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Volcanoes are a key component of the Earth system, with volcanic activity reaching from deep in the Earth’s mantle and extending to interactions with volcanic gases and the atmosphere. Volatile trace metals degas from volcanic eruptions and at fumaroles, but their behaviour is poorly understood. I designed and built a benchtop fumarole, from which I degassed a silicate melt with trace metals, to simulate the volatilization and sublimation of trace metals from volcanic gases. I collected sublimates along a temperature gradient to examine the behaviour of the trace metals. The experimental sublimates were analysed for their chemical composition and phase identification. Lithium, Cu, As, Rb, Mo, Ag, Cd, Cs, W, Pt, Tl, Pb and Bi were found to be volatile and sublimed in elevated concentrations at various temperatures between 250-600°C. Compared to natural fumarole studies, similar volatile behaviour is seen for Cu, As, Ag and Tl. Variability between the experimental and natural fumarole sublimates is proposed to be from a lack of ligands in the experiments. Ligands can complex with trace metals, to transport and sublime mineralogical phases. Given the importance of ligands to metal complexation, I proceeded to examine the importance of chloride as a ligand in volatile transport and sublimation of trace metals. I degassed a silicate melt with trace metals and variable concentrations of Cl-, up to 2 wt% Cl-, in air. Sublimates produced from these experiments were analysed for mineralogical and chemical information. Raman spectroscopy and scanning electron microscopy helped to determine that silica polymorphs occur at all temperatures and that halite forms below 600°C. Additional phases, including hydrated phases transporting Mo, Cu and Pb also formed as sublimates. These hydrated phases are suggested to be hydrated post-experiment or are Cl--bearing analogues. The addition of Cl- to the experiments increases the concentration of Li, Rb, Cs, Ag, Cr, Cu, Mo and W in the sublimates compared to Cl-free experiments and Cl-bearing phases are likely hosts of volatile trace metals. Volcanic gases in nature do not have the oxygen fugacity of air and contain considerable S. To conduct sublimation experiments at various lower oxygen fugacities and with S as it is a redox sensitive ligand, I adapted my original benchtop fumarole design to a gas-mixing furnace, in which I degassed silicate melts containing S, Cl and trace metals. Substantial loss of S and Zn, Sn, As, Bi, Pb and Cd occurred from the starting material melt in the most reduced experiment at 4.6 log units below the FMQ buffer. This loss corresponded to increased concentrations of the same elements in the sublimates of the same experiment. These trace elements are likely hosted as sulfide minerals, as the fO2 conditions are in the sulfide stability field. This agrees with thermodynamic calculations that determine that sulfides should be stable in similar conditions to this experiment. Chlorides are sublimed in experiments from ~200-650°C and are likely subliming as a NaCl-KCl-FeCl3 solid solution. Halite is calculated to form at all temperatures in the experiments, based on modelling. These chlorides are probably hosting Cu, Cd, Bi, Li, Rb and Ag in the experiments. In nature, if these metals are in soluble salts, when leached they provide a source of metals to the environment where they are deposited. Overall, I demonstrated that trace metal behaviour in the sublimates from volcanic gases will be affected by available ligands and the oxygen fugacity of the melt and the gas. Chlorides are a likely phase to host trace metals and are ubiquitous in experiments, even with variable melt compositions, fO2 conditions and across a wide temperature range. / Graduate

Various criteria or lines of evidence have been used to identify ancient Maya marketplaces, including location near trade routes, artifactual evidence of trade, open space adjacent to transportation routes, proximity to public structures, low platforms and rock alignments to denote market spaces, and regular patterns in soil and floor chemical concentrations. Seibal and Mayapán were important economic Maya polities controlling the trade routes at the apex of their civilizations. The objectives of these studies were to apply geochemical and geospatial analyses of the soils and floors from public plazas and household patios, to discover the anthropogenic chemical residues of phosphorus (P) and heavy metals associated with the trade of foodstuffs and workshop items that may have been marketed there. Public access, causeways, reservoirs and a pattern of high P and metal concentrations are consistent with marketing of organic foodstuffs and workshop items within suspected marketplaces of each site. In contrast, geochemical patterns of the soils and floors of household structures are consistent with ceremonial and household activities.

