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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
701

Avaliação da toxicidade em água e sedimento do Rio Cubatão-SP / Assessment of toxicity in water and sediment from Cubatão River - SP

GARCIA, VANESSA S.G. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:34:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:28Z (GMT). No. of bitstreams: 0 / O monitoramento de corpos hídricos receptores de efluentes pode ajudar na manutenção e conservação desses locais, pois os poluentes podem alterar o equilíbrio, a estrutura e o funcionamento do ecossistema. Neste aspecto, o estudo em sedimentos é importante ao permitir uma avaliação mais abrangente do ecossistema aquático, onde diferentes contaminantes podem estar associados ao sedimento em concentrações superiores às das águas, podendo resultar em impactos negativos à biota aquática, a depender da biodisponibilidade. A cidade de Cubatão abriga um dos maiores pólos industriais do Brasil, onde a descarga constante de efluentes industriais e domésticos no rio Cubatão e seus afluentes acabou ocasionando um panorama de degradação dos rios. A Bacia do Rio Cubatão esta localizada entre a Grande São Paulo e a Baixada Santista, com área de 177 km2, aproximadamente. O rio Cubatão é o principal rio da região, abastecendo as cidades de Cubatão, Santos, São Vicente e parte dos municípios de Praia Grande e Guarujá. Além do abastecimento de água para a população, o rio também abastece o pólo industrial de Cubatão. O objetivo deste trabalho foi avaliar efeitos agudos e crônicos de amostras de água e de sedimento do rio Cubatão e dois de seus afluentes (Perequê e Pilões), por meio de ensaios ecotoxicológicos. Os organismos aquáticos empregados nos ensaios foram Ceriodaphnia dubia e Vibrio fischeri para avaliação de água e Hyalella azteca para avaliação de sedimento integral. A análise de crescimento corpóreo destes últimos também foi realizada. Além disso, foram realizadas Análises Químicas Instrumentais e Análise por Ativação Neutrônica em amostras de sedimentos. O estudo foi realizado entre 2010 e 2011, totalizando quatro campanhas. Foram coletadas amostras de água em nove pontos da Bacia do Rio Cubatão, e amostras de sedimento em seis pontos. Através dos ensaios realizados com V. fischeri pôde ser verificada toxicidade em todos os pontos amostrados com valores de CE(I)50 que variaram entre 31,25% e 71,61%. Os resultados obtidos com exposição de C. dubia não identificaram toxicidade, com base na análise estatística utilizada (Teste t por bioequivalência). Os ensaios de toxicidade para efeitos agudos do sedimento integral em H.azteca resultaram em toxicidade para as amostras de P2 e P5 (2ª e 4ª campanhas), com uma mortalidade superior a 50% dos organismos expostos. A análise de crescimento corpóreo identificou menor crescimento corpóreo nos organismos expostos ao sedimento coletado em P4 e P5. Com relação aos sedimentos coletados no ponto P5, os compostos endrin, dibenzeno(a,h)antraceno e antraceno ultrapassaram os valores recomendados pela Resolução Conama 344/04. Os resultados das Análises por Ativação Neutrônica evidenciaram maior contaminação por metais nos sedimentos originários de P5 e PI. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
702

Residuos de agrotoxicos em lodo de estacao de tratamento de agua: validacao de metodologia analitica utilizando cromatografia liquida acoplada a espectrometria de massas em TANDEM (LC-MS/MS) / Pesticides residues in water treatment plant sludge: validation of analytical methodology using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)

