Magister Scientiae (Medical Bioscience) - MSc(MBS) / Mercury (Hg) is an example of a toxic metal that is not essential for nutrition. It exists in organic and inorganic forms in seafood and vapour from dental amalgam fillings respectively. Elemental mercury (Hg0) from dental amalgam was the focus of this study. Dental amalgam is one of the most commonly used dental filling materials and has been used for over 150 years. It is composed of Hg0 (approximately 50%) combined with other metals such as copper and zinc (Zn). These fillings give off Hg0 vapour throughout their existence, and is further enhanced by activities such as chewing, grinding of teeth and drinking hot liquids. Mercury consumption can lead to Zn loss or deficiency, and is reported to displace Zn and copper. Several European nations have outlawed the use of amalgam as a restorative material due to controversies regarding its safety in children, women of childbearing age and individuals with renal disease. Moreover, various studies have reported correlations between the number of amalgam fillings and Hg concentration in blood plasma, urine, faeces, saliva and different organs. Blood, urine, and hair mercury levels are used to predict possible health effects that may be caused by the different forms of Hg. Urine Hg is used to test exposure to metallic Hg0 vapour and inorganic Hg forms. This study aimed to evaluate the effects of Hg0 from dental amalgam restorations on the status of Zn in the urine. This was done by determining the concentrations of Hg0 in urine, buccal cells and the oral cavity, and its relationship with urinary Zn concentrations in the same individuals. Samples of urine, buccal tissues, chewing gum and completed questionnaires were collected from the participants (women and men) at the dental clinics in Tygerberg Hospital (TBH), Cape Town. Samples were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). Findings from this study show that there was a correlation between levels of urinary Hg0 and urinary Zn (p=0.02). However, urinary Hg0 did not predict the amount of urinary Zn. Also, no relationship was found between levels of Hg0 in buccal swab or the chew test samples and urinary Zn level. There was a significant difference between females and males in the level of urinary Zn, men had higher levels of Zn excreted in the urine than females (p=0.05). However, there was no significant difference in the level of urinary Hg0 between males and females. The number of fillings (4-7) and age of fillings were significantly associated with urinary Hg0 level (p˂0.05), while smoking ˃15 cigarettes/day increased the level of Hg0 in buccal swab samples (p=0.002). We were not able to demonstrate a causal effect of Hg0 leaching on urinary zinc levels.

Individuals within fish populations differ in many traits, such as sex, life-history, habitat residence, diet, and morphology. Such trait differences among individuals (i.e. intra-population variation) may be greater than the differences among populations (i.e. inter-population variation). My dissertation examines intra-population variation, with a focus on trophic relationships and morphology; as well as how variation in these attributes may reflect differences in bioaccumulation of contaminants. The second chapter of my dissertation examines the influence of spatial-temporal variation on the trophic structures of round goby (Neogobius melanstomus) and two age classes of yellow perch (Perca flavescens) within Saginaw Bay, Lake Huron. Using stable isotope ratios (δ13C, δ15N, δ2H, δ18O) and stomach contents as trophic indicators, I examined variation of diets. I found that spatial variation had a greater impact on diet indicators than both annual and seasonal variation. This spatial variation could represent a form of compartmentalization within the community of fish residing in Saginaw Bay, and could provide stability to the community. Chapter three of my dissertation examines intra-population variation in yellow perch morphology through a series of mesocosm experiments. My first mesocosm study determined that yellow perch could be experimentally manipulated to display divergent morphologies using simulated habitats, specifically pelagic and littoral habitats. Following this experiment, I focused on specific environmental drivers (structure, prey resources, and predation risk) as possible influences on yellow perch morphology. Within experimental pools, I exposed yellow perch to one of four treatments (an open pool, a structured pool, pools with chironomid prey resources and pools with a perceived, olfactory, predation risk) in the summer of 2015. Following exposure to these treatments I examined the morphological changes in yellow perch in magnitude and direction. I observed that while each treatment induced some difference in morphology, the open and structured treatments had the greatest magnitude of difference. I repeated the open and structure treatments during the following summer (2016). Again, I found that structure and open morphologies could be induced by my mesocosm treatments, but also observed that shapes differed from the previous year’s structure and open treatments. Finally, my fourth chapter examined how variation in trophic niches and morphology may reflect variation in contaminant concentration of fish in their natural environment. In this chapter, I extended my work with yellow perch to also include black crappie (Pomoxis nigromaculatus) and examined fish from 5 northern Indiana glacial lakes. Using model inference techniques, I found that variation in mercury was closely associated with not only fish total length, but also stable isotopes (δ13C and δ15N) and morphology. Interestingly, morphology-related variables of both species were strong predictors of mercury concentration in fish, following total length. Together, the chapters within my dissertation highlight the importance of considering intra-population variation, in which local factors such as habitat conditions and prey availability can influence individual variation in trophic structuring and morphology. These in turn may reflect other attributes of interest, such as the accumulation of contaminants.

