Estudos recentes constataram a existência de processos que permitem a atenuação natural dos contaminantes presentes nos lixiviados. O adequado entendimento destes processos pode originar benefícios possíveis de serem aplicados em aterros antigos, novos ou naqueles que ainda serão concebidos. O presente estudo avaliou o comportamento e a atenuação de contaminantes dos líxiviados no solo, por meio de experimento desenvolvido em colunas de percolação e, para a avaliação da atenuação este teste é indicado por refletir as condições naturais e as características adsortivas do solo, propiciando uma melhor simulação da atenuação. O lixiviado e o solo utilizados neste experimento são provenientes do aterro sanitário de São Carlos - SP. O solo utilizado foi caracterizado quanto à composição física, química, biológica e mineralógica para verificar o transporte do percolado nas colunas e a interação solo-contaminante. Na área do aterro foram feitas perfurações, ensaios de condutividade hidráulica e avaliação da geologia local, para conhecimento das características físicas, químicas, biológicas, mineralógicas e geológicas do solo in situ. Este foi classificado como arenoso, apresentando características físicas e químicas que não se enquadram nos parâmetros adequados para sua utilização em áreas de disposição de resíduos sólidos urbanos, pois, a capacidade de troca de cátions, superfície específica, potencial hidrogeniônico e classe textural arenosa, evidenciam que este solo possui deficiente capacidade de retenção e imobilização de contaminantes. Além disso, pela observação in situ, constata-se que a área de disposição de resíduos sólidos de São Carlos esta situado sobre rochas da Formação Botucatu, sendo que a mineralogia do solo presente no local é composta de quartzo, caulinita, goethita, hematita, gibsita e ilita. O ensaio de condutividade hidráulica indicou que o solo presente na base do Aterro sanitário não atende a valor de permeabilidade exigida por norma, o que poderá permitir a infiltração de água da chuva, aumentando a produção do lixiviado e sua movimentação no perfil, podendo atingir as águas subterrâneas. Assim, foram traçadas curvas características do transporte de contaminantes nas amostras efluentes monitoradas durante o processo de percolação, coletadas a cada 0,25 volume de poros até atingir 10,0 volume de poros percolados. As curvas características do transporte de contaminantes traçadas apresentaram baixas concentrações de Chumbo, Cádmio, Ferro, Zinco, Manganês, Cálcio, Magnésio, Cobre, Cromo nas amostras fluentes. Já o Sódio, Potássio, Cloro, Níquel e Alumínio foram preferencialmente percolados com o lixiviado, evidenciando a variação da faixa de concentração de cada elemento no percolado. Os perfis de concentração dos metais pesados mostraram que existe uma frente de contaminação. As curvas de retenção de metais no solo mostraram que a preferência de sorção apresentada pelos solos nas colunas foi : Cobre > Cádmio > Cálcio > Zinco > Magnésio > Potássio > Manganês > Fósforo > Ferro > Níquel > Alumínio. Cujos valores retidos no solo das colunas podem estar evidenciando a capacidade deste solo em reter contaminantes.O solo em questão apresentou baixo potencial para retenção dos contaminantes presentes no lixiviado, classificado como arenoso e, com características químicas que não se enquadram nos parâmetros adequados para sua utilização em áreas de disposição de resíduos sólidos urbanos. / Recent studies had found the existence of processes that allow a natural attenuation of the leachates\'s cotaminants. An adequate understanding of these processes may originate benefits, that may be applied in ancient, new or to be created landfills. This work evaluated the contaminant\'s behavior and attenuation, contaminants existing in soil\'s leaching, throughout an experiment developed in percolation columns. This is the indicated examination for evaluate the attenuation, because it reflects soil\'s natural conditions and adsorptive characteristics, providing a better simulation of it\'s attenuation. The leachate and the soil used in this experiment came from Sao Carlos-SP landfill. The used soil has been characterized as its mineralogical\'s and physical chemical-biological\'s composition, looking for the percolated\'s transportation inside the columns, and for the interaction soil-contaminant. The landfill\'s area has been several times drilled, tested as it\'s hydraulic conductivity and assessment of local geology, in order to know the physical, chemical, biological, mineralogical and geological in situ soil\'s characteristics. This, has been classified as sandy, and, by presenting chemical characteristics that does not reach the adequated value for utilization on solid urban wastes, due to the values of CTC, SE, pH, and the textural sandy class, what shows a deficient buffering capacity in retaining and immobilisating contaminants. By observation in situ, has been found that Sao Carlos\'s solids disposal waste is located over rocks from the Botucatu formation, and the mineralogy of it is composed of quartz, caulinith, goethith, hematith, gibsith an ilith. The hydraulic conductivity test has indicated that the soil in the base of the sanitary landfill does not reaches the permeability values required by the standards, what may allow rain water\'s infiltration, and raises the amount of leachate and it\'s movement onto the ground, and even the leachete to reach the underground waters. So, has been drawn the characteristics curves of the contaminant\'s transportation in the