RESUMO

Reservoir construction promotes many environmental impacts, including the enhancement of mercury concentrations in fish. The processes that can influence mercury concentrations in fish in Amazonian reservoirs are still little explored in depth, especially when we consider the possible particularities of the ecosystems in question. This study aims to investigate how mercury concentrations in fish could be influenced by the Tucuruí dam, considering possible changes in their feeding and trophic position according to the dam position (up or downstream). Fish were sampled upstream and downstream of the Tucuruí reservoir, and total mercury (THg) and stable isotopes of carbon and nitrogen (δ15N and δ13C) were measured in muscles. We observed three different Hg bioaccumulation patterns influenced by the dam. These differences occurred due to species trophic niche changes corroborated by the isotope analysis. Higher THg concentrations downstream compared to those upstream ones were only observed for Geophagus proximus. On the contrary, Plagioscion squamosissimus, from downstream, presented lower concentrations than upstream ones. The isotopic niche of these two species presented different changes according to the sampled site. THg biomagnification was higher upstream compared to downstream, considering that the regression slope was approximately two times higher upstream versus downstream. THg concentrations in fish were explained by the differences in their feeding habits according to their location in relation to the dam. The difference in THg biomagnification was able to reflect differences in structure of the food web chain in ecosystems under the dam's influence.

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RESUMO

The present study investigated the spatiotemporal changes in the structure of the population of the halftooth, Hemiodus unimaculatus (Bloch, 1794), in the area upstream from the Tucuruí hydroelectric dam on the Tocantins River, through quarterly samples obtained in 2001, 2003, 2005 and 2007. The variation in the total length and weight of the specimens was analyzed using the Kruskal-Wallis test, with a 5% significance level, while the spatiotemporal variation in population parameters was evaluated using a cluster analysis and SIMPER. A number of changes were found in the population structure of H. unimaculatus, with an increase in population size, a shift in the proportion of juveniles and adults, and alterations of the spatial distribution of the fish. The lack of data on the species and its occurrence in the study area reinforce the need for the development of adequate management measures to avoid overfishing in the future.(AU)

O presente estudo investigou as mudanças espaço-temporais na estrutura da população da jatuarana escama grossa, Hemiodus unimaculatus (Bloch, 1794), na área a montante da hidrelétrica de Tucuruí, no rio Tocantins, através de amostras trimestrais obtidas em 2001, 2003, 2005 e 2007. A variação no comprimento total e peso dos espécimes foi analisada pelo teste de Kruskal-Wallis, com nível de significância de 5%, enquanto a variação espaço-temporal nos parâmetros populacionais foi avaliada por meio de análise de agrupamento e SIMPER. Algumas mudanças foram encontradas na estrutura populacional de H. unimaculatus com aumento do comprimento total dos indivíduos, modificação na proporção de jovens e adultos e mudanças na distribuição espaço-temporal. A falta de dados sobre a espécie e sua ocorrência na área de estudo reforçam a necessidade do desenvolvimento de medidas de manejo adequadas para evitar a sobrepesca no futuro.(AU)

Assuntos

RESUMO

The present study investigated the spatiotemporal changes in the structure of the population of the halftooth, Hemiodus unimaculatus (Bloch, 1794), in the area upstream from the Tucuruí hydroelectric dam on the Tocantins River, through quarterly samples obtained in 2001, 2003, 2005 and 2007. The variation in the total length and weight of the specimens was analyzed using the Kruskal-Wallis test, with a 5% significance level, while the spatiotemporal variation in population parameters was evaluated using a cluster analysis and SIMPER. A number of changes were found in the population structure of H. unimaculatus, with an increase in population size, a shift in the proportion of juveniles and adults, and alterations of the spatial distribution of the fish. The lack of data on the species and its occurrence in the study area reinforce the need for the development of adequate management measures to avoid overfishing in the future.

