Dissimilatory sulphate reduction, brought about by the action of sulphate reducing bacteria (SRB) was used in the treatment of acid mine drainage (AMD) in a fluidised bed bioreactor. Biologically produced hydrogen sulphide and bicarbonate ions, by SRB, facilitated the precipitation of heavy metals and the generation of alkalinity in the synthetic acid mine water, respectively. The SRB that had been selected were able to utilize acetate as the sole carbon source and were capable of growing in the bioreactors at low pHs, facilitating an increase in the influent pH from 2.75-7.0 to 5.4-7.8, after a 24-hour hydraulic retention time (HRT). The precipitation efficiencies for Fe, Mn, Zn, Cu, Cr and Al after a HRT of 24 h as metal sulphides ranged between 84- 99% for influent pH values of between 4 and 7, and above 54% for influent pH values between 2.75 and 4. Microbial metabolic activity decreased with decreasing influent pH. This was inferred from the decreasing differences in chemical oxygen demand (COD) depletion rate over a 24 h HRT, as influent acidity levels approached pH 2.75. Molecular studies, using PCR-DGGE analysis on the microbial consortium in the bioreactor, revealed the presence of at least 8 different bacterial species in the consortium. Attempts at sequencing these bands yielded inconclusive results, with the bands showing sequence homology to a large number of previously uncultured and undescribed bacteria. Scanning electron microscopy confirmed the presence of bacteria of different morphology, as well as the presence of biofilms, which account for the heavy metal and low pH tolerances that the bacteria sustained.

Mine-impacted water bodies are considered to be one of the most serious threats to the environment. These can be highly acidic and often contain elevated concentrations of sulfate and soluble metals. The microbial generation of H2S by reduction of more oxidized sulfur species, and consequent precipitation of metal sulfides, known as biosulfidogenesis, is a promising technology for remediating acid mine drainage (AMD). The objective of this work was to develop an integrated system for remediating a target AMD at an operating mine in northern Brazil using a single low pH anaerobic sulfidogenic bioreactor (aSRBR) and an aerobic manganese-oxidizing bioreactor. A synthetic version of the mine water, which contained 7.5 mM copper and lower concentrations (< 0.25 mM) of other transition metals (Zn, Ni, Co and Mn) was used in the experimental work. In the first stage, H2S generated in the aSRBR was delivered to an off-line vessel containing synthetic AMD, which removed > 99% copper (as CuS) while no co-precipitation of other metals was apparent. The partly-processed AMD was then dosed with glycerol and fed into the aSRBR where zinc, nickel and cobalt were precipitated. The effect of varying the pH and temperature of the bioreactor was examined, and > 99% of Ni, Zn and Co were precipitated in the aSRBR when it was maintained at pH 5.0 and 35ºC. The bacterial communities, which were included 4 species of acidophilic sulfate-reducing bacteria, varied in composition depending on how the bioreactor was operated, but were both robust and adaptable, and changes in temperature or pH had only short-term impact on its performance. Manganese was subsequently removed from the partly-remediated synthetic AMD using upflow bioreactors packed with Mn(IV)-coated pebbles from a freshwater stream which contained Mn(II)-oxidizers, such as the bacterium Leptothrix discosphora and a fungal isolate belonging to the order Pleosporales. This caused soluble Mn (II) to be oxidised to Mn (IV) and the precipitation of solid-phase Mn (IV) oxides. Under optimised conditions, over 99% manganese in the processed AMD was removed. Metal sulfides (ZnS, CoS and NiS) that had accumulated in the aSRBR over 2 years of operation were solubilised by oxidative (bio)leaching at low pH. With this, ~ 99% Zn, ~ 98% Ni and ~ 92% Co were re-solubilised, generating a concentrated lixiviant from which metals could be selectively recovered in further downstream processes. The use of methanol and ethanol either alone or in combination with glycerol were evaluated as alternative electron donors for biosulfidogenesis. Methanol was not consumed in the bioreactor, though sulfate reduction was not inhibited in the presence of up to 12 mM methanol. In contrast, ethanol was readily metabolised by the bacterial community and sulfate reduction rates were relatively high compared to glycerol. Two acidophilic algae were characterised and their potential to act as providers of electron donors for biosulfidogenesis was also evaluated. Although algal biomass was able to fuel sulfate reduction in pure cultures of aSRB and in the aSRBR, rates were much lower than when either glycerol or ethanol were used.