effluents samples found during the percolation process, collected by every 0,25 VP until it reaches 10,0 VP percolated. The characteristical curves of the contaminant\'s transportation drawn showed low concentrations in the effluent samples of Lead, Cadmium, Iron, Zinc, Manganese, Calcium, Magnesium, Cooper, Chromium. Also, Sodium, Potassium, Chlorine, Nickel and Aluminium had been preferencially percolated within the leachate, what evidentiates the variation in the range of concentrations of every percolated element. The concentration profiles from heavy metal\'s had shown that there is a front of contamination. The retention curves from the soil\'s retaining metal showed that the preferency for the sorption was: Cooper > Cadmium > Calcium > Zinc > Magnesium > Potassium > Manganese > Phosphorus > Iron > Nickel > Aluminium, whose values may point the soil\'s ability in retaining contaminants. The studied soil has presented low potential in retain contaminants from the leachete, and is characterized as sandy, and it\'s chemical features shall not be framed according the standards parameters to be utilized in solid urban waste\'s disposal.

Clostridium difficile (C. difficile) is a gram positive, anaerobic, spore forming bacterium. C. difficile infections are triggered by dysbiosis of the intestinal microbiome linked to age, immune status, and medication; particularly use of antibiotics and proton pump inhibitors (PPI). The spore forming nature of the bacteria gives it the ability to persist in the environment for long periods of time and makes it impervious to many commonly-used hospital cleaning and disinfection products. C. difficile, along with Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant Enterococcus (VRE) are some of the leading multi-drug resistant hospital acquired infections in the United States. Environmental contamination and patient susceptibility are hypothesized as major contributors to infection transmission in a healthcare setting. We conducted a cross-sectional pilot study aimed at determining the bioaerosol concentration of C. difficile present in the toilet plume of C. difficile infected patients’ rooms. Patient rooms within the University of Iowa Hospital and Clinics (UIHC) were sampled using a customized bioaerosol air impactor device. Environmental samples were collected before and after flushing the toilet to determine the pre-flush and post-flush levels of aerosolized bacteria. Particle density was collected during both pre and post-flush sampling. Activity levels in the rooms were recorded as a potential confounding variable. A total of 144 environmental samples were collected in 24 rooms. Clostridium difficile was detected in two of the twenty-four rooms (8%). There was a 12% (9/72) positive culture rate pre-flush compared to 23% (19/72) post-flush. Wilcoxon rank sum tests revealed a significant increase in particle concentration at the 5.0µm and 10.0µm size between rooms that produced a bacterial culture compared to rooms that did not (p-values 0.0095 and 0.0082 respectively). There was no significant association between the amount of activity in the room and detectable bioaerosol production (p-value=0.605). Next, we performed a randomized control trial of hospital privacy curtains with antimicrobial properties to determine their ability to resist pathogenic bacterial contamination in an intensive care unit setting. Rooms within the surgical and neurological intensive care unit at UIHC were randomized to receive impregnated curtains, impregnated curtains plus Fuzion hypochlorite spray, or standard control curtains. MRSA, VRE, Pseudomonas spp. and Acinetobacter spp. were the four most frequently cultured pathogenic species. Time to event (contamination) analysis identified a significant difference in time to pathogenic contamination between the control curtains and the impregnated curtains post spray (p-value<0.001). The impregnated curtains post Fuzion spray also grew significantly less colonies of bacteria compared to the control curtains (p-value<0.001). After evaluating environmental risk factors that contribute to Clostridium difficile infection, patient related risk factors for infection were evaluated. Proton pump inhibitors are a class of gastric acid reducers that work by reducing the amount of hydrogen ions produced in the stomach. Recent evidence suggests that prolonged use could negatively affect the intestinal microbiome making it more susceptible to enteric pathogens. A nested case control study was done to determine the association between PPI medication duration and C. difficile infection. Fecal microbiome diversity was analyzed via logistic regression in relation to the development of Clostridium difficile infection. A co-morbidity score was created to adjust for other microbiome altering conditions. PPI duration remained a significant predictor of infection after adjusting for the microbiome influence (p-value=0.0123). Environmental contamination remains a significant risk factor for the transmission of hospital acquired infections including C. difficile. Toilets flushing has been shown to produce pathogenic bioaerosols in the healthcare setting. Hospital privacy curtains have been shown to routinely be contaminated with pathogenic bacteria including other gastrointestinal bacteria that could increase susceptibility to C. difficile infection. PPI medication, which is frequently prescribed in the hospital, has been shown to increase the risk of C. difficile infection, although specific microbiome changes could not be identified.

