid changes in deep ocean and sediment paleo-redox conditions. High contents of organic matter, sulfur and redox-sensitive trace metals (Cd, Mo, V, Zn), as well as continuous lamination, point to deposition under consistently oxygen-free and largely sulfidic bottom water conditions. However, rapid and cyclic changes in deep ocean redox are documented by short-term (~15-20 ka) intervals with decreased total organic carbon (TOC), S and redox-sensitive trace metal contents, and in particular pronounced phosphorus peaks (up to 2.5 wt% P) associated with elevated Fe oxide contents. Sequential iron and phosphate extractions confirm that P is dominantly bound to iron oxides and incorporated into authigenic apatite. Preservation of this Fe-P coupling in an otherwise sulfidic depositional environment (as indicated by Fe speciation and high amounts of sulfurized organic matter) may be unexpected, and provides evidence for temporarily non-sulfidic bottom waters. However, there is no evidence for deposition under oxic conditions. Instead, sulfidic conditions were punctuated by periods of anoxic, non-sulfidic bottom waters. During these periods, phosphate was effectively scavenged during precipitation of iron (oxyhydr)oxides in the upper water column, and was subsequently deposited and largely preserved at the sea floor. After ~15-25 ka, sulfidic bottom water conditions were re-established, leading to the initial precipitation of CdS, ZnS and pyrite. Subsequently, increasing concentrations of H2S in the water column led to extensive formation of sulfurized organic matter, which effectively scavenged particle-reactive Mo complexes (thiomolybdates). At Site 1261, sulfidic bottom waters lasted for ?90-100 ka, followed by another period of anoxic, non-sulfidic conditions lasting for ~15-20 ka. The observed cyclicity at the lower end of the redox scale may have been triggered by repeated incursions of more oxygenated surface- to mid-waters from the South Atlantic resulting in a lowering of the oxic-anoxic chemocline in the water column. Alternatively, sea water sulfate might have been stripped by long-lasting high rates of sulfate reduction, removing the ultimate source for HS**- production.

A survey on the composition of wines made with grapes produced by an organic system.

Summary There is concern about the health problems caused by pesticides in humans, which has led some grape producers to adopt organic procedures in their vineyards, and a certain amount of these grapes are directed to winemaking. Despite the approval awarded to this organic grape production by the certified organizations, there has been a demand to carry out a survey to determine the physicochemical composition of the wine derived from these products. Some of these wines were made from a single grape variety and others from more than one. For this survey, the samples consisted of five bottles of each type of wine, acquired from wineries and supermarkets in the Serra Gaúcha region, RS, Brazil. The analyses were carried out by physicochemical methods: volatile compounds by gas chromatography; minerals and trace elements by inductively coupled plasma optical emission spectrometry; and pesticide residues by liquid chromatography-mass spectrometry. The results showed that in general the physicochemical composition of these wines was within the limits established by Brazilian legislation. The mineral and trace element concentrations were very low and pesticide residues were not detected (MRL = 10 μg.kg?1) in any of the wines. Resumo: Há preocupação em relação a problemas causados por pesticidas no ser humano, o que levou uma parcela de viticultores a adotar procedimentos de agricultura orgânica em seus vinhedos. Assim, devido a essa preocupação, eles estão produzindo uva pelo sistema orgânico, sendo que uma parte dessa produção é direcionada à elaboração de vinho. Apesar de essas uvas terem sido aprovadas por entidades certificadoras, houve demanda para a realização de um levantamento para determinar a composição dos vinhos delas derivados. Portanto, cinco garrafas de cada tipo de vinho foram coletadas em vinícolas e supermercados da Serra Gaúcha, Rio Grande do Sul, sendo uma parte de vinhos varietais e outra, de cortes de diferentes variedades. As análises foram feitas por métodos físico-químicos: compostos voláteis, por cromatografia gasosa; minerais e elementos-traço, por espectrometria de emissão ótica com plasma acoplado indutivamente, e resíduos de pesticidas, por cromatografia líquida-espectrometria de massa. Os resultados mostram que a composição físico-química desses vinhos e dos minerais situou-se, em geral, dentro dos limites da legislação brasileira. As concentrações de minerais e de elementos-traço foram muito baixas, e não foram detectados resíduos de pesticidas (LMR = 10 μg.kg?1) em nenhum vinho.

