The Chlorine-Ammonia Process was developed recently as a preoxidation process to minimize the formation of bromate during ozonation of the waters containing a significant bromide concentration. Chlorine is added first, followed by ammonia 5-10 minutes later, with the goal of sequestering bromide in monobromamine before the subsequent ozonation step. The goal of this research was to improve the Chlorine-Ammonia Process by introducing a very short prechlorination step (i.e., 30 seconds before addition of ammonia) to minimize overall disinfection by-product formation. Also, in this strategy, formation of a powerful halogenating agent, HOBr, is minimized and bromochloramine (NHBrCl) is used predominantly instead of monobromamine to sequester bromide during ozonation. To support this improved approach to bromide sequestration, this study examined the formation and decay of bromochloramine as a function of operating conditions, such as pH and Cl2/N ratio, and refined a chemical kinetic model to predict haloamine concentrations over time. Two natural organic matter (NOM) sources were used in this study (Lake Austin, Texas and Claremore Lake, Oklahoma) to study the effect of NOM on monochloramine and total chlorine decay after 30 seconds of prechlorination. The rate of the reaction between haloamines and fast and slow sites on the NOM was estimated. A kinetics model was developed to model total chlorine decay after a short prechlorination time. The model is based on the Unified Haloamine Kinetic Model developed by Pope (2006). Pope`s model failed to model the initial monochloramine concentration after 30 seconds prechlorination time as well as the monochloramine and total chlorine decay over time. The modified model shows an excellent prediction of monochloramine and total chlorine decay after 30 seconds prechlorination time at pH range of 6.5-8.0 and over a carbonate buffer concentration range of 2-10 mM. The model includes a new bromochloramine decay scheme via the reaction with monochloramine and with itself. In addition, new rate constants for the reaction of HOCl with bromide ion and reaction of HOBr with monochloramine were added. The hypobromous acid formation rate was found to be an acid-catalyzed reaction, which confirms the finding of Kumar et al. (1987). A new value of the acid catalysis effect of hydrogen ion was estimated. New terms were introduced to the hyprobromous acid formation rate including the acid catalysis effect of bicarbonate, carbonic acid, and ammonium ion. In addition, the reaction of HOBr with monochloramine to form bromochloramine was found to be an acid-catalyzed reaction, and a new value of the rate constant was estimated. / text

Addition of alkalinity to acid mine drainage (AMD) results in the neutralisation of acidity and precipitation of dissolved metals as insoluble hydroxides. Two aspects of the current AMD treatment practice at the Stockton Mine could be enhanced. Firstly, residual water quality may be poor due to unreacted alkalinity reagents, particularly CaCO3, resulting in poor water clarity and elevated suspended solids (SS). Secondly, neutralisation to circum-neutral pH may not avoid the discharge of residual metals (Ni and Zn) due to incomplete adsorption and hydroxide precipitation. The aim of this project was to enhance the conventional neutralisation of AMD through addition of humic substances (HS) to reduce residual SS and trace metal concentrations. Humic substances are organically derived and have a high molecular weight. Functional groups on the surface of HS are capable of binding dissolved metals, forming HS-metal complexes. Incorporation of HS complexed metals into settling floc could result in increased metal removal from the dissolved phase. Modified jar testing was used to investigate the effects of HS addition before, after and during (pH 4.5) neutralisation of AMD in two treatment scenarios at the Stockton Mine; the Blackwater Treatment Plant (BTP) using NaOH and Ca(OH)2 and the Mangatini Stream-sump System (MSS) using CaCO3. Supernatant samples collected during the sedimentation period were analysed for basic water quality parameters (turbidity and suspended solids) and dissolved (< 0.45 µm) metal concentrations. The addition of HS to the BTP process before (pH 2.8) and during (pH 4.5) neutralisation resulted in HS precipitation. Precipitated HS subsequently acted as a nucleation site, triggering flocculation of precipitating metal hydroxides, resulting in low turbidity and suspended solids (SS) of less than 2 NTU and 5 mg/L, respectively. The addition of HS after neutralisation (pH 7) did not result in HS precipitation. Intermolecular bridging of HS by the divalent Ca resulted in incorporation of HS into floc when neutralised by Ca(OH)2, resulting in low turbidity and SS. However, in NaOH neutralised conditions, the monovalent Na was unable to bridge HS molecules, resulting in HS remaining dissolved and contributing to elevated turbidity and SS of up to 24.4 NTU and 18.4, respectively. The neutralisation efficiency of CaCO3 is relatively low, thus approximately 1000 mg/L CaCO3 remained unreacted in MSS scenarios, resulting in elevated turbidity and SS. When added after neutralisation, dissolved Solid Energy Humic Acid (SEHA) facilitated flocculation of residual CaCO3 SS, resulting in an up to 75% lower suspended solids than CaCO3 neutralisation alone conditions. Although the results are good, the efficiency of SEHA as a polymer compared unfavorably in a cost: benefit analysis to two commercially available polymers for the removal of residual CaCO3. Neutralisation of AMD in control samples resulted in decreased concentrations of the target metal group (Ni, Zn, Cu, Cd, and Pb) by hydroxide precipitation, co-precipitation, and adsorption. Equilibrium speciation modeling showed that the HS-metal binding affinity controlled the effectiveness of HS addition for metal removal. The low HS complexation affinity of Ni and Zn resulted in no additional metal removal by HS dosing. The removal of Cu was enhanced by over 50% for SEHA 20 during-neutralisation conditions neutralised by both NaOH and Ca(OH)2. Up to 80% lower Cd concentrations were observed for all HS dose conditions when neutralised by Ca(OH)2. Data for CaCO3 HS dosed metal removal was statistically indeterminate. The high detection limit for Pb made any HS dosed removal enhancement difficult to identify, which was unfortunate as Pb has a high HS complexation affinity (Čežı́ková, Kozler et al. 2001; Milne, Kinniburgh et al. 2003). A simple cost: benefit analysis showed that the additional removal of metals by HS dosing was less efficient than conventional neutralisation alone, on a cost basis. Overall, incorporation of HS into AMD treatment results in improved water quality for CaCO3 neutralisation and lower concentrations of metals with a high HS binding affinity, for some conditions. However, further investigation is required to improve the feasibility of HS incorporation into the AMD neutralisation process.