Orientador: Marcelo Antonio Amaro Pinheiro / Resumo: Na região Amazônica muitas áreas de manguezal ainda se encontram conservadas. Entretanto, atividades antrópicas de degradação e contaminação, especialmente por metais, começam a alcançar escalas preocupantes, podendo afetar esse ecossistema e seus recursos. O objetivo do presente estudo foi avaliar a contaminação e bioacumulação de metais (Cu, Cd, Cr, Pb e Mn) pelo caranguejo-uçá (Ucides cordatus) e o risco potencial para a saúde humana pela ingestão desse crustáceo, considerado um recurso pesqueiro de grande importância na região amazônica. Amostras de espécimes de U. cordatus, água, sedimento, e folhas de Rhizophora mangle foram coletadas em áreas de manguezais, sendo uma conservada e outra antropizada para ambos os estados do Pará e Maranhão. As concentrações metálicas nas amostras bióticas e abióticas foram quantificadas por Espectrometria de Emissão Óptica por Plasma Acoplado Indutivamente (ICP-OES), com posterior estimativa do Fator de Bioacumulação e de análises multinível para os metais avaliados. Para avaliação do risco de consumo humano foram estimados o consumo diário (EDI), o quociente de risco (THQ) e o número de refeições elegíveis por mês (CRmm). As concentrações de metais no sedimento estavam abaixo dos níveis estabelecidos pela legislação, diferindo do observado para as amostras de água, onde Cu, Mn e Pb, cujos valores estavam acima dos limites estabelecidos para águas estuarinas. Mesmo sendo em sua maioria de origem natural, observou-se que esses elementos e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the Amazon region many mangrove areas are still conserved. However, anthropogenic activities that promote degradation and metal contamination are beginning to reach worrying scales and may affect this ecosystem and its resources. The aim of the present study was to evaluate the contamination and bioaccumulation of metals (Cu, Cd, Cr, Pb, and Mn) by the mangrove crab (Ucides cordatus) and the potential risk to human health from ingestion of this crustacean, considered a fishing resource of great importance in the Amazon region. Specimens of U. cordatus, water, sediment, and leaves of Rhizophora mangle were collected from mangrove areas, being a conserved area and another anthropized for both states of Pará and Maranhão. Metallic concentrations in biotic and abiotic samples were quantified by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), with subsequent estimation of the Bioaccumulation Factor and multilevel analysis for the metals evaluated. To assess the risk of human consumption, daily intake (EDI), risk ratio (THQ) and number of eligible meals per month (CRmm) were estimated. Metal concentrations in the sediment were below the levels established by the legislation, differing from those observed for the water samples, where Cu, Mn and Pb, whose values were above the estuarine water limits. Even though, mostly of natural origin, it was observed that those elements are bioavailable and are being incorporated by biota. Concentrations of Cu, Cr, and Pb w... (Complete abstract click electronic access below) / Doutor

The retail food safety chain is vulnerable to deliberate contamination, yet food safety professionals and emergency managers typically respond to intentional contamination in different ways. Little is known about the practices of environmental health food safety professionals (EHFSP) as compared to emergency managers and whether those approaches can be combined to more successfully impede intentional food contamination. The purpose of this narrative policy analysis was to use routine activity theory to compare the narratives of EHFSPs and emergency managers to determine whether there are opportunities to better understand the relationship between vulnerability and resiliency of the retail food safety chain. Data were primarily collected through interviews with 5 EHFSPs and 5 emergency managers from various regions in the United States. Interview data were inductively coded and then subjected to Braun and Clarke's thematic analysis procedure. Key findings indicate that EHFSPs generally are ill-suited to meet resiliency goals, ambivalence voiced by EHFSPs results from a lack of continual preparedness training, and neither EHFSPs nor emergency management officials' familiarity with the social dimensions of resiliency is at a point where they can design adequate measures for a resilient retail food system. Therefore, recommendations to policy makers focus on a need for an enhanced training that is inspired by principles of emergency management so that they are better able to respond to acts of intentional contamination, thereby building a resilient retail food chain with economic and social benefits.

