This thesis is concerned with the effect of widespread internet use on the sales of audio CDs. It analyses trends in the American and Czech markets from the end of the 1990's to today. Its analysis is based on the relationship between musical genres and their respective target audiences with the hypothesis being that genres with listeners who have adopted the internet more rapidly are more affected than other genres. The thesis proves that the decrease in music sales in the last ten years, the bulk of which have been CDs, has been caused by the graudual establishment of the internet with its probable illegal downloading of recordings and the change in format to MP3 from CD.

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

Surface complexation models (SCMs) have proven to be a useful tool in predicting ion adsorption at the mineral – water interface. In particular, previous research has shown that the Diffuse Layer Model (DLM), Constant Capacitance Model (CCM), and Triple Layer Model (TLM), are all capable of predicting ion adsorption in relatively simple single solute systems. To better simulate the environmental conditions experienced by groundwater sources present in the Earth’s subsurface, experimental adsorption studies have been conducted for more complex multi-solute systems. Under these conditions, SCMs have not proven to be reliable in consistently predicting ion adsorption behavior for the adsorbates of interest. This inability of these SCMs to predict ion adsorption for more complex, multi-solute systems is thought to stem from the variable site density (NS) values utilized in these models. In this research, a methodology was developed for characterizing mineral surface heterogeneity that allows for the different site density values predicted from crystallography, microscopic imaging, tritium exchange, surface saturation data, and surface charging data to all be explained using a single unified theory. This methodology was applied to a goethite mineral sample used in performing batch adsorption studies in single and bi-solute systems with Cd(II), Pb(II), and Se(IV). The adsorption behavior of these adsorbates onto the goethite sample was successfully predicted using the Charge Distribution Multi-Site Complexation (CD-MUSIC) Model and surface complexes consistent with spectroscopic data and computational molecular modeling simulations. A second, separate modeling study was performed using CD-MUSIC to predict Hg(II) adsorption onto different goethite samples of varying size and crystal morphology in single and multi-solute systems. In this study, site density values were predicted for the mineral samples studied utilizing a linear relationship observed for goethite between specific surface area and proton reactive site density. The CD-MUSIC model proved successful in predicting Hg(II) adsorption over all conditions studied while employing only surface complexes consistent with molecular scale analyses. In addition, a novel method for quantifying carbonate’s presence in experimental systems was developed. / text

The adsorption behavior of silicic acid and arsenite alone and competitively on goethite over a broad pH range (3-11) at environmentally relevant concentrations was investigated utilizing pH adsorption data and zeta potential measurements. Both addition scenarios (Si before As(III) and As(III) before Si) were examined. The results of the adsorption experiments and zeta potential measurements were then used to model the single ion and competitive ion adsorption on goethite with the CD-MUSIC model implemented in the FITEQL 4.0 computer program. Silicic acid adsorption was reduced by the presence of arsenite for all but one of the adsorption scenarios examined, while in contrast silicic acid had little effect upon arsenite adsorption. However, the presence of silicic acid, regardless of the addition scenario, dramatically increased the arsenite equilibrium solution concentration over the entire pH range investigated. The CD-MUSIC model was able to predict the single ion adsorption behavior of silicic acid and arsenite on goethite. The modeled zeta potential data provided further evidence of the CD-MUSIC model's ability to describe the single anion adsorption on goethite. Our model was also able to collectively describe adsorption and zeta potential data for the low Si-arsenite adsorption scenario quite well however, our model under-predicted silicic acid adsorption for the high Si-arsenite competitive scenario. / Master of Science

MAAS / Department of Music