MORACCI, LUIZ F.S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:55:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:02Z (GMT). No. of bitstreams: 0 / O quadro evolutivo da agricultura brasileira resulta em benefícios à população exigindo crescentes avanços tecnológicos no setor. Constantemente, novos agrotóxicos são introduzidos estimulando estudos científicos com a finalidade de determinar e avaliar os impactos na população e no meio ambiente. No presente trabalho, a matriz avaliada foi o lodo gerado no processo de tratamento de água para consumo humano, coletado na região do Vale do Ribeira, SP. A técnica empregada foi a cromatografia líquida de fase reversa acoplada à espectrometria de massas triploquadrupolar em tandem com ionização por electrospray. Os compostos foram extraídos previamente da matriz. O desenvolvimento da metodologia exigiu tratamento dos dados para que esses pudessem ser utilizados e transformados em informações confiáveis. Os processos envolvidos foram avaliados usando o conceito da validação de ensaios químicos. Os indicadores avaliados foram seletividade, linearidade, intervalo de trabalho, sensibilidade, exatidão, precisão, limite de detecção, limite de quantificação e robustez. Esses indicadores produziram valores quantitativos e qualitativos que foram estatisticamente evidenciados de forma objetiva. A metodologia desenvolvida e validade é simples. Como resultado, mesmo explorando a sensibilidade da técnica, os compostos estudados não foram encontrados no lodo da ETA de Registro. Isso leva a crer que esses compostos podem estar presentes em concentrações muito baixas, podem sofrer degradação durante o tratamento da água ou não são retidos completamente pela ETA. 7 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
703

Avaliacao da qualidade da agua do corrego Franquinho, sub-bacia Tiquatira/Franquinho, unidade hidrografica do Alto Tiete, Sao Paulo, SP

COELHO, RICARDO dos S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:45:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:31Z (GMT). No. of bitstreams: 1 07157.pdf: 8474280 bytes, checksum: e1abd151fab0e19dd4d6f348fcc3f112 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
704

Potencial de poluição de aguas superficiais por fontes não pontuais de fosforo na Bacia hidrografica do Ribeirão do Pinhal, Limeira- SP