The breeding biology of western grebe was studied at Bear River Migratory Bird Refuge, Utah in 1973 and 1974. More than 300 nests were located and data gathered on nesting habitat and success. Western grebe at Bear River selected nest sites for nearness to open water of approximately 30 em in depth. At least one young was hatching in 21 percent of the nests. Avian predation and abandonment of nests following drops in water levels caused the greatest loss of nests. Chlorinated hydrocarbons monitored in western grebes showed DDE, DDD, PCB, 1260, and PCB 1254 levels in 24 breast muscle samples (wet weight) to average 12. 8, 0. 8, 3. 8, and 3. 5 ppm respectively. Contaminant concentration was found to be correlated to the condition of the bird as determined by visceral fat content. A significant (p<. 01) 2. 3 percent decline in western grebe eggshell thickness between preand post-DDT use periods was found. DDE was significantly (p<. 05) negatively correlated with eggshell thickness in western grebe. Contaminants were not linked to any reproductive failure in western grebe at Bear River MBR.

A fim de garantir a qualidade final de produtos os laboratórios de análise microbiológica fornecem dados sobre a qualidade dos mesmos em todas as suas etapas de produção. A crescente preocupação com a saúde dos pacientes conduz à busca de métodos que forneçam resultados precisos e rápidos, pois possibilitam que ações corretivas sejam tomadas em tempo real. O presente trabalho teve por objetivo avaliar o potencial de tecnologia alternativa no monitoramento de endotoxina bacteriana na água tratada para diálise e dialisato e avaliar o potencial da citometria de fluxo na análise de água. Para isso utilizou-se Portable Test System (PTS®) como método alternativo para detecção de endotoxina bacteriana no monitoramento da água tratada para diálise e dialisato, o qual foi validado frente ao método convencional farmacopeico. Paralelamente realizou-se revisão narrativa da literatura a fim de avaliar a aplicabilidade da citometria de fluxo em análises de água. A análise dos diferentes parâmetros de validação para endotoxina bacteriana no método alternativo mostrou que, exceto para a menor diluição analisada, houve linearidade e precisão nos resultados. Por outro lado a concentração de 0,25 UE/mL foi a menor que apresentou exatidão e especificidade. Observou-se ainda, que o limite de detecção foi de 0,125UE/mL e o de quantificação de 0,25 UE/mL, portanto o intervalo foi de 0,25-1,0 UE/mL. Adicionalmente pela análise de resistência pode-se perceber que ao variar analistas não houve diferença significativa. Em relação ao tempo de análise em uma condição de rotina laboratorial com muitas amostras, o PTS® mostrou-se demorado. Ressalta ainda, que seria importante que a legislação vigente deternimasse a análise mensal de endotoxinas no dialisato. A revisão da literatura evidencia o potencial da tecnologia de citometria de fluxo, pois a mesma mostrou-se satisfatória quando comparada a metodologias convencionais para análise de água. O trabalho desenvolvido permitiu concluir que o PTS®) mostrou-se adequado para analisar amostras in loco, permitindo análises em tempo real, que para as quais haja a expectativa de ausência de endotoxinas ou de concentração respeitando o intervalo de 0,25 UE/mL a 1,0 UE/mL. Quanto a citometria de fluxo, esta mostrou-se uma tecnologia promissora em analisar amostras de água, sendo portanto recomendável proceder a estudos de validação e aplicabilidade. / In order to guarantee the final quality of products, the microbiological analysis laboratories provide data about their quality at all production stages. The growing concern for patients\' health leads to the search for methods that provide accurate and fast results, as they enable corrective actions to be taken in real time. The present work aimed to evaluate the alternative technology potential in the monitoring of bacterial endotoxin in treated water for dialysis and dialysate and to evaluate the potential of flow cytometry in water analysis. The different validation parameters analysis for bacterial endotoxin in alternative method showed that, except for the lowest dilution analyzed, there was linearity and precision in the results. On the other hand, the concentration of 0.25 EU / mL was the lowest that presented accuracy and specificity. It was further observed that the detection limit was 0.125UE / mL and the quantification limit was 0.25 EU / mL, so the range was 0.25-1.0 EU / mL. Additionally by