published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

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Vitamin C is an essential water soluble vitamin found mainly in fruits, vegetables and their derivatives. Orange juice is a popular thirst quencher and a convenient way to reach the daily recommended intake of vitamin C. The aim of this thesis was to determine how the vitamin C content in orange juice is affected by storage temperature and oxygen content in the product. Bottles of orange juice were stored at different temperatures. Regular orange juice was compared to juice where dissolved oxygen in product water had been decreased before mixing the juice. One other aim was to determine the efficiency of a stress test room where a higher temperature was supposed to simulate longer storage time. The study showed a larger non-linear loss of vitamin C over time in the bottles stored at the higher temperatures. The samples with less dissolved oxygen showed a higher vitamin C content after five and six months of storage in room temperature. For a storage time up to one week the loss of vitamin C in the stress test does not appear to be equal to the corresponding storage time in room temperature.KeywordsOrange juice, / Vitamin C är en livsnödvändig vattenlöslig vitamin som främst förekommer i grönsaker, frukter och produkter framställda från dessa. Apelsinjuice är en populär törstsläckare och ett enkelt sätt att få i sig sin dagliga dos C-vitamin. Syftet med denna rapport är att undersöka hur halten C-vitamin i apelsinjuice från Kiviks Musteri ändras beroende på lagringstemperatur och syrehalt i produktvatten. Apelsinjuice tillverkad från kranvatten jämfördes med juice tillverkad med vatten där syrehalten minskats genom kokning. Ett annat syfte var att fastställa effektiviteten för ett lagringsrum som simulerade en längre lagringsperiod genom att höja temperaturen. Resultaten visade att det var en större ickelinjär förlust av C-vitamin i flaskor som lagras vid en högre temperatur. Juiceflaskor med mindre mängd löst syre visade en lägre förlust av C-vitamin efter fem respektive sex månaders lagring i rumstemperatur. Förlusten av C-vitamin i juice lagrad en vecka i rummet med högre temperatur var ej den mängd som förutspåddes enligt företagets modell.

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The Chattahoochee River is the most utilized surface water in Georgia, and it and Utoy Creek are receiving waters for Atlanta stormwater and wastewater effluent. Population growth and record-breaking rainfall in 2013 has led to potential stress from stormwater runoff and nonpoint source loading. The goals of this research are to examine spatial and temporal variations in E. coli and the bacteriophage MS2 and relationships with DO, turbidity, rainfall, and riverflow; to determine if E. coli in water is correlated with E. coli in sediment; and to determine if wastewater effluent discharges influence downstream sample sites. Water samples were collected at fifteen sample sites and two outfall sites in the Chattachoochee, and ten sites in Utoy Creek. No significant spatial variation in E. coli was found for the Chattahoochee, although there was significant temporal variation in mean E. coli concentrations. The lowest mean DO values and the highest mean turbidity levels both occurred on the date of the highest mean E. coli concentrations. Effluent from the two outfalls did not contaminate downstream sample sites. In Utoy Creek, E. coli concentrations showed spatial and temporal variation in water samples, but not for sediment samples. Turbidity was found to be positively correlated with both E. coli in sediment and MS2. These findings suggest that nonpoint source loading is a potential cause of contamination. Since DO, turbidity, and rainfall were correlated with E. coli and MS2, these parameters could be used as indicators of pollution for future monitoring of the Chattahoochee River and Utoy Creek.

The recent rise of inner shelf hypoxia in the California Current System has caused concern within the scientific community, sparking a surge in studies addressing the issue. While regional studies of hypoxia abound, relatively little attention has been focused on the smaller coastal estuarine systems in the Pacific Northwest. Here, we present results from Coos Bay, a small, highly seasonal estuary on the southern Oregon coast. Due to wide fluctuations in freshwater input, Coos Bay exhibits characteristics of a salt-wedge type estuary in the winter, a well-mixed estuary in the summer, and a partially-mixed estuary during times of moderate discharge. Despite a strong coupling with coastal waters, we did not find evidence for pervasive hypoxia in Coos Bay. The primary drivers of variability in dissolved oxygen levels in the estuary are upwelling wind stress, residence time, and in situ biologic processes.