Mansor, Maria Teresa Castilho 03 November 2005 (has links)
Orientadores: Denis Miguel Roston, Jose Teixeira Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-04T08:27:27Z (GMT). No. of bitstreams: 1 Mansor_MariaTeresaCastilho_D.pdf: 2529546 bytes, checksum: 5e7bcdd25d9104de1649f7fade2168ac (MD5) Previous issue date: 2005 / Resumo: Em áreas rurais onde há intensa atividade agrícola, a eutrofização de corpos de água pode ser acelerada pelo influxo de nutrientes, provenientes de fertilizantes, transportados por escoamento superficial. A eutrofização pode provocar mudanças indesejáveis na estrutura e funções do ecossistema, bem como na qualidade da água destinada ao abastecimento. O controle dos níveis de P nas águas superficiais é tido como a melhor maneira de minimizar a eutrofização, uma vez que o P é identificado como um nutriente limitante para o crescimento de algas. As águas da bacia do rio Piracicaba recebem grande aporte de efluentes domésticos e industriais pontuais, bem como grande aporte de efluentes agrícolas difusos, tendo sido documentado aí um elevado grau de eutrofização. Uma avaliação preliminar das contribuições difusas de nutrientes às águas superficiais da bacia hidrográfica do rio Jaguari - formador do rio Piracicaba - feita a partir de dados oficiais em uma área de estudo de 3394 Km2, mostrou que 68,2% da carga total anual de Ntotal e 77,3% da carga total anual de Ptotal foram transportados nos meses de chuva. Ao se estimar a razão entre a carga média anual de origem rural (difusa) e urbana (pontual), obteve-se o valor de 1,3 para o Ntotal e 2,6 para o Ptotal; os coeficientes de exportação a partir da área rural foram estimados em 2,3 Kg Ntotal.ha-I.ano-l e 0,4 Kg Ptotal.ha-l.ano-l. A área de drenagem da bacia do ribeirão do Pinhal - afluente do rio Jaguari e manancial de abastecimento de Limeira, SP - foi o foco principal deste estudo, ocorrido entre fevereiro de 2003 e fevereiro de 2004. Estimou-se, para uma área de 301,4 Km2 de ocupação majoritariamente agrícola, a quantidade de P aplicada ao solo como fertilizante, obtendo-se um total de 820 ton.anoo1, dos quais inferiu-se que 23% foram exportados pela biomassa. Monitorou-se, no mesmo período, as concentrações de Ptotal e SStotais em cinco pontos da bacia do ribeirão do Pinhal, objetivando a estimativa de fluxos. As cargas anuais de Ptotal e SStotais obtidas na entrada do reservatório do Tatu foram iguais a 5,7 e 2160 ton.ano-I, respectivamente, sendo que 67,5% do Ptotal e 84,5% dos SStotais foram transportados no período chuvoso. Os coeficientes de exportação obtidos na entrada do reservatório foram iguais a 0,2 KgPtotal.haol.anool e 7,4 tonSStotaiS.Km-2.ano-l. Ao se inferir sobre as cargas difusas de Ptotal transportadas por escoamento superficial pelo ribeirão do Pinhal, obteve-se uma razão de 0,6 entre a carga anual de origem difusa e aquela pontual, apontando a importância desta última na bacia. Por fim, fez-se um levantamento limnológico do reservatório do Tatu, e observou-se que o IET referente ao Ptotal e à clorofila a indicou estado eutrófico na cabeceira e barragem; entretanto, é provável que a alta taxa de descarga esteja limitando a proliferação de algas no reservatório. De modo geral, verificou-se preliminarmente a importância da poluição difusa de Ptotab de origem rural, na degradação das águas superficiais da bacia do rio Jaguari. Por outro lado, focando na bacia do ribeirão do Pinhal, concluiu-se que as altas concentrações de Ptotal aí obtidas foram influenciadas pela atividade industrial e ocupação humana, influência esta que se sobrepôs àquela do arraste de partículas causado pelo escoamento superficial decorrente das precipitações / Abstract: Intensive agricultural activities are known to cause anthropogenic inputs ofnutrients to surface waters in rural areas. The nutrient enrichment of water bodies, or eutrophication, can lead to highly undesirable changes in ecosystem structure and function, as well as in water quality for human consumption. It is known that nutrient loading restriction - specially the limiting nutrient phosphorus - is the essential comerstone of aquatic eutrophication controI. In a preliminary study, official water quality and flow data from Jaguari River were used to assess the diffuse loads of nutrients from rural areas into surface waters. Results showed that, in average, 68.2% of the TN annualloads and 77.3% of the TP annualloads were transported through a 3394 Km2 area during the raining season. The annual diffuse loads obtained coming primarily from rural sources - were equivalent to 55.1% and 69.4% ofthe total annual loads of TN and TP transported through the sub-basin, respectively. The mean export coefficients from diffuse loads were equal to 2.3 Kg TN.ha-1.year-1 and 0.4 Kg TP.ha-'.year-1. The main part of this study was realized at the Ribeirão do Pinhal - a Jaguari River affluent from February 2003 to February 2004. The annual phosphorus load applied as fertilizer to an area of301.4 Km2 ofthe ribeirão do Pinhal watershed was estimated to be 820 ton.year-', and 23% of it was calculated to be exported by the biomass of the agricultural fields. These results were based on the soil use and occupation of the area, mainly rural, producing basically sugarcane and citrus. The field sampling of Ribeirão do Pinhal superficial waters was done twice a month, in five locations at the watershed. Samples were analyzed for TP and TSS; the totalloads obtained were equal to 5.7 e 2160 ton.year-', respectively, at the entrance ofTatu reservoir; 67.5% of TP and 84.5% of TSS were transported during the raining season (October-March). The export coefficients obtained were equal to 7.4 ton TSS.Km-2.year-1 and 0.2 Kg TP.ha-1.year"'. A limnological profile of the Tatu reservoir was determined through field sampling in three locations on both dry and wet periods; results showed a eutrophic state at the entrance of the reservoir as well as at the damo Yet, the flushing rate is the possible limiting factor for the occurrence of eutrophication at the reservoir. In general, the importance of diffuse pollution, originally from rural areas, was verified at the Jaguari River watershed. On the other hand, at the Ribeirão do Pinhal watershed, the high TP concentrations observed were most1y influenced by the industrial and human activities occurring in the area / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola
705

