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Ocean acidification is occurring in response to rapidly increasing concentrations of atmospheric CO2. Shallow-water hydrothermal vent systems have been proposed as natural laboratories for studying the effects of elevated pCO2 on benthic communities. Hydrothermal vents occur at depths of approximately 10m in Tutum Bay, Ambitle Island, Papua New Guinea; these vents are surrounded by a typical-appearing fringing coral-reef community. Groups of live specimens of seven species of reef-dwelling, larger benthic foraminifers, along with segments of calcareous green algae broken from live thalli, were collected from a reef location, placed in small mesh bags, and deployed for five days at six different sites along a gradient of temperature (29.6oC-59.3oC) and pH (5.9-8.1) with distance from a large hydrothermal vent in Tutum Bay. Foraminiferal taxa used in the experiment included Amphisorus hemprichii, a species with Mg-calcite porcelaneous shells, three species of Amphistegina that produce hyaline calcite shells, and three species with hyaline Mg-calcite shells (Heterostegina depressa and two Calcarina spp.). Several specimens of four of the seven foraminiferal species examined survived exposure to elevated temperatures of 59.3oC and low pH of 6.2 for five days, while at least one specimen of each of the seven species survived exposure to 39.9oC and pH 5.9. Examination of shells at 600-1000x magnification using scanning electron microscopy revealed fine-scale dissolution in specimens up to 30m from the vent. Results of this experiment, as well as previously reported observations from the study site, indicate that the calcifying reef-dwelling organisms examined can survive pH extremes that result in dissolution of their shells following death.

Microbes are prevalent in geologic settings and a growing body of research suggests the roles they play in geologic processes may be more important than previously thought, and therefore underestimated. This dissertation addresses the influence of microbes on the dissolution of limestone in karst settings by analyzing the stable carbon isotopes and geochemistry of air and waters from three unique cave and karst settings: West-Central Florida, the Everglades (southern Florida) and The Bahamas. In Florida, these parameters as well as air/water temperature, rainfall, and water-level fluctuations were monitored for 22 and 10 months. In the Bahamas, geochemical data were collected from at varying time-intervals from a variety of cave and surface water bodies. Results showed that microbial respiration in these environments is an important source of carbon dioxide, which contributes to the formation of carbonic acid, which appears to be the major dissolving agent at each of these sites. At the same time, microbially-mediated oxidation of both organic matter and minerals exerts a secondary dissolution control by providing additional acid and inorganic ions that dissolve rock and/or inhibit limestone precipitation. This dissertation also includes a chapter discussing the role of the USF Department Geology in the evolution of assessment for Spreadsheets Across the Curriculum (SSAC) project, which promotes quantitative literacy (QL) by teaching math in the context of other disciplines. Assessment occurred primarily in the Computational Geology course from 2005 to 2008 and showed that this teaching strategy fostered gains in math knowledge and positive math association. Simultaneously, instructors learned that pre-planning and adaptability was central to developing a successful assessment strategy, which, when combined with the heterogeneity of subjects each year, presents challenges in the yearly comparison of results. These conditions are common in educational settings, illustrating the impracticality of standardized assessment instruments and practices, and the importance of the extensive preparation required in identifying assessment goals and the best strategies for achieving them in a given setting.

It has long been believed that passionate love wanes over time, whereas companionate love grows stronger with time. Using a sample of individuals in dating relationships who reported on their feelings of love for their partners up to 20 times over the course of several months, I tested whether passionate love and companionate love develop across the early months of romantic involvement in a manner consistent with theory. Additionally, I investigated whether certain developmental trajectories of both varieties of love are more predictive of relationship dissolution than others. To do this, I first examined the average trajectories of passionate and companionate love for those who stayed together with their partners and those who experienced a breakup, paying special attention to extraneous factors that were expected to influence the manner in which both varieties of love changed over time. The amount of time individuals knew their partners prior to becoming romantically involved, their feelings of the opposing variety of love, the extent to which individuals wanted to break up with their partners, their perceptions of their partners’ desire to break up, and gender all informed the ways in which love changed over time. Because it was expected that passionate love and companionate love would show substantial heterogeneity in their temporal trajectories, I then identified the prototypical patterns of development for passionate and companionate love. The results for passionate love revealed eight distinct linear trajectories, and six unique linear trajectories were identified for companionate love. For passionate love, individuals who experienced stable or declining levels of love were more likely to experience a breakup, but the connection between companionate love and relationship dissolution was less straightforward. Perhaps most importantly, passionate and companionate love interacted to predict the likelihood of dissolution, such that, to the extent that individuals who reported higher levels of passionate love also reported stronger feelings of companionate love, the lower their odds of dissolution. The current findings both complement and extend prior theoretical and empirical work on the developmental trajectories of passionate and companionate love and their connections to relationship dissolution. / text