the ruggedness analysis it was possible to perceived that when varying analysts there was no significant difference. Regarding the analysis time in a laboratory routine condition with many samples, the PTS® was was time consuming. It was also observed that it would be important to determine monthly analysis of endotoxins in dialysate. The literature review evidence the flow cytometry technology potential of the because it was satisfactory when compared to conventional methodologies for water analysis. The research showed that the PTS® was suitable for analyzing samples in loco, allowing real-time analyzes, for which there is expectation of endotoxins absence or concentration respecting the range of 0.25 EU / mL to 1.0 EU / mL. For the flow cytometry, it was shown to be a promising technology for analyzing water samples, and it is therefore advisable to carry out validation and applicability studies.

O uso de dispositivos para infusões intravasculares representa um desafio, principalmente, pela possibilidade da dispersão microbiana do local de inserção até a ponta do cateter. O procedimento de desinfecção poderá reduzir a colonização no sítio de inserção desses dispositivos, entretanto instiga uma série de questionamentos acerca da possibilidade de dispersão para o interior do lúmen, espectro de ação do antimicrobiano, e a técnica do procedimento de desinfecção. O objetivo deste estudo foi avaliar in vitro o procedimento de desinfecção das dânulas/torneiras de três vias contaminadas propositalmente com Staphylococcus aureus e Pseudomonas aeruginosa, bem como a dispersão de soluções para o interior dos lúmens. Trata-se de um experimento laboratorial in vitro, controlado e desenvolvido em duas etapas: avaliação da dispersão bacteriana por meio da contaminação intencional com cepas padrão: S. aureus (ATCC 25923) e P. aeruginosa (ATCC 27853), e a dispersão de líquidos para o interior do conector por meio do corante cristal violeta a 1%, após a fricção com solução fisiológica ou álcool etílico a 70%, visando simular o processo de desinfecção. Todos os experimentos foram realizados em triplicata por três pesquisadores distintos. A fricção dos conectores com solução fisiológica demonstrou crescimento bacteriano (P. aeruginosa e S. aureus) no interior de 41,7% dos lúmens, no entanto não houve crescimento bacteriano nas amostras após a desinfecção com solução alcoólica a 70% (p<0,001). Com relação aos percentuais das ausências de dispersão de soluções para o interior dos lúmens das dânulas, observou-se que a fricção com as soluções fisiológica e alcoólica foram de 81,5% e 66,7%, respectivamente (p=0,079). Assim, a ausência do crescimento bacteriano no lúmen das dânulas após a fricção com solução alcoólica a 70% está associada a uma série de variáveis controladas as quais remetem a preocupação, principalmente, na possibilidade de dispersão de soluções desinfetantes para o seu interior. Nesse sentido, infere-se sobre os riscos que ameaçam a segurança das pessoas submetidas a infusões intravenosas, especialmente, no que concerne a execução do procedimento de desinfecção das dânulas / The use of intravascular infusion devices presents a challenge, mainly, due to the possibility of microbial dispersion of insertion site up to catheter tip. Disinfection procedure can reduce colonization at insertion site of these devices, but it instigates a series of questions about the possibility of dispersion into the lumen, antimicrobial action spectrum, and the technique of the disinfection procedure. The objective of this study was to evaluate in vitro disinfection procedure of three-way taps purposely contaminated with Staphylococcus aureus and Pseudomonas aeruginosa as well as the dispersion of solutions into the lumens. This is an in vitro laboratory experiment, it was controlled and developed in two steps: evaluation of bacterial dispersion by intentional contamination with standard strains: S. aureus (ATCC 25923) and P. aeruginosa (ATCC 27853), and liquid dispersion into the connector through 1% violet crystal dye, after friction with physiological solution or 70% ethyl alcohol, in order to simulate disinfection process. All experiments were performed in triplicate by three distinct researchers. The friction of connectors with physiological solution showed bacterial growth (P. aeruginosa and S. aureus) within 41.7% of the lumens, but there was no bacterial growth in the samples after disinfection with 70% alcoholic solution (p<0.001). Regarding the absence of dispersion percentages of solutions into the lumens from three-way taps, it was observed that the friction with physiological and alcoholic solutions were 81.5% and 66.7%, respectively (p=0.079). Thus, the absence of bacterial growth in the lumen from three-way taps after the friction with 70% alcoholic solution is associated to a series of controlled variables which refer, mainly, to the possibility of dispersion of disinfectant solutions to its interior. In that sense, it is inferred about risks that threaten the safety of people undergoing intravenous infusion, especially, concerning the disinfecting procedure execution for three-way taps