Coal combustion is recognized as the primary source of anthropogenic mercury emission in South Africa followed by gold mining. Coal is also known to contain trace concentrations of mercury which is released to the environment during coal mining, beneficiation or combustion. Therefore, determining the mercury speciation in coal is of importance in order to understand its behavior and fate in the environment. Mercury was also used, at a large extent, in the Witwatersrand Basin (South Africa) for gold recoveries until 1915 and is still used in illegal artisanal mining. Consequences of these activities are the release of mercury to the environment. Nowadays, gold (and uranium) is also recovered through the reprocessing of old waste dumps increasing the concern related to mercury pollution. While much effort has been put in the northern hemisphere to understand and control problems related to anthropogenic mercury release and its fate to the ecosystem, risk assessment of mercury pollution in South Africa was based, until very recently, on total element concentrations only or on non systematic fragmental studies. It is necessary to evaluate mercury speciation under the country’s semi arid conditions, which are different to environmental conditions that exist in the northern hemisphere, and characterize potential sources, pathways, receptors and sinks in order to implement mitigation strategies and minimize risk. In this study, analytical methods and procedures have been developed and/or optimized for the determination of total mercury and the speciation of inorganic and organic forms of mercury in different sample matrices such as air, coal, sediment, water and biota. The development of an efficient and cost effective method for total gaseous mercury (TGM) determination was achieved using nano-gold supported metal oxide (1% wt Au) sorbents and cold vapor atomic fluorescence spectrometry (CV-AFS). Analytical figures of merit and TGM concentrations obtained when using Au/TiO2, as a mercury trap, were similar to those obtained with traditional sorbents. The combination of isotope dilution with the hyphenated gas chromatography-inductively coupled plasma mass spectrometry (ID GC-ICP-MS) was also achieved and used successfully for the speciation analysis of mercury in solid, liquid and biological samples. The developed, or optimized, methodologies were used to estimate the average mercury content and characterize the speciation of mercury in South African coals, and also to study the speciation of mercury in selected South African environmental compartments impacted by gold mining activities. The obtained average mercury content in coals collected from the Highveld and Waterberg coalfields (0.20 ± 0.03 mg kg-1) was close to the reported United States Geological Survey (USGS) average for South African coals. Speciated isotope dilution analyses and sequential extraction procedures revealed the occurrence of elemental mercury, inorganic and organo-mercury species, and also the association of mercury mainly to organic compounds and pyrite. The environmental pollution assessment was conducted within the Witwatersrand Basin, at four gold mining sites selected mainly for their mining history and from geophysical information obtained through satellite images. This study showed a relatively important pollution in three of the four sites, namely the Vaal River west site near Klerksdorp, the West Wits site near Carletonville (both in the North-West Province) and the Randfontein site in the West Rand (Gauteng Province). Only one site, the closed Rietfontein landfill site in the East Rand (Gauteng Province) was found to be not impacted by mercury pollution. The methylation of mercury was characterized in all sites and factors governing the mercury methylation process at the different study sites were also investigated. Geochemical models were also used to explain the distribution, transport and fate of mercury in the study systems.

O presente trabalho descreve uma forma inédita e simples de construção de eletrodos de ouro (CDtrodos) a partir de discos compactos graváveis (CD-Rs). Os CD-Rs possuem em sua constituição uma película de ouro com uma espessura entre 50 e 100 nm e com área aproximada de 100 cm2. Esta superfície de ouro pode ser facilmente utilizada para construção de eletrodos convencionais usados em células estacionárias ou em células em fluxo. Além disso, a espessura nanométrica do filme de ouro também pode ser utilizada para construção de microeletrodos de banda com áreas inferiores a 10-6 cm2. Devido ao fato do CD-R ser produzido em escala comercial, o custo do mesmo é muito baixo, tornando possível sua utilização na forma de eletrodos descartáveis. Para comprovar a viabilidade da utilização destes filmes na confecção de eletrodos, seu desempenho foi comparado com o de eletrodo de ouro comercial, sendo observado um comportamento análogo. Diferentes maneiras de utilização do disco compacto gravável foram testadas, tanto em amostras sintéticas, como também, em amostras reais. Utilizando o método de redissolução potenciométrica à corrente constante (CCPSA), foram analisadas amostras de mercúrio em água potável e em água do mar, adaptando o CD-R a uma célula de injeção em fluxo. Nestes estudos, o limite de detecção de mercúrio situou-se em 250 ng L-1, utilizando-se tempo de deposição de 300 segundos. Estudos preliminares em células estacionárias levaram a limites de detecção inferiores. Em célula estacionária, foram realizadas análises de cobre em aguardente e em água potável. Em alguns casos, os resultados obtidos com as amostras reais foram comparados com outra técnica (E.A.A.), onde os resultados obtidos foram muito próximos a àqueles obtidos com os eletrodos de ouro. Análises em água de abastecimento, mostraram que em células estacionárias o limite de detecção para cobre situa-se em 30 ng L-1, para tempos de deposição de 600 segundos. / This work describes an original and novel form of construction of gold electrodes (CDtrodes) from recordable CDs (CD-Rs). The CD-Rs contain in its constitution a fine gold layer with a thickness from 50 to 100 nm and an approx. 100 cm2 of area. This surface can be easily used for construction of conventional electrodes for stationary or flow electrochemical cells. Moreover, the nanometer thickness of the gold film can be employed for the construction of microelectrodes with areas smaller than 10-6 cm2. Due to the fact that CD-Rs are produced on commercial scale, the cost of each unit is very low, a feature that enables the use of these electrodes in disposable form. To prove the suitability of these films to make gold electrodes, their performance was compared with the response of a commercial electrode, and a similar behavior was observed. Different applications of recordable compact disk were tested either with synthetic or real samples. Using the Constant-Current Potentiometric Stripping Analysis (CCPSA) method, mercury was analyzed in seawater and drinking water samples, fitting the CD-R to flow injection analysis cell. In these studies, the detection limit for mercury was found to be 250 ng L-1, with a deposition time of 300 seconds. Preliminary studies involving stationary cells allowed lower detection limits for mercury to be attained. With a stationary cell, the analyses of copper in sugar cane spirits and drinking water were carried out. In some instances, comparisons were made between this and another analytical technique (namely A.A.S.) where the results were very close with the ones obtained with the gold electrodes. Analysis of drinking water showed that for stationary cells the detection limit for copper is 30 ng L-1, with a deposition time of 600 s.

