Origin, transport and deposition of leaf-wax biomarkers in the Amazon Basin and the adjacent Atlantic

NASA Astrophysics Data System (ADS)

Häggi, Christoph; Sawakuchi, André O.; Chiessi, Cristiano M.; Mulitza, Stefan; Mollenhauer, Gesine; Sawakuchi, Henrique O.; Baker, Paul A.; Zabel, Matthias; Schefuß, Enno

2016-11-01

Paleoenvironmental studies based on terrigenous biomarker proxies from sediment cores collected close to the mouth of large river systems rely on a proper understanding of the processes controlling origin, transport and deposition of biomarkers. Here, we contribute to the understanding of these processes by analyzing long-chain n-alkanes from the Amazon River system. We use the δD composition of long-chain n-alkanes from river bed sediments from the Amazon River and its major tributaries, as well as marine core-top samples collected off northeastern South America as tracers for different source areas. The δ13C composition of the same compounds is used to differentiate between long-chain n-alkanes from modern forest vegetation and petrogenic organic matter. Our δ13C results show depleted δ13C values (-33 to -36‰) in most samples, indicating a modern forest source for most of the samples. Enriched values (-31 to -33‰) are only found in a few samples poor in organic carbon indicating minor contributions from a fossil petrogenic source. Long-chain n-alkane δD analyses show more depleted values for the western tributaries, the Madeira and Solimões Rivers (-152 to -168‰), while n-alkanes from the lowland tributaries, the Negro, Xingu and Tocantins Rivers (-142 to -154‰), yield more enriched values. The n-alkane δD values thus reflect the mean annual isotopic composition of precipitation, which is most deuterium-depleted in the western Amazon Basin and more enriched in the eastern sector of the basin. Samples from the Amazon estuary show a mixed long-chain n-alkane δD signal from both eastern lowland and western tributaries. Marine core-top samples underlying the Amazon freshwater plume yield δD values similar to those from the Amazon estuary, while core-top samples from outside the plume showed more enriched values. Although the variability in the river bed data precludes quantitative assessment of relative contributions, our results indicate that long-chain n-alkanes from the Amazon estuary and plume represent an integrated signal of different regions of the onshore basin. Our results also imply that n-alkanes are not extensively remineralized during transport and that the signal at the Amazon estuary and plume includes refractory compounds derived from the western sector of the Basin. These findings will aid in the interpretation of plant wax-based records of marine sediment cores collected from the adjacent ocean.

Modeling surface water dynamics in the Amazon Basin using MOSART-Inundation v1.0: Impacts of geomorphological parameters and river flow representation

DOE PAGES

Luo, Xiangyu; Li, Hong -Yi; Leung, L. Ruby; ...

2017-03-23

In the Amazon Basin, floodplain inundation is a key component of surface water dynamics and plays an important role in water, energy and carbon cycles. The Model for Scale Adaptive River Transport (MOSART) was extended with a macroscale inundation scheme for representing floodplain inundation. The extended model, named MOSART-Inundation, was used to simulate surface hydrology of the entire Amazon Basin. Previous hydrologic modeling studies in the Amazon Basin identified and addressed a few challenges in simulating surface hydrology of this basin, including uncertainties of floodplain topography and channel geometry, and the representation of river flow in reaches with mild slopes.more » This study further addressed four aspects of these challenges. First, the spatial variability of vegetation-caused biases embedded in the HydroSHEDS digital elevation model (DEM) data was explicitly addressed. A vegetation height map of about 1 km resolution and a land cover dataset of about 90 m resolution were used in a DEM correction procedure that resulted in an average elevation reduction of 13.2 m for the entire basin and led to evident changes in the floodplain topography. Second, basin-wide empirical formulae for channel cross-sectional dimensions were refined for various subregions to improve the representation of spatial variability in channel geometry. Third, the channel Manning roughness coefficient was allowed to vary with the channel depth, as the effect of riverbed resistance on river flow generally declines with increasing river size. Lastly, backwater effects were accounted for to better represent river flow in mild-slope reaches. The model was evaluated against in situ streamflow records and remotely sensed Envisat altimetry data and Global Inundation Extent from Multi-Satellites (GIEMS) inundation data. In a sensitivity study, seven simulations were compared to evaluate the impacts of the five modeling aspects addressed in this study. The comparisons showed that representing floodplain inundation could significantly improve the simulated streamflow and river stages. Refining floodplain topography, channel geometry and Manning roughness coefficients, as well as accounting for backwater effects had notable impacts on the simulated surface water dynamics in the Amazon Basin. As a result, the understanding obtained in this study could be helpful in improving modeling of surface hydrology in basins with evident inundation, especially at regional to continental scales.« less

Modeling surface water dynamics in the Amazon Basin using MOSART-Inundation v1.0: Impacts of geomorphological parameters and river flow representation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Xiangyu; Li, Hong -Yi; Leung, L. Ruby

In the Amazon Basin, floodplain inundation is a key component of surface water dynamics and plays an important role in water, energy and carbon cycles. The Model for Scale Adaptive River Transport (MOSART) was extended with a macroscale inundation scheme for representing floodplain inundation. The extended model, named MOSART-Inundation, was used to simulate surface hydrology of the entire Amazon Basin. Previous hydrologic modeling studies in the Amazon Basin identified and addressed a few challenges in simulating surface hydrology of this basin, including uncertainties of floodplain topography and channel geometry, and the representation of river flow in reaches with mild slopes.more » This study further addressed four aspects of these challenges. First, the spatial variability of vegetation-caused biases embedded in the HydroSHEDS digital elevation model (DEM) data was explicitly addressed. A vegetation height map of about 1 km resolution and a land cover dataset of about 90 m resolution were used in a DEM correction procedure that resulted in an average elevation reduction of 13.2 m for the entire basin and led to evident changes in the floodplain topography. Second, basin-wide empirical formulae for channel cross-sectional dimensions were refined for various subregions to improve the representation of spatial variability in channel geometry. Third, the channel Manning roughness coefficient was allowed to vary with the channel depth, as the effect of riverbed resistance on river flow generally declines with increasing river size. Lastly, backwater effects were accounted for to better represent river flow in mild-slope reaches. The model was evaluated against in situ streamflow records and remotely sensed Envisat altimetry data and Global Inundation Extent from Multi-Satellites (GIEMS) inundation data. In a sensitivity study, seven simulations were compared to evaluate the impacts of the five modeling aspects addressed in this study. The comparisons showed that representing floodplain inundation could significantly improve the simulated streamflow and river stages. Refining floodplain topography, channel geometry and Manning roughness coefficients, as well as accounting for backwater effects had notable impacts on the simulated surface water dynamics in the Amazon Basin. As a result, the understanding obtained in this study could be helpful in improving modeling of surface hydrology in basins with evident inundation, especially at regional to continental scales.« less

Erosion of particulate organic material from an Andean river and its delivery to the Amazon Basin

NASA Astrophysics Data System (ADS)

Clark, Kathryn; Hilton, Robert; West, A. Joshua; Robles Caceres, Arturo; Grocke, Darren; Marthews, Toby; Asner, Greg; New, Mark; Mahli, Yadvinder

2016-04-01

Organic carbon and nutrients discharged by mountainous rivers can play an important role in biogeochemical cycles from regional to global scales. The eastern Andes host productive forests on steep, rapidly eroding slopes, a combination that is primed to deliver sediment, carbon and nutrients to the lowland Amazon River. We quantify clastic sediment and particulate organic carbon (POC) discharge for the Kosñipata River, Peru, an Andean tributary of the Madre de Dios River, using suspended sediment samples and discharge measurements over one year at two gauging stations. Calculations of sediment yield on the basis of this data suggest that the Madre de Dios basin may have erosion rates ˜10 times greater than the Amazon Basin average. The total POC yield over the sampling period was up to five times higher than the yield in the lowland Amazon Basin, with most POC (70-80%) exported between December and March in the wet season. We use radiocarbon, stable C isotopes and C/N ratios to distinguish between the erosion and discharge of POC from sedimentary rocks (petrogenic POC) and POC eroded from the modern terrestrial biosphere, from vegetation and soil (biospheric POC). We find that biospheric POC discharge was significantly enhanced during flood events, over that of clastic sediment and petrogenic POC. The ultimate fate of the eroded POC may play a central role in the net carbon budget of Andean forest. In these forests, net productivity minus heterotrophic respiration is close to zero at the scale of forest plots, and the erosion of biospheric POC by this Andean river is sufficiently rapid that its fate downstream (sedimentary burial/preservation versus oxidation/degradation) may determine whether the mountain forest is a carbon sink or source to the atmosphere. In addition, the measured discharge of petrogenic POC suggests that fluxes from the Andes may be considerably higher than measured downstream in the Madeira River. If this petrogenic POC is oxidised rather than stored in the Amazon River floodplains, it could contribute an important release of CO2 which is not considered in forest-plot scale measurements. Overall, our results suggest that the erosion of biospheric and petrogenic POC from the Andes and its discharge by rivers comprise an important part of the organic carbon budget of the Amazon River Basin, one that depends on the fate of material delivered to the lowlands.

Fragmentation of Andes-to-Amazon connectivity by hydropower dams

PubMed Central

Anderson, Elizabeth P.; Jenkins, Clinton N.; Heilpern, Sebastian; Maldonado-Ocampo, Javier A.; Carvajal-Vallejos, Fernando M.; Encalada, Andrea C.; Rivadeneira, Juan Francisco; Hidalgo, Max; Cañas, Carlos M.; Ortega, Hernan; Salcedo, Norma; Maldonado, Mabel; Tedesco, Pablo A.

2018-01-01

Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems—the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services. PMID:29399629

Fragmentation of Andes-to-Amazon connectivity by hydropower dams.

PubMed

Anderson, Elizabeth P; Jenkins, Clinton N; Heilpern, Sebastian; Maldonado-Ocampo, Javier A; Carvajal-Vallejos, Fernando M; Encalada, Andrea C; Rivadeneira, Juan Francisco; Hidalgo, Max; Cañas, Carlos M; Ortega, Hernan; Salcedo, Norma; Maldonado, Mabel; Tedesco, Pablo A

2018-01-01

Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems-the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services.

A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme

NASA Astrophysics Data System (ADS)

Vauchel, Philippe; Santini, William; Guyot, Jean Loup; Moquet, Jean Sébastien; Martinez, Jean Michel; Espinoza, Jhan Carlo; Baby, Patrice; Fuertes, Oscar; Noriega, Luis; Puita, Oscar; Sondag, Francis; Fraizy, Pascal; Armijos, Elisa; Cochonneau, Gérard; Timouk, Franck; de Oliveira, Eurides; Filizola, Naziano; Molina, Jorge; Ronchail, Josyane

2017-10-01

The Madeira River is the second largest tributary of the Amazon River. It contributes approximately 13% of the Amazon River flow and it may contribute up to 50% of its sediment discharge to the Atlantic Ocean. Until now, the suspended sediment load of the Madeira River was not well known and was estimated in a broad range from 240 to 715 Mt yr-1. Since 2002, the HYBAM international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents. It is based on the continuous monitoring of a set of 11 gauging stations in the Madeira River watershed from the Andes piedmont to the confluence with the Amazon River, and discrete sampling of the suspended sediment concentration every 7 or 10 days. This paper presents the results of the suspended sediment data obtained in the Madeira drainage basin during 2002-2011. The Madeira River suspended sediment load is estimated at 430 Mt yr-1 near its confluence with the Amazon River. The average production of the Madeira River Andean catchment is estimated at 640 Mt yr-1 (±30%), the corresponding sediment yield for the Andes is estimated at 3000 t km-2 yr-1 (±30%), and the average denudation rate is estimated at 1.20 mm yr-1 (±30%). Contrary to previous results that had mentioned high sedimentation rates in the Beni River floodplain, we detected no measurable sedimentation process in this part of the basin. On the Mamoré River basin, we observed heavy sediment deposition of approximately 210 Mt yr-1 that seem to confirm previous studies. But while these studies mentioned heavy sedimentation in the floodplain, we showed that sediment deposition occurred mainly in the Andean piedmont and immediate foreland in rivers (Parapeti, Grande, Pirai, Yapacani, Chimoré, Chaparé, Secure, Maniqui) with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands.

Source area and seasonal variation of dissolved Sr isotope composition in rivers of the Amazon basin

NASA Astrophysics Data System (ADS)

Santos, Roberto V.; Sondag, Francis; Cochonneau, Gerard; Lagane, Christelle; Brunet, Pierre; Hattingh, Karina; Chaves, Jeane G. S.

2014-05-01

We present dissolved Sr isotope data collected over 8 years from three main river systems from the Amazon Basin: Beni-Madeira, Solimões, Amazon, and Negro. The data show large 87Sr/86Sr ratio variations that were correlated with the water discharge and geology of the source areas of the suspended sediments. The Beni-Madeira system displays a high average 87Sr/86Sr ratio and large 87Sr/86Sr fluctuations during the hydrological cycle. This large average value and fluctuations were related to the presence of Precambrian rocks and Ordovician sediments in the source area of the suspended sediment of the river. In contrast, the Solimões system displays a narrow range of Sr isotope ratio variations and an average value close to 0.709. This river drains mostly Phanerozoic rocks of northern Peru and Ecuador that are characterized by low Sr isotope ratios. Despite draining areas underlain by Precambrian rocks and having high 87Sr/86Sr ratios, such rivers as the Negro and Tapajós play a minor role in the total Sr budget of the Amazon Basin. The isotopic fluctuations in the Beni-Madeira River were observed to propagate downstream at least as far as Óbidos, in the Amazon River. This signal is characterized by an inverse relationship between the concentration of elemental Sr and its isotopic ratios. During the raining season there is an increase in Sr isotopic ratio accompanied by a decrease in elemental Sr concentration. During the dry season, the Sr isotopic ration decreases and the elemental Sr concentration increases.

Sources and distributions of branched and isoprenoid tetraether lipids on the Amazon shelf and fan: Implications for the use of GDGT-based proxies in marine sediments

NASA Astrophysics Data System (ADS)

Zell, Claudia; Kim, Jung-Hyun; Hollander, David; Lorenzoni, Laura; Baker, Paul; Silva, Cleverson Guizan; Nittrouer, Charles; Sinninghe Damsté, Jaap S.