Creating management thresholds for fish communities exposed to coal mining

Jonker, Michiel-Nell 02 May 2012 (has links)
M.Sc. / This study aims to assess the potential impacts of coal mine activity on exposed fish assemblages in the Mpumalanga Highveld area. A control-impact-assessment method was applied, with sites located upstream and downstream from mining activity. All sites were located in the upper Olifants catchment. Field assessments were done over a high flow and low flow period. It was ascertained that water quality variables contributing towards differences between upstream and downstream environmental conditions are salt concentrations, pH and oxygen saturation. Alterations on fish community structures indicated a categorical decline in abundances and species richness at sites situated downstream from mining activity, while Fish Response Assessment Index (FRAI) scores similarly reflected more impaired fish assemblages at downstream sites. Redundancy analysis (RDA), using fish assemblages and FRAI driver metrics explained 36.5 % of variance obtained and reflected particular alteration in Barbus neefi, B. paludinosus, Tilapia sparrmanii and Pseudocrenilabrus philander populations. Sites most severely impacted were identified, as well as the main drivers responsible for changes in fish assemblages. The Cover metric contributed significantly (p<0.05 to variance measured. Subsequent community threshold management targets are presented for problem sites, which aim to manage each site at an ecological category one class higher than the Present Ecological State (PES).
706

Fish histopathology as a monitoring tool for aquatic health: a preliminary investigation

Van Dyk, Jacobus C. 16 October 2008 (has links)
M.Sc. / South Africa can be classified as a semi-arid country and the management of its precious water resources is essential. Environmental pollution, caused by the development of industry, technology and informal settlements, threaten the health status of many freshwater ecosystems. The health of all living organisms living in aquatic ecosystems is therefore subsequently affected by this decrease in water quality. The health of an ecosystem is thus often reflected by the health of its fauna. Fish are relatively sensitive to changes in their surrounding environment, including an increase in pollution. Fish health may as a result reflect, and give a good indication of the health status of the aquatic ecosystem in which the fish occurs. The initial toxic effects of the pollution may, however, only be evident on cellular or tissue level before significant changes can be identified in fish behaviour or external appearance. Histological analysis appears to be a very sensitive parameter and is crucial in determining cellular changes that may occur in target organs, including the liver. A histological investigation may therefore prove to be a cost-effective tool to determine the health of fish populations, hence reflecting the health of an entire aquatic ecosystem within a bio-monitoring process. Within the South African context, limited research has been conducted regarding the histology and histopathology of endemic fish species, and its value and effectiveness in aquatic monitoring. The aim of this study was to investigate and validate whether fish liver histology can be used as a monitoring tool, to indicate the health status of an aquatic ecosystem. In order to accomplish this, a preliminary histological study was done on the liver of Clarias gariepinus, a freshwater fish species endemic to the southern African region. Fish were collected in the Rietvlei Dam, Marais Dam and the Palala River, chosen as the three aquatic ecosystems for this study, due to their dissimilar pollution levels. Fish liver samples were fixed in 10% neutrally buffered formalin and prepared for light microscopy analysis using standard techniques for Haematoxylin and Eosin (H & E) staining. From the results obtained during this study, it was concluded that the liver histology of C. gariepinus did appear to be a sensitive monitoring tool of aquatic health. The histological investigation of the fish livers obtained in the Palala River, chosen as an unpolluted site, appeared to be in an overall healthier condition than the liver histology of fish obtained from the two relatively polluted sites, the Rietvlei Dam and the Marais Dam. This conclusion was obtained by means of an objective, quantitative analysis. The histological results in this study were quantified in terms of a histological index. An index value representing the specific histological characteristics of the liver was assigned to each individual specimen indicating either a healthy histological structure (index value of 0-2) or a possible pathological condition (index value of 3-6). According to the quantitative assessment, an average histological index value of 2.5 (indicating a relatively healthy histological condition) was calculated for the unpolluted site while a higher average index value of 3.2 (indicating a pathological condition) were calculated for both the relatively polluted sites. The fish liver histology did therefore reflect the health status of the aquatic ecosystem in which the fish specimen occurred. It was therefore concluded that the liver histology of C. gariepinus seemed to be a sensitive biomarker of environmental pollution, and hence an effective monitoring tool for estimating the health status of an aquatic ecosystem. / Dr. G.M. Pieterse
707

A histology-based health assessment of selected fish species from two rivers in the Kruger National Park