Two plazas at Cobá, Mexico, may have been the place of market activity during the classic Maya period. The intense decomposition in the warm, moist soils of the Yucatan Peninsula precludes the identification of organic artifacts in archaeological contexts, but phosphorus and trace elements accumulation in soils may provide evidence of marketing activities. The spatial patterns of P and trace element concentrations were used to elucidate the types of ancient Maya activities that took place in those plazas. Phosphorus concentrations are highly correlated (p-value <0.01) with Fe, Mn, and Zn levels in both Plaza B and D. Although the soil geochemistry of Plaza B does not show a marketplace pattern in comparison with previous studies, the elemental concentrations and distributions within Plaza D join other lines of evidence to support the premise that marketplace activities took place at that location. Soil samples were analyzed using DTPA extraction, Mehlich II, Olsen, and Portable X-Ray Fluorescence (PXRF). Experiments were performed to study the suitability of PXRF for field studies. Aspects that were studied include granule size, soil moisture content, protective plastic films that could interfere with the X-Ray signal when placing the samples on top of the analyzer, and a comparison of certified soil standards to the PXRF elemental concentration readings. The results suggest that a field laboratory could be set up to air-dry and sieve soil samples to a minimum mesh size of #10 (> 2 mm).

<p>Water-quality in freshwater ecosystems is linked to metal contaminant sequestration and transport by suspended aquatic floc. This doctoral thesis investigates the combined microscale biogeochemical processes as well as macroscale hydrodynamic mechanisms controlling trace metal dynamics of freshwater floc, through comparative assessments of floc versus bottom bed sediment metal(loid) (Ag, As, Co, Cu, Ni and Pb) sequestration/mobilization across aquatic ecosystems ranging in physico-chemistry (e.g. pH, organic carbon, Fe/trace metal concentrations) in the Boreal Forest Region of Ontario and under variable energy-regimes (i.e. calm, windy, prolonged-storm) in a shallow wave-dominated urban beach in Lake Ontario, Canada.</p> <p>The results establish differential biogeochemical controls in suspended floc versus bed sediments influencing the abundance, reactivity and type of Fe minerals affecting trace metal abundance and solid-phase partitioning patterns between these two compartments. Specifically, this work demonstrates a microbial underpinning to floc collection of amorphous Fe oxyhydroxides (FeOOH) controlling floc metal sorption, retention and overall metal concentrations that are significantly greater in suspended floc than bed sediment. In contrast, crystalline Fe oxides (FeOx) dominate sediment metal retention, due to reductive dissolution and/or mineral aging of FeOOH, where sediment solid-solution metal partitioning is more influenced by system physico-chemistry (i.e pH). Further, rapid fluctuations in energy regime influencing re-suspension/settling of floc and sediment (i.e. surficial fine-grained lamina (SFGL) versus underlying consolidated sediments) result in temporal and spatial hydrodynamic-dependent mixing of Fe mineral phases, altering metal abundance and solid-phase metal partitioning in each compartment.</p> <p>Collectively, findings of this innovative integrated thesis work provide new understanding of the physical and biogeochemical controls on Fe cycling/mineral transformations between floc and bed sediments, ultimately affecting trace metal iv behaviour between these compartments and fate in freshwater environments. This insight has important implications for policy development in improving risk management of aquatic systems under varying physico-chemical and hydrodynamic conditions.</p> / Doctor of Philosophy (PhD)

Ectomycorrhizal fungi are essential to seedling establishment in disturbed sites. This dissertation examines the effects of trace metals and soil disturbance on ectomycorrhizal fungi in the laboratory and the field. The first experiment assessed Cu and Zn impact on growth of three ectomycorrhizal species in pure culture. Suillus granulatus and Pisolithus tinctorius were more tolerant to Cu than Paxillus involutus, however, none of the species grew at 250 ppm Cu. Suillus granulatus had the highest Zn tolerance, followed by Paxillus involutus and Pisolithus tinctorius. Sectoring observed in Suillus granulatus was deemed spontaneous and not involved in metal tolerance. The second experiment examined the adsorption of copper and zinc to acidic Uchee fine loamy sand. Contrary to expectations, the soil adsorbed up to 667 ppm Cu and 238 ppm Zn. Adsorption occurred mainly in the non-crystalline fraction of the soil. This analysis is a new approach in mycorrhizal research, and the crucial need for such tactics is discussed. The third experiment surveyed ectomycorrhizae on a mine reclamation project in Wise County, Virginia. Pinus strobus trees planted 1, 8, 13, and 25 years prior to the experiment were sampled. Colonization was lower than in well developed soils, but occurred on all seedlings. Increased colonization and a late stage mycobiont (Tuber) occurred on roots taken from the 25 year old subsite. A new observation was made of Suillus americanus on one year old seedlings. Lack of species overlap among sites suggests localized inoculum sources. The last experiment explored Pinus strobus and Pinus virginiana seedlings naturally regenerating on acidic, bare-mineral soil exposed by a road cut in Floyd County, Virginia. Ectomycorrhizal colonization ranged between 30 to 80 percent. Wide variation among individual samples suggests patchy inoculum distribution. Scleroderma citrinum, a common early-stage fungus, was dominant throughout. Other early stage genera included Rhizopogon, Pisolithus, and Thelephora. Mid to late stage genera including Suillus and Lactarius were identified. Cenococcum, often a dominant taxon, was a minor taxon here. The unusual presence of the ericoid mycobionts Hymenoscyphus and Oidiodendron is discussed. These results suggest that native inoculum can be an important resource for seedling recruitment. / Ph. D.