O mercúrio é um metal tóxico, que pode causar diversas alterações no organismo humano. O presente estudo teve como objetivo investigar a ocorrência de disfunções neuropsicológicas em ex-trabalhadores de fábricas de lâmpadas fluorescentes que foram expostos a vapor de mercúrio, anos após a interrupção da exposição, além de investigar os efeitos dessa exposição sobre o Sistema Nervoso Autônomo a partir do método não-invasivo da pupilometria dinâmica. A avaliação neuropsicológica foi realizada através do Inventário Beck de Depressão e da bateria neuropsicológica computadorizada CANTABeclipse, utilizando-se subtestes que avaliam memória operacional (Spatial Span), memória espacial (Spatial Recognition Memory), memória visual (Pattern Recognition Memory), percepção visual (Delayed Matching to Sample), planejamento de ações (Stockings of Cambridge) e tomada de decisão (Information Sampling Task). A avaliação do Sistema Nervoso Autônomo, por sua vez, foi realizada através da pupilometria dinâmica, que provê informações acerca do funcionamento de ambas as funções simpática e parassimpática. Foram utilizados flashes de 631nm (luz vermelha) com 1 s de duração, com luminância de 1, 10 e 100 cd/m². Os escores de depressão foram significativamente mais altos entre os indivíduos com histórico de exposição em comparação aos sujeitos do grupo controle (p=0,025). Os pacientes expostos ao vapor de mercúrio apresentaram desempenho significativamente inferior à média do grupo controle nos testes: SSP direto (p=0,004), SRM (p=0,039), PRM (p=0,001), IST latência para abertura das caixas (p=0,001), IST latência para tomada de decisão (p=0,014), IST número de caixas abertas (p=0,045), DMS com intervalo (p=0,001) e DMS total (p=0,001). Portanto, foram encontrados prejuízos em: span atencional, memória espacial, memória visual de longa duração, memória visual de curta duração e tomada de decisão. No exame de pupilometria dinâmica, no parâmetro tempo em 75% de recuperação do diâmetro pupilar, em 10cd/m² de luminância, os sujeitos com histórico de exposição apresentaram resposta significativamente mais lenta do que os indivíduos do grupo controle (p=0,025). Os altos escores de depressão, além das perdas cognitivas em domínios variados, fazem parte do quadro de mercurialismo crônico e os achados do presente estudo são corroborados por pesquisas anteriores. O exame de pupilometria indicou perdas na função simpática do SNA. Estes últimos resultados já foram alcançados por algumas pesquisas anteriores, mas não foram encontrados registros de uso do exame de pupilometria dinâmica como forma de avaliação do SNA em pacientes com histórico de intoxicação por mercúrio / Mercury is a toxic metal which can cause several changes in the human body. The present study aimed to investigate the occurrence of neuropsychological dysfunction in former workers of fluorescent lamps factories that were exposed to mercury vapor (years after cessation of exposure), and to investigate the effects of such exposure on the Autonomic Nervous System using the non-invasive test of dynamic pupillometry. Neuropsychological evaluation was performed using the Beck Depression Inventory and the computerized neuropsychological battery CANTABeclipse, using subtests that assess working memory (Spatial Span), spatial memory (Spatial Recognition Memory), visual memory (Pattern Recognition Memory), visual perception (Delayed Matching to Sample), planning (Stockings of Cambridge) and decision making (Information Sampling Task). The Autonomic Nervous System assessment, in turn, was performed using dynamic pupillometry, which provides information on the operation on both the sympathetic and parasympathetic functions. We used flashes of red light (631nm) with 1 second duration and luminance of 1, 10 and 100cd/m². The depression scores were significantly higher among the former workers when compared with the control group (p=0,025). They also had significantly worse performance than the control group in the following tests: SSP direct (p=0,004), SRM (p=0,039), PRM (p=0,001), IST latency for opening the boxes (p=0,001), IST latency for decision making (p=0,014), IST number of boxes opened (p=0,045), DMS interval (p=0,001) e DMS complete (p=0,001). Therefore, deficits were found in: attentional spam, spatial memory, short term visual memory, long term visual memory, and decision making. In the dynamic pupillometry test, former workers had significantly lower response than the control group (p=0,025) in parameter time by 75% recovery of the pupil diameter, in 10cd/m² luminance. The high depression scores, in addition to cognitive impairments in several functions are expected in chronic mercurialism and our findings are supported by previous studies. The dynamic pupilllometry test indicated sympathetic function deficits. This latest result have already been achieved by some previous research, but we did not find any records of the dynamic pupillometry usage as a tool for assessing the Autonomic Nervous System in patients with previous mercury exposure