Smith, Warren Clifford 20 August 2012 (has links)
M.Sc. / The Olifants- and Luvuvhu rivers both flow through the Kruger National Park (KNP). The Olifants River (OR) is a major tributary of the Limpopo River with water quality being less than desirable due to high concentrations of pollutants as a result of the activities in the upper catchment. The crocodile population of the river declined from 1000 in 2008 to 347 in 2009 due to pansteatitis. Labeobarbus marequensis in the upper catchment also showed symptoms of the disease (Templehoff, 2010). This raised concern about the health of the fish in the OR, particularly in the section flowing through the KNP. The Luvuvhu River (LR) is also a tributary of the Limpopo River with main land uses in the catchment being agriculture, mining and communal lands. Of concern is the finding of DDT residues in water, sediment, and domestic and indigenous biota upstream of the sites sampled in this study (Barnhoorn et al., 2009) which raised concerns about the health of fish in the lower reaches of the river flowing through the KNP. Therefore, the aim of this study was to assess the health status of [9] selected fish species from the OR and LR in the KNP using a histology-based health assessment protocol (HBHA). The species selected for this study included Hydrocynus vittatus, Labeobarbus marequensis, Labeo cylindricus and Labeo rosae. The OR was sampled in September 2009 and May 2010 while the LR was sampled in November 2009 and April 2010. A necropsy was done to determine if there were any internal or external macroscopic alterations with any alterations noted on a score sheet. Blood was taken for haematocrit (Hct), leukocrit (Lct) and total plasma protein (TP) determination. As part of the HBHA, a necropsy-based health assessment index (HAI) was applied using a modified protocol of Adams et al. (1993) where the necropsy and blood parameters were used to calculate the mean and sum HAI for the different species sampled on each sampling trip. Biometric indices including the condition factor, hepatosomatic index, splenosomatic index and the gonadosomatic index were calculated. Age was determined using otoliths for tigerfish and scales for the other species. Samples of selected organs (liver, kidney, gill, testes or ovaries) were taken for histological analysis. Microscope slides were assessed qualitatively to identify any histological alterations present. These results were semi-quantitatively assessed according to the protocol of Van Dyk et al. (2009a) from which an organ index and fish index were calculated. The organ index is an indication of the number and severity of histological alterations in a particular organ of a selected species. The organ indices were classed according to the classes of Van Dyk et al. (2009a) with Class 1 (<10) being tissue with slight histological alterations; Class 2 (10-25) being tissue with moderate histological alterations. The fish index is a sum of all of the organ indices for any given fish sampled.
708

Antibiogram profiling of Escherichia coli pathotypes isolated from Kat River and Fort Beaufort abstraction water

Nontongana, Nolonwabo January 2014 (has links)
Escherichia coli (E. coli) is a widespread species that includes a broad variety of strains, ranging from highly pathogenic strains causing worldwide outbreaks of severe disease to virulent isolates which are part of the normal intestinal flora or which are well characterized and safe laboratory strains. The pathogenicity of a given E. coli strain is mainly determined by specific virulence factors which include adhesins, invasins, toxins and capsule. The aim of this study was to evaluate the prevalence and antibiogram profiles of E. coli pathotypes previously isolated from Kat River and Fort Beaufort abstraction water. A total of 171 E. coli isolates showed at least one pathogenic determinant among the isolated 278 E. coli. The other 107 isolates were negative for the tested virulence genes. All 278 presumptive isolates tested positive for the UidA gene, and were therefore classified as non-categorized pathogenic E. coli. The 171 pathogenic isolates had at least one characteristic gene of pathogenic E. coli and were identified and classified as enteropathogenic E. coli (6%), enterotoxigenicE. coli (131), uropathogenic E. coli (6), neonatal meningitis E. coli (14), diffusely adherent E. coli (1) and enterohaemrrhagic E. coli (1). Interestingly, no virulence genes were detected for the enteroinvasive E. coli and the enteroaggregative E. coli. The antibiotic resistance profiles for all isolates that were identified as E. coli showed 100% resistance to penicillin G, 98% resistance to ampicillin, 38% resistance to trimethoprim-sulphamethoxazole and 8% resistance to streptomycin. Multiple antibacterial resistance (MAR) was also observed, where 44% of the isolates were resistant to three antibiotics and 8% resistant to four antibiotics. The results of this study showed the Kat River and Fort Beaufort abstraction water are reservoirs of pathogenic strains of E. coli which harbour antibiotic resistance determinants that can cause serious health risks to the people in the surrounding communities.
709

Development of a novel in situ CPRG-based biosensor and bioprobe for monitoring coliform β-D-Galactosidase in water polluted by faecal matter