O presente estudo investigou as mudanças espaço-temporais na estrutura da população da jatuarana escama grossa, Hemiodus unimaculatus (Bloch, 1794), na área a montante da hidrelétrica de Tucuruí, no rio Tocantins, através de amostras trimestrais obtidas em 2001, 2003, 2005 e 2007. A variação no comprimento total e peso dos espécimes foi analisada pelo teste de Kruskal-Wallis, com nível de significância de 5%, enquanto a variação espaço-temporal nos parâmetros populacionais foi avaliada por meio de análise de agrupamento e SIMPER. Algumas mudanças foram encontradas na estrutura populacional de H. unimaculatus com aumento do comprimento total dos indivíduos, modificação na proporção de jovens e adultos e mudanças na distribuição espaço-temporal. A falta de dados sobre a espécie e sua ocorrência na área de estudo reforçam a necessidade do desenvolvimento de medidas de manejo adequadas para evitar a sobrepesca no futuro.

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RESUMO

The Amazon River basin is the largest tropical forest in the world. Most of the Amazon belongs to Brazil, a developing country that currently faces huge challenges related to the consolidation of its universal healthcare system. Noncommunicable diseases (NCDs) are the leading cause of death in Brazil, accounting for 74% of all deaths, and NCDs are probably underestimated in Amazonian population because of their geographical isolation and the precariousness of riverine communities. Important risk factors, such as genetic susceptibility, remain undetermined in the riverine population. This study performed fasting blood sugar (FBS) and blood pressure measurements and investigated the presence of the ε4 allele of apolipoprotein E (APOE4) to determine the prevalence of diabetes, hypertension and the genetic risk of NCDs. FBS and APOE4 were measured in blood samples from 763 participants using spectrometry and real-time PCR; 67.5% showed altered measurements, and 57.9% had never been diagnosed or treated. Altered FBS was found in 28.3% of the participants, hypertension in 57.6% and APOE4 in 32.0%. The health profile of the riverine population appears to differ from that of urban population in the Amazon. Additional risk factors for NCDs, such as environmental contamination and nutritional transition, may contribute more than increased genetic susceptibility to the prevalence of altered FBS and hypertension. Our results will help guide the development of preventive strategies and governmental actions for more effective management of NCDs in the Amazon area.

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RESUMO

Mercury is a heavy metal responsible for human intoxication worldwide and especially in the Amazon, where both natural and anthropogenic sources are responsible for exposure in riverine populations. Methylmercury is the most toxic specie of mercury with recognized neurotoxicity due to its affinity for the central nervous system. S100B protein is a well-established biomarker of brain damage and it was recently associated with mercury-related neurotoxicity. Accurate measurement is especially challenging in isolated/remote populations due to the difficulty of adequate sample conservation, therefore here we use S100B mRNA levels in blood as a way to assay mercury neurotoxicity. We hypothesized that individuals from chronically exposed populations showing mercury levels above the limit of 10 µg/g in hair would present increased levels of S100B mRNA, likely due to early brain damage. A total of 224 riverine individuals were evaluated for anthropometric data (age, body mass index), self-reported symptoms of mercury intoxication, c-reactive protein in blood, and mercury speciation in hair. Approximately 20% of participants showed mercury levels above the limit, and prevalence for most symptoms was not different between individuals exposed to high or low mercury levels. Rigorous exclusion criteria were applied to avoid confounding factors and S100B mRNA in blood was tested by RT-qPCR. Participants with ≥10 µg/g of mercury had S100B mRNA levels over two times higher than that of individuals with lower exposure. A significant correlation was also detected between mercury content in hair and S100B mRNA levels in blood, supporting the use of the latter as a possible candidate to predict mercury-induced neurotoxicity. This is the first report of an association between S100B mRNA and mercury exposure in humans. The combination of both exposure and intoxication biomarkers could provide additional support for the screening and early identification of high-risk individuals in isolated populations and subsequent referral to specialized centers.