Avaliação da correlação entre os parâmetros, carbono orgânico total e elementos tóxicos, em solo de um posto de serviço e revenda de combustíveis

Today a major responsibility for the contamination of soil and groundwater and surface water are establishments known as gas stations of fuel which has attracted increasing attention from both the general population as the state agencies of environmental control due to leaks in storage tanks and mainly to disruption of pipe corrosion of tanks and pumping. Other services, like oil changes and car wash are also causes for concern in this type of establishment. These leaks can cause or waste produced, and the contamination of aquifers, serious health problems and public safety, since most of these stations located in urban areas. Based on this, the work was to evaluate soil contamination of a particular service station and fuel sales in the city of Natal, through the quantification of heavy metals like Cd, Cu, Cr, Ni, Pb, Zn of total organic carbon (TOC) and organic matter using different techniques such as optical emission spectrometry with inductively coupled plasma source (ICP OES), Total Organic Carbon analyzer and gravimetric analysis respectively. And also to characterize the soil through particle size analysis. Samples were taken in 21 georeferenced points and collected in the same period. The soils sampled in sampling stations P3, P5, P6, P10, P11, P12, P13, P14, P15, P17, P18 and P20 showed the smallest size fractions ranging from fine sand to medium sand. The other study sites ranged from fine sand to medium sand, except the point P8 showed that only the type size medium sand and P19, indicating a particle size of the coarse type. The small correlation of organic matter with the elements studied in this work suggests that these are not of anthropogenic origin but geochemical support

Geochemical analysis at ODP Site 207-1259 from the Demerara Rise in the western equatorial Atlantic

Organic carbon-rich shales deposited during the Coniacian-Santonian Oceanic Anoxic Event 3 were drilled during ODP Leg 207 at Demerara Rise. We present integrated high-resolution geochemical records of core intervals from ODP Sites 1259 and 1261 both from nannofossil biozone CC14. Our results reveal systematic variations in marine and detrital sediment contribution, depositional processes, and bottom water redox conditions during black shale formation at two locations on Demerara Rise in different paleo-water depths. A combination of redox proxies (Fe/S, P/Al, C/P, redox-sensitive/sulfide-forming trace metals Mn, Cd, Mo, Ni, V, Zn) and other analytical approaches (bulk sediment composition, P speciation, electron microscopy, X-ray diffraction) evidence anoxic to sulfidic bottom water and sediment conditions throughout the deposition of black shale. These extreme redox conditions persisted and were periodically punctuated by short-termed periods with less reducing bottom waters irrespective of paleo-water depth. Sediment supply at both sites was generally dominated by marine material (carbonate, organic matter, opal) although relationships of detrital proxies as well as glauconitic horizons support some influence of turbidites, winnowing bottom currents and/or variable detritus sources, along with less reducing bottom water at the proposed shallower location (ODP Site 1259). At Site 1261, located at greater paleo-depth, redox fluctuations were more regular, and steady hemipelagic sedimentation sustained the development of mostly undisturbed lamination in the sedimentary record. Strong similarities of the studied deposits exist with the stratigraphic older Cenomanian-Turonian OAE2 black shale sections at Demerara Rise, suggesting that the primary mechanisms controlling continental supply and ocean redox state were time-invariant and kept the western equatorial Atlantic margin widely anoxic over millions of years.

FABRICATION, CHARACTERIZATION, AND IRRADIATION OF AN AUSTENITIC OXIDE DISPERSION STRENGTHENED STEEL SUITED FOR NEXT GENERATION NUCLEAR APPLICATIONS