Estudos apontam que a região Amazônica apresenta concentrações significativas de selênio nos solos e que, por isso, a população não estaria susceptível à deficiência desse mineral. Em contrapartida, a região também apresenta dados de concentrações elevadas de mercúrio nos solos e rios, entretanto, a população não apresenta sinais clínicos evidentes de contaminação. Acredita-se que o selênio, um mineral antioxidante, possa ser um possível colaborador para a aparente tolerância ao mercúrio, pois uma das ações desse mineral é a de destoxificar o organismo contra metais tóxicos. Dependendo das concentrações no organismo, o mercúrio pode potencializar a geração das espécies reativas de oxigênio e, dessa forma, as defesas antioxidantes intrínsecas das células podem ser prejudicadas, resultando na condição conhecida por estresse oxidativo. A contaminação por mercúrio pode, ainda, comprometer a saúde tanto das mulheres quanto das crianças, pois esse metal, na forma de metilmercúrio, pode atravessar a barreira placentária e se concentrar, principalmente, no cérebro do feto. Aliado a isso, a presença de polimorfismos em certos genes podem alterar a expressão de enzimas antioxidantes como a glutationa peroxidase 1, que é dependente de selênio, assim como da glutationa S-transferase, que atua na destoxificação do mercúrio no organismo. Vários estudos apresentam dados de concentrações de mercúrio em ribeirinhos da Amazônia, no entanto, resultados referentes às concentrações de selênio, ao estresse oxidativo e a polimorfismos genéticos na população da área urbana são raros. Diante disso, este estudo objetivou avaliar o estado nutricional relativo ao selênio, concentrações de mercúrio e a possível relação desses parâmetros com o estresse oxidativo e os polimorfimos Pro198Leu (rs 1050450) no gene da glutationa peroxidase 1 e GSTM1 no gene da glutationa S-transferase em mulheres em idade fértil residentes em área de risco de exposição ao mercúrio, da cidade de Porto Velho (RO). As voluntárias foram avaliadas por meio de medidas antropométricas (peso, estatura e circunferência da cintura) e aplicou-se o registro alimentar para avaliação do consumo alimentar. Realizou-se uma coleta de sangue para análise de selênio, atividade da enzima glutationa peroxidase, marcadores de estresse oxidativo e polimorfismos genéticos. O selênio foi determinado por espectrometria de absorção atômica com geração de hidretos acoplados à cela de quartzo (HGQTAAS). Para análise de mercúrio, foi coletada uma amostra do cabelo das voluntárias, sendo sua concentração determinada pelo método de espectrometria de absorção atômica com geração de vapor frio (CV AAS). Para avaliar o estresse oxidativo foram determinadas: a concentração plasmática de Malondialdeído (MDA) e a Capacidade de Absorção de Radicais de Oxigênio (ORAC). Participaram do estudo 200 mulheres com idade entre 19 e 50 anos. A ingestão alimentar média de selênio foi de 49,3 ± 19,2 µg/dia e a prevalência de ingestão inadequada foi de 40,9%. As concentrações médias do mineral no plasma e nos eritrócitos foram, respectivamente, 49,8 + 18,6 µg/L e 75,4 + 29,9 µg/L. A atividade média da glutationa peroxidase foi de 45,1+ 19,4 U/g Hb. A concentração média de mercúrio nos cabelos foi de 625 + 766 ng g-1. Ao avaliar a presença do SNP Pro198Leu, observou-se que 56,7% das participantes apresentaram genótipo selvagem, 36,8% heterozigotos e 6,8% homoizgotos para leucina. Quanto ao polimorfismo de deleção GSTM1, 42,5% das voluntárias apresentaram o genótipo nulo ou deletado, ou seja, relacionado a ausência de expressão da glutationa S-transferase. Esses resultados permitem concluir que a maioria das participantes apresentou estado nutricional deficiente em relação ao selênio. Apesar disso, tanto a atividade enzimática da glutationa peroxidase, como os biomarcadores do estresse oxidativo não sofreram interferência desta deficiência. O polimorfismo Pro198Leu, também não interferiu no status de selênio e no estresse oxidativo. Quanto à avaliação do polimorfismo GSTM1, o genótipo nulo ou deletado também não mostrou associação com as concentrações de mercúrio e o estresse oxidativo. / Studies have shown that the Amazon region has significant concentrations of selenium in soils and therefore, the population is not susceptible to deficiency of this mineral. However, the region also presents data from high levels of mercury in soils and rivers, however, the population has no obvious clinical signs of contamination. It is believed that selenium, an antioxidant mineral may be a possible contributor to the apparent tolerance because of its actions in the detoxification of the body from toxic metals. Depending on the concentrations in the body, mercury can increase the generation of reactive oxygen species and thus the intrinsic antioxidant defenses of cells can be damaged, resulting in the condition known as oxidative stress. The mercury contamination may also compromise the health of both women and children, since this metal in the form of methylmercury can cross the placental barrier and concentrate mainly in the fetal brain. In addition, the presence of genetic polymorphisms can alter the expression of antioxidant