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RESUMO

Human exposure to mercury is a serious problem of public health in Amazon. As in other vulnerable populations throughout the world, Amazonian riverine populations are chronically exposed to this metal and some symptoms of mercury intoxication were already detected in these populations. However, studies on the genetic susceptibility to mercury toxicity in the Amazon are scarce, and they tested a limited number of individuals. In this context, apolipoprotein E gene (APOE) is a key element with a well-established association among their alleles and the neurodegenerative consequences of mercury intoxication. However, no studies have addressed APOE genotyping in Amazonian exposed populations. Additionally, epidemiological studies with APOE genotyping in Amazon have been restricted to indigenous populations. Therefore, this work analyzed for the first time the genotypic and allelic profiles of APOE in Amazonian riverine populations chronically exposed to mercury. Eight hundred and twenty three individuals were enrolled in our study donating blood (794) and/or hair (757). APOE genotyping was analyzed by real-time PCR. Total mercury and mercury species were quantified by ICP-MS and GC-pyro-AFS, respectively. Genomic ancestry markers were evaluated by multiplex-PCR reaction, separated by capillary electrophoresis on the ABI 3130 Genetic Analyzer instrument and analyzed on GeneMapper ID v3.2. The 𝜀3 and 𝜀3/𝜀3 were the most frequent allele and genotype, respectively, followed by 𝜀4 allele and 𝜀3/𝜀4 genotype. Only 𝜀2/𝜀2 genotype was not found, suggesting that the absence of this genotype is a generalized phenomenon in Amazon. Also, our data supported an association between the presence of APOE4 and the Amerindian origin in these populations. Fifty-nine individuals were identified at maximum risk with levels of mercury above 10 µg/g and the presence of APOE4. Interestingly, among individuals with high mercury content, APOE4-carriers had high mercury levels than APOE2-carriers, pointing to a different heavy metal accumulation according to the APOE allele. These data suggest that APOE4, in addition to a possible pharmacodynamic effect, may influence pharmacokinetically the mercury exposure causing its higher accumulation and leading to worse deleterious consequences. Our results may aid in the development of prevention strategies and health policy decision-making regarding these at-risk vulnerable populations.

RESUMO

The Tucuruí Dam is one of the largest dams ever built in the Amazon. The area is not highly influenced by gold mining as a source of mercury contamination. Still, we recently noted that one of the most consumed fishes (Cichla sp.) is possibly contaminated with methylmercury. Therefore, this work evaluated the mercury content in the human population living near the Tucuruí Dam. Strict exclusion/inclusion criteria were applied for the selection of participants avoiding those with altered hepatic and/or renal functions. Methylmercury and total mercury contents were analyzed in hair samples. The median level of total mercury in hair was above the safe limit (10µg/g) recommended by the World Health Organization, with values up to 75µg/g (about 90% as methylmercury). A large percentage of the participants (57% and 30%) showed high concentrations of total mercury (≥ 10µg/g and ≥ 20µg/g, respectively), with a median value of 12.0µg/g. These are among the highest concentrations ever detected in populations living near Amazonian dams. Interestingly, the concentrations are relatively higher than those currently shown for human populations highly influenced by gold mining areas. Although additional studies are needed to confirm the possible biomagnification and bioaccumulation of mercury by the dams in the Amazon, our data already support the importance of adequate impact studies and continuous monitoring. More than 400 hydropower dams are operational or under construction in the Amazon, and an additional 334 dams are presently planned/proposed. Continuous monitoring of the populations will assist in the development of prevention strategies and government actions to face the problem of the impacts caused by the dams.

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O objetivo da pesquisa foi determinar as curvas de seletividade das redes que capturam a jatuarana-escama-grossa, Hemiodus unimaculatus (Bloch, 1794), uma das espécies de peixe mais desembarcadas na área de influência do reservatório de Tucuruí, rio Tocantins, Pará. O local de estudo corresponde à área localizada a montante da barragem da Usina Hidrelétrica de Tucuruí. As coletas foram efetuadas trimestralmente nos anos de 2001, 2003, 2005, 2006 e 2007 e semestralmente nos anos de 2002 e 2004, em cinco locais do reservatório e dois a montante, utilizando bateria de redes de emalhar de 50 m de comprimento e 3 m de altura, com malhas de 40, 60 e 80 mm entre nós opostos. A seletividade das redes foi determinada por meio da construção de curvas de seleção, que evidenciaram ser a malha de 60 mm a mais indicada para a pesca, considerando a captura de 50% de indivíduos adultos.