Wutor, Victor Collins January 2008 (has links)
The ultimate objective of this work was to develop a real-time method for detecting and monitoring β-D-galactosidase as a suitable indicator of the potential presence of total coliform bacteria in water environments. Preliminary comparison of the chromogenic substrate, chlorophenol red β-D-galactopyranoside and the fluorogenic substrate, MuGAL, revealed unreliable results with the fluorogenic technique due to interference from compounds commonly found in environmental water samples. Thus, the chromogenic assay was further explored. Hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside by β-D-galactosidase to yield chlorophenol red was the basis of this assay. Fundamental studies with chlorophenol red β-Dgalactopyranoside showed that β-D-galactosidase occurs extracellularly and in low concentrations in the polluted water environment. A direct correlation between enzyme activity and an increase in environmental water sample volume, as well as enzyme activity with total coliform colony forming unit counts were observed. Spectrophotometric detection was achieved within a maximum period of 24 h with a limit of detection level of 1 colony forming unit 100 ml[superscript -1]. This enzyme also exhibited physical and kinetic properties different from those of the pure commercially available β-D-galactosidase. Cell permeabilisation was not required for releasing enzymes into the extracellular environment. PEG 20 000 offered the best option for concentrating β-D-galactosidase. The source of β-D-galactosidase in the polluted environmental water samples was confirmed as Escherichia coli through SDS-PAGE, tryptic mapping and MALDI-TOF, thus justifying the further use of this method for detecting and/or monitoring total coliforms. Several compounds and metal ions commonly found in environmental water samples (as well as those used in water treatment processes) did have an effect on β-D-galactosidase. All the divalent cations except Mg [superscript 2+], at the concentrations studied, inhibited the relative activity of β-D-galactosidase in both commercial β-D-galactosidase and environmental samples. Immobilisation of chlorophenol red β-D-galactopyranoside onto a solid support material for the development of a strip bioprobe was unsuccessful, even though the nylon support material yielded some positive results. A monthly (seasonal) variation in β-Dgalactosidase activity from the environmental water samples was observed, with the highest activity coinciding with the highest monthly temperatures. Electro-oxidative detection and/or monitoring of chlorophenol red was possible. Chlorophenol red detection was linear over a wide range of concentrations (0.001-0.01 μg ml[superscript -1]). Interference by chlorophenol red β-D-galactopyranoside in the reduction window affected analysis. A range of phthalocyanine metal complexes were studied in an attempt to reduce fouling and/or increase the sensitivity of the biosensor. The selected phthalocyanine metal complexes were generally sensitive to changes in pH with a reduction in sensitivity from acidic pH to alkaline pH. The tetrasulphonated phthalocyanine metal complex of copper was, however, more stable with a minimum change of sensitivity. The phthalocyanine metal complexes were generally stable to changes in temperature. While only two consecutive scans were possible with the unmodified glassy carbon electrode, 77 consecutive scans were performed successfully with the CuPc-modified glassy carbon electrode. Among the phthalocyanine metal complexes studied, the CuPc-modified glassy carbon electrode therefore provided excellent results for the development of a biosensor. The CuPc modified-glassy carbon electrode detected 1 colony forming unit 100 ml[superscript -1] in 15 minutes, while the plain unmodified glassy carbon electrode required 6 hours to detect the equivalent number of colony forming units. CoPc, ZnPc and CuTSPc required 2, 2.25 and 1.75 h, respectively, to detect the same numbers of colony forming units. The CuPcmodified glassy carbon electrode detected 40 colony forming units 100 ml[superscript -1] instantly. In general, a direct correlation between colony forming units and current generated in the sensor was observed (R2=0.92). A higher correlation coefficient of 0.99 for 0-30 coliform colony forming units 100 ml[superscript -1] was determined. Current was detected in some water samples which did not show any colony forming units on the media, probably due to the phenomenon of viable but non-culturable bacteria, which is the major disadvantage encountered in the use of media for detecting indicator microorganisms. This novel biosensor therefore presents a very robust and sensitive technique for the detection and/or monitoring of coliform bacterial activity in water.
710

Phenolic compounds in water and the implications for rapid detection of indicator micro-organisms using ß-D-Galactosidase and ß-D-Glucuronidase

Abboo, Sagaran January 2009 (has links)
Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.

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