Anthropogenic activities are often considered to be the main sources of mercury (Hg) found in aquatic systems. The aim of this study was to reconstruct the historic input of Hg to a large lake (Lake Ekoln) situated downstream the City of Uppsala using a dated sediment core. The main objective was to reveal general long-term (millennia-scale) trend in mercury loadings to the lake assess to what extent the lake has received an increase input of mercury during the last century from atmospheric inputs or local sources (mining activities, hospital effluents, industries or agricultural activities). Sediment samples were analyzed with X-ray fluorescence spectroscopy for measurements of lead and phosphorous (used as a proxy for atmospheric inputs and effluent water, respectively). Total Hg was analyzed using a mercury analyzer. My results indicate high Hg concentrations in sediment of Lake Ekoln during the last three centuries. Hg concentrations was not correlated to atmospheric derived metals (Pb) or effluent water derived nutrients (P) and only weakly correlated to the organic matter content of the sediment. Highest concentrations was found during a period around 1850 and in the last few years. The weak correlation with Pb suggest that the Hg is entering the lake from other sources than atmospheric inputs. The most likely local sources are argued to be mining activities (including fossil fuel burning during the production of iron) or Uppsala university hospital situated upstream of Lake Ekoln. However, there is a large uncertainty regarding the importance of these historical Hg sources for the lake.

Understanding pore network structure of a porous medium and fluid flow in the pore network has been an interest to researchers for decades. This study focuses on the characterization and simulation of the pore networks in petroleum reservoir rocks using conventional characterization techniques. A Representative Elemental Volume (REV) model is developed which simulates the pore network as a series of non-interconnected capillary tubes of varying sizes. The model implements mercury porosimetry (MP) results and capillary pressure principles to calculate the size of each bundle of capillary tubes based on a pore throat size distribution produced by the MP experiment. It also implements electrical properties of the rocks to estimate the average length of the capillary tubes. To verify the validity of the simulated network, permeability is calculated for the simulated network using Poiseuille’s flow principles for capillary tubes. Preliminary work showed that the model is capable of simulating the pore network reasonably well because permeability estimations for the simulated network matched measurements. In this study, MP and nuclear magnetic resonance (NMR) tests as well as centrifuge and permeability tests are performed on a suite of 11 sandstone and carbonate rock samples. Because electrical tests were not available, average length of flow paths is calculated with an alternative method that uses porosity to calculate tortuosity. Permeability estimations of the simulated network are compared with measurements. Estimations are also compared to other predictions using methods that implement MP and NMR data to simulate the pore network and the results show that the developed REV model out performs all the other techniques. / October 2015

Mercury is a toxic metal that has been released to the environment through numerous industrial activities. It can exist in various solid, aqueous, and gaseous forms. Volatile Hg(0) is frequently present at the source of a spill where it behaves as a dense non-aqueous phase liquid (DNAPL) contaminant that can change oxidation state and speciation via chemical or biological reactions. Mercury speciation is a key factor determining the mobility, bioavailability, and toxicity of Hg in the environment. Previous research has demonstrated that In Situ Thermal Desorption (ISTD) can be used in various modes to treat soil contaminants including Hg(0). The application of ISTD and other remediation processes must incorporate potential speciation during remediation and assess mobility of any mercury remaining in the soil post-remediation. However, research examining the impact of mercury speciation on ISTD processes is limited. The goals of this research are to investigate the fate and transport of mercury in soils from the source where concentrations are expected to be high to dilute solutions associated with down gradient groundwater, lakes, and rivers. For high concentrations of mercury, equilibrium speciation has been investigated to identify potential transformations at high temperatures consistent with those applied in ISTD processes. A model has been developed that describes mercury speciation over a range of environmental conditions. At low mercury concentrations, competitive Hg(II) adsorption on the soil minerals, goethite and gibbsite, has been evaluated over a range of experimental conditions. Models describing Hg(II) adsorption and aqueous speciation have been developed to provide a tool for predicting the fate and transport of residual mercury after thermal remediation applications. The results of these studies demonstrate that ISTD is feasible, but the off-gas speciation will depend on both the applied temperatures and the soil composition and redox conditions of the site. Pure phase mercury was predicted to be vaporized at temperatures well within the range of typical ISTD processes. The adsorption of trace levels of Hg(II) remaining after ISTD was successfully modeled on goethite and gibbsite using the 1-pK CD-MUSIC model. / text

published_or_final_version / Chemistry / Master / Master of Philosophy

Mercury is the only metal that is in liquid form at room temperature and it has over the years been used in various combinations to extract gold, in measuring devices, medicaments, paper industry, batteries and fluorescent lights as well as in dentistry as dental amalgam. Dental amalgam is a mixture of 50 % mercury and 50% of an alloy consisting of silver, tin, copper and zink particles and has been used in dentistry for many years. The environmental effect of mercury release into the sewer from dental practices and clinics, and the inability of the wastewater treatment plants to remove it from the sludge lead to the introduction of amalgam separators in Sweden in 1980. The ISO standard 11143 regulates the efficacy of the amalgam separators, which should be at a 95% level, but is based on a laboratory test rather than a clinical evaluation. This study looks at the available amalgam separators in use in four areas of Sweden, Uppsala, Stockholm, Östergötland and Skåne and compares their clinical efficiency. The clinical efficiency ranged between 75 to 95%, with most units below the 90% mark. In Östergötland a new improved separator is being tried, the Capere unit, which is based on finely ground pine bark treated with a chelator sensitive to all metals and used in conjunction with a cotton filter and a regular amalgam separator. This was shown to be superior to the other separators, with a 99, 9% removal of even the smallest amalgam particles and ionic mercury from the wastewater before leaving the clinic. Otherwise, combining more than one amalgam separator of the brands available on the Swedish market did not improve the efficiency of them.