Part of the natural progression of any romantic relationship is that, over time, individuals will meet and form connections with each other’s friends and family (Milardo, 1982). Interestingly, the examination of social network introductions has largely been neglected by researchers. We do not know when couple members introduce each other to their friends and parents. We also do not know what effect, if any, these network introductions have on future relationship outcomes. The present study addressed these gaps. Specifically, I examined when couple members typically met each other’s friends and parents for the first time, whether relationship quality influenced the likelihood of making these introductions, and whether these introductions predicted later relationship outcomes (i.e., relationship quality, likelihood of breakup, and post-breakup adjustment). In the present study, participants in new romantic relationships (less than 6 months duration) completed a survey every two weeks for nine months. In each survey, participants indicated whether friend and family introductions had occurred, their current relationship quality, and whether they had broken up with their partners since the previous survey. If individuals reported having broken up, they were asked about their reactions to the breakup. Results revealed that friends were typically introduced before parents, and that relationship quality predicted the likelihood of newly dating individuals introducing their parents (but not friends) to their romantic partners. Largely, network introductions failed to predict later perceptions of relationship quality but did influence the likelihood of relationship dissolution over the course of the study. Furthermore, introductions to participants’ mothers predicted worse emotional reactions to a breakup, and introductions to participants’ fathers and best friends were associated with greater relationship longing. The results of this study represent an important first step in understanding when individuals introduce their romantic partners to their friends and family and how these introductions influence relationship development. / text

Geological carbon dioxide (CO₂) capture and storage in geological formations has the potential to reduce anthropogenic emissions. The viability of technology depends on the long-term security of the geological CO₂ storage. Dissolution of CO₂ into the brine, resulting in stable stratification, has been identified as the key to long-term storage security. The dissolution rate determined by convection in the brine is driven by the increase of brine density with CO₂ saturation. Here we present a new analog laboratory experiment system to characterize convective dissolution in homogeneous porous medium. By understanding the relationship between dissolution and the Rayleigh number in homogeneous porous media, we can evaluate if convective dissolution occurs in the field and, in turn, to estimate the security of geological CO₂ storage fields. The large experimental assembly will allow us to quantify the relationship between convective dynamics and the Rayleigh number of the system, which could be essential to trapping process at Bravo Dome. A series of pictures with high resolution are taken to show the existence and movement of fingers of analog fluid. Also, these pictures are processed, clearly showed the concentration of analog fluid, which is essential to analyze the convective dissolution in detail. We measured the reduction in the convective flux due to hydraulic dispersion effect compared to that in homogeneous media, to determine if convective dissolution is an important trapping process at Bravo Dome. / text