2014-08-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in river fan sediments have been used successfully to reconstruct mean annual air temperature (MAAT) and soil pH of the Congo River drainage basin. However, in a previous study of Amazon deep-sea fan sediments the reconstructed MAATs were ca. 10 °C colder than the actual MAAT of the Amazon basin. In this study we investigated this apparent offset, by comparing the concentrations and distributions of brGDGTs in Amazon River suspended particulate matter (SPM) and sediments to those in marine SPM and surface sediments. The riverine brGDGT input was evident from the elevated brGDGT concentrations in marine SPM and surface sediments close to the river mouth. The distributions of brGDGTs in marine SPM and sediments varied widely, but generally showed a higher relative abundance of methylated and cyclic brGDGTs than those in the river. Since this difference in brGDGT distribution was also found in intact polar lipid (IPL)-derived brGDGTs, which were more recently produced, the change in the marine brGDGT distribution was most likely due to marine in situ production. Consequently, the MAATs calculated based on the methylation of branched tetraethers (MBT) and the cyclisation of branched tetraethers (CBT) were lower and the CBT-derived pH values were higher than those of the Amazon basin. However, SPM and sediments from stations close to the river mouth still showed MBT/CBT values that were similar to those of the river. Therefore, we recommend caution when applying the MBT/CBT proxy, it should only be used in sediment cores that were under high river influence. The influence of riverine derived isoprenoid GDGT (isoGDGT) on the isoGDGT-based TEX86 temperature proxy was also examined in marine SPM and sediments. An input of riverine isoGDGTs from the Amazon River was apparent, but its influence on the marine TEX86 was minor since the TEX86 of SPM in the Amazon River was similar to that in the marine SPM and sediments.

Evapotranspiration seasonality across the Amazon Basin

NASA Astrophysics Data System (ADS)

Eiji Maeda, Eduardo; Ma, Xuanlong; Wagner, Fabien Hubert; Kim, Hyungjun; Oki, Taikan; Eamus, Derek; Huete, Alfredo

2017-06-01

Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon Basin. We used in situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (˜ 1497 mm year-1) and the lowest values in the Solimões River basin (˜ 986 mm year-1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.

Luminescence of quartz and feldspar fingerprints provenance and correlates with the source area denudation in the Amazon River basin

NASA Astrophysics Data System (ADS)

Sawakuchi, A. O.; Jain, M.; Mineli, T. D.; Nogueira, L.; Bertassoli, D. J.; Häggi, C.; Sawakuchi, H. O.; Pupim, F. N.; Grohmann, C. H.; Chiessi, C. M.; Zabel, M.; Mulitza, S.; Mazoca, C. E. M.; Cunha, D. F.

2018-06-01

The Amazon region hosts the world's largest watershed spanning from high elevation Andean terrains to lowland cratonic shield areas in tropical South America. This study explores variations in optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) signals in suspended silt and riverbed sands retrieved from major Amazon rivers. These rivers drain Pre-Cambrian to Cenozoic source rocks in areas with contrasting denudation rates. In contrast to the previous studies, we do not observe an increase in the OSL sensitivity of quartz with transport distance; for example, Tapajós and Xingu Rivers show more sensitive quartz than Solimões and Madeira Rivers, even though the latter have a significantly larger catchment area and longer sediment transport distance. Interestingly, high sensitivity quartz is observed in rivers draining relatively stable Central Brazil and Guiana shield areas (denudation rate ξ = 0.04 mmyr-1), while low sensitivity quartz occurs in less stable Andean terrains (ξ = 0.24 mmyr-1). An apparent linear correlation between quartz OSL sensitivity and denudation rate suggests that OSL sensitivity may be used as a proxy for erosion rates in the Amazon basin. Furthermore, luminescence sensitivity measured in sand or silt arises from the same mineral components (quartz and feldspar) and clearly discriminates between Andean and shield sediments, avoiding the grain size bias in provenance analysis. These results have implications for using luminescence sensitivity as a proxy for Andean and shield contributions in the stratigraphic record, providing a new tool to reconstruct past drainage configurations within the Amazon basin.

Origin and processing of terrestrial organic carbon in the Amazon system: lignin phenols in river, shelf, and fan sediments

NASA Astrophysics Data System (ADS)

Sun, Shuwen; Schefuß, Enno; Mulitza, Stefan; Chiessi, Cristiano M.; Sawakuchi, André O.; Zabel, Matthias; Baker, Paul A.; Hefter, Jens; Mollenhauer, Gesine

2017-05-01

The Amazon River transports large amounts of terrestrial organic carbon (OCterr) from the Andean and Amazon neotropical forests to the Atlantic Ocean. In order to compare the biogeochemical characteristics of OCterr in the fluvial sediments from the Amazon drainage basin and in the adjacent marine sediments, we analysed riverbed sediments from the Amazon mainstream and its main tributaries as well as marine surface sediments from the Amazon shelf and fan for total organic carbon (TOC) content, organic carbon isotopic composition (δ13CTOC), and lignin phenol compositions. TOC and lignin content exhibit positive correlations with Al / Si ratios (indicative of the sediment grain size) implying that the grain size of sediment discharged by the Amazon River plays an important role in the preservation of TOC and leads to preferential preservation of lignin phenols in fine particles. Depleted δ13CTOC values (-26.1 to -29.9 ‰) in the main tributaries consistently correspond with the dominance of C3 vegetation. Ratios of syringyl to vanillyl (S / V) and cinnamyl to vanillyl (C / V) lignin phenols suggest that non-woody angiosperm tissues are the dominant source of lignin in the Amazon basin. Although the Amazon basin hosts a rich diversity of vascular plant types, distinct regional lignin compositions are not observed. In the marine sediments, the distribution of δ13CTOC and Λ8 (sum of eight lignin phenols in organic carbon (OC), expressed as mg/100 mg OC) values implies that OCterr discharged by the Amazon River is transported north-westward by the North Brazil Current and mostly deposited on the inner shelf. The lignin compositions in offshore sediments under the influence of the Amazon plume are consistent with the riverbed samples suggesting that processing of OCterr during offshore transport does not change the encoded source information. Therefore, the lignin compositions preserved in these offshore sediments can reliably reflect the vegetation in the Amazon River catchment. In sediments from the Amazon fan, low lignin content, relatively depleted δ13CTOC values and high (Ad / Al)V ratios indicating highly degraded lignin imply that a significant fraction of the deposited OCterr is derived from petrogenic (sourced from ancient rocks) sources.

Delimiting Evolutionarily Significant Units of the Fish, Piaractus brachypomus (Characiformes: Serrasalmidae), from the Orinoco and Amazon River Basins with Insight on Routes of Historical Connectivity.

PubMed

Escobar, Maria Doris; Andrade-López, Juana; Farias, Izeni P; Hrbek, Tomas

2015-01-01

The freshwater fish Piaractus brachypomus is an economically important for human consumption both in commercial fisheries and aquaculture in all South American countries where it occurs. In recent years the species has decreased in abundance due to heavy fishing pressure. The species occurs in the Amazon and Orinoco basins, but lack of meristic differences between fishes from the 2 basins, and extensive migration associated with reproduction, have resulted in P. brachypomus being considered a single panmictic species. Analysis of 7 nuclear microsatellites, mitochondrial DNA sequences (D-loop and COI), and body shape variables demonstrated that each river basin is populated by a distinct evolutionarily significant unit (ESU); the 2 groups had an average COI divergence of 3.5% and differed in body depth and relative head length. Historical connection between the 2 basins most probably occurred via the Rupununi portal rather than via the Casiquiare canal. The 2 ESUs will require independent fishery management, and translocation of fisheries stocks between basins should be avoided to prevent loss of local adaptations or extinction associated with outbreeding depression. Introductions of fishes from the Orinoco basin into the Putumayo River basin, an Amazon basin drainage, and evidence of hybridization between the 2 ESUs have already been detected. © The American Genetic Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Scale Invariant Power Laws Capture the 3-D Coupling Between Water, Energy and Carbon Budgets Across River Basins of Increasing Horton-Strahler Orders in the Andes-Amazon System

NASA Astrophysics Data System (ADS)

Poveda, G.; Zapata, A. F.

2016-12-01

The Andes-Amazon system exhibits complex interactions and feedbacks between hydrological, ecological, biogeochemical and climatic factors in a broad range of temporal and spatial scales. We aim to understand the coupling existing between water, energy and carbon budgets in the Andes-Amazon system, by performing a systematic study of the system for river basins of increasing Horton-Strahler orders, from the headwaters of the Amazon River basin along the Andes (order ω=1 river sub-basins) to the low-lying larger river sub-basins (order ω=10). To that end, this works introduces a 3-D generalization of the Budyko framework that aims to link the water, energy, and Carbon budgets in river basins. The newly proposed 3-D non-dimensional space is defined by: (1) the ratio between long-term mean values of Actual Evapotranspiration (AET) and Precipitation (P), α=AET/P, representing the water balance; (2) the ratio between AET and Potential Evapotranspiration (PET), β=AET/PET, representing the energy balance; and (3) the ratio between AET and Aboveground Net Primary Productivity, δ=AET/ANPP, representing the carbon budget. We use a 3" Digital Elevation Model (DEM), which allows defining river basins with Horton-Strahler orders from 1 to 10. The long-term water, energy, and carbon budgets are estimated for increasing values of the Horton-Strahler orders during the period 1987-2007. Data sets pertaining to the water balance come from ORE-HYBAM, potential evapotranspiration (PET) from GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology). Data for the energy budget are from the Surface Radiation Budget (SRB). Data for the Carbon budget (annual mean net primary productivity, ANPP, gross primary productivity, GPP, and respiration rates, Rr, come from AMAZALERT and ORCHEDEE (Organizing Carbon and Hydrology In Dynamic EcosystEms), as well as from Flux Tower Data and the LBA project. Our results show that scale invariant power-laws emerge to capture the three 2-D cross-sections of the newly proposed 3-D non-dimensional space. The scaling exponents of the identified power laws remain invariant for river basins of Horton-Strahler orders from ω=2 to ω=8. We advance to explain the scaling exponents of the identified power laws in terms of the main physical processes.

Surface Freshwater Storage and Variability in the Amazon Basin from Multi-Satellite Observations, 1993-2007

NASA Technical Reports Server (NTRS)

Papa, Fabrice; Frappart, Frederic; Guntner, Andreas; Prigent, Catherine; Aires, Filipe; Getirana, Augusto; Maurer, Raffael

2013-01-01

The amount of water stored and moving through the surface water bodies of large river basins (river, floodplains, wetlands) plays a major role in the global water and biochemical cycles and is a critical parameter for water resources management. However, the spatio-temporal variations of these freshwater reservoirs are still widely unknown at the global scale. Here, we propose a hypsographic curve approach to estimate surface freshwater storage variations over the Amazon basin combining surface water extent from a multi-satellite-technique with topographic data from the Global Digital Elevation Model (GDEM) from Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Monthly surface water storage variations for 1993-2007 are presented, showing a strong seasonal and interannual variability, and are evaluated against in situ river discharge and precipitation. The basin-scale mean annual amplitude of approx. 1200 cu km is in the range of previous estimates and contributes to about half of the Gravity Recovery And Climate Experiment (GRACE) total water storage variations. For the first time, we map the surface water volume anomaly during the extreme droughts of 1997 (October-November) and 2005 (September-October) and found that during these dry events the water stored in the river and flood-plains of the Amazon basin was, respectively, approx. 230 (approx. 40%) and 210 (approx. 50%) cu km below the 1993-2007 average. This new 15year data set of surface water volume represents an unprecedented source of information for future hydrological or climate modeling of the Amazon. It is also a first step toward the development of such database at the global scale.

Fluvial bar dynamics in large meandering rivers with different sediment supply in the Amazon River basin

NASA Astrophysics Data System (ADS)

Monegaglia, Federico; Zolezzi, Guido; Tubino, Marco; Henshaw, Alex

2017-04-01

Sediments in the large meandering rivers of the Amazon basin are known to be supplied by sources providing highly different magnitudes of sediment input and storage, ranging from the sediment-rich Andean region to the sediment-poor Central Trough. Recent observations have highlighted how such differences in sediment supply have an important, net effect on the rates of planform activity of meandering rivers in the basin, in terms of meander migration and frequency of cutoffs. In this work we quantify and discuss the effect of sediment supply on the organization of macroscale sediment bedforms on several large meandering rivers in the Amazon basin, and we link our findings with those regarding the rates of planform activity. Our analysis is conducted through the newly developed software PyRIS, which enables us to perform extensive multitemporal analysis of river morphodynamics from multispectral remotely sensed Landsat imagery in a fully automated fashion. We show that large rivers with low sediment supply tend to develop alternate bars that consistently migrate through long reaches, characterized at the same time by limited planform development. On the contrary, high sediment supply is associated with the development of point bars that are well-attached to the evolving meander bends and that follow temporal oscillations around the bend apexes, which in turn show rapid evlution towards complex meander shapes. Finally, rivers with intermediate rates of sediment supply develop rather steady point bars associated with slowly migrating, regular meanders. We finally discuss the results of the image analysis in the light of the properties of river planform metrics (like channel curvature and width) for the examined classes of river reaches with different sediment supply rates.

The ecological and cultural functions of invertebrates in the Congo River basin.

Treesearch

Bruce G. Marcot

2005-01-01

One of the entomologically richest, yet least studied, regions of Africa is the interior Congo River Basin. Forests of this region have been called Earth's "second lung" (after the Amazon Basin forests) and harbor an immense diversity of invertebrates. In these tropical rainforests live people of several cultures whose lives and livelihoods are...

River mixing in the Amazon as a driver of concentration-discharge relationships

NASA Astrophysics Data System (ADS)

Moquet, Jean-Sébastien; Bouchez, Julien; Carlo Espinoza, Jhan; Martinez, Jean-Michel; Guyot, Jean-Loup; Lagane, Christelle; Filizola, Naziano; Aniceto, Keila; Noriega, Luis; Hidalgo Sanchez, Liz; Pombosa, Rodrigo; Fraizy, Pascal; Santini, William; Timouk, Franck; Vauchel, Philippe

2017-04-01

Large hydrological systems such as continental-scale river basins aggregate water from compositionally different tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We compute 10 day-frequency time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations of the SNO-HYBAM Monitoring Program (Geodynamical, hydrological and Biogeochemical control of erosion/weathering and material transport in the Amazon, Orinoco and Congo basins) located throughout the Amazon basin, the largest river basin in the world. Concentration-discharge relationships vary in a systematic manner, shifting for most solutes from a nearly "chemostatic" behavior (constant C) at the Andean mountain front to a more "dilutional" pattern (negative C-Q relationship) towards the system mouth. Associated to this shift in trend is a shift in shape: C-Q hysteresis becomes more prominent at the most downstream stations. A simple model of tributary mixing allows us to identify the important parameters controlling C-Q trends and shapes in the mixture, and we show that for the Amazon case, the model results are in qualitative agreement with the observations. Altogether, this study suggests that mixing of water and solutes between different flowpaths leads to altered C-Q relationships.

Genetic structure and historical diversification of catfish Brachyplatystoma platynemum (Siluriformes: Pimelodidae) in the Amazon basin with implications for its conservation.

PubMed

Ochoa, Luz Eneida; Pereira, Luiz Henrique G; Costa-Silva, Guilherme Jose; Roxo, Fábio F; Batista, Jacqueline S; Formiga, Kyara; Foresti, Fausto; Oliveira, Claudio

2015-05-01

Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for F ST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2-2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2-2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin.

Genetic structure and historical diversification of catfish Brachyplatystoma platynemum (Siluriformes: Pimelodidae) in the Amazon basin with implications for its conservation

PubMed Central

Ochoa, Luz Eneida; Pereira, Luiz Henrique G; Costa-Silva, Guilherme Jose; Roxo, Fábio F; Batista, Jacqueline S; Formiga, Kyara; Foresti, Fausto; Oliveira, Claudio

2015-01-01

Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for FST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2–2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2–2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin. PMID:26045952

Atmospheric mercury concentrations in the basin of the amazon, Brazil.