As nuclear energy systems become more advanced, the materials encompassing them need to perform at higher temperatures for longer periods of time. In this Master’s thesis we experiment with an oxide dispersion strengthened (ODS) austenitic steel that has been recently developed. ODS materials have a small concentration of nano oxide particles dispersed in their matrix, and typically have higher strength and better extreme temperature creep resistance characteristics than ordinary steels. However, no ODS materials have ever been installed in a commercial power reactor to date. Being a newer research material, there are many unanswered phenomena that need to be addressed regarding the performance under irradiation. Furthermore, due to the ODS material traditionally needing to follow a powder metallurgy fabrication route, there are many processing parameters that need to be optimized before achieving a nuclear grade material specification. In this Master’s thesis we explore the development of a novel ODS processing technology conducted in Beijing, China, to produce solutionized bulk ODS samples with ~97% theoretical density. This is done using relatively low temperatures and ultra high pressure (UHP) equipment, to compact the mechanically alloyed (MA) steel powder into bulk samples without any thermal phase change influence or oxide precipitation. By having solutionized bulk ODS samples, transmission electron microscopy (TEM) observation of nano oxide precipitation within the steel material can be studied by applying post heat treatments. These types of samples will be very useful to the science and engineering community, to answer questions regarding material powder compacting, oxide synthesis, and performance. Subsequent analysis performed at Queen’s University included X-ray diffraction (XRD) and inductively coupled plasma optical emission spectrometry (ICP-OES). Additional TEM in-situ 1MeV Kr2+ irradiation experiments coupled with energy dispersive X-ray (EDX) techniques, were also performed on large (200nm+) non-stoichiometric oxides embedded within the austenite steel grains, in an attempt to quantify the elemental compositional changes during high temperature (520oC) heavy ion irradiation.

Evaluation of laser induced breakdown spectrometry for the determination of macro and micronutrients in pharmaceutical tablets

The aim of this work is to demonstrate the feasibility of laser induced breakdown spectrometry (LIBS) for the determination of macro and micronutrients in multielement tablets. The experimental setup was designed by using a laser Q-switch (Nd:YAG, 10 Hz, lambda = 1064 nm) and the emission signals were collected by lenses into an optical fiber coupled to an echelle spectrometer equipped with a high-resolution intensified charge coupled device (ICCD). Tablets were cryogenically ground and thereafter pelletized before LIBS analysis. Calibration curves were made by employing samples and mixtures of commercial multielement tablets with binders at different ratios. Best results were achieved by using the following experimental conditions: 29 J cm(-2) laser fluence, 165 mm lens to sample distance (f = 200 mm), 2.0 mu s delay time, 5.0 mu s integration time and 5 accumulated laser pulses. In general, the results obtained by the proposed LIBS procedure were in agreement with those obtained by ICP OES from the corresponding acid digests and coefficients variation of LIBS measurements varied from 2 to 16%. The metrological figures of merit indicate that LIBS fits for the intended purposes, and can be recommended for the analysis of multielement tablets and similar matrices aiming the determination of Ca, Cu, Fe, Mg, Mn, P and Zn.

Slurry sample injection for determination of ferrite nanocolloids chemical composition by ICP spectrometry

This work proposes a new method to determine the chemical composition of magnetic ferrite nanoparticles by the slurry injection technique using the inductively coupled plasma optical emission spectroscopy. In this way, experimental conditions such as aerosol gas flow rate and colloidal stability were optimized in order to use aqueous calibration curves in the slurry nebulization and to determine the chemical composition of a series of sols containing chemically synthesized size-tailored NiFe 2O 4 nanograms. Then, the results of direct sampling and those of conventional aqueous introduction analysis are compared, showing the efficiency of the proposed method.

Développement et caractérisation de sources de neutres réactifs pour l’étude des interactions plasmas-surfaces

L’objectif de ce mémoire de maîtrise est de développer et de caractériser diverses sources de neutres réactifs destinées à des études fondamentales des interactions plasmas-surfaces. Ce projet s’inscrit dans le cadre d’une vaste étude de la physique des interactions plasmas-parois mises en jeu dans les procédés de gravure par plasma des matériaux de pointe. Une revue de la littérature scientifique sur les diverses méthodes permettant de générer des faisceaux de neutres réactifs nous a permis de sélectionner deux types de sources. La première, une source pyrolitique, a été caractérisée par spectrométrie de masse en utilisant le C2F6 comme molécule mère. Nous avons montré que le C2F6 était dissocié à plus de 90% à 1000ºC et qu’il formait du CF4, lui-même dissocié en CF2 vers 900ºC. Ces résultats ont été validés à l’aide d’un modèle basé sur des calculs d’équilibres chimiques, qui a aussi prédit la formation de F à 1500ºC. La seconde source, un plasma entretenu par une onde électromagnétique de surfaces, a été caractérisée par spectroscopie optique d’émission et par interférométrie haute fréquence. Dans le cas du plasma d’argon créé par un champ électromagnétique (>GHz), nos travaux ont révélé une distribution en énergie des électrons à trois températures avec Te-low>Te-high