A potable water distribution system (WDS) consists of pipes, pumps, valves, storage tanks, control and supporting components. Traditionally, it has two basic functions. First, provides end users with potable water at sufficient pressures and good water quality. Second, provides sufficient pressure and flow for fire fighting. Currently, potable water is still the least expensive material for fire fighting. To accomplish these two goals, water utilities have to consider the integrity and security of the water network. As a result, this research selected three research topics that are closely related to the daily operation of water utilities and water quality simulation. The first study is on optimal sampling design for chlorine decay model calibration. Three questions are investigated: (1) What is the minimum number of chlorine sample locations a water network needs? (2) How many combinations of sampling locations are available? (3) What is the optimal location combination? To answer the first two questions, the mathematical expressions of the chlorine concentrations between any two sampling locations are developed and sampling point relationship matrices are generated, then a mixed integer programming (MIP) algorithm is developed. Once obtained, the solutions to the first two questions are used to calculate the chlorine decay wall reaction coefficients and sensitivity matrix of chlorine concentration wall reaction coefficients; then, sampling location combinations achieved in the second question are sorted using a D-optimality algorithm. The model frame is demonstrated in a case study. The advantage of this method, compared to the traditional iterative sensitivity matrix method, is that a prior knowledge or estimation of wall reaction coefficients is not necessary. The second study is on optimizing the operation scheduling of automatic flushing device (AFD) in water distribution system. Discharging stagnant water from the pipeline through AFD is a feasible method to maintain water quality. This study presents a simulation-based optimization method to minimize total AFD discharge volume during a 24-hour horizon. EPANET 2.0 is used as hydraulics and water quality simulator. This is formulated as a single objective optimization problem. The decision variables are the AFD operation patterns. The methodology has three phases. In the first phase, AFD discharge capacities are calculated, whether existing AFDs are able to maintain chlorine residuals in the water network is also evaluated. In the second phase, the decision variables are converted to AFD discharge rates. A reduced gradient algorithm is used to quickly explore and narrow down the solution space. At the end of this phase, decision variables are switched back to the AFD operation patterns. In the third phase, simulated annealing is used to search intensively to exploit the global minimum. The method is demonstrated on the water system located at the south end of Pinellas County, Florida where AFD optimal operation patterns are achieved. The third study is on simulating contaminant intrusion in water distribution system. When contaminant matrix is introduced into water distribution system, it reacts with chlorine in bulk water rapidly and causes fast disinfectant depletion. Due to the difficulties in identifying contaminant types and chemical and biological properties, it is a challenging task to use EPANET-MSX to simulate chlorine decay under contaminant attack. EPANET 2.0 is used in the study to accomplish this goal. However, EPANET 2.0 cannot directly simulate chlorine depletion in the event of contamination attack because it assigns one time-independent bulk reaction coefficient to one specific pipe during the simulation. While under contaminant intrusion, chlorine decay bulk coefficient is not a constant. Instead, it is a temporal and spatial variable. This