abstract: This study reports on benzene and toluene biodegradation under different dissolved oxygen conditions, and the goal of this study is to evaluate and model their removal. Benzene and toluene were tested for obligate anaerobic degradation in batch reactors with sulfate as the electron acceptor. A group of sulfate-reducing bacteria capable of toluene degradation was enriched after 252 days of incubation. Those cultures, originated from anaerobic digester, were able to degrade toluene coupled to sulfate reduction with benzene coexistence, while they were not able to utilize benzene. Methanogens also were present, although their contribution to toluene biodegradation was not defined. Aerobic biodegradation of benzene and toluene by Pseudomonas putida F1 occurred, and biomass production lagged behind substrate loss and continued after complete substrate removal. This pattern suggests that biodegradation of intermediates, rather than direct benzene and toluene transformation, caused bacterial growth. Supporting this explanation is that the calculated biomass growth from a two-step model basically fit the experimental biomass results during benzene and toluene degradation with depleted dissolved oxygen. Catechol was tested for anaerobic biodegradation in batch experiments and in a column study. Sulfate- and nitrate-reducing bacteria enriched from a wastewater treatment plant hardly degraded catechol within 20 days. However, an inoculum from a contaminated site was able to remove 90% of the initial 16.5 mg/L catechol, and Chemical Oxygen Demand was oxidized in parallel. Catechol biodegradation was inhibited when nitrite accumulated, presumably by a toxic catechol-nitrite complex. The membrane biofilm reactor (MBfR) offers the potential for biodegrading benzene in a linked aerobic and anaerobic pathway by controlling the O2 delivery. At an average benzene surface loading of 1.3 g/m2-day and an average hydraulic retention time of 2.2 day, an MBfR supplied with pure O2 successfully achieved 99% benzene removal at steady state. A lower oxygen partial pressure led to decreased benzene removal, and nitrate removal increased, indicating multiple mechanisms, including oxygenation and nitrate reduction, were involved in the system being responsible for benzene removal. Microbial community analysis indicated that Comamonadaceae, a known aerobic benzene-degrader and denitrifier, dominated the biofilm at the end of operation. / Dissertation/Thesis / Masters Thesis Civil and Environmental Engineering 2015

Orientador: Ivo Milton Raimundo Junior / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T14:29:52Z (GMT). No. of bitstreams: 1 Silva_KarimeRitaBentesda_D.pdf: 987159 bytes, checksum: fbf95cdeef4cddf9f7dda16d5efcb700 (MD5) Previous issue date: 2007 / Resumo: Foram construídos optodos para a determinação de SO2 em amostras de ar e de vinho, com base no cromóforo Pd2(dppm)2Cl2 [(bisdifenilfosfinometano-dicloreto de paládio (I)] imobilizado em matrizes de PVC [poli(cloreto de vinila)] e plastificadas com o-NPOE [o-nitrofeniloctiléter]. As membranas que apresentaram os melhores resultados continham 20% de PVC, 4% do cromóforo e 76% de o-NPOE, para uma massa final de 100 mg. Para amostras de ar, as membranas foram preparadas pela deposição de 200 mL de solução em filmes de poliéster, apresentando espessura média de 500 mm, faixa linear de resposta de 0-5 ppmv SO2, limite de detecção de 130 ppbv SO2 e tempo de vida útil de 2 meses ou 250 medidas. Esse optodo responde também para monóxido de carbono, na faixa linear de 1-5% de concentração. Para amostras de vinhos, as membranas foram preparadas pela deposição manual de 10 mL de solução em filmes de poliéster e foram obtidas faixas lineares de trabalho de 0-50 mg L para SO2 livre e 0-150 mg L para SO2 total, com limites de detecção da ordem de 0,37 e 0,70 mg L, respectivamente. Na validação do método, foi observada uma boa correlação com o método padrão, não havendo diferença significativa no nível de 95% de confiança. Observou-se que sacarose e etanol geram efeito de matriz. Para ambos os optodos, observou-se que é grande o efeito da umidade. Na presença de NO2, H2S, HCl e Cl2 10 ppmv a fase sensora é inutilizada. Também foi desenvolvido um optodo para a determinação de oxigênio dissolvido com base no fluoróforo PtOEP [octaetilporfirinato de platina] imobilizado em PDMS [poli(dimetilsiloxano)]. Os melhores resultados foram obtidos para as membranas preparadas a partir de uma solução contendo 8 x 10 mol L de PtOEP e 20% de sílica. A espessura média das membranas foi de 0,22 ± 0,02 mm. Foi obtido um limite de detecção de 0,077 mg L de O2 dissolvido e com desvio padrão relativo de 0,53%. A faixa linear de resposta foi de 0,07-5,95 mg L de O2 dissolvido em água. Observou-se que não há erro sistemático com o uso deste optodo, e que o mesmo pode ser empregado na determinação oxigênio dissolvido em amostras reais / Abstract: Optodes for determination of sulphur dioxide in air and wine samples were constructed, based on the dichloro-bis-(diphenylphosphino)-methane dipalladium I [Pd2(dppm)2Cl2] complex immobilised in PVC films, plasticised with onitrophenyloctylether [o-NPOE]. The sensing phase that presented best performance was prepared from a THF solution (1 mL), containing 20 mg PVC, 4 mg Pd complex and 76 mg o-NPOE. For air sample analysis, membranes were prepared by the deposition of 200 µL of the cocktail solution on polyester sheet (average thickness of 500 µm), presenting a linear response range of 0-5 ppmv SO2, detection limit of (0.13 ± 0.02) ppmv SO2 and lifetime of 2 months or 250 measurements. This optode also presented a linear response to carbon monoxide in the 1-5 % range. For wine samples, membranes were prepared by the manual deposition of 10 µL of the cocktail solution on polyester sheet, presenting linear response ranges of 0 -50 mg L for free SO2 and 0 -150 mg L for total SO2, with detection limits of 0.37 and 0.70 mg L, respectively. The results showed good correlation with the reference method, presenting no significant differences at the 95 % confidence level. It was observed that sucrose and ethanol affects slightly the sensitivity. For both optodes, it was observed a significant effect of the humidity, as well as poisoning by NO2, H2S, HCl and Cl2 10 ppmv. It was also developed an optode for determination of dissolved O2, based on the fluorophore platinum octaethylporphyrin [PtOEP] immobilised in polydimethylsiloxane [PDMS]. The membrane prepared from a solution containing 8 x 10 mol L PtOEP and 20 % silica presented the best performance, with an average thickness of 0.22 ± 0.02 mm. The optode showed a detection limit of 0.077 mg L dissolved O2, relative standard deviation of 0.53 % and a linear response range from 0.07 to 5.95 mg L O2. It was not observed a systematic error for the developed sensor, which can be applied to the determination of dissolved oxygen in water samples / Doutorado / Quimica Analitica / Doutor em Ciências

