Background, aim and scope Although many recent studies have focused on sediment potential toxicity, few of them were performed in tropical shallow aquatic environments. Those places can suffer short-time variations, especially due to water column circulations generated by changes in temperature and wind. Rio Grande reservoir is such an example; aside from that, it suffers various anthropogenic impacts, despite its multiple uses. Materials and methods This work presents the first screening step for understanding sediment quality from Rio Grande reservoir by comparing metal content using three different sediment quality guidelines. We also aimed at verifying any possible spatial heterogeneity. Results and discussion We found spatial heterogeneity varying according to the specific metal. Results showed a tendency for metals to remain as insoluble as metal sulfide (potentially not bioavailable), since sulfide was in excess and sediment physical-chemical characteristics contribute to sulfide maintenance (low redox potential, neutral pH, low dissolved oxygen, and high organic matter content). On the other hand, metal concentrations were much higher than suggested by Canadian guidelines and regional background values, especially Cu, which raises the risk of metal remobilization in cases of water circulation. Further study steps include the temporal evaluation of AVS/SEM, a battery of bioassays and the characterization of organic compounds.Sediments are an important phase in controlling metal toxicity to organisms, since they can act as both a source and a sink for such contaminants (Chapman et al. 1998). Physical and chemical parameters of sediments affect metal speciation and, hence, metal bioavailability and toxicity to organisms. Although many studies have been dedicated for the understanding of sediment dynamics and processes controlling the bioavailability of metals, few of them were performed in tropical shallow aquatic environments. In such places, minor changes in temperature and wind can have an enormous influence on water circulation over a 24-h basis, meaning that the water column changes from being stratified to non-stratified. Besides, high temperatures accelerate the metabolism of the whole system, including production/consumption of organic matter and equilibrium of chemical reactions.Water bodies located near urban areas are subjected to multiple stresses, among which metal contamination is of great importance, since metals are not degradable and can be biomagnified along the food web. Furthermore, the sources of metals are variable (atmospheric deposition, run off from ore exploration, input from industrial, and urban sewage). In this context, Rio Grande reservoir fulfills the characteristics for a good case of study. It is part of the Billings Complex, the greatest body of accumulated water in the São Paulo Metropolitan Region (São Paulo State, Brazil); it is polymictic, of multiple uses and suffers greatly from a variety of anthropogenic impacts.

In the Amazon Basin, naturally occurring methylmercury bioaccumulates in fish, which is a key source of protein consumed by riverine populations. The hydroelectric power-plant project at Santo Antônio Falls allows us to compare the Hg exposure of riverine populations sparsely distributed on both sides of the Madeira river before the area is to be flooded. From 2009 to 2011, we concluded a population survey of the area (N = 2,008; representing circa 80% of community residents) that estimated fish consumption and mercury exposure of riverine populations with different degrees of lifestyle related to fish consumption. Fish samples from the Madeira river (N = 1,615) and 110 species were analyzed for Hg. Hair-Hg was significantly lower (p < 0.001) in less isolated communities near to the capital of Porto Velho (median 2.32 ppm) than in subsistence communities in the Cuniã Lake, 180 km from Porto Velho city (median 6.3 ppm). Fish Hg concentrations ranged from 0.01 to 6.06 µg/g, depending on fish size and feeding behavior. Currently available fish in the Madeira river show a wide variability in Hg concentrations. Despite cultural similarities, riparians showed hair-Hg distribution patterns that reflect changes in fish-eating habits driven by subsistence characteristics.

The aim of this cross-sectional study was to estimate the prevalence of hypertension among adults (n = 841) in communities along the Madeira River in the Brazilian Amazon, prior to startup of the Santo Antônio Hydroelectric Plant. The study gathered information on sociodemographic conditions, history of diseases, habits, fish consumption, and anthropometric parameters. Logistic regression was used to calculate odds ratios and the respective confidence intervals. Among the riverine communities, 26% (95%CI: 23%-29%) of adults presented hypertension (29% in men [95%CI: 24%-33%] and 23% in women [95%CI: 19%-27%]). Factors associated with hypertension were age, BMI, and place of residence in men and age, triglycerides, and blood glucose in women. The findings can contribute to strategies for state and municipal health services to monitor and prevent cardiovascular events.

Agradeço ao Prof. Dr. Marcelo L. M. Pompêo, por ser um orientador de verdade (coisa rara nos dias de hoje), pelo apoio, incentivo e liberdade para tomar decisões. Ao Instituto de Biociências, ao Programa de Pós Graduação em Ecologia e aos funcionários e professores do Depto. de Ecologia. A Viviane Moschini-Carlos, pela amizade e pelo apoio. Ao pessoal do laboratório Sheila Cardoso da Silva, Felipe Lobo, Juliana Costa Braidotti (duplamente, por ter que me agüentar um pouco a mais), Pedro Kawamura, Paula Cookie Nishimura pela ajuda nas análises, pela amizade e pelas cervejas. Ao Prof. Dr. Antônio A. Mozeto, pela iniciação na geoquímica ambiental e pela imensa ajuda na instalação da técnica, na bibliografia e na discussão deste trabalho. Ao Prof. Dr. Jorge C. Masini, pela ajuda com a parte química. À Profa. Dra. Elizabeth de Oliveira, pelas análises no ICP/AES. Ao Prof. Dr. Sérgio Tadeu Meireles, pela ajuda com a estatística. À Prof. Dra. Marisa Bitencourt pelo auxílio com o Sensoriamento Remoto. Ao Giba barqueiro, pela simpatia ao nos guiar pelo Rio Grande. Aos técnicos Maurício e P.C. pela ajuda nas análises granulométricas. À Fapesp, pelo apoio financeiro através do projeto processo n° 2002/13376-4. Ao Ale, (mais um agradecimento, heim!), pelo carinho, companheirismo e apoio. A Patrícia Carvalho, pela amizade, pelo incentivo, pela correção, etc. Ao pessoal do Tai-Chi pela amizade e pelo incentivo. Aos meus pais e aos meus avós pelo incentivo e apoio, inclusive financeiro.

No abstract