The authors set out to determine the selectivity curves of the nets that capture the jatuarana, Hemiodus unimaculatus (Bloch, 1794). The study site corresponds the area located upstream of the dam of the Tucuruí Hydroelectric Power Plant. The collections were made quarterly in 2001, 2003, 2005, 2006 and 2007 and semiannually in the years of 2002 and 2004, in five sites in the reservoir and two upstream, using a battery of gill nets with 50 m long and 3 m height, with meshes of 40, 60 and 80 mm between opposing nodes. The selectivity was determined through the construction of the selection curves, indicating that the 60 mm mesh is the most suitable for fishing, considering the capture of 50% of adult individuals.

Assuntos

RESUMO

O objetivo da pesquisa foi determinar as curvas de seletividade das redes que capturam a jatuarana-escama-grossa, Hemiodus unimaculatus (Bloch, 1794), uma das espécies de peixe mais desembarcadas na área de influência do reservatório de Tucuruí, rio Tocantins, Pará. O local de estudo corresponde à área localizada a montante da barragem da Usina Hidrelétrica de Tucuruí. As coletas foram efetuadas trimestralmente nos anos de 2001, 2003, 2005, 2006 e 2007 e semestralmente nos anos de 2002 e 2004, em cinco locais do reservatório e dois a montante, utilizando bateria de redes de emalhar de 50 m de comprimento e 3 m de altura, com malhas de 40, 60 e 80 mm entre nós opostos. A seletividade das redes foi determinada por meio da construção de curvas de seleção, que evidenciaram ser a malha de 60 mm a mais indicada para a pesca, considerando a captura de 50% de indivíduos adultos.(AU)

The authors set out to determine the selectivity curves of the nets that capture the jatuarana, Hemiodus unimaculatus (Bloch, 1794). The study site corresponds the area located upstream of the dam of the Tucuruí Hydroelectric Power Plant. The collections were made quarterly in 2001, 2003, 2005, 2006 and 2007 and semiannually in the years of 2002 and 2004, in five sites in the reservoir and two upstream, using a battery of gill nets with 50 m long and 3 m height, with meshes of 40, 60 and 80 mm between opposing nodes. The selectivity was determined through the construction of the selection curves, indicating that the 60 mm mesh is the most suitable for fishing, considering the capture of 50% of adult individuals.(AU)

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RESUMO

Fishing is one of the most traditional activities downstream Tucuruí dam, northeast Pará state, generating occupation to many coastal families. The main fishing tackles used in the study area are the fishing nets and the main species are Plagioscion squamosissimus (Heckel, 1840) and Hypophthalmus marginatus (Valenciennes in Cuvier and Valenciennes, 1840. Most of the fish are sell cold. The socioeconomic characterization was conduct through semi-structured interviews using questionnaires with 109 anglers during June, August and September 2006 and April 2008. Respondents were mostly born in Para state (98%), male (89%), lived under a stable relationship (38%), 82.6% had children; family income of the majority was below the minimum wage (67%) and aged between 14 and 70 years, with incomplete secondary education (62%), about 27% of the fishermen are working on fisheries at last 5 to 9 years. The anglers interviewed associated fish stocks decline to factors such as use of fishing tackles out of specifications established in legislation.

A pesca é uma das atividades mais tradicionais realizadas a jusante da Usina Hidrelétrica de Tucuruí, nordeste paraense, gerando emprego e renda a inúmeras famílias ribeirinhas. O apetrecho de pesca mais utilizado na área de estudo é a rede de emalhar fixa e as principais espécies capturadas são a pescada branca (Plagioscion squamosissimus) e o mapará (Hypophthalmus marginatus). A maior parte do pescado é comercializada fresco. A caracterização socioeconômica dos pescadores foi realizada por meio entrevistas semiestruturadas, com questionários aplicados a 109 pescadores nos meses de junho, agosto e setembro de 2006 e em abril de 2008. Os entrevistados, em sua maioria, são paraenses (98%), homens (89%) que vivem em regime de união estável (38%), 82,6% possuem filhos; a renda familiar é inferior a um salário mínimo (67%) e possuem idade entre 14 e 70 anos, com ensino médio incompleto (62%), e cerca de 27% exerce a atividade a um tempo que varia entre 5 a 9 anos. Para os pescadores entrevistados há redução na produção pesqueira associada a fatores como uso de apetrechos de pesca fora das especificações previstas na legislação.