Stormwater ponds (SWPs) are becoming increasingly important due to the negative impacts on flood mitigation and water quality control that results from rapid urbanization. These ponds are not only designed to control the discharge of large precipitation and snow melt events, but also to mitigate the water quality of the retained stormwater. Consequently, improper design and maintenance may lead to hypoxic conditions in SWPs, which result in poor water quality and generation of noxious gases. Riverside South Stormwater Pond II (RSPII) in Ottawa periodically experiences low dissolved oxygen (DO) concentrations and subsequently hypoxic conditions at depth in the pond, especially during summer days with less precipitation and winter ice covered periods. Hydrogen sulfide gas (H2S) has been generated and released into the ambient atmosphere during these periods of lesser water quality. Hence, there is a need to understand how DO spatial distribution and seasonal change trigger and affect H2S production. The conventional shallow design criteria of SWPs likely cause these systems to be susceptible to wind conditions. Very few research has demonstrated the correlation between wind-driven hydraulic performance and detained stormwater quality. Hence an understanding of pond-scale mixing generated by wind-induced flow and the subsequent correlation to DO concentrations and stratification in SWPs are important to understanding the water quality and performance of these systems, especially in a wind-induced flow dominated SWPs. The overall research objective is to develop a comprehensive understanding of hypoxic conditions of SWPs and to investigate the impact of wind induced hydraulics on DO seasonal characteristics and the subsequent production of H2S. RSPII was shown to experience lower DO and longer hypoxic conditions than an adjacent reference pond (RSPI) at both non-ice covered and ice covered months. In addition, hypoxia was shown to be initiated at the outlet of RSPII where the depth of the pond was a maximum. Interestingly, chlorophyll-α blooms were observed during ice covered conditions in the study, with synurids, tabellaria, and asterionella being identified as the dominant species. A bottom-mount acoustic Doppler current profiler (aDcp) was used to collect small wind-generated currents in RSPII. The three-dimensional current and DO model produced by MIKE 3 (DHI software) suggests a conclusive result of pond scale mixing produced by wind-driven flow as well as countercurrents near the bed opposite to wind direction. A wind dominated circulation was shown to be generated even with moderate wind speed, and with a higher wind condition pond-scale complete DO mixing was created. The MIKE 3 simulation further provided a comprehensive understanding of the correlation between wind-induced hydraulics and DO concentrations distribution in a shallow stormwater pond. Therefore, this research demonstrates that wind is an essential hydraulic driver in shallow ponds, which also likely affects water quality by initiating pond mixing.