Analyse des processus de dérive lors de la gravure profonde du silicium dans des plasmas SF6 et C4F8

L’objectif de ce mémoire de maîtrise est de développer des outils de diagnostics non-invasifs et de caractériser in-situ les dérives de procédé dans un réacteur industriel utilisé en production pour la gravure profonde du silicium par le procédé Bosch. Ce dernier repose sur l’alternance d’un plasma de SF6 pour la gravure isotrope du Si et d’un plasma de C4F8 pour la passivation des parois dans l’optique d’obtenir des tranchées profondes et étroites. Dans un premier temps, nous avons installé une sonde courant-tension sur la ligne de transmission du signal rf au porte-substrat pour l’étude de son impédance caractéristique et un spectromètre optique pour l’étude de l’émission optique du plasma. Nos travaux ont montré que l’évolution temporelle de l’impédance constitue un excellent moyen pour identifier des changements dans la dynamique du procédé, notamment une gravure complète de la photorésine. De plus, à partir des spectres d’émission, nous avons pu montrer que des produits carbonés sont libérés du substrat et des parois lors de l’alternance passivation/gravure et que ceux-ci modifient considérablement la concentration de fluor atomique dans le plasma. Dans un second temps, nous avons développé un réacteur à « substrat-tournant » pour l’analyse in-situ des interactions plasma-parois dans le procédé Bosch. Nos travaux sur ce réacteur visaient à caractériser par spectrométrie de masse l’évolution temporelle des populations de neutres réactifs et d’ions positifs. Dans les conditions opératoires étudiées, le SF6 se dissocie à près de 45% alors que le degré de dissociation du C4F8 atteint 70%. Le SF6 est avant tout dissocié en F et SF3 et l’ion dominant est le SF3+ alors que le C4F8 est fragmenté en CF, CF3 et CF4 et nous mesurons plusieurs ions significatifs. Dans les deux cas, la chaîne de dissociation demeure loin d’être complète. Nous avons noté une désorption importante des parois de CF4 lors du passage du cycle de passivation au cycle de gravure. Un modèle d’interactions plasmas-parois est proposé pour expliquer cette observation.

Dynamique de croissance par plasma RF magnétron des couches minces à base d’oxyde de zinc

Le but de cette thèse était d’étudier la dynamique de croissance par pulvérisation par plasma RF magnétron des couches minces à base d’oxyde de zinc destinées à des applications électroniques, optoélectroniques et photoniques de pointe. Dans ce contexte, nous avons mis au point plusieurs diagnostics permettant de caractériser les espèces neutres et chargées dans ce type de plasmas, notamment la sonde électrostatique, la spectroscopie optique d’émission et d’absorption, ainsi que la spectrométrie de masse. Par la suite, nous avons tenté de corréler certaines caractéristiques physiques de croissance des couches de ZnO, en particulier la vitesse de dépôt, aux propriétés fondamentales du plasma. Nos résultats ont montré que l’éjection d’atomes de Zn, In et O au cours de la pulvérisation RF magnétron de cibles de Zn, ZnO et In2O3 n’influence que très peu la densité d’ions positifs (et donc la densité d’électrons en supposant la quasi-neutralité) ainsi que la fonction de distribution en énergie des électrons (populations de basse et haute énergie). Cependant, le rapport entre la densité d’atomes d’argon métastables (3P2) sur la densité électronique décroît lorsque la densité d’atomes de Zn augmente, un effet pouvant être attribué à l’ionisation des atomes de Zn par effet Penning. De plus, dans les conditions opératoires étudiées (plasmas de basse pression, < 100 mTorr), la thermalisation des atomes pulvérisés par collisions avec les atomes en phase gazeuse demeure incomplète. Nous avons montré que l’une des conséquences de ce résultat est la présence d’ions Zn+ suprathermiques près du substrat. Finalement, nous avons corrélé la quantité d’atomes de Zn pulvérisés déterminée par spectroscopie d’émission avec la vitesse de dépôt d’une couche mince de ZnO mesurée par ellipsométrie spectroscopique. Ces travaux ont permis de mettre en évidence que ce sont majoritairement les atomes de Zn (et non les espèces excitées et/ou ioniques) qui gouvernent la dynamique de croissance par pulvérisation RF magnétron des couches minces de ZnO.