enzymes such as glutathione peroxidase 1, which is selenium dependent, as well as glutathione S-transferase, which can be responsible for the mercury detoxification in the body. Several studies have shown mercury levels of riverine people from Amazon, however, results regarding selenium concentrations, oxidative stress and polymorphisms in the urban population are area. Thus, this study aimed to evaluate selenium status, mercury levels and the possible relationship of these with oxidative stress and genetic polymorphisms Pro198Leu (rs 1050450) in glutathione peroxidase 1 gene and GSTM1 in the glutathione S-transferase gene in women living in mercury exposure risk area, from the city of Porto Velho (RO). The of the volunteers was assessed using anthropometric measurements (weight, height and waist circumference) and evaluation of food consumption, by the food record. Blood samples were collected for selenium analysis, glutathione peroxidase enzyme\'s activity, oxidative stress and genetic polymorphisms. Selenium was determined by hydride generation quartz tube atomic absorption spectroscopy (HGQT AAS). For mercury analysis, a hair sample of volunteers was collected, and its concentration was determined by atomic absorption spectrometry method with cold vapor (CV AAS). To evaluate oxidative stress plasma concentrations of malondialdehyde (MDA) and Oxygen Radical Absorbance Capacity (ORAC) were determined We enrolled 200 volunteers aged between 19 and 50. The average of selenium intake was 49,3 ± 19,2 µg/day and the prevalence of inadequate intake was 40,9%. Mean selenium concentration on plasma and erythrocytes were respectively 49,8 + 18,6 µg/L and 75,4 + 29,9 µg/L. Glutathione peroxidase showed mean activity of 45,1 + 19,4 U/g Hb and mercury levels of 625 + 766 ng g-1. Evaluating the presence of the SNP Pro198Leu, it was observed that 56,7% of the were participants had wild type genotype, 36,8% heterozygous and 6,8% were homozygous for leucine. For the GSTM1 null deletion polymorphism, 42,5% of the volunteers had a null genotype, ie, do not express the enzyme glutathione S-transferase. These results indicate that the majority of participants had selenium deficiency in plasma and erythrocytes. Nevertheless, most of them had adequate activity of glutathione peroxidase. There was no association between selenium concentrations and the biomarkers used to assess oxidative stress. The Pro198Leu polymorphism did not interfere in selenium concentrations, as well as in the oxidative stress. The evaluation of GSTM1 polymorphism had no association with mercury levels and oxidative stress

O presente trabalho teve como objetivo o desenvolvimento e validação de um método analítico para a especiação de mercúrio em água com preparação de amostra por microextração em sorvente empacotado (MEPS) e determinação das espécies de mercúrio utilizando cromatografia líquida de alta eficiência hifenada à espectrometria de massa com plasma indutivamente acoplado (HPLC-ICP-MS). Para isso foram otimizadas as condições do sistema cromatográfico, do sistema de detecção e do procedimento de extração, considerando os parâmetros que influenciam diretamente na eficiência da análise, como o solvente de eluição, o agente complexante, o número de ciclos de extração e a velocidade de amostragem da seringa semi-automática eVol®. As melhores condições para o preparo de amostra foram encontradas com o uso de ditizona 0,001% m/v como agente complexante e eluição com 50?L de fase móvel, composta por 2-mercaptoetanol 0,05% v/v + L-cisteína 0,4% m/v + acetato de amônio 0,06 mol.L-1. Esse método apresentou valores de limite de detecção (LOD) de 0,19ng/L, 0,13ng/L e 0,16ng/L e recuperação de 100 ± 3%, 112 ± 0,9% e 91 ± 0,9% para mercúrio inorgânico (IHg), metilmercúrio (MeHg) e etilmercúrio (EtHg), respectivamente. A precisão intra-dia para cada espécie apresentou valores inferiores a 6,2% e a precisão inter-dia, valores interiores a 8,3%. Finalmente, o método proposto é uma excelente alternativa para a especiação química de mercúrio em amostras de água, garantindo uma melhor sensibilidade e reduzido volume de amostra. Além disso, poderá ser uma boa opção para pré-concentração de espécies de mercúrio in loco em estudos de contaminação ambiental em locais de difícil acesso e com pouca infraestrutura. / The aim of this study was to develop and validate a novel preconcentration method for determination of mercury species in water using a microextraction by packed sorbent (MEPS) based protocol followed by high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The optimized conditions of the HPLC and ICP-MS were determined and critical factors in MEPS protocol were established, including elution solvent, complexing agent, number of extraction cycles and sample flow rate of the semi-automated MEPS format (eVol®). The best sample preparation conditions were found with the use of dithizone 0,001% m/v as complexing agent and elution in 50?L of the mobile phase, containing 2-mercaptoethanol 0,05% v/v + L-cysteine 0,4% m/v + ammonium acetate 0,06 mol/L. The proposed method detection limit (LOD) was 0,19ng/L, 0,13ng/L and 0,16ng/L and the recovery was 100 ± 3%, 112 ± 0,9% and 91 ± 0,9% for inorganic mercury (IHg), methylmercury (MeHg) and ethylmercury (EtHg), respectively. The within-day precision was always lower than 6,2%, while the between-day precision was lower than 8,3% for the species determined. Finally, the proposed method is an excellent alternative for mercury speciation in water samples, ensuring a better sensitivity associated to small sample volume. Additionally, it may be a good option for preconcentration of mercury species in situ for environmental contamination studies in places of difficult access and poor infrastructure