Employee turnover is an inherent challenge encountered by managers at nonprofit organizations. The purpose of this single case study was to explore the strategies some community-based organization managers used to reduce employee turnover in western New York. Five organizational managers were selected who had successfully implemented strategies to reduce employee turnover. Herzberg's 2-factor theory was the conceptual framework for this doctoral study. Data collection occurred through semistructured interviews and review of organizational documents. Data analysis involved collecting data, organizing the data into codes and themes, and interpreting and revealing information about the themes. Member checking and methodological triangulation increased the validity and reliability of the study. The 3 themes that emerged from the study were building positive relationships to promote communication, offering employee training and advancement, and recognizing that compensation is an important factor but does not influence employee behavior. Recommendations for action include redesigning processes to change organizational culture and implementing strategies to mitigate employee resignations. The findings from this study may contribute to social change, because organizational managers could use the study results to reduce employee turnover, which could lead to increased service quality in communities.

Petrographic and SEM study of flu vial-deltaic sections of the Woodbine Group in the East Texas Basin indicates that authigenic mineral suites are controlled, in part, by the presence of organic-rich matrix. During early, precompaction diagenesis, organic matter supplied the metabolic fuel required by sulfate-reducing bacteria to reduce sulfate in depositional waters ultimately to pyrite. With burial the sulfate supply was ultimately exhausted, and bicarbonate activity thereafter controlled the precipitation of siderite and Fe-calcite. Matrix material supplied the components and reaction sites for the most import ant porosity-occluding reaction: kaolinite --> Fe,M g chlorite. Matrix physically inhibited the growth of quartz overgrowths, yet, through compaction and as a product of the above reaction, provided a supply of silica for quartz cementation. Dissolution of salt dome cap rock has played a minor role in the cementation of the Woodbine in the East Texas Basin. Pore-filling calcite, barite, and pyrite were observed in the Woodbine where the Woodbine is in direct hydraulic communication with salt dome cap rock. In the deep, central portion of the basin Na-Cl brine resulting from salt-dome dissolution is evolving toward a Na-Ca(Mg)-Cl brine. The evolution of the brine chemistry may be the result of cation exchange on clay minerals, albitization of plagioclase feldspars, or the dissolution of magnesium - and calcium- chloride-rich phases. The present study could not confirm any of these reactions. WATEQF was used to calculate mineral-saturation states in Woodbine waters. Program output appears to represent accurately in situ individual mineral-saturation states at measured pH, as confirmed by petrographic and SEM identification of authigenic minerals. Relative stability between mineral pairs can be tested with thermodynamically-derived activity diagrams for the mineral pairs.

<p>Economists today agree that growth is fundamental in reducing poverty. But the strength of the relationship between the two has been debated, and there is a lack of satisfactory explanations to why the growth elasticity of poverty differs between countries. Solid democratic institutions have been mentioned as a means to ensure that growth is shared by the poor, but this proposition has not been assessed empirically. Using a data set including 157 intervals from 57 developing countries I estimate the elasticity of poverty to growth. I also use two different democracy indices to test the hypothesis that growth in democracies is more poverty-reducing than in non-democracies. Several other macroeconomic variables are also included in the model to analyze the determinants of the growth elasticity of poverty. Using several measures of growth and poverty, I find strong support that poverty is reduced by economic growth, with the elasticity estimated to be around -2. I do not, however, find any robustly significant determinants of the impact of growth on poverty. The results give some indication that the growth elasticity of poverty is higher in partly free countries than in nonfree countries. However, contrary to the hypothesis, there is stronger evidence that growth in fully democratic countries reduces poverty less than it does in partly free countries. None of the other macroeconomic variables are found to have a significant impact on how poverty responds to growth.</p>

