9 documents found, page 1 of 1
Diffusive methane fluxes from Negro, Solimões and Madeira rivers and fringing l...
Barbosa, Pedro Maia; Melack, John M.; Farjalla, Vinícius Fortes; Amaral, João Henrique Fernandes; Scofield, Vinicius; Forsberg, Bruce RiderThe first extensive set of measurements of methane concentrations and fluxes for the Negro River and its major tributaries combined with complementary data for the Solimões and Madeira rivers and several tributaries are presented and their temporal and spatial variations examined. Fluxes were measured using floating chambers, and dissolved CH4 concentrations were measured by the headspace technique. In the Soli...
The potential impact of new Andean dams on Amazon fluvial ecosystems
Forsberg, Bruce Rider; Melack, John M.; Dunne, Thomas; Barthem, Ronaldo Borges; Goulding, Michael; Paiva, Rodrigo C.D.; Sorribas, Mino VianaIncreased energy demand has led to plans for building many new dams in the western Amazon, mostly in the Andean region. Historical data and mechanistic scenarios are used to examine potential impacts above and below six of the largest dams planned for the region, including reductions in downstream sediment and nutrient supplies, changes in downstream flood pulse, changes in upstream and downstream fish yields, ...
Vertical Distribution Of Zooplankton And Physico-Chemical Conditions During A 2...
Fisher, Thomas R.; Melack, John M.; Robertson, Barbara A.; Hardy, Elsa Rodrigues; Alves, Luiz FernandoEm maio de 1980 o lago Calado apresentava uma profundidade de 9 metros e, abaixo dos 4 metros, condições anóxicas. Todo o zooplâncton se encontrava na camada oxigenada. Adultos e jovens de Daphnia gessneri, a espécie mais abundante, ocorreram entre 0.5 - 4.5 metros. Nauplius de copepoda ocorreram mais perto da superfície entre 0-2 metros. Não houve uma migração vertical evidente. No epilimnion, o oxigênio apres...
Reducing greenhouse gas emissions of Amazon hydropower with strategic dam planning
Almeida, Rafael M.; Shi, Qinru; Gomes-Selman, Jonathan M.; Wu, Xiaojian; Xue, Yexiang; Angarita, Héctor A.; Barros, Nathan OliveiraHundreds of dams have been proposed throughout the Amazon basin, one of the world’s largest untapped hydropower frontiers. While hydropower is a potentially clean source of renewable energy, some projects produce high greenhouse gas (GHG) emissions per unit electricity generated (carbon intensity). Here we show how carbon intensities of proposed Amazon upland dams (median = 39 kg CO2eq MWh−1, 100-year horizon) ...
Carbon dioxide and methane emissions from interfluvial wetlands in the upper Ne...
Belger, Lauren; Forsberg, Bruce Rider; Melack, John M.Extensive interfluvial wetlands occur in the upper Negro River basin (Brazil) and contain a mosaic of vegetation dominated by emergent grasses and sedges with patches of shrubs and palms. To characterize the release of carbon dioxide and methane from these habitats, diffusive and ebullitive emissions and transport through plant aerenchyma were measured monthly during 2005 in permanently and seasonally flooded a...
Turbulence and Gas Transfer Velocities in Sheltered Flooded Forests of the Amaz...
MacIntyre, Sally; Fernandes Amaral, Joao H.; Barbosa, Pedro Maia; Cortés, Alicia; Forsberg, Bruce Rider; Melack, John M.Seasonally flooded forests along tropical rivers cover extensive areas, yet the processes driving air-water exchanges of radiatively active gases are uncertain. To quantify the controls on gas transfer velocities, we combined measurements of water-column temperature, meteorology in the forest and adjacent open water, turbulence with an acoustic Doppler velocimeter, gas concentrations, and fluxes with floating c...
Projections of climate change effects on discharge and inundation in the Amazon...
Sorribas, Mino Viana; Paiva, Rodrigo C. D.; Melack, John M.; Bravo, Juan Martin; Jones, Charles; Carvalho, Leila; Beighley, Edward; Forsberg, BruceClimate change and its effects on the hydrologic regime of the Amazon basin can impact biogeochemical processes, transportation, flood vulnerability, fisheries and hydropower generation. We examined projections of climate change on discharge and inundation extent in the Amazon basin using the regional hydrological model MGB-IPH with 1-dimensional river hydraulic and water storage simulation in floodplains. Futu...
The potential impact of new Andean dams on Amazon fluvial ecosystems
Forsberg, Bruce R.; Melack, John M.; Dunne, Thomas; Barthem, Ronaldo B.; Goulding, Michael; Paiva, Rodrigo C. D.O aumento da demanda de energia levou a planos para a construção de muitas novas barragens na Amazônia Ocidental, principalmente na região andina. Dados históricos e cenários mecanicistas são usados para examinar os impactos potenciais acima e abaixo de seis das maiores barragens planejadas para a região, incluindo reduções nos estoques a jusante de sedimentos e nutrientes, mudanças no pulso de inundação a jusa...
A multisensor, multitemporal approach for monitoring herbaceous vegetation grow...
Freire Silva, Thiago Sanna [UNESP]; Costa, Maycira P. F.; Novo, Evlyn M. L. M.; Melack, John M.Made available in DSpace on 2015-03-18T15:55:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-01; The Amazon River floodplain is an important source of atmospheric CO2 and CH4. Aquatic herbaceous vegetation (macrophytes) have been shown to contribute significantly to floodplain net primary productivity (NPP) and methane emission in the region. Their fast growth rates under both flooded and dry condi...