Os diferentes efeitos que Hg(II), As(III) e Se(IV) causam ao meio ambiente e à saúde dos seres vivos levaram ao desenvolvimento de uma ampla variedade de técnicas analíticas para a determinação destas espécies, com destaque para a voltametria e cronopotenciometria de redissolução. As interações com ligantes heterogêneos de ocorrência natural são fundamentais para o transporte e disponibilidade de Hg(II), As(III) e Se(IV) no meio ambiente. O estudo das interações pode contribuir com tecnologias de remediação mais eficientes, evitando a introdução, ou permitindo a remoção de espécies de Hg(II), As(III) e Se(IV) de meios impactados. Na presente tese foram desenvolvidos métodos controlados por Análise por Injeção Sequencial (SIA) com detecção eletroquímica, especificamente voltametria de onda quadrada (SIA-SWASV) para Hg(II), As(III) e Se(IV) e um método com detecção por cronopotenciometria (SIA-SCP) para Hg(II) visando sua utilização em estudos de interação com vermiculita natural e modificada com tióis, microalga Chlamydomonas reinhardtii e vermiculita modificada com poli-hidróxi-cátions de Fe(III). Em todos os casos foram usados eletrodos de ouro como eletrodo de trabalho. Os limites de detecção (LD) para Hg(II) foram de 0,01 e 0,02 &#181;mol L-1 para os métodos SIA-CSP e SIA-SWASV, respectivamente. Para As(III) e Se(IV) os valores de LD foram de 0,02 e 0,06 &#181;mol L-1, respectivamente. Para a adsorção de Hg(II) em amostras de vermiculita, a amostra modificada com cisteamina foi a que apresentou maior capacidade de adsorção (qmax), 83±30 &#181;mol g-1. A variação da força iônica e do pH não afetou significativamente a adsorção nos materiais modificados com cisteamina, cisteína e (3-mercaptopropil)trimetoxisilano, devido a alta afinidade entre Hg(II) e os grupos tióis. Dessorções em HCl foram sempre < 21%, sugerindo que todos os materiais possuem potencialidade para aplicação in situ em ambientes impactados. A adsorção de Se(IV) na FeOH-VT resultou um qmax = 45±4 &#181;mol g-1, sendo que a capacidade diminui com o aumento da força iônica, indicando que a atração eletrostática exerce papel importante na adsorção. A biossorção de Hg(II) na C. reinhardtii teve seu maior valor de qmax, 3,3±0,8 mmol g-1, em pH 4,0, sendo o Hg(II) concentrado no interior das células. A capacidade de adsorção de Hg(II) em C. reinhardtii foi significativamente maior do que na vermiculita, natural e modificada, sugerindo a elevada potencialidade para biorremediação de águas contaminadas. As medidas cronopotenciométricas feitas na presença das células sugerem que a interação é parcialmente lábil, de modo que essa fração trocável com o ambiente deveria ser considerada nos processos de tratamento. O aumento da força iônica praticamente não afetou a biossorção, indicando pouca influência de atração eletrostática. Estudos preliminares de biossorção de As(III) por C. reinhardii em um tempo de contato de 120 min resultaram em qmax = 41±1 &#181;mol g-1, independente da variação do pH entre 4 e 7, enquanto que o aumento da força iônica aumentou as quantidades de As(III) biossorvido. / The different effects that Hg(II), As(III) and Se IV) cause to the environment and to the health of living beings led to the development of a wide range of analytical techniques for the determination of these species, especially stripping voltammetry and chronopotenciometry. Interactions with heterogeneous naturally occurring ligands play a key role in the transport and availability of Hg(II), As(III) and Se(IV) in the environment. The study of these interactions may contribute to more effective remediation technologies, avoiding their loading in environmental compartments, or enabling the removal of Hg(II), As(III) and Se(IV) species from impacted medium. The present thesis describes the development of methods controlled by Sequential Injection Analysis (SIA) with electrochemical detection, specifically square wave voltammetry (SIA-SWASV) for determination of Hg(II), As(III) and Se(IV), and chronopotentiometry (SIA-SCP) for Hg(II) aiming their use in interaction studies with the clay mineral vermiculite (natural and modified with thiols and polyhydroxy cations of Fe(III)) and with the microalgae Chlamydomonas reinhardtii. In all cases gold electrodes were used as working electrode. The limits of detection (LOD) for Hg(II) were 0.01 and 0.02 &#181;mol L-1 for SIA-SCP and SIA-SWASV methods, respectively. For As(III) and Se(IV) the LOD values were 0.02 and 