This research was divided into four objectives for assessing the impacts of coal mining on ecosystem health. The first objective was to provide an ecotoxicological assessment in the upper Clinch River using standard bioassessment techniques. Analysis of sediments and interstitial water (porewater) indicate higher concentrations of trace metals in samples from sites located above both a power plant (CRP) and Dumps Creek mining influences. The furthest sampling site located near Pounding Mill, Virginia (CR-PM) had higher concentrations of aluminum (2,250.9 mg/kg), copper (5.9 mg/kg) and iron (12,322.6 mg/kg) compared to samples collected directly below the Dumps Creek confluence (site CR-2). Similar results were obtained from bioaccumulation in-situ tests with the Asian clam (Corbicula fluminea) in 2009. Aluminum (7.81 mg/kg), Fe (48.25 mg/kg) and Zn (7.69 mg/kg) were accumulated in higher concentrations at CR-PM site than CR-2. However, the site located below the CRP effluent discharges (CR-3L) on the left bank had substantially higher concentrations of Al (14.19 mg/kg), Cu (6.78 mg/kg), Fe (88.78 mg/kg) and Zn (7.75 mg/kg) than both CR-PM and samples collected directly opposite of this site at CR-3R. To further understand the potential impact active mining on the Clinch River, a more comprehensive ecotoxicological evaluation was conducting in the Dumps Creek subwatershed. Field bioassessments determined that biological impairment occurred directly below a deep mine discharge (CBP 001), which was characterized by a distinct hydrogen sulfide odor. Total abundance and richness of benthic macroinvertebrates decreased to 3.5-20 and 1.25-2.3, respectively at DC-1 Dn. The discharge also caused the proliferation of a sulfur-oxidizing bacterium, Thiothrix nivea. During continuous discharge of the effluent, the bacteria was observed coating all surfaces at DC-1 Dn and may also contribute to an Fe-encrusted biofilm observed on in-situ clams at downstream site, DC-2 Dn. Toxicity tests with mining effluents indicate some potential toxicity of the 001 discharge, but this was variable between test organisms. Selecting the most appropriate test species for sediment and water column assays has been a primary goal for ecotoxicologists. Standard test organisms and established test guidelines exist, but US EPA recommended species may not be the most sensitive organisms to anthropogenic inputs. Therefore, Chapter Three and Four addressed the use of mayflies in routine laboratory testing. Preliminary results of toxicity tests with the mayfly, Isonychia sp. (Ephemeroptera) suggested that Isonychia were moderately sensitive to NaCl after 96-hr with an average LC50 value of 3.10 g NaCl/L. When exposed to a coal-mine processed effluent, Isonychia generated LC50 values that ranged from 13 to 39% effluent and were more sensitive to the effluent than Ceriodaphnia dubia. Based on results of the feasibility study in presented in Chapter Four, field collected organisms appear to be too unpredictable in test responses and therefore, such tests would be unreliable as stand-alone indicators of effluent toxicity. / Ph. D.