PubMed

Hachiya, N; Takizawa, Y; Hisamatsu, S; Abe, T; Abe, Y; Motohashi, Y

1998-01-01

A wide regional mercury pollution in Amazon, Brazil is closely associated with goldmining that has been carried out in the basin of tributaries of the Amazon since the eighteenth century. Possible involvement has been discussed on atmospheric circulation in distributing the volatile pollutant. We developed a portable air sampler for the collection of mercury compounds and determined atmospheric mercury concentrations at several sites in Brazil including the basin of the Amazon tributaries. The mean concentration of total mercury was between 9.1 and 14.0 ng/m(3) in the basin of the Uatumã River located in the tropical rain forest far from goldmining sites and from urbanized area. These mercury levels exceeded the background level previously reported in rural area and, furthermore, were higher than concentrations observed in Rio de Janeiro and in Manaus that were compatible with the reference values for urban area. Mercury concentrations were also determined in gold refineries in the basin of the Tapajos River, and detected at a significant but not a health deteriorating level. Although only preliminary data were available, the present observations were in favor of the hypothesis that mercury is distributed widely by long distant transport by the atmospheric circulation after released at gold mining sites.

A snapshot on prokaryotic diversity of the Solimões River basin (Amazon, Brazil).

PubMed

Toyama, D; Santos-Júnior, C D; Kishi, L T; Oliveira, T C S; Garcia, J W; Sarmento, H; Miranda, F P; Henrique-Silva, F

2017-05-18

The Amazon region has the largest hydrographic basin on the planet and 
is well known for its huge biodiversity of plants and animals. However, 
there is a lack of studies on aquatic microbial biodiversity in the 
Solimões River, one of its main water courses. To investigate the 
microbial biodiversity of this region, we performed 16S rRNA gene clone 
libraries from Solimões River and adjacent rivers and lakes. Our question was which microorganisms inhabit the different types of aquatic 
environments in this part of the basin, and how diversity varies among 
these environments (rivers and lakes). The microbial 
diversity generating 13 clone libraries of the bacterial 16S rRNA gene 
and 5 libraries of the archaeal 16S rRNA gene was assessed. Diversity measured by several alpha diversity indices (ACE, Chao, Shannon and Simpson) revealed significant differences in diversity indices between lake and river samples. The site with higher microbial diversity was in the Solimões River (4S), downstream the confluence with Purus River. The most common bacterial taxon was the cosmopolitan Polynucleobacter genus, widely observed in all samples. The phylum Thaumarchaeota was the prevailing archaeal taxon. Our results provide the first insight into the microbial diversity of the world's largest river basin.

Erosion of organic carbon from the Andes and its effects on ecosystem carbon dioxide balance

NASA Astrophysics Data System (ADS)

Clark, K. E.; Hilton, R. G.; West, A. J.; Robles Caceres, A.; Gröcke, D. R.; Marthews, T. R.; Ferguson, R. I.; Asner, G. P.; New, M.; Malhi, Y.

2017-03-01

Productive forests of the Andes are subject to high erosion rates that supply to the Amazon River sediment and carbon from both recently photosynthesized biomass and geological sources. Despite this recognition, the source and discharge of particulate organic carbon (POC) in Andean Rivers remain poorly constrained. We collected suspended sediments from the Kosñipata River, Peru, over 1 year at two river gauging stations. Carbon isotopes (14C, 13C, and 12C) and nitrogen to organic carbon ratios of the suspended sediments suggest a mixture of POC from sedimentary rocks (POCpetro) and from the terrestrial biosphere (POCbiosphere). The majority of the POCbiosphere has a composition similar to surface soil horizons, and we estimate that it is mostly younger than 850 14C years. The suspended sediment yield in 2010 was 3500 ± 210 t km-2 yr-1, >10 times the yield from the Amazon Basin. The POCbiosphere yield was 12.6 ± 0.4 t C km-2 yr-1 and the POCpetro yield was 16.1 ± 1.4 t C km-2 yr-1, mostly discharged in the wet season (December to March) during flood events. The river POCbiosphere discharge is large enough to play a role in determining whether Andean forests are a source or sink of carbon dioxide. The estimated erosional discharge of POCpetro from the Andes is much larger ( 1 Mt C yr-1) than the POCpetro discharge by the Madeira River downstream in the Amazon Basin, suggesting that oxidation of POCpetro counters CO2 drawdown by silicate weathering. The flux and fate of Andean POCbiosphere and POCpetro need to be better constrained to fully understand the carbon budget of the Amazon River basin.

U-Pbdating on detrital zircon and Nd and Hf isotopes related to the provenance of siliciclastic rocks of the Amazon Basin: Implications for the origin of Proto-Amazonas River

NASA Astrophysics Data System (ADS)

Dantas, Elton Luiz; Silva Souza, Valmir; Nogueira, Afonso C. R.; Ventura Santos, Roberto; Poitrasson, Franck; Vieira Cruz, Lucieth; Mendes Conceição, Anderson

2014-05-01

Previous provenance studies along the Amazonas river have demonstrated that the Amazon drainage basin has been reorganized since the Late Cretaceous with the uplift of the Andes and the establishment of the transcontinental Amazon fluvial system from Late Miocene to Late Pleistocene (Hoorn et al., 1995; Potter, 1997, Wesselingh et al., 2002; Figueiredo et al. 2009, Campbell et al., 2006, Nogueira et al. 2013).There is a lack of data from Eastern and Central Amazonia and only limited core data from the Continental Platform near to current Amazonas river mouth. Central Amazonia is strategic to unveil the origin of Amazonas River because it represents the region where the connection of the Solimões and Amazonas basin can be studied through time (Nogueira et al. 2013). Also, there is a shortage of information on the old Precambrian and Paleozoic sediment sources relative to Cretaceous and Miocene siliciclastic deposits of the Solimões and Amazonas basins. We collected stratigraphic data, detrital zircon U-Pb ages and Nd and Hf isotopes from Precambrian, Paleozoic, Cretaceous and Miocene siliciclastic deposits of the Northwestern border of Amazonas Basin. They are exposed in the Presidente Figueiredo region and in the scarps of Amazon River, and occur to the east of the Purus Arch. This Northwest-Southeast trending structural feature that divides the Solimões and Amazonas basin was active at various times since the Paleozoic. Detrital zircon ages for the Neoproterozoic Prosperança Formation yielded a complex signature, with different populations of Neoproterozoic (550, 630 and 800 Ma) and Paleoproterozoic to Archean sources (1.6, 2.1 and 2.6 Ga). Also Nd and Hf isotopes show two groups of TDM model ages between 1.4 to 1.53 Ga and 2.2 and 3.1 Ga. Sediments typical of Paleozoic sedimentary rocks of the Nhamundá and Manacapuru Formations revealed NdTDM model ages of 1.7, 2.2 and 2.7 Ga, but Hf isotopes and U-Pb zircon ages are more varied. They characterize a provenance dominated by Mesoproterozoic sources (1.0, 1.2 Ga) and subordinate Neoproterozoic(550-800 Ma) and Archean derivation (2.67 Ga). On the other hand, detrital zircon and Hf and NdTDM model ages for the Cretaceous Alter do Chão Formation yielded a unique Paleoproterozoicages between 2.0 and 2.3 Ga that can be correlated to sources derived from Maroni-Itacaiúnas and Central Amazonian basement provinces. The contribution of Precambrian and Paleozoic rocks exposed during the installationof the Amazonas drainage were probably significant .Such a large contribution from Neoproterozoic and Mesoproterozoic sources are not common in the proximal Amazon Craton basement .This new proposal open new perspectives to understand better the initial history of Amazon River with indication of the probable source areas during Late Cenozoic. Campbell Jr.; Frailey,C.D.; Romero-Pittman, G. 2006. The Pan-Amazonian UcayliPeneplain, late Neogenesedimentacion in Amazonia, and the Birth on the Modern Amazon River system.Palaeogeography,Palaeoclimatology, Palaeoecology. 239 (2006) 166-219 Figueiredo, J.,Hoorn, C., Van der Vem, P., Soares, E. 2009. Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Fozdo Amazonas Basin. Geology, 37(7):619-622. Hoorn,C.; Guerrero, J.; Sarmiento, G. 1995. Andean tectonics as a cause for changing drainage patterns in Miocene Northern South America. Geology, v.23, p-237-240. Nogueira, A.C.R.; Silveira, R.R.; Guimarães, J.T.F. 2013. Neogene-Quaternary sedimentary and paleovegetation history of the eastern Solimões Basin, central Amazon region.Journal of South American Earth Sciences , v. 46, p. 89-99, 2013. Potter, P.E. 1997. The Mesozoic and Cenozoic paleodrainage of South America: a natural history. Journal of South American Earth Science.v.10. p.331-344 Wesselingh, F. P., et al., 2002. Lake-Pebas: a palaeocological reconstruction of a Miocene long-lived lake comples in Western Amazônia. Cainozoic Research 1 (1-2), 35-81.

Divergent biophysical controls of aquatic CO2 and CH4 in the World's two largest rivers.

PubMed

Borges, Alberto V; Abril, Gwenaël; Darchambeau, François; Teodoru, Cristian R; Deborde, Jonathan; Vidal, Luciana O; Lambert, Thibault; Bouillon, Steven

2015-10-23

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels.

Simulating floods in the Amazon River Basin: Impacts of new river geomorphic and dynamic flow parameterizations

NASA Astrophysics Data System (ADS)

Coe, M. T.; Costa, M. H.; Howard, E. A.

2006-12-01

In this paper we analyze the hydrology of the Amazon River system for the latter half of the 20th century with our recently completed model of terrestrial hydrology (Terrestrial Hydrology Model with Biogeochemistry, THMB). We evaluate the simulated hydrology of the Central Amazon basin against limited observations of river discharge, floodplain inundation, and water height and analyze the spatial and temporal variability of the hydrology for the period 1939-1998. We compare the simulated discharge and floodplain inundated area to the simulations by Coe et al., 2002 using a previous version of this model. The new model simulates the discharge and flooded area in better agreement with the observations than the previous model. The coefficient of correlation between the simulated and observed discharge for the greater than 27000 monthly observations of discharge at 120 sites throughout the Brazilian Amazon is 0.9874 compared to 0.9744 for the previous model. The coefficient of correlation between the simulated monthly flooded area and the satellite-based estimates by Sippel et al., 1998 exceeds 0.7 for 8 of the 12 mainstem reaches. The seasonal and inter-annual variability of the water height and the river slope compares favorably to the satellite altimetric measurements of height reported by Birkett et al., 2002.

Effects of future land use on biogeography of aquatic ecosystems of Amazonia

NASA Astrophysics Data System (ADS)

Howard, E. A.; Coe, M. T.; Foley, J. A.; Costa, M. H.

2006-12-01

Amazonian ecosystems provide key ecosystem services, such as regulating the amount and timing of water and carbon flows through the Amazon Basin. Land use in these ecosystems affects regional water balance, which in turn affects biogeography of aquatic ecosystems, including wetlands and floodplains. We combined a hydrological model (Terrestrial Hydrology Model with Biogeochemistry, THMB), remote sensing observations (Hess et al. 2003), and empirical data to identify the distribution of aquatic biogeographic types throughout the central Amazon basin over time. We explored how future land-use scenarios for the Amazon Basin through 2030 (Soares-Filho et al. 2004) would modify the spatial and temporal patterns of aquatic ecosystems as compared to a baseline of natural potential vegetation cover under historical climate variability for the 20th century. We calibrated monthly simulation results with remotely sensed observations of flooded area and extent of different wetland categories for high and low water periods over a 1.7 million sq. km region of the central Amazon. Two additional dimensions of floodplain biogeography (river size and color) were added to provide insight into the geographic distribution of key ecosystem types and their flooding seasonality. For historical conditions, the model results reproduced regional differences in seasonal flood extent and timing north and south of the Amazon mainstem, reflecting the dominant climatic regimes. Black-water streams and medium-sized rivers, followed by large white-water rivers, were the most extensive types across the study region. However much of the black water was in areas likely to be influenced by white-water rivers while flooded. The monthly extent of flooded areas dominated by woody vegetation was consistently more strongly seasonal than non-woody areas. Also, the extent of flooding in muddy and semi-muddy rivers and floodplains tended to be more highly seasonal than in black- and clear-water areas. We discuss our efforts to use our simulation results to extrapolate and bound estimates and patterns of aquatic ecosystem extent in the Amazon River system under future land-use scenarios. Regional flooding variability has disproportionate effects on different ecosystem types, suggesting that persistent, long-term changes to flooding regimes may have long-lasting consequences for floodplain vegetation, wildlife, and human residents.

The Belterra Clay: The Last Terrestrial Connection Between the Brazilian Shield and the Guiana Shield

NASA Astrophysics Data System (ADS)

Campbell, K.

2016-12-01

The Belterra Clay is a sedimentary deposit that covers much of the eastern Amazon Basin in Brazil. It is notable in forming a very flat plain that occurs on both sides of the Amazon River, the Tapajos River, the Xingu River, and many smaller, tributary rivers east of 56° 32' W. The origin of the Belterra Clay is very controversial, with proponents of both allochthonous and autochthonous means of formation. There is little agreement as to its age. The fact that it occurs on both sides of the Amazon River indicates that its origin predates the formation of the modern Amazon River system, the timing of origin of which is itself highly controversial, with age estimates given for the river system formation that extend from the late Miocene, or 10 mya, to the late Pleistocene. From the time of origin of the Belterra Clay deposit until the modern Amazon River evolved, it formed an unbroken, terrestrial connection between the Brazilian Shield to the south and the Guiana Shield to the north, as well as east-west connections across what are today major river valleys, such as the Tapajos River and Xingu River. The formation and later severing of this once unbroken plain are predicted to have had major impacts on the distribution and evolutionary pathways of biotas inhabiting the region as once disparate communities were joined and later separated once again. Molecular clock ages for sister taxa north and south of the Amazon River have the potential of dating the time of formation of the Amazon River.

On Dams in the Amazon Basin, Teleconnected Impacts, and Neighbors Unaware of the Damage to their Natural Resources and Assets.

NASA Astrophysics Data System (ADS)

Latrubesse, E. M.; Park, E.