0.06 &#181;mol L-1, respectively. For the adsorption of Hg(II) in vermiculite samples, the sample modified with cysteamine showed the highest adsorption capacity (qmax), 83 ± 30 &#181;mol g-1. As a consequence of the high affinity between Hg(II) and the thiols, the variation of the ionic strength and pH did not significantly affect the adsorption on materials modified with cysteamine, cysteine, and (3-mercaptopropyl) trimethoxysilane. Desorption in HCl was always < 21%, suggesting that all materials have potential for in situ application in impacted environments. Adsorption of Se(IV) in FeOH-VT resulted in a qmax = 45 ± 4 &#181;mol g-1, and the capacity decreased with increasing ionic strength, indicating that the electrostatic attraction played an important role in adsorption. The biosorption of Hg(II) by C. reinhardtii had its greatest value qmax, 3.3 ± 0.8 mmol g-1, at pH 4.0, and Hg(II) concentrated in the cells. The adsorption capacity of Hg(II) in C. reinhardtii was significantly higher than that in vermiculite, natural or modified, suggesting high potential for bioremediation of contaminated water. The chronopotentiometric measurements in the presence of cells suggested that the interaction was partially labile, so that the exchangeable fraction with the environment should be considered for treatment processes. The increase in ionic strength did not affect the biosorption, indicating little influence of electrostatic attraction. Preliminary studies on biosorption of As(III) by C. reinhardii with a contact time of 120 min resulted in qmax = 41 ± 1 &#181;mol g-1, independent of pH variation between 4 and 7, whereas the increase of ionic strength increased amounts of As(III) biosorbed.

O atual modelo de desenvolvimento econômico, que tem como uma de suas bases a acentuada produção de bens de consumo, é responsável pelo aumento crescente de riscos ambientais que incidem nas questões de saúde das populações. Esse modelo é também responsável por um aumento na geração de resíduos sólidos, considerado um dos problemas ambientais emergentes com significativos impactos para a saúde humana. O crescimento na geração de resíduos vem sendo acompanhado por um aumento considerável no número de catadores de material reciclável, que encontram nessa atividade uma estratégia de sobrevivência. Esse grupo de trabalhadores encontra-se potencialmente exposto a maiores riscos no campo da saúde em função de sua ocupação. Na presente investigação, avaliaram-se os níveis de exposição aos metais cádmio (Cd), chumbo (Pb), mercúrio (Hg) e níquel (Ni) em catadores de material reciclável de quatro cooperativas na Região Metropolitana de São Paulo (RMSP) e os resultados foram comparados com estudos de biomonitoramento também realizados na RMSP .Foram coletadas amostras de sangue de 226 indivíduos (IC:95%, precisão 6%) e aplicados questionários para o levantamento de características associadas às concentrações de metais e à presença de valores acima dos Valores de Referência (VR) definidos por estudos de biomonitoramento. As concentrações médias de Cd (MA: 0,47 ug/L; MG: 0,34 ug/L) foram quase quatro vezes superiores às apontadas no estudo de referência e 24,3% dos indivíduos apresentaram concentrações de Cd acima dos VR. As concentrações médias de Pb (MA: 39,13 ug/L; MG: 34,11 ug/L) foram 1,4 vezes superiores às da população de referência e 10,6% dos indivíduos apresentaram concentrações de Pb acima do VR. As concentrações médias de Hg (MA: 1,46 ug/L; MG: 0,94 ug/L) não foram significativamente diferentes da população de referência, porém 4,9% dos indivíduos apresentaram concentrações de Hg acima do VR. As concentrações médias de níquel (Ni) (MA:3,3 ug/L; MG:1,89 ug/L) apresentaram grande variabilidade, não sendo possível realizar inferências sobre os níveis de exposição. Os resultados encontrados apontam para uma maior exposição ao Cd entre os catadores, possivelmente relacionada ao trabalho com a reciclagem, porém as fontes específicas não puderam ser determinadas por este estudo. Os resultados apontam também uma maior exposição ao Pb, porém de menor magnitude, o que pode estar relacionado com a condição socioeconômica e maior percentual de tabagistas na população do estudo e não necessariamente com a ocupação que exercem / The current model of economic development, which has as one of its bases a constant increase in production and consumption, is responsible for the intensification of environmental risks that can compromise a population\'s health. This model is also responsible for the continued growth in waste generation which is accompanied by a considerable increase in the number of recyclable materials collectors, who find in this activity a survival strategy. This population group that has for decades played an important role in solid waste management, now has greater exposures to health risks due to their daily activity. In the present study, the levels of exposure to the metals cadmium (Cd), lead (Pb), mercury (Hg) and nickel (Ni) were evaluated in recyclable materials collectors from four cooperatives in the Metropolitan Region of São Paulo (MRSP). Blood