Carbon sequestration is a method of capturing and storing excess anthropogenic CO₂ in the subsurface. When CO₂ is injected, the temperature and pressure at depth turn it into a supercritical (SC) fluid, where density is that of a liquid, but viscosity and compressibility resemble a gas. Ultimately the SC CO₂ is trapped at depth either by low permeability sealing layers, by reactions with minerals, or by dissolving into fluids. The injected CO₂ is buoyant and initially exists as a non-aqueous hydrophobic layer floating on top of the subsurface brine, up against the upper sealing formation, but over time it will dissolve into the brine and potentially react with minerals. The details of that initial dissolution reaction, however, are only poorly understood, and I address three basic questions for this research: What is the fundamental kinetics of SC CO₂ dissolution into water? How fast does dissolved CO₂ diffuse away from the source point? And what geochemical conditions influence the dissolution rate? To answer these questions I employed a high pressure flow-through approach using a column packed with coarse quartz sand. The system was both pressure and temperature controlled to have either liquid or SC CO₂ present, and was typically run at 100 Bar, 0.5 to 2.5 mls/min, and 28-60°C. After establishing the hydraulic parameters for the column using two conservative tracers (Br, As), injections (5 and 20 [mu]l) were made either as aqueous solutions equilibrated to high pressure CO₂, or as pure liquid or SC CO₂ into 0.1 mmol NaOH. For all experiments the pH of the system was monitored, and [CO₂] over time was calculated from those data. For injections of brine with dissolved CO₂, transport was conservative and was nearly identical to the conservative tracers. The CO₂ quickly mixes in the column and does not react with the quartz. The liquid and SC CO₂ injections, however, do not act conservatively, and have a very long tailing breakthrough curve that extends to tens of pore volumes. I hypothesize that the SC CO₂ is becoming trapped as a droplet or many droplets in the pore spaces, and the long breakthrough tail is related either to the rate of dissolution into the aqueous phase, the diffusion of dissolved CO₂ away from the phase boundary, or the reaction with the NaOH, limited to the narrow contact zones in the pore throats. Because of the speed at which acid-base reactions occur (nanosecond kinetics), I infer that the rate limiting step is either surface dissolution or diffusion. From plots of ln[CO₂] v. time I obtained values for k, the specific rate of the dissolution reaction R=-k[CO₂]. No trend for k was seen with respect to changes in temperature, but k did show a trend with respect to changing flow rate. k increased from an average value of 3.05x10⁻³ at 0.5 ml/min to an average value of 3.38x10⁻³ at 1.6 ml/min, and then held constant at the higher flow rates, up to 2.5 ml/min. I interpret these data to show that at low flow rates, the reaction is diffusion limited; the fluid nearest the contact zone becomes saturated with dissolved CO₂. At higher flow rates, the fluid is moving fast enough that saturation cannot occur, and the kinetics of the dissolution reaction dominate. Simple geometric models indicate that the CO₂/water interface is shaped like a spherical cap, indicating that the snapped-off CO₂ is forming a meniscus in the pore throat, limiting the surface area across which dissolution can occur. / text

Microbial communities influence the kinetics and pathways of reactions involved in the dissolution of a number of minerals (Ehrlich 1996). On a smaller scale these interactions can affect substrate permeability, porosity, and create highly localized biogeochemical conditions. However, a mechanistic understanding of the consequences of microbial surface colonization on calcite dissolution rate has yet to be achieved. More specifically, little is known about the impact of sulfur-oxidizing bacteria activity on the rate of carbonate mineral dissolution, or the nature of the microbe-limestone attachment and interaction. Through a series of laboratory and field experiments the effect of mineral surface colonization by microbial communities, obtained from an active sulfuric acid cave (Lower Kane Cave (LKC), Big Horn Basin, WY), on the dissolution rate of Madison Limestone was quantified. Results from laboratory experiments showed that a microbial biofilm, composed primarily of Epsilonproteobacteria and Gammaproteobacteria growing on a limestone surface oxidized thiosulfate and increased carbonate dissolution rates up to 3.3 times faster than abiotic rates. When all thiosulfate substrate was withheld the community oxidized stored intracellular sulfur, continuing to accelerate limestone dissolution and decreasing pH. This process is sensitive to O2 limitations. Characterization of this aggressive sub-biofilm corrosion was more closely examined by SEM imaging. By comparing mineral surface morphology of colonized chips to non-colonized chips of various carbonate substrates, it was shown that even under conditions near equilibrium with calcite, aggressive dissolution of carbonate substratum occurs exclusively beneath the biofilm. These findings support the hypothesis that (1) sulfur-oxidizing microbial communities aggressively dissolve carbonates in order to buffer the production of excess acidity by neutrophilic communities and (2) biofilm presence affects carbonate mineral dissolution by physically separating a bulk stream water from the sub-biomat environment. Furthermore, it was found that mineralogy affects the degree of establishment of microbial communities in this environment. Results from a series of four laboratory and one in situ reactor experiment showed that limestone and dolostone substratum consistently had higher biomass accumulations than silicate minerals or pure Iceland spar calcite in the same reactor. These results provide evidence to support the hypothesis that mineralogy influences microbial accumulation in sulfuric-acid karst systems. Particularly, neutrophilic sulfur-oxidizing communities accumulate in greater quantities on solid substrates that buffer metabolically-generated acidity. These results also demonstrated the dependence of microorganisms on colonization of a particular mineral surface, possibly in order to gain access to micronutrients bound within solid substrates when exposed to nutrient-limited conditions. / text