2017-12-01

In a recent study, Latrubesse et al., (2017) demonstrated that the accumulated negative environmental effects of more than one hundred existing dams and at least 288 proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. The authors introduced a Dam Environmental Vulnerability Index (DEVI) to quantify the current and potential impacts of dams in the basin. The current and potential vulnerabilities of different regions of the Amazon basin was assessed, and the results highlighted the need for a more efficient and integrative legal framework involving all nine countries of the basin in an anticipatory assessment to minimize the negative socio-environmental and biotic impacts of hydropower developments. Here we present expanded information on the potential impacts of dams in the lower Amazon and the northeast Atlantic coast of South America, and revisit our proposed integrative strategies for basin management which are based on the adaptation and functionality of the institutional and legal framework already existing in the Amazon countries. Participative strategies involving members from the Amazon Cooperation Treaty Organization (ACTO) countries, and additional members (for example, France), such as the creation of a basin committee -as defined by the Brazilian Law of Waters of Brazil-, and the creation of an Amazon Basin Panel allowing the participation of scientists that could have a policy-relevant role but should be not policy-prescriptive, are also discussed. ReferencesLatrubesse, E., Arima E. Dunne T., Park E., Baker V, Horta F.,Wight, C., Wittmann F., Zuanon, J., Baker P., Ribas C, Norgaard R., Filizola N., Ansar A., Flyvbjerg B., Stevaux, J. 2017. Damming the rivers of the Amazon basin. Nature, 546, 363-369.

How Amazonian deforestation can alter the South American circulation regime: Insights from a non-linear moisture transport model

NASA Astrophysics Data System (ADS)

Boers, Niklas; Marwan, Norbert; Barbosa, Henrique; Kurths, Jürgen

2015-04-01

A key driver of South American climate are the low-level trade winds from the tropical Atlantic Ocean towards the continent. After crossing the Amazon Basin, they are blocked by the Andes mountain range, and forced southward to the subtropics. These winds are crucial for the atmospheric moisture supply in most parts of South America. In particular, the hydrology of the two largest river basins of the Continent, namely the Amazon and the La Plata Basins, strongly depend on the moisture inflow provided by the trade winds. In turn, the Amazon rainforest can be assumed to have a strong influence on this low-level moisture circulation over South America by exchanging moisture with the atmosphere through precipitation and evapotranspiration. A pronounced positive feedback in this context is established through precipitation-induced release of latent heat over the Amazon Basin, which significantly enhances the moisture inflow from the tropical Atlantic Ocean toward the continent and can thus be considered to be crucial for the existence of today's South American climate. Ongoing deforestation and resulting reduction in evapotranspiration rates in particular in the eastern Amazon carry the risk of a strongly nonlinear response in these interactions with the low-level atmosphere. We propose a simple differential transport model describing the cascading moisture transport from the eastern coast of South America across the Amazon Basin to the Andes, taking into account the nonlinearity associated with the release of latent heat. The results of the model suggest that the system is indeed very sensitive to relatively small reductions of the evapotranspiration rates in the eastern Amazon Basin. These reductions increase river runoff, but limit the moisture availability farther west. This leads to a reduction in precipitation rates and thereby diminishes the release of latent heat which, in turn, reduces the overall moisture inflow. We show that, according to our model, there exist critical thresholds on the spatial extents and intensities of deforestation. Beyond these thresholds, the positive feedback between the Amazon rainforest and the low-level circulation would collapse, resulting in substantial reductions in moisture available for precipitation in the western part of the Amazon Basin and further downstream of the low-level flow, including most of subtropical South America.

Cosmogenic nuclide budgeting of floodplain sediment transfer

NASA Astrophysics Data System (ADS)

Wittmann, H.; von Blanckenburg, F.

2009-08-01

Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth- and time-dependent cosmogenic nuclide concentration changes for 10Be, 26Al, and 14C during sediment storage and mixing in various active floodplain settings ranging from confined, shallow rivers with small floodplains to foreland-basin scale floodplains traversed by deep rivers. Floodplain storage time, estimated from channel migration rates, ranges from 0.4 kyr for the Beni River basin (Bolivia) to 7 kyr for the Amazon River basin, while floodplain storage depth, estimated from channel depth, ranges from 1 to 25 m. For all modeled active floodplain settings, the long-lived nuclides 10Be and 26Al show neither significant increase in nuclide concentration from irradiation nor decrease from decay. We predict a hypothetical response time after which changes in 10Be or 26Al concentrations become analytically resolvable. This interval ranges from 0.07 to 2 Myr and exceeds in all cases the typical residence time of sediment in a floodplain. Due to the much shorter half life of 14C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 kyr. The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them is predicted to either increase or decrease in 10Be and 26Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26Al/ 10Be ratio that readily discloses the depth and duration of storage. We illustrate these models with examples from the Amazon basin. As predicted, modern bedload collected from an Amazon tributary, the Bolivian Beni River, shows no systematic change in nuclide concentration as sediment is moved through 500 km of floodplain by river meandering. In contrast, in the central Amazon floodplain currently untouched by the modern river system, low 26Al/ 10Be ratios account for minimum burial depths of 5 to 10 m for a duration of > 5 Myr. The important result of this analysis is that in all likely cases of active floodplains, cosmogenic 10Be and 26Al concentrations remain virtually unchanged over the interval sediment usually spends in the basin. Thus, spatially-averaged denudation rates of the sediment-producing area can be inferred throughout the entire basin, provided that nuclide production rates are scaled for the altitudes of the sediment-producing area only, because floodplain storage does not modify nuclide concentrations introduced from the sediment source area.

Artisanal fisheries of the Xingu River basin in Brazilian Amazon.

PubMed

Isaac, V J; Almeida, M C; Cruz, R E A; Nunes, L G

2015-08-01

The present study characterises the commercial fisheries of the basin of the Xingu River, a major tributary of the Amazon River, between the towns of Gurupá (at the mouth of the Amazon) and São Félix do Xingu. Between April, 2012, and March, 2014, a total of 23,939 fishing trips were recorded, yielding a total production of 1,484 tons of fish, harvested by almost three thousand fishers. The analysis of the catches emphasizes the small-scale and artisanal nature of the region's fisheries, with emphasis on the contribution of the motorised canoes powered by "long-tail" outboard motors. Larger motorboats operate only at the mouth of the Xingu and on the Amazon. Peacock bass (Cichla spp.), croakers (Plagioscion spp.), pacu (a group containing numerous serrasalmid species), aracu (various anostomids), and curimatã (Prochilodus nigricans) together contributed more than 60% of the total catch. Mean catch per unit effort was 18 kg/fisher-1.day-1, which varied among fishing methods (type of vessel and fishing equipment used), river sections, and time of the year. In most cases, yields varied little between years (2012 and 2013). The technical database provided by this study constitutes an important resource for the regulation of the region's fisheries, as well as for the evaluation of future changes resulting from the construction of the Belo Monte dam on the Xingu River.

Amazon River dissolved load: temporal dynamics and annual budget from the Andes to the ocean.

PubMed

Moquet, Jean-Sébastien; Guyot, Jean-Loup; Crave, Alain; Viers, Jérôme; Filizola, Naziano; Martinez, Jean-Michel; Oliveira, Tereza Cristina; Sánchez, Liz Stefanny Hidalgo; Lagane, Christelle; Casimiro, Waldo Sven Lavado; Noriega, Luis; Pombosa, Rodrigo

2016-06-01

The aim of the present study is to estimate the export fluxes of major dissolved species at the scale of the Amazon basin, to identify the main parameters controlling their spatial distribution and to identify the role of discharge variability in the variability of the total dissolved solid (TDS) flux through the hydrological cycle. Data are compiled from the monthly hydrochemistry and daily discharge database of the "Programa Climatologico y Hidrologico de la Cuenca Amazonica de Bolivia" (PHICAB) and the HYBAM observatories from 34 stations distributed over the Amazon basin (for the 1983-1992 and 2000-2012 periods, respectively). This paper consists of a first global observation of the fluxes and temporal dynamics of each geomorphological domain of the Amazon basin. Based on mean interannual monthly flux calculations, we estimated that the Amazon basin delivered approximately 272 × 10(6) t year(-1) (263-278) of TDS during the 2003-2012 period, which represents approximately 7 % of the continental inputs to the oceans. This flux is mainly made up by HCO3, Ca and SiO2, reflecting the preferential contributions of carbonate and silicate chemical weathering to the Amazon River Basin. The main tributaries contributing to the TDS flux are the Marañon and Ucayali Rivers (approximately 50 % of the TDS production over 14 % of the Amazon basin area) due to the weathering of carbonates and evaporites drained by their Andean tributaries. An Andes-sedimentary area-shield TDS flux (and specific flux) gradient is observed throughout the basin and is first explained by the TDS concentration contrast between these domains, rather than variability in runoff. This observation highlights that, under tropical context, the weathering flux repartition is primarily controlled by the geomorphological/geological setting and confirms that sedimentary areas are currently active in terms of the production of dissolved load. The log relationships of concentration vs discharge have been characterized over all the studied stations and for all elements. The analysis of the slope of the relationship within the selected contexts reveals that the variability in TDS flux is mainly controlled by the discharge variability throughout the hydrological year. At the outlet of the basin, a clockwise hysteresis is observed for TDS concentration and is mainly controlled by Ca and HCO3 hysteresis, highlighting the need for a sampling strategy with a monthly frequency to accurately determine the TDS fluxes of the basin. The evaporite dissolution flux tends to be constant, whereas dissolved load fluxes released from other sources (silicate weathering, carbonate weathering, biological and/or atmospheric inputs) are mainly driven by variability in discharge. These results suggest that past and further climate variability had or will have a direct impact on the variability of dissolved fluxes in the Amazon. Further studies need to be performed to better understand the processes controlling the dynamics of weathering fluxes and their applicability to present-day concentration-discharge relationships at longer timescales.

Deforestation, floodplain dynamics, and carbon biogeochemistry in the Amazon Basin

NASA Technical Reports Server (NTRS)

Bryan, M. L.; Dunne, T.; Richey, J.; Melack, J.; Simonett, D. S.; Woodwell, G.

1984-01-01

Three aspects of the physical geographic environment of the Amazon Basin are considered: (1) deforestation and reforestation, (2) floodplain dynamics, and (3) fluvial geomorphology. Three independent projects are coupled in this experiment to improve the in-place research and to ensure that the Shuttle Imaging Radar-B (SIR-B) experiment stands on a secure base of ongoing work. Major benefits to be obtained center on: (1) areal and locational information, (2) data from various depression angles, and (3) digital radar signatures. Analysis will be conducted for selected sites to define how well SIR-B data can be used for: (1) definition of extent and location of deforestation in a tropical moist forest, (2) definition and quantification of the nature of the vegetation and edaphic conditions on the (floodplain) of the Amazon River, and (3) quantification of the accuracy with which the geometry and channel shifting of the Amazon River may be mapped using SIR-B imagery in conjunction with other remote sensing data.

Divergent biophysical controls of aquatic CO2 and CH4 in the World’s two largest rivers

PubMed Central

Borges, Alberto V.; Abril, Gwenaël; Darchambeau, François; Teodoru, Cristian R.; Deborde, Jonathan; Vidal, Luciana O.; Lambert, Thibault; Bouillon, Steven

2015-01-01

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels. PMID:26494107

Revision of Tympanopleura Eigenmann (Siluriformes: Auchenipteridae) with description of two new species

USGS Publications Warehouse

Walsh, Stephen J.; Ribeiro, Frank R.V.; Rapp Py-Daniel, Lúcia H.

2015-01-01

The Neotropical catfish genus Tympanopleura, previously synonymized within Ageneiosus, is revalidated and included species are reviewed. Six species are recognized, two of which are described as new. Tympanopleura is distinguished from Ageneiosus by having an enlarged gas bladder not strongly encapsulated in bone; a prominent pseudotympanum consisting of an area on the side of the body devoid of epaxial musculature where the gas bladder contacts the internal coelomic wall; short, blunt head without greatly elongated jaws; and smaller adult body size. Species of Tympanopleura are distinguished from each other on the basis of unique meristic, morphometric, and pigmentation differences. Ageneiosus melanopogon and Tympanopleura nigricollis are junior synonyms ofTympanopleura atronasus. Tympanopleura alta is a junior synonym of Tympanopleura brevis. A lectotype is designated for T. brevis. Ageneiosus madeirensis is a junior synonym of Tympanopleura rondoni. Tympanopleura atronasus, T. brevis, T. longipinna, and T. rondoni are relatively widespread in the middle and upper Amazon River basin. Tympanopleura cryptica is described from relatively few specimens collected in the upper portion of the Amazon River basin in Peru and the middle portion of that basin in Brazil. Tympanopleura piperata is distributed in the upper and middle Amazon River basin, as well as in the Essequibo River drainage of Guyana.

Spatial patterns of water quality in Xingu River Basin (Amazonia) prior to the Belo Monte dam impoundment.

PubMed

Rodrigues-Filho, J L; Abe, D S; Gatti-Junior, P; Medeiros, G R; Degani, R M; Blanco, F P; Faria, C R L; Campanelli, L; Soares, F S; Sidagis-Galli, C V; Teixeira-Silva, V; Tundisi, J E M; Matsmura-Tundisi, T; Tundisi, J G

2015-08-01

The Xingu River, one of the most important of the Amazon Basin, is characterized by clear and transparent waters that drain a 509.685 km2 watershed with distinct hydrological and ecological conditions and anthropogenic pressures along its course. As in other basins of the Amazon system, studies in the Xingu are scarce. Furthermore, the eminent construction of the Belo Monte for hydropower production, which will alter the environmental conditions in the basin in its lower middle portion, denotes high importance of studies that generate relevant information that may subsidize a more balanced and equitable development in the Amazon region. Thus, the aim of this study was to analyze the water quality in the Xingu River and its tributaries focusing on spatial patterns by the use of multivariate statistical techniques, identifying which water quality parameters were more important for the environmental changes in the watershed. Data sampling were carried out during two complete hydrological cycles in twenty-five sampling stations. The data of twenty seven variables were analyzed by Spearman's correlation coefficients, cluster analysis (CA), and principal component analysis (PCA). The results showed a high auto-correlation between variables (> 0.7). These variables were removed from multivariate analyzes because they provided redundant information about the environment. The CA resulted in the formation of six clusters, which were clearly observed in the PCA and were characterized by different water quality. The statistical results allowed to identify a high spatial variation in the water quality, which were related to specific features of the environment, different uses, influences of anthropogenic activities and geochemical characteristics of the drained basins. It was also demonstrated that most of the sampling stations in the Xingu River basin showed good water quality, due to the absence of local impacts and high power of depuration of the river itself.

C-13/C-12 of atmospheric CO2 in the Amazon basin - Forest and river sources

NASA Technical Reports Server (NTRS)

Quay, Paul; King, Stagg; Wilbur, Dave; Richey, Jeffrey; Wofsy, Steven

1989-01-01

Results are presented of measurements of the CO2 concentrations and C-13/C-12 ratios in CO2 in air samples collected from within the Amazonian rain forest and over the Amazon river between 1982 and 1987. Results indicate the presence of a diurnal cycle in the CO2 concentration and the C-13/C-12 ratio. It was found that the CO2 input to air in the forest was derived from the soil respiration, and the CO2 input to air over the Amazon river was derived from the degassing of CO2 from the river. It was also found that plants growing at heights lower than 7 m assimilate soil-derived CO2 with a low C-13/C-12 ratio.

Assessment of climate change impacts on streamflow dynamics in the headwaters of the Amazon River basin

NASA Astrophysics Data System (ADS)

Yoon, Y.; Beighley, E.