study presents an innovative approach for simulating contaminant intrusion in water distribution systems using EPANET multiple times. The methodology has six general steps. First, test bulk reaction coefficients of contaminant matrix in chemical lab. The uniqueness of this study is that the contaminant matrix is studied as a whole. The investigations of chemical, biological properties of individual aqueous constituents are not needed. Second, assume the contaminants as nonreactive, using EPANET 2.0 to identify where, when and at what concentrations of the inert contaminants will pass by in the water network. Third, determine the number of chlorine residual simulations based on the results in step two. Fourth, use EPANET to simulate the chlorine residual in the water network without the occurrence of contamination. Fifth, assign contaminated bulk coefficients to contaminated pipes; use EPANET to simulate the chlorine residual in the pipe network. Lastly, the chlorine concentrations of the impacted moments of impacted junctions are replaced with the results calculated in step five. This methodology is demonstrated in the south Pinellas County water distribution system.

Calluna vulgaris L.Hull readily colonises arsenate contaminated mine spoil soils in south-west(SW)England.At these sites, it forms mycorrhizal association with the ericoid ascomycete fungus Hymenoscyphus ericae. The initial aim of this study was to investigate the physiological response of H.ericae populations to arsenate.Mine site populations were found to have evolved arsenate resistance in comparison to the heathland population.This research demonstrates the evolution of arsenate resistance through an enhanced arsenite efflux in populations of H.ericae from As contaminated mine spoil soils. H.ericae also confers arsenate resistance to C.vulgaris. The ecological significance of these findings is discussed. / Doctor of Philosophy (PhD)

A study was undertaken to determine the food safety of the fermented Māori delicacy, Toroi. Ten batches of Toroi were prepared by a commonly used traditional method that consisted of boiling the vegetable component, either watercress or puha, and combining it with chopped mussel flesh. The mixture was cooled and then stored in a refrigerator for up to eight months to allow natural fermentation to take place. All ingredients were sourced from retail outlets. The Toroi was examined at intervals over eight months for a range of pathogens (seven in all) that have been related to incidents of food poisoning in ready-to-eat foods in New Zealand. The survival of a faecal contamination indicator, the laboratory grown strain Escherichia coli NZRM 916, was mapped over eight months. Two strategies to prevent the growth of Listeria monocytogenes in Toroi were also investigated. Only one of the seven pathogens sought was recovered from any sample. This pathogen was Bacillus cereus, a spore-former known to be associated with vegetables. All batches contained B. cereus on the day of preparation but after two weeks refrigerated storage there was no further recovery from any sample. There was a very low incidence of natural E. coli in the Toroi, consistent with levels permitted in mussels sold in retail outlets. The laboratory grown strain, E. coli declined substantially over two months and was not recovered from any samples at eight months. A laboratory grown strain of Listeria monocytogenes, (L70) was added to Toroi and grew well with an increase in concentration of about seven-fold, over 19 days storage in a refrigerator. A bacteriocin producing lactic acid bacterium, Lactobacillus sake Lb706, was added in combined culture with L. monocytogenes to Toroi. It was found that at least 5 x108 L. sake cells were required as an inoculum to ensure elimination of L. monocytogenes from the Toroi. When a purified bacteriocin; nisin, was added, a concentration of 10 mg g-1 in the Toroi was required to eliminate L. monocytogenes. The inhibition study results suggest that unacceptably high inocula or purified bacteriocin would be required to prevent the growth of L. monocytogenes in Toroi. The results of this suggest that Toroi be prepared from mussels either purchased from a retail outlet or harvested from sites known to be free from contamination. Toroi should be safe to eat if prepared carefully, chilled promptly and thoroughly and allowed to ferment for at least two weeks. In addition, care should be taken to maintain Toroi at refrigerated temperatures until it is eaten.