Η συγκεκριμένη εργασία πραγματεύεται μία διδακτική προσέγγιση του φαινομένου της διάλυσης λευκών στερεών ουσιών σε δύο διαφορετικούς διαφανείς διαλύτες. Σαφέστερα, σκοπός της εργασίας είναι η μελέτη της ενδεχόμενης εννοιολογικής αλλαγής στη σκέψη παιδιών προσχολικής ηλικίας αναφορικά με το εν λόγω φαινόμενο μετά την υλοποίηση ενός εκπαιδευτικού προγράμματος. Τα αποτελέσματα της έρευνας έδειξαν ότι οι μαθητές προσχολικής ηλικίας μετά την εφαρμογή του εκπαιδευτικού προγράμματος είναι σε θέση να συγκροτήσουν συλλογισμούς συμβατούς με το σχολικό μοντέλο για το φαινόμενο της διάλυσης στερεών ουσιών σε υγρούς διαλύτες. / This paper deals with a teaching approach about the phenomenon of dissolution of white solids in two different transparent solvents. The aim of this paper is the study of the possible conceptual change in preschool children's thinking about this phenomenon after the implementation of an educational program. The results showed that preschool students are able to compose reasoning compatible with the school model about the effect of the dissolution of solids in liquid solvents after the implementation of the educational program.

Minimal research has been conducted to examine dissolution and remediation of NAPL located in lower-permeability (K) media. The purpose of this research was to investigate dissolution of non-uniformly distributed residual NAPL located in lower-K media and how mass transfer was affected. Additionally, in situ chemical oxidation (ISCO) effectiveness using KMnO₄ in the laboratory and field was examined. A series of column and flow cell experiments were conducted with trichloroethene (TCE). For uniformly distributed residual NAPL control experiments, reduced interfacial pool area and resonance time were likely the most important mass transfer limitation. For non-uniformly distributed residual NAPL, by-pass flow attributed to reduced effective permeability was initially the most important factor affecting nonideal mass transfer. Dissolution times increased with physical heterogeneity due to bypass flow. Mass transfer was more non-ideal for non-uniformly distributed NAPL. Nonideal mass transfer was most pronounced for non-uniformly distributed NAPL in lower-K zones. NAPL location influences dissolution behavior and ultimately remediation. Mass flux reduction versus mass reduction comparisons for the experiments exhibited how mass transfer trends vary between systems. The effectiveness of KMnO₄ ISCO of residual TCE located in lower-K media was examined. KMnO₄ solution was flushed through a flow cell followed by water flushing to evaluate long-term mass flux behavior, which was then compared to a water-flush control. For water flushing following KMnO₄ flushing, mass flux was similar to the control experiment. However, since contaminant mass was reduced, the number of pore volumes required for complete TCE removal via water flushing was estimated to be reduced by half. 1,1-Dichloroethene (DCE) is thought to be located in lower permeability strata adjacent to the water table at the Samsonite Building Area. Eight injection wells were emplaced in the source zone area, with well screens spanning the vadose and saturated zones, and injected with ~250 kg of 1.7% KMnO₄ solution. Bench-scale studies using core material determined that DCE was readily degraded by KMnO₄, even at lower reagent concentrations (< 1 mM). The natural oxidant demand was determined to be 1.0 x 10⁻⁵ g of KMnO₄/g of sediment. Aqueous DCE levels dropped below detection after KMnO₄ solution was present.