2015-12-01

The Amazon River basin is the largest watershed in the world containing thousands of tributaries. Although the mainstream and its larger tributaries have been the focus on much research, there has been few studies focused on the hydrodynamics of smaller rivers in the foothills of the Andes Mountains. These smaller rivers are of particular importance for the fishery industry because fish migrate up these headwater rivers to spawn. During the rainy season, fish wait for storm event to increase water depths to a sufficient level for their passage. Understanding how streamflow dynamics will change in response to future conditions is vital for the sustainable management of the fishery industry. In this paper, we focus on improving the accuracy of river discharge estimates on relatively small-scale sub-catchments (100 ~ 40,000 km2) in the headwaters of the Amazon River basin. The Hillslope River Routing (HRR) hydrologic model and remotely sensed datasets are used. We provide annual runoff, seasonal patterns, and daily discharge characteristics for 81 known migration reaches. The model is calibrated for the period 2000-2014 and climate forecasts for the period 2070-2100 are used to assess future changes in streamflow dynamics. The forecasts for the 2070 to 2100 period were obtained by selecting 5 climate models from IPCC's Fifth Assessment Report (AR5) Coupled Model Intercomparison Project Phase 5 (CMIP5) based on their ability to represent the main aspects of recent (1970 to 2000) Amazon climate. The river network for the HRR model is developing using surface topography based on the SRTM digital elevation model. Key model forcings include precipitation (TRMM 3B42) and evapotranspiration (MODIS ET, MOD16). Model parameters for soil depth, hydraulic conductivity, runoff coefficients and lateral routing were initially approximated based on literature values and adjusted during calibration. Measurements from stream gauges located near the reaches of interest were used for calibration. Model calibration results and simulated changes in future streamflow dynamics for the 81 river reaches are presented.

Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales.

PubMed

Stickler, Claudia M; Coe, Michael T; Costa, Marcos H; Nepstad, Daniel C; McGrath, David G; Dias, Livia C P; Rodrigues, Hermann O; Soares-Filho, Britaldo S

2013-06-04

Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations' energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local "direct" effects (through changes in ET within the watershed) and the potential regional "indirect" effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world's largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4-8% and 10-12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6-36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry's own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests.

Multi-temporal flood mapping and satellite altimetry used to evaluate the flood dynamics of the Bolivian Amazon wetlands

NASA Astrophysics Data System (ADS)

Ovando, A.; Martinez, J. M.; Tomasella, J.; Rodriguez, D. A.; von Randow, C.

2018-07-01

The Bolivian Amazon wetlands are extensive floodplains distributed over the Mamore, Beni, Madre de Dios and Guapore Rivers. Located within the upper Madeira River Basin, the wetlands play important roles in regulating the biogeochemical processes and hydrological cycle of the region. In addition, they have major ecological and hydrological relevance for the entire Amazon Basin. These wetlands are characterized by the occurrence of episodic floods that result from contrasting hydro-meteorological processes in the Andean Mountain region, the piedmont area and the Amazon lowlands. In this study, we characterized the flood dynamics of the region using multi-temporal flood mapping based on optical altimetry (MODIS - Moderate Resolution Imaging Spectroradiometer - M*D09A1) and satellite altimetry (ENVISAT RA-2 and SARAL AltiKa altimeters). This study provides new insights regarding the frequency, magnitude and spatial distribution of exogenous floods, which are created by flood waves from the Andes; and endogenous floods, which result from runoff originating in the lowlands. The maximum extent of flooding during 2001-2014 was 43144 km2 in the Mamore Basin and 34852 km2 in the Guapore Basin, and the total surface water storage in these floodplains reached 94 km3. The regionalization of flood regimes based on water stage time series signatures allowed those regions that are exposed to frequent floods, which are generally located along rivers without a direct connection with the Andes, to be distinguished from floodplains that are more dependent on flood waves originating in the Andes and its piedmonts. This information is of great importance for understanding the roles of these wetlands in the provision of ecosystem services.

Freshwater shrimps (Macrobrachium depressimanum and Macrobrachium jelskii) as biomonitors of Hg availability in the Madeira River Basin, Western Amazon.

PubMed

Galvão, R C F; Holanda, I B B; De Carvalho, D P; Almeida, R; Souza, C M M; Lacerda, L D; Bastos, W R

2018-01-10

Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira River Basin, Western Amazon. Between August 2009 and May 2010, 212 shrimp samples were collected in the confluence of the Madeira River with three of its tributaries (Western Amazon). THg concentration was quantified in the exoskeleton, hepatopancreas and muscle tissue of the shrimps by cold vapor atomic absorption spectrophotometry. There were no significant differences between the two shrimp species when samples came from the Madeira River, but Hg concentrations were significantly lower in a tributary outside the influence of the gold mining area. Average THg concentrations were higher in the hepatopancreas (up to 160.0 ng g -1 ) and lower in the exoskeleton and muscle tissue (10.0-35.0 ng g -1 and < 0.9-42.0 ng g -1 , respectively). Freshwater shrimps from the Madeira River respond to local environmental levels of Hg and can be considered as biomonitors for environmental Hg at this spatial scale. These organisms are important for moving Hg up food webs including those that harbor economic significant fish species and thus enhancing human exposure.

Stage-discharge rating curves based on satellite altimetry and modeled discharge in the Amazon basin

NASA Astrophysics Data System (ADS)

Paris, Adrien; Dias de Paiva, Rodrigo; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stephane; Garambois, Pierre-André; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frederique

2016-05-01

In this study, rating curves (RCs) were determined by applying satellite altimetry to a poorly gauged basin. This study demonstrates the synergistic application of remote sensing and watershed modeling to capture the dynamics and quantity of flow in the Amazon River Basin, respectively. Three major advancements for estimating basin-scale patterns in river discharge are described. The first advancement is the preservation of the hydrological meanings of the parameters expressed by Manning's equation to obtain a data set containing the elevations of the river beds throughout the basin. The second advancement is the provision of parameter uncertainties and, therefore, the uncertainties in the rated discharge. The third advancement concerns estimating the discharge while considering backwater effects. We analyzed the Amazon Basin using nearly one thousand series that were obtained from ENVISAT and Jason-2 altimetry for more than 100 tributaries. Discharge values and related uncertainties were obtained from the rain-discharge MGB-IPH model. We used a global optimization algorithm based on the Monte Carlo Markov Chain and Bayesian framework to determine the rating curves. The data were randomly allocated into 80% calibration and 20% validation subsets. A comparison with the validation samples produced a Nash-Sutcliffe efficiency (Ens) of 0.68. When the MGB discharge uncertainties were less than 5%, the Ens value increased to 0.81 (mean). A comparison with the in situ discharge resulted in an Ens value of 0.71 for the validation samples (and 0.77 for calibration). The Ens values at the mouths of the rivers that experienced backwater effects significantly improved when the mean monthly slope was included in the RC. Our RCs were not mission-dependent, and the Ens value was preserved when applying ENVISAT rating curves to Jason-2 altimetry at crossovers. The cease-to-flow parameter of our RCs provided a good proxy for determining river bed elevation. This proxy was validated against Acoustic Doppler current profiler (ADCP) cross sections with an accuracy of more than 90%. Altimetry measurements are routinely delivered within a few days, and this RC data set provides a simple and cost-effective tool for predicting discharge throughout the basin in nearly real time.

Low-level nocturnal wind maximum over the Central Amazon Basin

NASA Technical Reports Server (NTRS)

Greco, Steven; Ulanski, Stanley; Garstang, Michael; Houston, Samuel

1992-01-01

A low-level nocturnal wind maximum is shown to exist over extensive and nearly undisturbed rainforest near the central Amazon city of Manaus. Meteorological data indicate the presence of this nocturnal wind maximum during both the wet and dry seasons of the Central Amazon Basin. Daytime wind speeds which are characteristically 3-7 m/s between 300 and 1000 m increase to 10-15 m/s shortly after sunset. The wind-speed maximum is reached in the early evening, with wind speeds remaining high until several hours after sunrise. The nocturnal wind maximum is closely linked to a strong low-level inversion formed by radiational cooling of the rainforest canopy. Surface and low-level pressure gradients between the undisturbed forest and the large Amazon river system and the city of Manaus are shown to be responsible for much of the nocturnal wind increase. The pressure gradients are interpreted as a function of the thermal differences between undisturbed forest and the river/city. The importance of both the frictional decoupling and the horizontal pressure gradient suggest that the nocturnal wind maximum does not occur uniformly over all Amazonia. Low-level winds are thought to be pervasive under clear skies and strong surface cooling and that, in many places (i.e., near rivers), local pressure gradients enhance the low-level nocturnal winds.

Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales

PubMed Central

Stickler, Claudia M.; Coe, Michael T.; Costa, Marcos H.; Nepstad, Daniel C.; McGrath, David G.; Dias, Livia C. P.; Rodrigues, Hermann O.; Soares-Filho, Britaldo S.

2013-01-01

Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations’ energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local “direct” effects (through changes in ET within the watershed) and the potential regional “indirect” effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world’s largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4–8% and 10–12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6–36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry’s own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests. PMID:23671098

Area Assessment: Peru.

DTIC Science & Technology

1985-09-24

covers over half the country, including the vast Amazon River Basin and the Madre de Dio River Basin. The sierra, which makes up over one-fourth of Peru...departments. d. FOURTH (HQ CUSCO): Puno, Cusco, Apurimac, Junin, Pasco, Huanuco, San Martin, Auacucho, and Madre de Dios departments. e. FIFTH (HQ...panies. In Peru the gold boom began in 1978 in the southeastern jungle region ( Madre de Dios ) when the Peruvian Government issued Decree-Law No. 22178

Soil Organic Carbon Transport in Headwater Tributaries of the Amazon River Traced by Branched GDGTs

NASA Astrophysics Data System (ADS)

Kirkels, F.; Peterse, F.; Ponton, C.; Feakins, S. J.; West, A. J.

2016-12-01

Transfer of soil organic carbon from land to sea by rivers plays a key role in the global carbon cycle by enabling long-term storage upon deposition in the marine environment, and generates archives of paleoinformation. Specific soil bacterial membrane lipids (branched glycerol dialkyl glycerol tetraethers, brGDGTs) can trace soil inputs to a river. BrGDGT distributions relate to soil pH and mean annual air temperature and can be inferred by a novel calibration [1]. In the Amazon Fan, down-core changes in brGDGTs have been used for paleoclimate reconstructions [2]. However, the effects of fluvial sourcing and transport on brGDGT signals in sedimentary deposits are largely unknown. In this study, we investigated the implications of upstream dynamics and hydrological variability (wet/dry season) on brGDGT distributions carried by the Madre de Dios River (Peru), a tributary of the upper Amazon River. The Madre de Dios basin covers a 4.5 km elevation gradient draining the eastern flank of the Andes to the Amazonian floodplains [3], along which we examined organic and mineral soils, and river suspended particulate matter (SPM). BrGDGT signals of SPM indicate sourcing of soils within the catchment, with concentrations increasing downstream indicating accumulation of this biomarker. River depth profiles demonstrated uniform brGDGT distributions and concentrations, suggesting no preferential transport and that brGDGTs are well-mixed in the river. These findings add to prior studies on brGDGTs in the downstream Amazon River [4, 5]. Our study highlights the importance of the upstream drainage basin to constrain the source of brGDGTs in rivers, to better interpret climate reconstructions with this proxy. [1] De Jonge et al. (2014) Geochim Cosmochim Act 141, 97-112 [2] Bendle et al. (2010) Geochem Geoph Geosy 11 [3] Ponton et al. (2014) Geophys. Res. Lett 41, 6420-6427. [4] Kim et al. (2012) Geochim Cosmochim Act 90, 163-180. [5] Zell et al. (2013) Front Microbio 4, 228.

Constancy in the vegetation of the Amazon Basin during the late Pleistocene: Evidence from the organic matter composition of Amazon deep sea fan sediments

NASA Astrophysics Data System (ADS)

Kastner, Thomas P.; Goñi, Miguel A.

2003-04-01

Analyses of more than 60 sediment samples from the Amazon deep sea fan show remarkably constant terrigenous biomarkers (lignin phenols and cutin acids) and stable carbon isotopic compositions of organic matter (δ13COM) deposited from 10 to 70 ka. Sediments from the nine Amazon deep sea fan channel-levee systems investigated in this study yielded relatively narrow ranges for diagnostic parameters such as organic carbon (OC) normalized total lignin yields (Λ = 3.1 ± 1.1 mg/100 mg OC), syringyl:vanillyl phenol ratios (S/V = 0.84 ± 0.06), cinnamyl:vanillyl phenol ratios (C/V = 0.08 ± 0.02), isomeric abundances of cutin-derived dihydroxyhexadecanoic acid (f10,16-OH = 0.65 ± 0.02), and δ13COM (-27.6% ± 0.6 ‰). Our measurements support the hypothesis that the vegetation of the Amazon Basin did not change significantly during the late Pleistocene, even during the Last Glacial Maximum. Moreover, the compositions obtained from the Amazon deep sea fan are similar to those of modern Amazon River suspended sediments. Such results strongly indicate that the current tropical rainforest vegetation has been a permanent and dominant feature of the Amazon River watershed over the past 70 k.y. Specifically, we found no evidence for the development of large savannas that had been previously postulated as indicators of increased glacial aridity in Amazonia. Climate models need to be modified to account for the uninterrupted input of moisture to the tropical Amazon region over the late Pleistocene Holocene period.

Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles

NASA Astrophysics Data System (ADS)

Bouchez, Julien; Galy, Valier; Hilton, Robert G.; Gaillardet, Jérôme; Moreira-Turcq, Patricia; Pérez, Marcela Andrea; France-Lanord, Christian; Maurice, Laurence

2014-05-01

In order to reveal particulate organic carbon (POC) source and mode of transport in the largest river basin on Earth, we sampled the main sediment-laden tributaries of the Amazon system (Solimões, Madeira and Amazon) during two sampling campaigns, following vertical depth-profiles. This sampling technique takes advantage of hydrodynamic sorting to access the full range of solid erosion products transported by the river. Using the Al/Si ratio of the river sediments as a proxy for grain size, we find a general increase in POC content with Al/Si, as sediments become finer. However, the sample set shows marked variability in the POC content for a given Al/Si ratio, with the Madeira River having lower POC content across the measured range in Al/Si. The POC content is not strongly related to the specific surface area (SSA) of the suspended load, and bed sediments have a much lower POC/SSA ratio. These data suggest that SSA exerts a significant, yet partial, control on POC transport in Amazon River suspended sediment. We suggest that the role of clay mineralogy, discrete POC particles and rock-derived POC warrant further attention in order to fully understand POC transport in large rivers.