Assuntos

RESUMO

Fishing is one of the most traditional activities downstream Tucuruí dam, northeast Pará state, generating occupation to many coastal families. The main fishing tackles used in the study area are the fishing nets and the main species are Plagioscion squamosissimus (Heckel, 1840) and Hypophthalmus marginatus (Valenciennes in Cuvier and Valenciennes, 1840. Most of the fish are sell cold. The socioeconomic characterization was conduct through semi-structured interviews using questionnaires with 109 anglers during June, August and September 2006 and April 2008. Respondents were mostly born in Para state (98%), male (89%), lived under a stable relationship (38%), 82.6% had children; family income of the majority was below the minimum wage (67%) and aged between 14 and 70 years, with incomplete secondary education (62%), about 27% of the fishermen are working on fisheries at last 5 to 9 years. The anglers interviewed associated fish stocks decline to factors such as use of fishing tackles out of specifications established in legislation.(AU)

A pesca é uma das atividades mais tradicionais realizadas a jusante da Usina Hidrelétrica de Tucuruí, nordeste paraense, gerando emprego e renda a inúmeras famílias ribeirinhas. O apetrecho de pesca mais utilizado na área de estudo é a rede de emalhar fixa e as principais espécies capturadas são a pescada branca (Plagioscion squamosissimus) e o mapará (Hypophthalmus marginatus). A maior parte do pescado é comercializada fresco. A caracterização socioeconômica dos pescadores foi realizada por meio entrevistas semiestruturadas, com questionários aplicados a 109 pescadores nos meses de junho, agosto e setembro de 2006 e em abril de 2008. Os entrevistados, em sua maioria, são paraenses (98%), homens (89%) que vivem em regime de união estável (38%), 82,6% possuem filhos; a renda familiar é inferior a um salário mínimo (67%) e possuem idade entre 14 e 70 anos, com ensino médio incompleto (62%), e cerca de 27% exerce a atividade a um tempo que varia entre 5 a 9 anos. Para os pescadores entrevistados há redução na produção pesqueira associada a fatores como uso de apetrechos de pesca fora das especificações previstas na legislação.(AU)

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RESUMO

Recent dental microwear studies have shown that fossil species differ from one another in texture attributes-both in terms of central tendency and dispersion. Most comparative studies used to interpret these results have relied on poorly provenienced museum samples that are not well-suited to consideration of within species variation in diet. Here we present a study of two species of platyrrhine monkeys, Alouatta belzebul (n = 60) and Sapajus apella (n = 28) from Pará State in the Brazilian Amazon in order to assess effects of habitat variation on microwear (each species was sampled from forests that differ in the degree of disturbance from highly disturbed to minimally disturbed). Results indicate that microwear texture values vary between habitats-more for the capuchins than the howler monkeys. This is consistent with the notion that diets of the more folivorous A. belzebul are less affected by habitat disturbance than those of the more frugivorous S. apella. It also suggests that microwear holds the potential to reflect comparatively subtle differences in within-species variation in fossil taxa if sample size and control over paleohabitat allow.

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The objective of this study was to detect antibodies for human T lymphotropic virus (HTLV) in subjects residing in two communities located in the eastern Brazilian Amazon and on the shores of the Tucuruí hydroelectric power plant. A total of 657 serum samples were analysed using an enzyme-linked immunosorbent assay with an anti-HTLV antibody (Symbiosis™, São Paulo, Brazil), demonstrating a virus prevalence of 4.7%. Most individuals with HTLV were aged over 30 years (P = 0.013), were unmarried (P = 0.019), resided in the area for more than 10 years (P = 0.001), had a low level of education (P = 0.015), and had a family income of up to $305 (100%). In contrast, there was no significant association between infection and sex, city of birth, haemotransfusion, or previous surgery. The prevalence observed in these communities suggests that the residents should be concerned about HTLV infection, and that some areas may become endemic for HTLV.