Economists today agree that growth is fundamental in reducing poverty. But the strength of the relationship between the two has been debated, and there is a lack of satisfactory explanations to why the growth elasticity of poverty differs between countries. Solid democratic institutions have been mentioned as a means to ensure that growth is shared by the poor, but this proposition has not been assessed empirically. Using a data set including 157 intervals from 57 developing countries I estimate the elasticity of poverty to growth. I also use two different democracy indices to test the hypothesis that growth in democracies is more poverty-reducing than in non-democracies. Several other macroeconomic variables are also included in the model to analyze the determinants of the growth elasticity of poverty. Using several measures of growth and poverty, I find strong support that poverty is reduced by economic growth, with the elasticity estimated to be around -2. I do not, however, find any robustly significant determinants of the impact of growth on poverty. The results give some indication that the growth elasticity of poverty is higher in partly free countries than in nonfree countries. However, contrary to the hypothesis, there is stronger evidence that growth in fully democratic countries reduces poverty less than it does in partly free countries. None of the other macroeconomic variables are found to have a significant impact on how poverty responds to growth.

No description available.

The interactions of sulfate-reducing bacteria and Spartina alterniflora marsh grass have been established using a simulated salt marsh system and these interactions have been quantified using geochemical and molecular tools. Plant activities have a direct influence on mercury methylators and therefore control mercury transformation in the environment. Biogeochemical data show that sulfate and sulfide profiles change seasonally due to plant growth and senescence. Spartina alterniflora impact the two drivers for sulfate and sulfide transformation. The community of sulfate-reducing bacteria serve as the anaerobic driver and transform sulfate to sulfide (sulfate reduction). Sulfate-reducing bacteria have been identified as the principal methylators of mercury (Andersson, et al., 1990; Compeau and Bartha, 1985; Compeau and Bartha, 1984; Blum and Bartha, 1980; Gilmour and Capone). The aerobic driver is dissolved oxygen present in both porewater and plant root exudates, which transform sulfide back to sulfate (sulfide oxidation). Sulfate is not limiting in the vegetated sediment, even at the lower depths. Therefore, although sulfate reduction rates were high when plant activity was high, oxidative processes were also significant in the upper 4-cm of the sediment. In addition, demethylation of methylmercury to ionic Hg(II) in the porewater can occur through oxidative processes (Oremland et al., 1991). Therefore, the significance of sulfide oxidation may have strong implications for methylmercury demethylation in our marsh system.

In this study, we use the swelling characteristics of bentonite to discussion about the performance of bentonite mortar anti-seepage and the performance of resistance to sulfate. And add the AE water-reducing to improve its workability. To compare with different rate of bentonite added at different ratio of AE water-reducing in the condition of Standard Test for Flow Table. We planning in different water-cement ratio (0.445,0.485,0.550) to test for its fresh properties and hardened properties, and discussion the effect by AE water-reducing on the marine engineering. According to this study, adding bentonite will make the flow value dropped, and affecting the workability. Because of the positive ion exchange properties between bentonite and water will make it a high volume exchange rate, it means that absorption is high, so when the mixing time, the bentonite will form clumps, in this study, we add the AE water-reducing to improve. After we add AE water-reducing, the absorption, compressive strength are increase, but we still had to pay attention to the ratio between bentonite and AE water-reducing, the strength of structure perhaps decrease if added too much bentonite. This study can get the best positive effect when added ratio of 0.25% of bentonite to replaced cement.

Riboflavin is an essential part of the human diet. Although the United States does not have a major problem with a riboflavin deficiency, other regions of the world do. This is especially true for those regions whose main subsistence is rice. To help prevent and control riboflavin deficiencies, many cereal grains are now being fortified with riboflavin. The recommended dietary allowance of riboflavin is 1.1-1.6 mg per day. This value increases slightly for pregnant women, breast feeding women, and athletes. Because riboflavin is an essential part of the diet, it is important to ensure that the minimum requirements for this nutrient are met. By determining the amount of riboflavin in food products, an accurate estimate of daily riboflavin intake can be determined. The AOAC (Association of Official Analytical Chemists) approved microbiological riboflavin assay can be tedious and time consuming. A faster approach to the riboflavin assay would greatly benefit the food industry. By scaling down the assay to microtiter plates both, time and materials can be conserved. Use of microtiter plates would also allow for numerous samples to be assayed simultaneously. The goal for developing the microtiter plate assay is to obtain results more rapidly while maintaining the accuracy and precision of the AOAC ( method 940.33I) tube assay.