The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system

NASA Astrophysics Data System (ADS)

Latrubesse, Edgardo M.; Cozzuol, Mario; da Silva-Caminha, Silane A. F.; Rigsby, Catherine A.; Absy, Maria Lucia; Jaramillo, Carlos

2010-05-01

On the basis of paleontological content (vertebrates and palynology) and facies analysis from river banks, road cuts, and three wells, we have assigned the uppermost levels of the Solimões Formation in western Amazonia, Brazil, to the Late Miocene. The vertebrate fossil record from outcropping sediments is assigned to the Huayquerian-Mesopotamian mammalian biozones, spanning 9-6.5 Ma. Additionally, we present results that demonstrate that deposits in Peruvian Amazonia attributed to Miocene tidal environments are actually fluvial sediments that have been misinterpreted (both environmentally and chronologically) by several authors. The entire Late Miocene sequence was deposited in a continental environment within a subsiding basin. The facies analysis, fossil fauna content, and palynological record indicate that the environment of deposition was dominated by avulsive rivers associated with megafan systems, and avulsive rivers in flood basins (swamps, lakes, internal deltas, and splays). Soils developed on the flatter, drier areas, which were dominated by grasslands and gallery forest in a tropical to subtropical climate. These Late Miocene sediments were deposited from westward of the Purus arch up to the border of Brazil with Peru (Divisor Ranges) and Bolivia (Pando block). Eastward of the Iquitos structural high, however, more detailed studies, including vertebrate paleontology, need to be performed to calibrate with more precision the ages of the uppermost levels of the Solimões Formation. The evolution of the basin during the late Miocene is mainly related to the tectonic behavior of the Central Andes (˜ 3°-15°S). At approximately 5 Ma, a segment of low angle of subduction was well developed in the Nazca Plate, and the deformation in the Subandean foreland produced the inland reactivation of the Divisor/Contamana Ranges and tectonic arrangements in the Eastern Andes. During the Pliocene southwestern Brazilian Amazonia ceased to be an effective sedimentary basin, and became instead an erosional area that contributed sediments to the Amazon fluvial system. At that time, the lowland fluvial systems of southwestern Amazonia (the Purus, Jurua and Javarí basins) become isolated from the Andes by the newly formed north-flowing Ucayali system and south-east flowing Madre de Dios System. It was during the early Pliocene that the Amazon fluvial system integrated regionally and acquired its present appearance, and also when it started to drain water and sediments on a large scale to the Atlantic Ocean.

A multi-approach and multi-scale study on water quantity and quality changes in the Tapajós River basin, Amazon

NASA Astrophysics Data System (ADS)

Bezerra Nóbrega, Rodolfo Luiz; Lamparter, Gabriele; Hughes, Harold; Chenjerayi Guzha, Alphonce; Santos Silva Amorim, Ricardo; Gerold, Gerhard

2018-04-01

We analyzed changes in water quantity and quality at different spatial scales within the Tapajós River basin (Amazon) based on experimental fieldwork, hydrological modelling, and statistical time-trend analysis. At a small scale, we compared the river discharge (Q) and suspended-sediment concentrations (SSC) of two adjacent micro-catchments ( < 1 km2) with similar characteristics but contrasting land uses (forest vs. pasture) using empirical data from field measurements. At an intermediary scale, we simulated the hydrological responses of a sub-basin of the Tapajós (Jamanxim River basin, 37 400 km2), using a hydrological model (SWAT) and land-use change scenario in order to quantify the changes in the water balance components due to deforestation. At the Tapajós' River basin scale, we investigated trends in Q, sediments, hydrochemistry, and geochemistry in the river using available data from the HYBAM Observation Service. The results in the micro-catchments showed a higher runoff coefficient in the pasture (0.67) than in the forest catchment (0.28). At this scale, the SSC were also significantly greater during stormflows in the pasture than in the forest catchment. At the Jamanxim watershed scale, the hydrological modelling results showed a 2 % increase in Q and a 5 % reduction of baseflow contribution to total Q after a conversion of 22 % of forest to pasture. In the Tapajós River, however, trend analysis did not show any significant trend in discharge and sediment concentration. However, we found upward trends in dissolved organic carbon and NO3- over the last 20 years. Although the magnitude of anthropogenic impact has shown be scale-dependent, we were able to find changes in the Tapajós River basin in streamflow, sediment concentration, and water quality across all studied scales.

Characterization of Terrestrial Water Dynamics in the Congo Basin Using GRACE and Satellite Radar Altimetry

NASA Technical Reports Server (NTRS)

Lee, Hyongki; Beighley, R. Edward; Alsdorf, Douglas; Jung, Hahn Chul; Shum, C. K.; Duan, Jianbin; Guo, Junyi; Yamazaki, Dai; Andreadis, Konstantinos

2011-01-01

The Congo Basin is the world's third largest in size (approx.3.7 million sq km), and second only to the Amazon River in discharge (approx.40,200 cu m/s annual average). However, the hydrological dynamics of seasonally flooded wetlands and floodplains remains poorly quantified. Here, we separate the Congo wetland into four 3deg 3deg regions, and use remote sensing measurements (i.e., GRACE, satellite radar altimeter, GPCP, JERS-1, SRTM, and MODIS) to estimate the amounts of water filling and draining from the Congo wetland, and to determine the source of the water. We find that the amount of water annually filling and draining the Congo wetlands is 111 cu km, which is about one-third the size of the water volumes found on the mainstem Amazon floodplain. Based on amplitude comparisons among the water volume changes and timing comparisons among their fluxes, we conclude that the local upland runoff is the main source of the Congo wetland water, not the fluvial process of river-floodplain water exchange as in the Amazon. Our hydraulic analysis using altimeter measurements also supports our conclusion by demonstrating that water surface elevations in the wetlands are consistently higher than the adjacent river water levels. Our research highlights differences in the hydrology and hydrodynamics between the Congo wetland and the mainstem Amazon floodplain.

Characterization of Terrestrial Water Dynamics in the Congo Basin Using GRACE and Satellite Radar Altimetry

NASA Technical Reports Server (NTRS)

Lee, Lyongki; Beighley, R. Edward; Alsdorf, Douglas; Jung, Hahn Chul; Shum, C. K.; Duan, Jianbin; Guo, Junyi; Yamazaki, Dai; Andreadis, Konstantinos

2011-01-01

The Congo Basin is the world's third largest in size (approximately 3.7 million km^2), and second only to the Amazon River in discharge (approximately 40,200 cms annual average). However, the hydrological dynamics of seasonally flooded wetlands and floodplains remains poorly quantified. Here, we separate the Congo wetland into four 3 degree x 3 degree regions, and use remote sensing measurements (i.e., GRACE, satellite radar altimeter, GPCP, JERS-1, SRTM, and MODIS) to estimate the amounts of water filling and draining from the Congo wetland, and to determine the source of the water. We find that the amount of water annually filling and draining the Congo wetlands is 111 km^3, which is about one-third the size of the water volumes found on the mainstem Amazon floodplain. Based on amplitude comparisons among the water volume changes and timing comparisons among their fluxes, we conclude that the local upland runoff is the main source of the Congo wetland water, not the fluvial process of river-floodplain water exchange as in the Amazon. Our hydraulic analysis using altimeter measurements also supports our conclusion by demonstrating that water surface elevations in the wetlands are consistently higher than the adjacent river water levels. Our research also highlights differences in the hydrology and hydrodynamics between the Congo wetland and the mainstem Amazon floodplain.

Insight on the Peruvian Amazon River: A Planform Metric Characterization of its Morphodynamics

NASA Astrophysics Data System (ADS)

Garcia, A. M. P.; Ortals, C.; Frias, C. E.; Abad, J. D.; Vizcarra, J.

2014-12-01

Starting in Peru, the Amazon River flows through Colombia and Brazil; additionally, tributaries from Bolivia, Venezuela, and Ecuador contribute to the massive river and its unique geomorphic features. Accordingly, the Amazon Basin has become an important aspect of South America; it is an area of extraordinary biodiversity, rich resources, and unique cultures. However, due to the sheer magnitude and exceptionality of the Amazon River, research regarding the morphodynamic processes that shape and define the river has been difficult. Consequently, current research has not completely understood the planform dynamics of some portions of this river that present a main channel and secondary channels known as "anabranching structures". The purpose of this research was to gain an understanding of the geomorphology of the upper Amazon, the Peruvian section, by obtaining migration rates and planform metrics, including channel count, length, width, and sinuosity, as well as island count, area, and shape. With this data, the morphodynamics of the Peruvian Amazon, especially the relationship between the main channel and its secondary channels in each "anabranching structure" along the river, could be analyzed according to correlations found between various metrics. This analysis was carried out for 5-year time spans over a period of 25 years. Preliminary results showed that the average migration rate versus channel bend radius envelope peak is lower for the secondary channels than for the main channel. However, the maximum migration rate was not always found in the main channel; for several structures, the most dynamic channels were the secondary ones. This implies a certain periodicity to the river's migratory patterns that could be related to the valley boundaries, the local channel sinuosity or geological formations in the study area.

Spatial and seasonal dynamics of total suspended sediment and organic carbon species in the Congo River

NASA Astrophysics Data System (ADS)

Coynel, Alexandra; Seyler, Patrick; Etcheber, Henri; Meybeck, Michel; Orange, Didier

2005-12-01

The Congo (Zaire) River, the world's second largest river in terms both of water discharges and of drainage area after the Amazon River, has remained to date in a near-pristine state. For a period between 2 and 6 years, the mainstream near the river mouth (Brazzaville/Kinshasa station) and some of the major and minor tributaries (the Oubangui, Mpoko, and Ngoko-Sangha) were monitored every month for total suspended sediment (TSS), particulate organic carbon (POC), and dissolved organic carbon (DOC). In this large but relatively flat equatorial basin, TSS levels are very low and organic carbon is essentially exported as DOC: from 74% of TOC for the tributaries flowing in savannah regions and 86% for those flowing in the rain forest. The seasonal patterns of TSS, POC, and DOC show clockwise hysteresis in relation to river discharges, with maximum levels recorded 2 to 4 months before peak flows. At the Kinshasa/Brazzaville station, the DOC distribution is largely influenced by the input from the tributaries draining the large marshy forest area located in the center of the basin. There is a marked difference between specific fluxes, threefold higher in the forest basins than in the savannah basins. The computation of inputs to the Atlantic Ocean demonstrates that the Congo is responsible for 14.4 × 106 t/yr of TOC of which 12.4 × 106 t/yr is DOC and 2 × 106 t/yr is POC. The three biggest tropical rivers (the Amazon, the Congo, and the Orinoco), with only 10% of the exoreic world area drained to world oceans, contribute ˜4% of its TSS inputs but 15-18% of its organic carbon inputs. These proportions may double when considering only world rivers discharging into the open ocean.

A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin.

NASA Astrophysics Data System (ADS)

Carmona, A.; Poveda, G.; Sivapalan, M.; Vallejo-Bernal, S. M.; Bustamante, E.

2015-12-01

We study a 3-D generalization of Budyko's framework that involves the complementary relationship between long-term mean actual evapotranspiration (E) and potential evapotranspiration (Ep), and that captures the mutual interdependence among E, Ep, and mean annual precipitation (P). For this purpose we use three dimensionless and dependent quantities: Ψ=E/P, Φ=Ep/P and Ω=E/Ep. We demonstrate analytically that Budyko-type equations are unable to capture the physical limit of the relation between Ω and Φ in humid environments, owing to the unfeasibility of Ep/P→0 at E/Ep=1. Using independent datasets from 146 sub-catchments in the Amazon River basin we overcome this physical inconsistency by proposing a physically consistent power law Ψ=kΦ e with pre-factor k=0.66 and scaling exponent e=0.83 (R2=0.93). The proposed power law is compared with other Budyko-type equations, namely those by Yang et al (2008) and Cheng et al (2011). Taking into account the goodness of fits with confidence bounds set at 95% level and the ability to comply with the physical limits of the 3-D space, our results show that the power law works better to model the long-term water and energy balances within the Amazon River basin. At the interannual time scale, parameters from the three studied equations are estimated for each catchment using 27 years of information and interesting regional patterns emerge, as well as evidence of space-time symmetry. In addition, results show that within individual catchments the parameters from the linear relationship by Cheng et al (2011) and from the power law resemble and are related to the partitioning of energy via evapotranspiration in terms of Ω. Finally, signs of co-evolution of catchments are explored by linking the emerging spatial patterns of the parameters with landscape properties that represent some of the main features of the Amazon River basin, including topography, water in soils and vegetation.

A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin

NASA Astrophysics Data System (ADS)

Carmona, A. M.; Poveda, G.; Sivapalan, M.; Vallejo-Bernal, S. M.; Bustamante, E.

2015-10-01

This paper studies a 3-D generalization of Budyko's framework designed to capture the mutual interdependence among long-term mean actual evapotranspiration (E), potential evapotranspiration (Ep) and precipitation (P). For this purpose we use three dimensionless and dependent quantities: Ψ = E/P, Φ = Ep/P and Ω = E/Ep. This 3-D space and its 2-D projections provide an interesting setting to test the physical soundness of Budyko's hypothesis. We demonstrate analytically that Budyko-type equations are unable to capture the physical limit of the relation between Ω and Φ in humid environments, owing to the unfeasibility of Ep/P → 0 at E/Ep = 1. Using data from 146 sub-catchments in the Amazon River basin we overcome this inconsistency by proposing a physically consistent power law: Ψ = k Φe, with k = 0.66, and e = 0.83 (R2 = 0.93). This power law is compared with two other Budyko-type equations. Taking into account the goodness of fits and the ability to comply with the physical limits of the 3-D space, our results show that the power law is better suited to model the coupled water and energy balances within the Amazon River basin. Moreover, k is found to be related to the partitioning of energy via evapotranspiration in terms of Ω. This suggests that our power law implicitly incorporates the complementary relationship of evapotranspiration into the Budyko curve, which is a consequence of the dependent nature of the studied variables within our 3-D space. This scaling approach is also consistent with the asymmetrical nature of the complementary relationship of evapotranspiration. Looking for a physical explanation for the parameters k and e, the inter-annual variability of individual catchments is studied. Evidence of space-time symmetry in Amazonia emerges, since both between-catchment and between-year variability follow the same Budyko curves. Finally, signs of co-evolution of catchments are explored by linking spatial patterns of the power law parameters with fundamental characteristics of the Amazon River basin. In general, k and e are found to be related to vegetation, topography and water in soils.

Rainfall trends in the Brazilian Amazon Basin in the past eight decades

NASA Astrophysics Data System (ADS)

Satyamurty, Prakki; de Castro, Aline Anderson; Tota, Julio; da Silva Gularte, Lucia Eliane; Manzi, Antonio Ocimar

2010-01-01

Rainfall series at 18 stations along the major rivers of the Brazilian Amazon Basin, having data since 1920s or 1930s, are analyzed to verify if there are appreciable long-term trends. Annual, rainy-season, and dry-season rainfalls are individually analyzed for each station and for the region as a whole. Some stations showed positive trends and some negative trends. The trends in the annual rainfall are significant at only six stations, five of which reporting increasing trends (Barcelos, Belem, Manaus, Rio Branco, and Soure stations) and just one (Itaituba station) reporting decreasing trend. The climatological values of rainfall before and after 1970 show significant differences at six stations (Barcelos, Belem, Benjamin Constant, Iaurete, Itaituba, and Soure). The region as a whole shows an insignificant and weak downward trend; therefore, we cannot affirm that the rainfall in the Brazilian Amazon basin is experiencing a significant change, except at a few individual stations. Subregions with upward and downward trends are interspersed in space from the far eastern Amazon to western Amazon. Most of the seasonal trends follow the annual trends, thus, indicating a certain consistency in the datasets and analysis.