samples were collected from 226 individuals (CI: 95%, accuracy 6%) and the results were compared with other biomonitoring studies from MRSP. Questionnaires were applied to obtain information regarding variables that could influence the blood levels of the metals under study. The mean concentrations of Cd found (AM: 0.47 ug/L; GM: 0.34 ug/L) were almost four times that the ones found in the reference study and 24,3% of the individuals presented Cd concentrations above the Reference Values (RV). The mean concentrations of Pb in the collectors (AM: 39.13 ug/L; GM: 34.11 ug/L) were also significantly higher than the mean concentration in the reference study population (about 1.4 times) and 10,6% of the collectors presented Pb concentrations above the RV. The mean concentrations of mercury (AM: 1.46 ug/L; GM: 0.94 ug/L) were not significantly higher than the mean concentration found in the reference study. The concentration of Ni presented a large variability, so it was not possible to make inferences about the exposure to this metal. This study indicates that recyclable materials collectors have a greater exposure to Cd when compared with the general population, and this is possibly related to the work developed by these individuals, even though the sources could not be determined by this study. It also indicated that the collectors have a greater exposure to Pb, but the magnitude of the results might be explained by the socioeconomic characteristics and the larger amount of smokers among the sampled population

A Grande São Paulo, composta por 39 municípios, apresenta crescimento urbano e industrial expoente que contribuem para o constante acúmulo de poluentes no ambiente. Ainda assim, exibe áreas verdes remanescentes que contribuem para a sustentabilidade ambiental da cidade, como por exemplo, o Parque Ibirapuera e o Parque Ecológico do Tietê. Nesse contexto, o presente estudo visa verificar a viabilidade em utilizar as O. niloticus como bioindicadoras da poluição por mercúrio no ecossistema aquático dos dois parques da Grande São Paulo. Obteram-se para as tilápias do Nilo do Parque Ibirapuera pertencentes aos pontos de coleta A, B e C durante o inverno as respectivas concentrações de mercúrio total no sangue 2,72±4,20&micro;g/L, 2,45±1,90&micro;g/L e 1,19±0,05&micro;g/L e, no hepatopâncreas as respectivas concentrações de mercúrio de 0,07±0,02 &micro;g/g, 0,06 ±0,005 &micro;g/g e 0,16 ±0,07 &micro;g/g. No verão as tilápias do Parque Ibirapuera apresentaram nos mesmos pontos de coleta as respectivas concentrações de mercúrio total no sangue 2,50±0,84&micro;g/L, 2,67±1,03&micro;g/L e 2,430±0,790&micro;g/L e, no hepatopâncreas as respectivas concentrações de mercúrio de 0,08 ±0,03 &micro;g/L, 0,16 ±0,10 &micro;g/L e 0,09 ±0,03 &micro;g/L. Os peixes do Parque Ecológico do Tietê pertencentes ao ponto de coleta B durante o inverno e verão apresentaram no hepatopâncreas as concentrações de mercúrio total de 0,08±0,01&micro;g/g e 0,10±0,0&micro;g/g e, no sangue as concentrações e mercúrio de 3,59 &micro;g/L e 2,00±1,00 &micro;g/L. A análise estatística de regressão linear foi negativa, alta e com significância estatística apenas entre a idade estimada e a concentração do mercúrio no sangue sugerindo que as tilápias jovens são mais susceptíveis ao acúmulo de mercúrio. Viabilizou-se através deste estudo o uso das tilápias do Nilo como bioindicadores para a poluição por mercúrio nos lagos dos parques da Grande São Paulo. / The Greater São Paulo, formed by 39 cities, presents high urban and industrial growth that contribute to environmental pollution accumulation. In contrast, the same area has residual green areas that contributes to the city\'s environmental sustainability, such as Parque Ibirapuera and Parque Ecológico do Tietê. This study intends to verify the feasebility of using O. niloticus as bioindicators of mercury pollution on the aquatic ecosystem of two Greater São Paulo parks. At winter, on Parque Ibirapuera, the collected Nile Tilapia presented 2,72±4,20&micro;g/L, 2,45±1,90&micro;g/L e 1,19±0,05&micro;g/L mercury concentration on blood and 0,07±0,02 &micro;g/g, 0,06 ±0,005&micro;g/g e 0,16 ±0,07 &micro;g/g mercury concentration on liver for collect points A, B and C respectively. At summer, Nile Tilapias collected on the same three points, presented 2,50±0,84&micro;g/L, 2,67±1,03&micro;g/L e 2,430±0,790&micro;g/L mercury concentration on blood and 0,08 ±0,03 &micro;g/L, 0,16 ±0,10 &micro;g/L e 0,09 ±0,03 &micro;g/L on liver. The Parque Ecológico do Tietê\'s fish, from point B, presented 0,08±0,01&micro;g/g mercury concentration on liver and 3,59 &micro;g/L mercury concentration on blood. At summer, the mercury concentrations were 0,10±0,0&micro;g/g on liver and 2,00±1,00 &micro;g/L on blood. The linear regression statistical analisys was negative, high and with statistical significance only between estimated age and blood mercury concentration, indicating that young tilapia are more likely to accumulate mercury. The use of Nile Tilapia as bioindicators for mercury pollution on Greater São Paulo\'s park lakes was made viable through this study.