I asked whether there is female sterility in hybrid offspring of Mus musculus domesticus and M. m. musculus using two wild derived inbred strains representing each subspecies. I evaluated F1 hybrid female fertility by crossing F1 females to a tester male and comparing multiple reproductive parameters between intra-subspecific controls and inter-subspecific hybrids. Hybrid females had smaller litter size, reduced embryo survival, fewer ovulations, and fewer small follicles relative to controls. Significant variation in reproductive parameters was seen among different genotypes. Genes contributing to hybrid female infertility are polymorphic within subspecies. Differences in reproductive phenotypes in F1's of reciprocal crosses suggest that female subfertility may be due to either cyto-nuclear incompatibility or to imprinting. These findings suggest a greater complexity in hybrid sterility than has been previously appreciated and highlight the potential importance of hybrid female sterility in the early stages of speciation.

It is well known that in contrast to the Prisoner's Dilemma, the snowdrift game can lead to a stable coexistence of cooperators and cheaters. Recent theoretical evidence on the snowdrift game suggests that gradual evolution for individuals choosing to contribute in continuous degrees can result in the social diversification to a 100% contribution and 0% contribution through so-called evolutionary branching. Until now, however, game-theoretical studies have shed little light on the evolutionary dynamics and consequences of the loss of diversity in strategy. Here, we analyze continuous snowdrift games with quadratic payoff functions in dimorphic populations. Subsequently, conditions are clarified under which gradual evolution can lead a population consisting of those with 100% contribution and those with 0% contribution to merge into one species with an intermediate contribution level. The key finding is that the continuous snowdrift game is more likely to lead to assimilation of different cooperation levels rather than maintenance of diversity. Importantly, this implies that allowing the gradual evolution of cooperative behavior can facilitate social inequity aversion in joint ventures that otherwise could cause conflicts that are based on commonly accepted notions of fairness. (authors' abstract)