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RESUMO

The fisheries in the reservoir of UHE-Tucuruí employ about 6.000 fishermen generating approximately R$ 4.2 million/year. There are three main target-species: Tucunaré Cichla monoculus (caught with hook and line), Pescada Plagioscion squamosissimus (caught with gill net and/or hook and line) and Mapará Hypophthalmus marginatus (caught with gill net). Published information was reviewed and data collected during two field trips in 1999 and 2000 that included interviews with community leaders and fishermen. The aims were: to get information on the reservoir fisheries and fishermen; create scenarios of fishing effort increase; and, forecast potential conflicts due to the collapse of resources. The following variables were considered: target-species landings (data records supplied by the fishermen's associations), fishing gear, fishing strategies, conflicts, fishing spot allocation systems, and income. These variables, covering a period of 10 years starting from 1999, were entered into a dynamic model, simulated with the Vensim PLE software. The results indicate that the hook and line fishery is the most profitable, and potential conflicts due to resource scarcity could occur in short time (2005). The methodology used for the simulations and risk analysis was found to be suitable for the local reality and available data set.

As pescarias no reservatório da UHE-Tucuruí no rio Tocantins, Pará, envolvem cerca de 6.000 pescadores e movimentam cerca de R$ 4,2 milhões/ano. A atividade se concentra em três espécies principais: tucunaré Cichla monoculus (capturado com anzol), pescada Plagioscion squamosissimus (capturado com rede e/ou anzol) e mapará Hypophthalmus marginatus (capturado com rede). Com o objetivo de caracterizar os pescadores e as pescarias do reservatório, criar cenários de aumento do esforço pesqueiro e prever os momentos de conflito pela escassez de recursos, foram levantadas informações da literatura e realizadas duas campanhas de coleta de dados nos anos de 1999 e 2000, envolvendo entrevistas com líderes comunitários e pescadores. As seguintes variáveis foram consideradas: desembarque por espécie-alvo (de acordo com os registros fornecidos pelas colônias de pescadores), artes de pesca, estratégias dos pescadores, conflitos e formas de apropriação do espaço e rendimentos da atividade. Estas variáveis foram inseridas em um modelo dinâmico, simulado no software Vensim PLE para um período de 10 anos a partir de 1999. Os resultados indicam que a pesca de anzol é a estratégia mais rentável, e que possíveis momentos de conflito devido à escassez de recursos podem acontecer em curto prazo (2005). A metodologia utilizada para as simulações e análises de risco também se revelou adequada à realidade local e ao conjunto de dados disponíveis.

RESUMO

The objective of this work was to study the genesis of an Oxisol-Ultisol-Entisol sequence, developed from sediments of the Barreiras Formation in the Tucurui region. The area is located about 65 km from Tucurui. In this area a soil topo sequence was selected, represented by a clayey oxisol in the higher parts, a clayey ultisol in the middle part, ending in an ample valley of sandy botton, with strong hidromorphism. The temperature regimes are isohyperthermic and hyperthermic and the moisture regimes are udic and aquic, in the higher parts and valley botton, respectively. Four profiles were examined and auger samples were taken in eight representative sites. The parent material is represented by clayey sediments from the Barreiras Formation. Chemically, the soils are leached with high aluminum saturation, dominated by kaolinite clay minerals. In the higher parts of the sequence the textura! gradient is similar and the iron oxides are mainly in crystalline forms. Downslope the textural gradient increases and the iron forms are less crystalline. At the valley botton the process of the fine fraction loss (also due to the hydromorphism) is completed remaining a sandy deep mantle. The iron oxides dissapear, remaining the kaolinite in smaller proportion. The soil sequence evolution may probably be developed by the degradation of the latossolic clayey material of the higher portions of the landscape.

Estudou-se uma seqüência de Latossolo Amarelo-Podzólico Amarelo-Areia Quartzosa desenvolvida em sedimentos da Formação Barreiras. A área se localiza no sul do Pará, nas proximidades entre Tucuruí e o Rio Moju, distando 65km da Usina Hidroelétrica de Tucuruí. Foi escolhida uma encosta de aproximadamente 1500 metros formada por Latossolo na parte alta e Podzólico Amarelo na encosta, ambos argilosos, terminando em amplo vale de fundo arenoso, com forte hidromorfísmo. Os regimes de temperatura são isohipertérmico e hipertérmico e os de umidade ústico e áquico, nas partes elevadas e fundo do vale, respectivamente. Foram abertas quatro trincheiras ao longo da encosta e feitas oito tradagens para apoio. O material de origem é representado pela caolinita. Verificou-se que a diferenciação lateral dos solos: Latossolo Amarelo na parte alta, Podzólico Latossólico na encosta e Areia Quartzosa no fundo do vale, pode ser devida principalmente a processos de remoção e/ou destruição de finos (argila silicatada + óxidos). O encharcamento temporário e a gleização acentuada, exerceram papel preponderante na diferenciação da seqüência estudada.

