Tropical reservoirs upstream from hydroelectric dams are known to release significant amounts of methane to the atmosphere. Here we demonstrate that methane emissions downstream from hydroelectric dams can also be large. Emissions of CH4 downstream of Balbina reservoir in the central Amazon basin (Brazil) were calculated from regular measurements of degassing in the outflow of the turbines and downstream diffusive losses. Annual emissions from the reservoir surface and downstream from the dam were 34 and 39 Gg C, respectively. The downstream emission alone represented the equivalent of 3% of all methane released from central Amazon floodplain.

[1] Hydroelectric reservoirs can release significant quantities of CO 2 , but very few results are available from the tropics. The objective of the present study was to estimate the emission of CO 2 from the Balbina hydroelectric reservoir in the central Brazilian Amazon. Diffusive and ebullitive emissions were estimated at regular intervals, both above and below the dam, using a combination of static chambers and submerged funnels. Gas releases immediately below the dam were calculated as the difference between gas flux at the entrance and the outflow of the hydroelectric turbines. An inundation model derived from a bathymetric map and daily stage readings was used for spatial and temporal interpolation of reservoir emissions. Annual emissions of CO 2 , upstream and downstream of Balbina dam for 2005, were estimated as 2450 and 81 Gg C, respectively, for a total annual flux of 2531 Gg C. Upstream emissions were predominantly diffusive with only 0.02 Gg C yr −1 resulting from ebullition. On average, 51% of the downstream emission was released by degassing at the turbine outflow, and the remainder was lost by diffusion from the downstream river. The total annual greenhouse gas emission from Balbina dam, including the CO 2 equivalent of previously estimated CH 4 emissions, was 3 Tg C yr −1 , equivalent to approximately 50% of the CO 2 emissions derived from the burning of fossil fuels in the Brazilian metropolis of São Paulo.

Carbon dioxide (CO 2) and methane (CH 4) generated in reservoirs are released downstream of dams, and few studies have considered these downstream emissions. Fluxes downstream of 3 Amazon hydroelectric reservoirs (Tucuruí, Samuel, and Curuá-Una) are reported here. Degassing through turbines was calculated as the difference between intake and outflow concentrations. Additional releases along the Tocantins, Jamari, and Curuá rivers were measured at downstream sites over a distance of 30 km. About 50% of the CH 4 and 30% of the CO 2 emitted downstream of the dam were liberated at the turbine outflow. The total downstream emissions are sufficiently large to require consideration in assessments of greenhouse gas emissions from hydroelectric reservoirs.

No abstract

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November-December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities.

-(Spatial distribution of terrestrial fanerogamic flora in the Abrolhos National Marine Park, BA). Oceanic islands are highly vulnerable to environmental changes. Thus, the vegetation mapping of these systems are of fundamental importance. The objective of the present work was to study the composition and distribution of plant species to classify and describe the vegetation types of the islands of Abrolhos (Santa Barbara, Siriba, Sueste, Redonda and Guarita) in southern Bahia during August, October and December 1995 and in March and May 1996. The isolation of the archipelago from the mainland and its structural features offer a great potential for geographic studies. The spatial distribution of seven vegetation types (after beach, after rocks, mild slope, sheer slope, top shrub, top herb, top grass) were delimited, using as indicators physiognomy, relief and floristic composition. The vegetation types were classified according to their geographic characteristics and vegetation structure, were associated to the 40 species identified.

Este estudio fue realizado en las playas Del rio Abufari que hace parte de la Reserva Biológica de Abufari, situada en El bajo rio Purus, Amazonas, Brasil. El estudio se condujo en los períodos secos (agosto/diciembre) desde 1998 hasta 2004. Fue analizada la selección de microhábitat de desove de Podocnemis expansa, P. sextuberculata y P. unifilis. Fue verificado que las tres especies estudiadas poseen patrones distintos en la escogencia del local de postura de su nido. P. expansa desova en grandes aglomeraciones y en las porciones más altas de la playa (encima de 400 cm), P. sextuberculata también desova en locales con altura elevada, sin embargo, los nidos están dispersos a la largo de la playa. No fue observado un patrón de selección de locales de desove para P. unifilis. La principal causa de pérdida de nidos de P. expansa es la remoción de nidadas de esta especie hecha por las hembras que ingresan a la playa a desovar al final del período de nidificación. En los casos de P. sextuberculata e P. unifilis las causas de pérdida de nidos en la playa de Abufari se relacionan con depredación causada principalmente por el lagarto Tupinambis sp. y por el ave Coragips atratus, y la inundación ocasionada por las aguas del rio Purus, dado que los nidos de la playa se encontraban por debajo de 100 cm de altura en relación al nivel, lo que les daba una mayor probabilidad de ser anegados

| CRB6/2422 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores. 2019 Permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores, mas sem a possibilidade de alterá-la de nenhuma forma ou utilizá-la para fins comerciais. www.atenaeditora.com.br APRESENTAÇÃO A obra "Engenharia Sanitária e Ambiental Tecnologias para a Sustentabilidade" aborda uma série de livros de publicação da Atena Editora, em seu II volume, apresenta, em seus 22 capítulos, os conhecimentos tecnológicos da engenharia sanitária e ambiental. As Ciências estão globalizadas, englobam, atualmente, diversos campos em termos de pesquisas tecnológicas. Com o crescimento populacional e a demanda por alimentos tem contribuído para o aumento da poluição, por meio de problemas como assoreamento, drenagem, erosão e, a contaminação das águas pelos defensivos agrícolas. Tais fatos, podem ser minimizados por meio de estudos e tecnologias que visem acompanhar as alterações do meio ambiente pela ação antrópica. Portanto, para garantir a sustentabilidade do planeta é imprescindível o cuidado com o meio ambiente. Este volume dedicado à diversas áreas de conhecimento trazem artigos alinhados com a Engenharia Sanitária e Ambiental Tecnologias para a Sustentabilidade. A sustentabilidade do planeta é possível devido o aprimoramento constante, com base em novos conhecimentos científicos.Aos autores dos diversos capítulos, pela dedicação e esforços sem limites, que viabilizaram esta obra que retrata os recentes avanços científicos e tecnológicos, os agradecimentos do Organizador e da Atena Editora.Por fim, esperamos que este livro possa colaborar e instigar mais estudantes e pesquisadores na constante busca de novas tecnologias para a Engenharia Sanitária e Ambiental, assim, garantir perspectivas de solução de problemas de poluição dos solos, rios, entre outros e, assim garantir para as atuais e futuras gerações a sustentabilidade.