Lead (Pb), a trace metal notorious for its impacts on human health, has achieved worldwide environmental dispersal resulting from centuries of use by human society. The toxicity of Pb is governed largely by its mineral form, which is in turn controlled by pH, localized reactivity and soil processes that differ according to soil type, location and Pb source. Given the context of these localized dependencies, or site specificity, efforts to predict Pb toxicity and refine sustainable remediation techniques are most useful when Pb behavior is constrained and predicted within environments with homogeneous conditions, such as a single soil. I evaluated and predicted the behavior of Pb, a typical anthropogenic contaminant, within a single soil using bioaccessibility testing and predictive geospatial modeling to assess potential impacts and refine sustainable remediation methods. To test the hypothesis that Pb speciation is influenced by competitive sorption processes in soils, I investigated changes in mobility and speciation of Pb upon addition of amendments at multiple scales using flow-through column experiments, soil characterization and synchrotron-based x-ray techniques. Kriging and cokriging maps provided a successful estimation of background and total Pb, the latter incorporating housing age as a secondary variable to increase model accuracy, though efforts to automate detection of background Pb were complicated by approximation of building extents, and overall heterogeneity of soil Pb concentration gives high error. Acute Pb heterogeneity is observed at the scale of a single site among near-structure samples. At the city-scale, determination of bioaccessibility revealed that bioaccessible and total Pb are well-correlated, to the extent that bioaccessibility may be predicted for the soil underlying Burlington, VT; this information, combined with predictive blood lead level modeling and the CDC's recent establishment of 5 μg kg-1 as a threshold for blood lead toxicity, enabled the establishment of a site-specific revised soil Pb limit of 360 mg kg-1, lower than the EPA's general soil Pb threshold of 400 mg kg-1. Characterization of leached and unleached soil using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and microfocused x-ray techniques provided a first look at Pb paint species using synchrotron technologies. Pb was present within paint chips as hydrocerussite, but appeared to weather to anglesite over time. Pb also seemed to act as cation bridge, attracting clay minerals electrostatically and becoming incorporated into heterogeneous soil aggregates. Accessory paint elements are identified in soil and within paint chips and may further complicate these systems. Column experiments, at acidic pH, yielded little evidence of Pb mobility change in response to modification of competitive sorbents. Kinetics of Pb release were driven by pH, with Pb solubilizing at pH of ˜4.9 as column soil acidifies. This work provides evidence for changes in Pb speciation over time in urban soils impacted by Pb paint, and presents a framework for predictive risk analysis at a local site using experimental and modeling tools. Multiscale observations and analytical results can be used in future efforts to model and refine sustainable remediation solutions within a site-specific context.

This thesis investigated the impact of aluminum (Al) substitution in ferrihydrite (FH) on both its chemical and physical properties. Al was coprecipitated with FH under controlled hydrolysis conditions to yield various % mol substitutions. Sulfate adsorption was measured across pHs to examine any changes in surface reactivity. The samples’ morphology, specific surface areas (SSAs), crystallinity, and phase transformation upon heating were evaluated and parameterized to allow conclusions on the role of Al on the physical properties. Sulfate sorption diminished across pHs for all Al saturation levels. X-ray Diffraction revealed goethite (GT) presence was negatively influenced by Al. The SSAs of samples increased non-linearly with increasing % mol Al, indicating a decreasing particle size with more Al content. Transmission Electron Microscopy micrographs showed the FH nanoparticles transformed to acicular/blocky laths of GT crystals and lenticular/platy hematite (HM) crystals with occasional grainy appearance at both room temperature and upon active heating. The phase transformation alongside the derived aspect ratios (length/width) of the GT crystals were retarded by the Al substitution.

Genic data from two chromosomal races of Geomys bursarius from a contact zone in central Texas indicated that the two races possessed distinct gene pools which would define them as separate species. Data from proteins encoded from 21 loci in this study substantiated this hypothesis. A pattern of alternately fixed alleles at the ADH-l, MDH-2, LDH-l, and IDH-1 loci with no apparent gene flow in zones of contact strongly suggested that these two races should be designated as separate species. Levels of heterozygosity and high FST values indicate that genomic structuring within Geomys is most heavily influenced by high levels of inbreeding and low migration rates. Fossorial rodents were suggested to undergo speciation primarily through parapatric means.