RESUMO

The objective of this work was to study the genesis of an Oxisol-Ultisol-Entisol sequence, developed from sediments of the Barreiras Formation in the Tucurui region. The area is located about 65 km from Tucurui. In this area a soil topo sequence was selected, represented by a clayey oxisol in the higher parts, a clayey ultisol in the middle part, ending in an ample valley of sandy botton, with strong hidromorphism. The temperature regimes are isohyperthermic and hyperthermic and the moisture regimes are udic and aquic, in the higher parts and valley botton, respectively. Four profiles were examined and auger samples were taken in eight representative sites. The parent material is represented by clayey sediments from the Barreiras Formation. Chemically, the soils are leached with high aluminum saturation, dominated by kaolinite clay minerals. In the higher parts of the sequence the textura! gradient is similar and the iron oxides are mainly in crystalline forms. Downslope the textural gradient increases and the iron forms are less crystalline. At the valley botton the process of the fine fraction loss (also due to the hydromorphism) is completed remaining a sandy deep mantle. The iron oxides dissapear, remaining the kaolinite in smaller proportion. The soil sequence evolution may probably be developed by the degradation of the latossolic clayey material of the higher portions of the landscape.

Estudou-se uma seqüência de Latossolo Amarelo-Podzólico Amarelo-Areia Quartzosa desenvolvida em sedimentos da Formação Barreiras. A área se localiza no sul do Pará, nas proximidades entre Tucuruí e o Rio Moju, distando 65km da Usina Hidroelétrica de Tucuruí. Foi escolhida uma encosta de aproximadamente 1500 metros formada por Latossolo na parte alta e Podzólico Amarelo na encosta, ambos argilosos, terminando em amplo vale de fundo arenoso, com forte hidromorfísmo. Os regimes de temperatura são isohipertérmico e hipertérmico e os de umidade ústico e áquico, nas partes elevadas e fundo do vale, respectivamente. Foram abertas quatro trincheiras ao longo da encosta e feitas oito tradagens para apoio. O material de origem é representado pela caolinita. Verificou-se que a diferenciação lateral dos solos: Latossolo Amarelo na parte alta, Podzólico Latossólico na encosta e Areia Quartzosa no fundo do vale, pode ser devida principalmente a processos de remoção e/ou destruição de finos (argila silicatada + óxidos). O encharcamento temporário e a gleização acentuada, exerceram papel preponderante na diferenciação da seqüência estudada.

RESUMO

Em agosto de 1980, em um canteiro de obras da hidrelétrica de Tucuruí, no Estado do Pará, ocorreu um surto epidêmico de salmonelose, durante o qual foram isoladas, no Hospital Vila Temporária, 101 cepas de Saimonellà sp., através de hemocultura e coprocultura; 62 cepas foram enviadas à Seção de Bacteriologia do Instituto Adolfo Lutz, São Paulo, e 39 à Seção de Bacteriologia do Instituto Evandro Chagas, Belém, onde foi feita a confirmação bioquímica do gênero e a sorotipagem. A lisotipagem de 55 cepas, efetuada no Centro de Lisotipia Entérica do Instituto Pasteur de Paris, França, demonstrou que todas pertenciam ao lisotipo lb, fato este que sugere origem única para o surto epidêmico em tela. Todas as cepas mostraram alta sensibilidade aos antimicrobianos aos quais foram submetidas: ampicilina, ácido nalidixico, cefalotina, estreptomicina, canamicina, cloranfenicol, tetraciclina, gentamicina, amicacina e colistina. Este foi o primeiro surto epidêmico de salmonelose por Salmonella pamtyphi A assinalado no Brasil (AU).

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