Aplicação de microssensores no monitoramento de oxigênio dissolvido, potencial REDOX e temperatura em estudos limnológicos
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
A importância do monitoramento de parâmetros físico-químicos e biológicos no meio ambiente torna-se cada vez mais evidenciada quando se busca o entendimento dos processos que ocorrem na natureza, sejam eles decorrentes de ações antrópicas ou naturais, ou ainda, como efetivo auxilio na gestão de ecossistemas aquáticos. Entre os parâmetros de interesse no monitoramento do meio aquático, o oxigênio dissolvido (OD) é, indubitavelmente, uma das variáveis fundamentais na caracterização de ecossistemas, pois este elemento está intimamente ligado à capacidade de respiração de peixes, plantas e de micro-organismos. Assim como o OD, o Potencial de Oxido- Redução (POR) assume papel importante no monitoramento de ambientes aquáticos, pois se relaciona com reações químicas óxido-redutoras e bioquímicas. Ainda, nesse contexto, a temperatura interfere significativamente nas taxas em que ocorrem as reações químicas e bioquímicas. Devido à importância desses parâmetros para o monitoramento ambiental, o presente trabalho teve como objetivo o desenvolvimento de microssensores eletroquímicos amperométricos para medição de oxigênio dissolvido (OD) tipo Clark, potenciométricos para medição de POR e de temperatura, bem como, sistemas eletrônicos compactos para leitura e software para visualização e armazenamento de dados de maneira autônoma, por meio de notebook ou PC. O sistema de aquisição conta com um módulo GPS para registro das coordenadas dos pontos de aquisição e módulo GPRS para transmissão de dados via celular. Foram desenvolvidos eletrodos com base na tecnologia de microssensores utilizados em estudos de biofilmes; recentemente introduzidos no Brasil e desenvolvidos no Departamento de Hidráulica e Saneamento da Escola de Engenharia de São Carlos da Universidade de São Paulo desde 2007, mediante apoio da Universidade de Montana EUA e FAPESP. O método proposto para sua fabricação visa produção com custos minimizados, podendo atingir 50% dos custos de sistemas convencionais para o mesmo propósito; isso decorre da miniaturização de componentes internos, pois assim como nos macro eletrodos, são empregados metais nobres como ouro, platina e prata. Os microssensores, sistemas eletrônicos e software foram validados através de testes de desempenho em laboratório. Em campo, foram avaliados por meio de medições realizadas no reservatório do Lobo (Itirapina - SP), para obtenção de dados limnológicos do reservatório, onde foram aquisicionados perfis de OD, POR e temperatura por meio de um traçado longitudinal com embarcação de pequeno porte e os pontos de medição foram vinculados às coordenadas GPS ao longo do trajeto do levantamento. Na foz dos principais afluentes do reservatório, foram coletadas amostras para análises complementares, buscando identificar alterações antrópicas e os níveis de trofia do reservatório para Fósforo Total e Profundidade (Secchi ZDS). Foi também observada a distribuição espaciais da comunidade fitoplanctônica.
The importance of the physicochemical and biological monitoring parameters in the environment becomes more and more evidenced when the understanding of the processes is looked at what happens in nature, whether they are from anthropic or natural actions. Among the parameters of interest in the aquatic mean monitoring, dissolved oxygen (DO) is undoubtedly, one of the fundamental items in the characterization of aquatic ecosystems, because this element is intimately linked to the breathing capacity of fish, plants and microorganisms of oxidizing substances present on that media. As well as DO, the ORP assumes an important role in aquatic monitoring, acting in the levels of oxide reduction and biochemical reactions that happen. Still, in that context, the temperature represents effective interference in the rates where chemical and biochemical reactions take place in the environment, even in the ones that concern DO and ORP. Due to the importance of these parameters for the environmental monitoring to better know the appropriate conditions and to plan solutions the present work seeks the development of amperometric electrochemistry micro electrodes for dissolved oxygen (DO) measurement Clark type, potentiometric for ORP measurement and temperature with the LM35component, as well as, compact electronic systems for reading and software for visualization and storage of data in an autonomous way, through notebook or PC. Yet, the data acquisition system foresees the application of a GPS module for data acquisition recordings of the coordinates points and a GPRS module for data transmission from cellular. The electrodes were developed based on the microsensors technology used in biofilms studies; recently introduced in Brazil and developed at the Hydraulics and Sanitation Department at School of Engineering of São Carlos at the São Paulo State University since 2007, through the support of the Montana State University USA and FAPESP. The proposed method for construction seeks production with minimized costs, it could reach 50% of the conventional systems costs for the same purpose, due to the internal components miniaturization, because as well as for macro electrodes, noble metals are used as gold, platinum and silver. The microsensors, electronic systems and software were validated through the tests carried out at the laboratory and through comparison with commercially found electrodes. In the field, they will be evaluated through acting tests in measurements carried out at the Lobo Reservoir (Itirapina SP Brazil), throughout the whole reservoir by using a small boat and the data acquisitions points were indexed to the GPS coordinate along the trajectory. Samples were collected at the main affuents of the reservoir for additional analysis, seeking identification of anthropic changes as well as the trophic level of the reservoir for Phosphorus and depth of the Secchi disk (ZDS). It was also observed the spatial distribution of phytoplankton community.
The importance of the physicochemical and biological monitoring parameters in the environment becomes more and more evidenced when the understanding of the processes is looked at what happens in nature, whether they are from anthropic or natural actions. Among the parameters of interest in the aquatic mean monitoring, dissolved oxygen (DO) is undoubtedly, one of the fundamental items in the characterization of aquatic ecosystems, because this element is intimately linked to the breathing capacity of fish, plants and microorganisms of oxidizing substances present on that media. As well as DO, the ORP assumes an important role in aquatic monitoring, acting in the levels of oxide reduction and biochemical reactions that happen. Still, in that context, the temperature represents effective interference in the rates where chemical and biochemical reactions take place in the environment, even in the ones that concern DO and ORP. Due to the importance of these parameters for the environmental monitoring to better know the appropriate conditions and to plan solutions the present work seeks the development of amperometric electrochemistry micro electrodes for dissolved oxygen (DO) measurement Clark type, potentiometric for ORP measurement and temperature with the LM35component, as well as, compact electronic systems for reading and software for visualization and storage of data in an autonomous way, through notebook or PC. Yet, the data acquisition system foresees the application of a GPS module for data acquisition recordings of the coordinates points and a GPRS module for data transmission from cellular. The electrodes were developed based on the microsensors technology used in biofilms studies; recently introduced in Brazil and developed at the Hydraulics and Sanitation Department at School of Engineering of São Carlos at the São Paulo State University since 2007, through the support of the Montana State University USA and FAPESP. The proposed method for construction seeks production with minimized costs, it could reach 50% of the conventional systems costs for the same purpose, due to the internal components miniaturization, because as well as for macro electrodes, noble metals are used as gold, platinum and silver. The microsensors, electronic systems and software were validated through the tests carried out at the laboratory and through comparison with commercially found electrodes. In the field, they will be evaluated through acting tests in measurements carried out at the Lobo Reservoir (Itirapina SP Brazil), throughout the whole reservoir by using a small boat and the data acquisitions points were indexed to the GPS coordinate along the trajectory. Samples were collected at the main affuents of the reservoir for additional analysis, seeking identification of anthropic changes as well as the trophic level of the reservoir for Phosphorus and depth of the Secchi disk (ZDS). It was also observed the spatial distribution of phytoplankton community.
Palavras-chave
Microssensor, Monitoramento ambiental, Oxigênio dissolvido, POR, Dissolved oxygen, Environmental monitoring, ORP