The streaming plasma in the solar wind is a never ending source of energy, plasma, and momentum for planetary magnetospheres, and it continuously drives large-scale plasma convection systems in our magnetosphere and over our polar ionosphere. This coupling between the solar wind and the magnetosphere is primarily explained by two different processes: magnetic reconnection at high latitudes, which interconnects the interplanetary magnetic field (IMF) with the planetary dipole field, and low-latitude dynamos such as viscous interaction, where the streaming plasma in the solar wind may trigger waves and instabilities at the flanks of the magnetosphere, and thereby allow solar wind plasma to enter into the system.This work aims to further determine the nature and properties of these driving dynamos, both by statistical studies of their relative importance for ionospheric convection at Earth, and by assessment and analysis of the Kelvin-Helmholtz instability at Mercury, utilizing data from the MESSENGER spacecraft's first and third flyby of the planet.It is shown that the presence of the low-latitude dynamos is primarily dependent on the IMF direction: the driving is close to non-existent when the IMF is southward, but increases to the order of a third of the total ionospheric driving when the IMF turns northward (here, the magnitude of the driving is also shown to be dependent on the viscous parameters in the solar wind). The work also discusses the saturation of the reconnection generated potential, and shows that the terrestrial response follows a non-linear behavior for strong solar wind driving both when the IMF is southward and northward.Comparative studies of different magnetospheres provide an excellent path for increasing our understanding of space-related phenomena. Here, study of the Kelvin-Helmholtz instability at Mercury allows us to investigate how the different parameters of the system affect the mass, energy, and momentum transfer at the flanks of the magnetosphere. The large ion gyro radius expected is shown to develop a dawn-dusk asymmetry in the growth rates, with the dawn side as the more unstable of the two. This effect should be particularly visible when the planet is close to perihelion. Mercury's smaller scale size combined with the relatively high spacecraft velocity is also shown to provide excellent opportunities for studying the spatial structure of the waves, and a vortex reconstruction that can explain all the large-scale variations in the Kelvin-Helmholtz waves observed during MESSENGER's third Mercury flyby is presented. / QC 20110405

No description available.

No description available.

The Cataraqui River, which drains 930 square km of watershed before emptying into the inner harbour of Kingston, Ontario (pop: 113,000), has a long history of anthropogenic use. More than 40 industries have existed within the inner harbour over the last century, and while many of these industries are no longer present, the properties that they operated on remain to the present day as potential sources of persistent contamination. This study examined total mercury (THg) concentrations in depth profiles of 21 sediment cores within the inner harbour. THg in pore waters was measured in some selected cores along with methylmercury (MeHg), and total organic carbon measured as % Organic Matter (OM). Results show that the spatial distribution of THg in the surface sediment is not homogenous; concentrations in surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater than the rest of the inner harbour, and above the severe effect limit (2000 μg/kg) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in surface sediment. THg in pore water was below detection limits in most cores, indicating possible strong associations with sediments, however OM only showed significant, positive correlations with THg in one core sampled. To determine the sources of Hg to sediments, soils, runoff and storm sewer discharges near high concentration sediments were measured for THg. Hg was not detected in storm sewers, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 μg/kg. Significant [THg] was detected in runoff draining shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to sediment. Since [THg] was correlated to the [MeHg] in surface sediment, reducing the amount of Hg entering the river from terrestrial sources may reduce the amount of bioavailable Hg in sediments of the inner harbour. / Thesis (Master, Biology) -- Queen's University, 2007-11-01 19:12:24.364

Bythotrephes longimanus, a predatory exotic cladoceran, has spread rapidly to numerous lakes through the Laurentian Great Lakes region of Ontario and North America. Post-invaded lakes are known to have reduced zooplankton species richness, biomass and altered community structure. Bythotrephes may also affect the diet and trophic position of macroinvertebrate predators and prey species for fish (e.g., Mysis relicta). However, the effects of this species in altering higher trophic levels remain largely unexamined. Using a combined approach of stable isotope (d13C and d15N) and THg analysis, the trophic position of Bythotrephes in two invaded lakes was investigated. Based on d15N values, Bythotrephes shared a similar trophic position to native macroinvertebrate predators (9 and 7‰ for Peninsula and Harp lakes, respectively). Using a mixing model and stomach content analysis we show that, despite low and patchy lake abundance, Bythotrephes may be a key prey item to fish and has approximate dietary contributions similar to native prey items, such as zooplankton, Chaoborus and Mysis. In both lakes, Hg conformed to predicted biomagnification trends as indicated by 15N. When Bythotrephes invades lakes with native macroinvertebrate predators, it inserts itself into the same trophic position and does not have major effects on food web length. / Thesis (Master, Biology) -- Queen's University, 2008-01-10 22:00:22.188