Trace metal concentrations in soil solution, and hence trace metal bioavailability and toxicity, are primarily controlled by sorption/desorption reactions at the mineral-water interface. While numerous studies have been conducted to understand the initial adsorption of these metals to soil minerals, less in known about long-term adsorption/ desorption processes. The objective of this study was to examine the influence of residence time and organic acids on the desorption of Pb2+and Cd2+ from goethite. Adsorption experiments were conducted at pH 6.0. Lead adsorption was nearly completed after 4 hours, with very little additional sorption during a 20-week period. In contrast cadmium showed a continuous slight increase in the amount of adsorption over the 20-week period. Desorption experiments were conducted at pH 4.5 and similar to previous studies examining trace metal desorption from oxide surfaces, the desorption kinetics for Pb2+and Cd2+ were slow compared to the sorption reaction. None of the experiments were completely reversible after an eight-hour desorption period. For all experiments except long-term Pb2+ desorption, the quantity of metal desorbed from goethite followed the order salicylate >NaNO3 > oxalate. Based on differences in cation affinity for the iron oxide surface one would expect a greater quantity of Cd2+ to be removed compared to Pb2+, for each of the extracting solutions. However at a pH of 4.5 we did not find a statistically significant trend. We observed a difference between the amount of metal removed for short and long-term experiments in five of six experiments, but these differences were only significant for Pb2+ experiments in the presence of salicylate. Two first order rate equations best fit the kinetics of trace metals desorption, with R2 values greater than 0.910 in all cases. Although our results show a decrease in rate coefficients (expect k1 for oxalate) with increased residence time, statistical analysis indicates that these results were only significant for Pb2+ experiments in the presence of salicylate. However raw and transformed data both suggest that desorption values are diverging as a function of aging time. Similar to other researchers we believe that Pb2+ and Cd2+ are sequestered by the goethite surface with an increase in residence time. These results suggest that residence time effects observed by many researchers are much less prevalent at low pH values. Therefore a reduction in soil pH created by natural anthropogenic processes may reduce the ability of soils to naturally sequester metals over time. / Master of Science

O presente estudo analisou aspectos do ciclo de vida e níveis de metais em Atherinella brasiliensis da praia de Itamambuca, Ubatuba (SP). As coletas foram mensais, nos períodos diurno e noturno, de setembro de 2003 a fevereiro de 2005, em quatro estações na praia e uma no rio Itamambuca, utilizando-se picaré. Os indivíduos migram diariamente para dentro do rio no período noturno. O melhor ajuste ao modelo de von Bertalanffy (CT= 164,85*(1-e-2,16(t+0,0038))) e à longevidade (A0,95= 1,378 ano) foi obtido pelo método de Ford-Walford. O índice de performance de crescimento e a mortalidade variaram de 2,77 a 2,91 e 1,64 a 1,82 ano-1, respectivamente. O valor de L50 estimado para sexos agrupados foi 86,6 mm, e os de RGS, DK e a freqüência de desovantes sugerem desova durante todo o ano, com maior intensidade do final da primavera até início do outono. A desova é parcelada, com alta freqüência e em pequenos lotes. Altas concentrações de Cr, Fe e Zn foram detectadas na musculatura, sendo maiores em indivíduos jovens e na alta temporada turística. Pode-se concluir que o peixe-rei passa todo seu ciclo de vida na praia de Itamambuca, apresenta altas taxas de crescimento e mortalidade natural, e desova ao longo de todo o ano. / The present study analyzed the life history and metal levels of Atherinella brasiliensis from Itamambuca beach, Ubatuba (SP). Surveys were conducted monthly, in diurnal and nocturnal periods, between September 2003 and February 2005, in four stations at the beach and one at the Itamambuca river, using beach seine. Individuals showed daily migration into the river at nocturnal period. The better adjustment to von Bertalanffy?s model (Lt = 164.85*(1-e-2.16(t+0.0038))) and to longevity (A0.95= 1.378 year) was obtained through Ford-Walford method. The value of estimated L50 for grouped gender was 86.6 mm, and the GSR, the DK and the spawning frequency suggest spawning during all year around, with higher intensity in late spring until middle autumn. The high frequency of spawning and the low batch fecundity indicate that the species is a batch spawner. High concentrations of Cr, Fe and Zn were detected in musculature, being higher among young individuals, and during tourist high season. In conclusion, the Brazilian silverside spends its life cycle on the Itamambuca beach, shows high growth and natural mortality rates, and spawning throughout the year.