Coupling a basin erosion and river sediment transport model into a large scale hydrological model: an application in the Amazon basin

NASA Astrophysics Data System (ADS)

Buarque, D. C.; Collischonn, W.; Paiva, R. C. D.

2012-04-01

This study presents the first application and preliminary results of the large scale hydrodynamic/hydrological model MGB-IPH with a new module to predict the spatial distribution of the basin erosion and river sediment transport in a daily time step. The MGB-IPH is a large-scale, distributed and process based hydrological model that uses a catchment based discretization and the Hydrological Response Units (HRU) approach. It uses physical based equations to simulate the hydrological processes, such as the Penman Monteith model for evapotranspiration, and uses the Muskingum Cunge approach and a full 1D hydrodynamic model for river routing; including backwater effects and seasonal flooding. The sediment module of the MGB-IPH model is divided into two components: 1) prediction of erosion over the basin and sediment yield to river network; 2) sediment transport along the river channels. Both MGB-IPH and the sediment module use GIS tools to display relevant maps and to extract parameters from SRTM DEM (a 15" resolution was adopted). Using the catchment discretization the sediment module applies the Modified Universal Soil Loss Equation to predict soil loss from each HRU considering three sediment classes defined according to the soil texture: sand, silt and clay. The effects of topography on soil erosion are estimated by a two-dimensional slope length (LS) factor which using the contributing area approach and a local slope steepness (S), both estimated for each DEM pixel using GIS algorithms. The amount of sediment releasing to the catchment river reach in each day is calculated using a linear reservoir. Once the sediment reaches the river they are transported into the river channel using an advection equation for silt and clay and a sediment continuity equation for sand. A sediment balance based on the Yang sediment transport capacity, allowing to compute the amount of erosion and deposition along the rivers, is performed for sand particles as bed load, whilst no erosion or deposition is allowed for silt and clay. The model was first applied on the Madeira River basin, one of the major tributaries of the Amazon River (~1.4*106 km2) accounting for 35% of the suspended sediment amount annually transported for the Amazon river to the ocean. Model results agree with observed data, mainly for monthly and annual time scales. The spatial distribution of soil erosion within the basin showed a large amount of sediment being delivered from the Andean regions of Bolivia and Peru. Spatial distribution of mean annual sediment along the river showed that Madre de Dios, Mamoré and Beni rivers transport the major amount of sediment. Simulated daily suspended solid discharge agree with observed data. The model is able to provide temporaly and spatialy distributed estimates of soil loss source over the basin, locations with tendency for erosion or deposition along the rivers, and to reproduce long term sediment yield at several locations. Despite model results are encouraging, further effort is needed to validate the model considering the scarcity of data at large scale.

Changes in the Carbon Cycle of Amazon Ecosystems During the 2010 Drought

NASA Technical Reports Server (NTRS)

Potter, Christophera; Klooster, Steven; Hiatt, Cyrus; Genovese, Vanessa; Castilla-Rubino, Juan Carlos

2011-01-01

Satellite remote sensing was combined with the NASA-CASA carbon cycle simulation model to evaluate the impact of the 2010 drought (July through September) throughout tropical South America. Results indicated that net primary production (NPP) in Amazon forest areas declined by an average of 7% in 2010 compared to 2008. This represented a loss of vegetation CO2 uptake and potential Amazon rainforest growth of nearly 0.5 Pg C in 2010. The largest overall decline in ecosystem carbon gains by land cover type was predicted for closed broadleaf forest areas of the Amazon River basin, including a large fraction of regularly flooded forest areas. Model results support the hypothesis that soil and dead wood carbon decomposition fluxes of CO2 to the atmosphere were elevated during the drought period of 2010 in periodically flooded forest areas, compared to forests outside the main river floodplains.

The Amazon at sea: Onset and stages of the Amazon River from a marine record, with special reference to Neogene plant turnover in the drainage basin

NASA Astrophysics Data System (ADS)

Hoorn, Carina; Bogotá-A, Giovanni R.; Romero-Baez, Millerlandy; Lammertsma, Emmy I.; Flantua, Suzette G. A.; Dantas, Elton L.; Dino, Rodolfo; do Carmo, Dermeval A.; Chemale, Farid

2017-06-01

The Amazon submarine fan is a large sediment apron situated offshore Pará (Brazil) and represents the most distal extent of the Amazon River. The age of onset of this transcontinental river remains debated, yet is of great importance for understanding biotic evolutionary processes on land and at sea. Here we present new geochemical and palynological data from a borehole drilled at the continental slope and dated based on nannofossil biostratigraphy. We found that sediments of mixed source (craton and adjacent) occur at least from the late Oligocene (NP25) to late Miocene (NN9), and that the earliest Andes-derived sediments occur in NN10 (late Miocene). Our geochemical record indicates an onset of the transcontinental Amazon River between 9.4 and 9 Ma, which postdates the regional unconformity by 1 to 1.5 My. The shift in sediment geochemistry is more gradually replicated in the palynological record by a change from coastal plain and tropical lowland taxa to a mixture of tropical lowland, and montane forest to open Andean taxa. In particular, the appearance of taxa such as Jamesonia and Huperzia, followed by Valeriana, Polylepis-Acaena, Lysipomia and Plantago (with a current altitudinal range from 3200 to 4000 m) suggests the development of open, treeless, vegetation between 9.5 and 5.4 Ma, and highlight the presence of a high Andes in the late Miocene hinterland. Poaceae progressively increased from 9 Ma, with a notable rise from 4 Ma onwards, and percentages well above post-glacial and modern values, particularly between 2.6 and 0.8 Ma. We hypothesize that the rise of the grasses is a basin-wide phenomenon, but that the Plio-Pleistocene expansion of open, treeless vegetation on the Andean slopes and foothills are the main contributor. This rise in grasses was likely caused by climatic fluctuations, and subsequent changes in relief and erosion rates. We conclude that the onset of the Amazon River is coupled with Neogene Andean tectonism and that subsequent developments, both of river and biota, are closely linked to the Plio-Pleistocene climatic fluctuations. From latest Neogene onwards these major landscape changes determined the composition of the montane and lowland forest in the Andes-Amazonian system.

Applying NASA Imaging Radar Datasets to Investigate the Geomorphology of the Amazon's Planalto

NASA Astrophysics Data System (ADS)

McDonald, K. C.; Campbell, K.; Islam, R.; Alexander, P. M.; Cracraft, J.

2016-12-01

The Amazon basin is a biodiversity rich biome and plays a significant role into shaping Earth's climate, ocean and atmospheric gases. Understanding the history of the formation of this basin is essential to our understanding of the region's biodiversity and its response to climate change. During March 2013, the NASA/JPL L-band polarimetric airborne imaging radar, UAVSAR, conducted airborne studies over regions of South America including portions of the western Amazon basin. We utilize UAVSAR imagery acquired during that time over the Planalto, in the Madre de Dios region of southeastern Peru in an assessment of the underlying geomorphology, its relationship to the current distribution of vegetation, and its relationship to geologic processes through deep time. We employ UAVSAR data collections to assess the utility of these high quality imaging radar data for use in identifying geomorphologic features and vegetation communities within the context of improving the understanding of evolutionary processes, and their utility in aiding interpretation of datasets from Earth-orbiting satellites to support a basin-wide characterization across the Amazon. We derive maps of landcover and river branching structure from UAVSAR imagery. We compare these maps to those derived using imaging radar datasets from the Japanese Space Agency's ALOS PALSAR and Digital Elevation Models (DEMs) from NASA's Shuttle Radar Topography Mission (SRTM). Results provide an understanding of the underlying geomorphology of the Amazon planalto as well as its relationship to geologic processes and will support interpretation of the evolutionary history of the Amazon Basin. Portions of this work have been carried out within the framework of the ALOS Kyoto & Carbon Initiative. PALSAR data were provided by JAXA/EORC and the Alaska Satellite Facility.This work is carried out with support from the NASA Biodiversity Program and the NSF DIMENSIONS of Biodiversity Program.

Water Balance in the Amazon Basin from a Land Surface Model Ensemble

NASA Technical Reports Server (NTRS)

Getirana, Augusto C. V.; Dutra, Emanuel; Guimberteau, Matthieu; Kam, Jonghun; Li, Hong-Yi; Decharme, Bertrand; Zhang, Zhengqiu; Ducharne, Agnes; Boone, Aaron; Balsamo, Gianpaolo;

Sr and Nd isotopes of suspended sediments from rivers of the Amazon basin

NASA Astrophysics Data System (ADS)

Hatting, Karina; Santos, Roberto V.; Sondag, Francis

2014-05-01

The Rb-Sr and Sm-Nd isotopic systems are important tools to constrain the provenance of sediment load in river systems. This study presents the isotopic composition of Sr and Nd isotopes and major and minor elements in suspended sediments from the Marañón-Solimões, Amazonas and Beni-Madeira rivers. The data were used to constrain the source region of the sediments and to better understand the main seasonal and spatial transport processes within the basin based on the variations of the chemical and isotopic signals. They also allow establishing a relationship between sediment concentrations and flow rate values. The study presents data collected during a hydrological year between 2009 and 2010. The Marañón-Solimões River presents low Sr isotopic values (0.7090-0.7186), broad EpslonNd(0) range (-15.17 to -8.09) and Nd model (TDM) ages varying from 0.99 to 1.81 Ga. Sources of sediments to the Marañón-Solimões River include recent volcanic rocks in northern Peru and Ecuador, as well as rocks with long crustal residence time and carbonates from the Marañón Basin, Peru. The Beni-Madeira River has more radiogenic Sr isotope values (0.7255-0.7403), more negative EpslonNd(0) values (-20.46 to -10.47), and older Nd isotope model ages (from 1.40 to 2.35 Ga) when compared to the Marañón-Solimões River. These isotope data were related to the erosion of Paleozoic and Cenozoic foreland basins that are filled with Precambrian sediments derived from the Amazonian Craton. These basins are located in Bolivian Subandina Zone. The Amazon River presents intermediate isotopic values when compared to those found in the Marañón-Solimões and Beni-Madeira rivers. Its Sr isotope ratios range between 0.7193 and 0.7290, and its EpslonNd(0) values varies between -11.09 and -9.51. The Nd isotope model ages of the suspended sediments vary between 1.28 and 1.77 Ga. Concentrations of soluble and insoluble elements indicate a more intense weathering activity in sediments of the Beni-Madeira River. This river has a larger difference in the Sr isotopic composition between the diluted and solid phases, which has been assigned to the high level of weathering of its sediment source area. In the Beni-Madeira River sub-basin dominates weathering of silicate rocks, while in the Marañón-Solimões River sub-basin there also weathering of carbonate and evaporitic rocks.

Seasonal dynamics and Organic Carbon Flux in the Congo River

NASA Astrophysics Data System (ADS)

Seyler, P.; Coynel, A.; Etcheber, H.; Meybeck, M.

2006-12-01

The Congo (Zaire) River, the second world river in terms of discharges and drainage area (Q=40600 m3/s; A=3.5 106 km2) after the Amazon River, is -up to now- in near-pristine state. For up to two years , the mainstream near river mouth (Kinshasa/Brazzaville station) and some major and minor tributaries (Oubangui, Mpoko and Ngoko-Sangha) were surveyed every month, for total suspended sediment (TSS), particulate organic carbon (POC) and dissolved organic carbon (DOC). In this very flat basin, TSS levels were very low and organic carbon was essentially exported as DOC: 74% of TOC for the tributaries flowing in savannah regions to 86% for those flowing in the rainforest). The seasonal patterns of TSS, POC and DOC showed clockwise hysteresis with river discharges, with maximum levels two to four months before peak flows. At the Kinshasa/Brazzaville station, the DOC distribution is largely influenced by the input of the tributaries draining the marshy forest area (Central depression). In term of fluxes, a marked difference is pointed out between specific fluxes, threefold higher in the forested basin than in savannahs basins. Computation of inputs to Atlantic Ocean showed that the Congo was responsible for 14.4 106 t/yr of TOC of which 12.4 106 t/yr is DOC and 2 106 t/yr is POC. The three biggest tropical rivers (Amazon, Congo and Orinoco) with only 10 percent of the exoreic world area drained to ocean world contribute to 4 percent of its TSS inputs but 29-33 percent of its organic carbon inputs.

The United States Air Force and Humanitarian Airlift Operations 1947-1994

DTIC Science & Technology

1998-01-01

Flood. Location: Republic of Bolivia. Date(s): February 13 and 28, 1971. Emergency: Heavy rain flooded the Beni and Madre de Dios River valleys of...descended on the Beni and Madre de Dios River valleys of northern Bolivia on the edge of the Amazon basin, flooding Riberalta and surrounding areas... heavy rain flooded river valleys south of Volcan de Fuego, Guatemala, threatening the towns of Singuinala and La Democracia. The Pantaleon River near

Assessing changes in extreme river flow regulation from non-stationarity in hydrological scaling laws

NASA Astrophysics Data System (ADS)

Rodríguez, Estiven; Salazar, Juan Fernando; Villegas, Juan Camilo; Mercado-Bettín, Daniel

2018-07-01

Extreme flows are key components of river flow regimes that affect manifold hydrological, geomorphological and ecological processes with societal relevance. One fundamental characteristic of extreme flows in river basins is that they exhibit scaling properties which can be identified through scaling (power) laws. Understanding the physical mechanisms behind such scaling laws is a continuing challenge in hydrology, with potential implications for the prediction of river flow regimes in a changing environment and ungauged basins. After highlighting that the scaling properties are sensitive to environmental change, we develop a physical interpretation of how temporal changes in scaling exponents relate to the capacity of river basins to regulate extreme river flows. Regulation is defined here as the basins' capacity to either dampen high flows or to enhance low flows. Further, we use this framework to infer temporal changes in the regulation capacity of five large basins in tropical South America. Our results indicate that, during the last few decades, the Amazon river basin has been reducing its capacity to enhance low flows, likely as a consequence of pronounced environmental change in its south and south-eastern sub-basins. The proposed framework is widely applicable to different basins, and provides foundations for using scaling laws as empirical tools for inferring temporal changes of hydrological regulation, particularly relevant for identifying and managing hydrological consequences of environmental change.