The genetic structure of 26 natural populations of three species (S. tridecemlineatus, S. mexicanus, and S. spilosoma) of the Ictidomys subgenus of ground squirrels was analyzed using chromosomal and electrophoretic techniques. Chromosomal variation was not observed in S. mexicanus, and only slight karyotypic variation was found in the other two species. Chromosomal evidence indicated hybridization between S. tridecemlineatus and S. mexicanus, placing these species within the classical definition of semispecies. Analysis of electrophoretic variation at 29 genetic loci indicated close genetic relationships between these species. Evolution in Ictidomys appears to be linked with Pleistocene events, and speciation appears to have occurred within the last 155,000 years.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Les éléments de terres rares (REEs) sont de plus en plus utilisés dans une multitude d’applications, notamment la fabrication d’aimants, de batteries rechargeables et les écrans de téléviseurs. Ils sont pour la plupart des métaux trivalents peu solubles dans les eaux naturelles. Comme pour les métaux divalents, le risque écologique des REEs est très probablement étroitement lié à leurs spéciations chimiques. Cependant, le comportement du samarium (Sm) dans les matrices environnementales est très peu connu et il n'existe actuellement aucune technique pour évaluer sa spéciation chimique. Dans cette optique, la technique d'échange d'ions (IET) sur la résine Dowex a été optimisée pour mesurer le samarium libre en solution. Les temps d'équilibre ont d'abord été déterminés pour des solutions tamponnées de samarium (Sm 6,7x10-8 M ; MES 1,0 mM M ; pH 6,0) en présence du nitrate de sodium (de 0,01M à 0,5 M). Pour ces diverses forces ioniques, l’équilibre thermodynamique n’est atteint que pour NaNO3 0,5M. Un autre mode d’utilisation de la résine (mode dynamique) a donc été développé pour tenir compte des conditions environnementales et évaluer efficacement le samarium libre. Les impacts des ligands organiques tels le NTA, l’EDTA, le citrate, l’acide malique et l’acide fulvique Suwannee River Standard I (SRFA) ont été étudiés par l’IET en mode dynamique. Une grande corrélation a été trouvée plus entre les taux d’accumulation de samarium sur la résine d’échange pour différents rapports NTA : Sm, EDTA : Sm, SRFA : Sm et le samarium libre. Par contre, aucune corrélation significative n’a été observée pour les ligands citrate et acide malique compte tenu des complexes qu’ils forment avec le samarium et qui s’adsorbent aussi sur la résine Dowex. Les concentrations Sm3+ mesurées par la technique IET ont été fortement corrélées avec celles prédites par le modèle WHAM 7.0 en utilisant la constante de stabilité obtenue par titration de SRFA par extinction de la fluorescence. Par ailleurs, la formation de colloïdes de samarium en fonction du pH influe grandement sur la détermination du samarium libre et doit être prise en compte dans la spéciation du samarium. L'IET assisté par des techniques auxiliaires comme le dosage par extinction de la fluorescence et le SP-ICPMS pourrait être une technique utile pour évaluer les concentrations de Sm biodisponible dans les eaux naturelles. / Samarium is present in several high technology products such as magnets, lasers, etc., however little is known about to what extent it can pollute environmental matrices. For divalent metals such as Cd, Cu and Ni, toxicity has often been closely correlated with the free ion concentration. Unfortunately, there are currently no techniques available for evaluating the speciation of samarium in environmental matrices. In this study, an economical and easy to use ion exchange technique (IET) using a resin has been studied for use in measuring free samarium. In order to optimize the IET for free samarium determinations, equilibrium times were first determined for pH buffered solutions of samarium (6.7x10 8 M Sm, 1.0 mM MES, pH 6.0) in the presence of different concentrations of sodium nitrate (NaNO3: 0.01 M to 0.5 M). Equilibrium was only attained for the highest concentration of NaNO3. Therefore, another technique using dynamic measurements on the Dowex resin was developed. Thus, the impacts of different organic ligands such as EDTA, citrate, malic acid and Suwannee River fulvic acid Standard I (SRFA) have been investigated using IET in dynamic mode. The calibration of the technique using different concentrations of NTA, EDTA, citrate, malic acid and fulvic acid (SRFA) allowed the determination of accumulation rates. Strong correlations were found between accumulation rates and the free samarium when using EDTA and NTA to control free samarium. The correlation was very low in case of citrate and malic acid suggesting that their complexes with samarium were adsorbed on the resin. Finally, fluorescence quenching titrations (FQT) and SP-ICPMS were used to determine samarium speciation. The free samarium determined by IET is strongly correlated to that calculated by WHAM 7.0 using the stability constant from FQT and that from Sonke (2006). However, the free Sm resulted from IEC-SP-ICPMS technique has been overestimated once compared to that found using VMinteQ or WHAM 7.0 models. The Sm particulates determined by SP-ICPMS have demonstrated that pH has a great influence on Sm exchange on resin and has to be considered while measuring free samarium. Thus, the IET should be associated to other techniques such as fluorescence quenching titration and SP-ICPMS for evaluating the bioavailable Sm concentrations in natural waters.