L’étude réalisée porte sur l’évaluation du niveau de contamination par les éléments traces métalliques (ETM) des sédiments de la rade de Toulon, une rade semi-fermée soumise à un fort impact anthropique. Le prélèvement de carottes d’interface en 52 points répartis sur l’intégralité de la Rade a permis d’établir une cartographie précise des caractéristiques sédimentaires et des teneurs en métaux/métalloïdes. Les résultats obtenus sur les sédiments de surface ont montré l’état de contamination significatif de la rade (en particulier en Cu, Hg, Pb, et Zn), notamment dans les zones les plus enclavées de la petite rade, où les teneurs peuvent dépasser de plusieurs ordres de grandeur les limites définies par la législation en vue d’opérations de dragage. La distribution de la contamination observée a clairement indiqué un export de la petite vers la grande rade (normalement moins exposée), probablement gouverné par des processus hydrodynamiques responsables de la remise en suspension du sédiment contaminé. Les profils sédimentaires de carottes d’interface prélevées dans des zones de contamination contrastée ont révélé la présence systématique de pics de contamination dans les 20 premiers cm. Compte tenu des taux de sédimentation déterminés, ceci démontrerait que la rade a été soumise à un épisode de multi-contaminations majeur, probablement lié aux conséquences de la 2nde guerre mondiale. L’analyse des eaux interstitielles et surnageantes (paramètres physico-chimiques, majeurs, traceurs diagénétiques et ETM) de ces carottes d’interface a permis d’étudier la mobilité des ETM dans le sédiment. Les profils obtenus apparaissent essentiellement contrôlés par des mécanismes diagénétiques et démontrent le rôle exercé par les principales phases porteuses présentes dans le sédiment (oxy-hydroxydes de Fe et de Mn, sulfures) sur la mobilité des ETM. La modélisation de ces profils a permis d’évaluer les flux diffusifs à l’interface eau sédiment, afin de déterminer l’action du sédiment, en tant que puits ou source de contamination pour la colonne d’eau. Les flux diffusifs sortant calculés apparaissent relativement faibles en comparaison des teneurs totales mesurées dans le sédiment, démontrant que la majorité des ETM est fortement immobilisée dans le sédiment.Enfin, ce travail a été complété par des expériences de remise en suspension en laboratoire et sur le terrain, visant à simuler différents scénarios possibles (tempête,trafic maritime, dragage). Dans les conditions étudiées, si pour certains ETM la remobilisation en solution est faible (ex. As, Hg), elle peut au contraire être très significative pour d’autres (ex. Cd, Cu, Pb) conduisant à une contamination non négligeable de la colonne d’eau. / This study deals with the assessment of sediment contamination levels by trace metals in the Toulon bay, a semi-closed Mediterranean area submitted to heavy anthropogenic inputs. The sampling of interface cores in 52 points located in thewhole bay allowed establishing a precise mapping of the sedimentary characteristics and the metals/metalloids contents. The obtained results from the surface sediments revealed a significant contamination of the bay (especially for Cu, Hg, Pb and Zn), mainly in the most enclosed parts of the small bay. There, the levels may exceed by several orders of magnitude the limits concerning dredging operations defined by the French legislation. The observed contamination distribution clearly indicated an export from the small to the large bay (normally less exposed) probably governed by hydrodynamic processes, responsible for the contaminated sediment resuspension. The sedimentary profiles of interface cores sampled in contrasted contamination areas revealed the presence of systematic contamination peaks in the first 20 cm. Taking into account the calculated sedimentation rate, this would demonstrate that the Toulon bay was submitted to a strong multi-contamination, probably linked to the 2nd world war. The analysis of interstitial waters (physico-chemical parameters,major, trace metals, and diagenetic tracers) allowed studying trace metals mobility. The obtained profiles appeared mainly controlled by diagenetic mechanisms and showed the major role of the main carrier phases present in the sediments (oxyhydroxides of Fe and Mn, sulphides). The modeling of these profiles led to the determination of the diffusive fluxes at the sediment/water interface, and so, to the action of the sediment as a sink or a source of contamination for the water column.The calculated outgoing diffusive fluxes appeared relatively low in comparison to the total contents measured in the sediment, proving that the main part of the studied trace metals remains in the sediment. Finally, resuspension experiments in lab and on field were performed with the aim to simulate different possible scenarios (storm,nautical traffic, dredging). Under the studied conditions, the remobilization can be low for some trace metals (e.g. As, Hg), but it may contrariwise be quite important for others (e.g. Cd, Cu, Pb) leading to a non-negligible contamination of the water column.