Deforestation in Amazonia impacts riverine carbon dynamics

NASA Astrophysics Data System (ADS)

Langerwisch, Fanny; Walz, Ariane; Rammig, Anja; Tietjen, Britta; Thonicke, Kirsten; Cramer, Wolfgang

2016-12-01

Fluxes of organic and inorganic carbon within the Amazon basin are considerably controlled by annual flooding, which triggers the export of terrigenous organic material to the river and ultimately to the Atlantic Ocean. The amount of carbon imported to the river and the further conversion, transport and export of it depend on temperature, atmospheric CO2, terrestrial productivity and carbon storage, as well as discharge. Both terrestrial productivity and discharge are influenced by climate and land use change. The coupled LPJmL and RivCM model system (Langerwisch et al., 2016) has been applied to assess the combined impacts of climate and land use change on the Amazon riverine carbon dynamics. Vegetation dynamics (in LPJmL) as well as export and conversion of terrigenous carbon to and within the river (RivCM) are included. The model system has been applied for the years 1901 to 2099 under two deforestation scenarios and with climate forcing of three SRES emission scenarios, each for five climate models. We find that high deforestation (business-as-usual scenario) will strongly decrease (locally by up to 90 %) riverine particulate and dissolved organic carbon amount until the end of the current century. At the same time, increase in discharge leaves net carbon transport during the first decades of the century roughly unchanged only if a sufficient area is still forested. After 2050 the amount of transported carbon will decrease drastically. In contrast to that, increased temperature and atmospheric CO2 concentration determine the amount of riverine inorganic carbon stored in the Amazon basin. Higher atmospheric CO2 concentrations increase riverine inorganic carbon amount by up to 20 % (SRES A2). The changes in riverine carbon fluxes have direct effects on carbon export, either to the atmosphere via outgassing or to the Atlantic Ocean via discharge. The outgassed carbon will increase slightly in the Amazon basin, but can be regionally reduced by up to 60 % due to deforestation. The discharge of organic carbon to the ocean will be reduced by about 40 % under the most severe deforestation and climate change scenario. These changes would have local and regional consequences on the carbon balance and habitat characteristics in the Amazon basin itself as well as in the adjacent Atlantic Ocean.

Pathogenesis of Eastern Equine Encephalitis Virus in Mice and Development of a Second Generation Vaccine

DTIC Science & Technology

2012-01-31

equine encephalitis in the Amazon region of Peru ." Am J Trop Med Hyg 76(2): 293-298. Alsharifi, M., Y. Furuya, et al. (2009). "Intranasal flu...the Amazon River Basin. The strains in these groups are highly divergent, polyphyletic, co- circulating, geographically-associated, and primarily...well understood and serological associations with wild birds, ground-dwelling rodents , marsupials, and reptiles have been reported (Monath, Sabattini

Forecasting Total Water Storage Changes in the Amazon basin using Atlantic and Pacific Sea Surface Temperatures

NASA Astrophysics Data System (ADS)

De Linage, C.; Famiglietti, J. S.; Randerson, J. T.

2013-12-01

Floods and droughts frequently affect the Amazon River basin, impacting the transportation, river navigation, agriculture, economy and the carbon balance and biodiversity of several South American countries. The present study aims to find the main variables controlling the natural interannual variability of terrestrial water storage in the Amazon region and to propose a modeling framework for flood and drought forecasting. We propose three simple empirical models using a linear combination of lagged spatial averages of central Pacific (Niño 4 index) and tropical North Atlantic (TNAI index) sea surface temperatures (SST) to predict a decade-long record of 3°, monthly terrestrial water storage anomalies (TWSA) observed by the Gravity Recovery And Climate Experiment (GRACE) mission. In addition to a SST forcing term, the models included a relaxation term to simulate the memory of water storage anomalies in response to external variability in forcing. Model parameters were spatially-variable and individually optimized for each 3° grid cell. We also investigated the evolution of the predictive capability of our models with increasing minimum lead times for TWSA forecasts. TNAI was the primary external forcing for the central and western regions of the southern Amazon (35% of variance explained with a 3-month forecast), whereas Niño 4 was dominant in the northeastern part of the basin (61% of variance explained with a 3-month forecast). Forcing the model with a combination of the two indices improved the fit significantly (p<0.05) for at least 64% of the grid cells, compared to models forced solely with Niño 4 or TNAI. The combined model was able to explain 43% of the variance in the Amazon basin as a whole with a 3-month lead time. While 66% of the observed variance was explained in the northeastern Amazon, only 39% of the variance was captured by the combined model in the central and western regions, suggesting that other, more local, forcing sources were important in these regions. The predictive capability of the combined model was monotonically degraded with increasing lead times. Degradation was smaller in the northeastern Amazon (where 49% of the variance was explained using a 8-month lead time versus 69% for a 1 month lead time) compared to the western and central regions of southern Amazon (where 22% of the variance was explained at 8 months versus 43% at 1 month). Our model may provide early warning information about flooding in the northeastern region of the Amazon basin, where floodplain areas are extensive and the sensitivity of floods to external SST forcing was shown to be high. This work also strengthens our understanding of the mechanisms regulating interannual variability in Amazon fires, as TWSA deficits may subsequently lead to atmospheric water vapor deficits and reduced cloudiness via water-limited evapotranspiration. Finally, this work helps to bridge the gap between the current GRACE mission and the follow-on gravity mission.

Projected increases in the annual flood pulse of the Western Amazon

NASA Astrophysics Data System (ADS)

Zulkafli, Zed; Buytaert, Wouter; Manz, Bastian; Véliz Rosas, Claudia; Willems, Patrick; Lavado-Casimiro, Waldo; Guyot, Jean-Loup; Santini, William

2016-01-01

The impact of a changing climate on the Amazon basin is a subject of intensive research because of its rich biodiversity and the significant role of rainforests in carbon cycling. Climate change has also a direct hydrological impact, and increasing efforts have focused on understanding the hydrological dynamics at continental and subregional scales, such as the Western Amazon. New projections from the Coupled Model Inter-comparison Project Phase 5 ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the upper Amazon river. Using extreme value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 yr. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100 yr return floods). These findings agree with previously projected increases in high extremes under the Special Report on Emissions Scenarios climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amidst a growing literature that more strongly emphasises future droughts and their impact on the viability of the rainforest system over greater Amazonia.

A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin

NASA Astrophysics Data System (ADS)

Carmona, A. M.; Poveda, G.; Sivapalan, M.; Vallejo-Bernal, S. M.; Bustamante, E.

2016-02-01

This paper studies a 3-D state space representation of Budyko's framework designed to capture the mutual interdependence among long-term mean actual evapotranspiration (E), potential evapotranspiration (Ep) and precipitation (P). For this purpose we use three dimensionless and dependent quantities: Ψ = E ⁄ P, Φ = Ep ⁄ P and Ω = E ⁄ Ep. This 3-D space and its 2-D projections provide an interesting setting to test the physical soundness of Budyko's hypothesis. We demonstrate analytically that Budyko-type equations are unable to capture the physical limit of the relation between Ω and Φ in humid environments, owing to the unfeasibility of Ep ⁄ P = 0 when E ⁄ Ep → 1. Using data from 146 sub-catchments in the Amazon River basin we overcome this inconsistency by proposing a physically consistent power law: Ψ = kΦe, with k = 0.66, and e = 0.83 (R2 = 0.93). This power law is compared with two other Budyko-type equations. Taking into account the goodness of fits and the ability to comply with the physical limits of the 3-D space, our results show that the power law is better suited to model the coupled water and energy balances within the Amazon River basin. Moreover, k is found to be related to the partitioning of energy via evapotranspiration in terms of Ω. This suggests that our power law implicitly incorporates the complementary relationship of evapotranspiration into the Budyko curve, which is a consequence of the dependent nature of the studied variables within our 3-D space. This scaling approach is also consistent with the asymmetrical nature of the complementary relationship of evapotranspiration. Looking for a physical explanation for the parameters k and e, the inter-annual variability of individual catchments is studied. Evidence of space-time symmetry in Amazonia emerges, since both between-catchment and between-year variability follow the same Budyko curves. Finally, signs of co-evolution of catchments are explored by linking spatial patterns of the power law parameters with fundamental characteristics of the Amazon River basin. In general, k and e are found to be related to vegetation, topography and water in soils.

Examining the eastern Amazon Basin breeze circulations, channeling and boundary layer properties using altitude controlled meteorological balloons

NASA Astrophysics Data System (ADS)

Fitzjarrald, D. R.; Voss, P. B.; Silva, R. D.; Callahan, S.; Dewald, A.; do Vale, R. S.

2017-12-01

During the period August 24-28, 2016, in a delayed component the GO-Amazon Project, we launched nine altitude-controlled free balloons (CMET). Smaller than typical rawinsondes, CMET are equipped with altitude control, global communication via Iridium satellite, and aspirated sensors. The aims of our effort were to examine the interactions among convective boundary layer and dual river breeze circulations near the confluence of the Tapajos and Amazon Rivers in the eastern Basin. The week-long field campaign was timed to examine the reestablishment of the breeze circulations shortly after the passage of a strong instability line on August 22. Nine CMET were launched at the Curua-Una hydroelectric dam (2.8S; 54.3W), timed to encounter the Tapajos river breeze front by late afternoon. Soundings were made to establish the thickness of interface between the easterly trade and westerly Tapajos breeze circulation. Careful use of sounding strategies allowed these free balloons to track along the northerly channeled flow in the lowest 300 m above the River. Following the river encounter, balloons tracked to the west, sounding to describe the diurnal course of boundary layer in the forest west of the Tapajos River. The longest flight traveled more than 770 km over three days and twice rested overnight in the rain forest canopy. Ancillary data from surface climate and flux stations as well as the Santarem radiosonde, satellite images will be used to illustrate how the breeze circulations are seen near the surface and how they were disrupted by larger-scale events. Comparisons with HYSPLIT trajectories will illustrate how sensitive real trajectories are to the refraction that the encounter with the breeze effects.

Dynamics of floodplain lakes in the Upper Amazon Basin during the late Holocene

NASA Astrophysics Data System (ADS)

Quintana-Cobo, Isabel; Moreira-Turcq, Patricia; Cordeiro, Renato C.; Aniceto, Keila; Crave, Alain; Fraizy, Pascal; Moreira, Luciane S.; Duarte Contrera, Julia Maria de Aguiar; Turcq, Bruno

2018-01-01

To better understand the impact of channel migration processes and climate change on the depositional dynamics of floodplain lakes of the upper Amazon Basin during the late Holocene, we collected three sediment cores from floodplain lakes of the Ucayali River and one from the Marañón River. The cores were dated with 14C, radiographed and described. Bulk density, grain size analysis and total organic carbon (TOC) were determined. The results show that sedimentation in Ucayali floodplain lakes was marked by variations during the late Holocene, with periods of intense hydrodynamic energy and abrupt accumulations, a gap in the record between about 2870 and 690 cal yr BP, and periods of more lacustrine conditions. These changes in sedimentation were associated with variations in the river's influence related to changes in its meandering course (2870 cal yr BP) and a period of severe flooding between 3550 and 3000 cal yr BP. Lake Lagarto on the Marañón River floodplain exhibits a different sedimentary environment of low hydrodynamics with palm trees and macrophytes. Apparently, the lake has not experienced intense migration processes during the last 600 cal yr BP (base of the core). Nevertheless, the river sediment flux to the lake was important from 600 to 500 cal yr BP, although it decreased thereafter until the present. This decrease in the mineral accumulation rate indicates a decrease in river discharge since 500 cal yr BP, which coincides with precipitation records from the central Andes. In the upper part of the three Ucayali floodplain cores, a 30- to 250-cm-thick layer of reworked sediments has been deposited since 1950 AD (post-bomb). In Lake Carmen, this layer is associated with invasion of the lake by the levee of a migrating meander of the Ucayali. In Lakes Hubos and La Moringa, however, the river is still far away and the deposition must be interpreted as the result of extreme flooding. The beginning of the Ucayali meander migration is dated back to 2000 AD, suggesting that these extreme floods could be very recent and linked to hydrologic extremes registered instrumentally in the Amazon Basin.

The Role of Forests in Regulating the River Flow Regime of Large Basins of the World

NASA Astrophysics Data System (ADS)

Salazar, J. F.; Villegas, J. C.; Mercado-Bettin, D. A.; Rodríguez, E.

2016-12-01

Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we explore potential linkages between the presence of forests and the capacity of river basins for regulating river flows. Regulation is defined here as the capacity of river basins to attenuate the amplitude of the river flow regime, that is to reduce the difference between high and low flows. We first use scaling theory to show how scaling properties of observed river flows can be used to classify river basins as regulated or unregulated. This parsimonious classification is based on a physical interpretation of the scaling properties (particularly the scaling exponents) that is novel (most previous studies have focused on the interpretation of the scaling exponents for floods only), and widely-applicable to different basins (the only assumption is that river flows in a given river basin exhibit scaling properties through well-known power laws). Then we show how this scaling framework can be used to explore global-change-induced temporal variations in the regulation capacity of river basins. Finally, we propose a conceptual hypothesis (the "Forest reservoir concept") to explain how large-scale forests can exert important effects on the long-term water balance partitioning and regulation capacity of large basins of the world. Our quantitative results are based on data analysis (river flows and land cover features) from 22 large basins of the world, with emphasis in the Amazon river and its main tributaries. Collectively, our findings support the hypothesis that forest cover enhances the capacity of large river basins to maintain relatively high mean river flows, as well as to regulate (ameliorate) extreme river flows. Advancing towards this quantitative understanding of the relation between forest cover and river flow regimes is crucial for water management- and land cover-related decisions.

The Role of Forests in Regulating the River Flow Regime of Large Basins of the World

NASA Astrophysics Data System (ADS)

Salazar, J. F.; Villegas, J. C.; Mercado-Bettin, D. A.; Rodríguez, E.

2017-12-01

Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we explore potential linkages between the presence of forests and the capacity of river basins for regulating river flows. Regulation is defined here as the capacity of river basins to attenuate the amplitude of the river flow regime, that is to reduce the difference between high and low flows. We first use scaling theory to show how scaling properties of observed river flows can be used to classify river basins as regulated or unregulated. This parsimonious classification is based on a physical interpretation of the scaling properties (particularly the scaling exponents) that is novel (most previous studies have focused on the interpretation of the scaling exponents for floods only), and widely-applicable to different basins (the only assumption is that river flows in a given river basin exhibit scaling properties through well-known power laws). Then we show how this scaling framework can be used to explore global-change-induced temporal variations in the regulation capacity of river basins. Finally, we propose a conceptual hypothesis (the "Forest reservoir concept") to explain how large-scale forests can exert important effects on the long-term water balance partitioning and regulation capacity of large basins of the world. Our quantitative results are based on data analysis (river flows and land cover features) from 22 large basins of the world, with emphasis in the Amazon river and its main tributaries. Collectively, our findings support the hypothesis that forest cover enhances the capacity of large river basins to maintain relatively high mean river flows, as well as to regulate (ameliorate) extreme river flows. Advancing towards this quantitative understanding of the relation between forest cover and river flow regimes is crucial for water management- and land cover-related decisions.

The density and biomass of mesozooplankton and ichthyoplankton in the Negro and the Amazon Rivers during the rainy season: the ecological importance of the confluence boundary

PubMed Central

Rimachi, Elvis V.; Santos-Silva, Edinaldo N.; Calixto, Laura S.F.; Leite, Rosseval G.; Khen, Adi; Yamane, Tetsuo; Mazeroll, Anthony I.; Inuma, Jomber C.; Utumi, Erika Y.K.; Tanaka, Akira

2017-01-01

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for consumers by investigating the density, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers during the rainy season. Our results show that mean mesozooplankton density (2,730 inds. m−3) and biomass (4.8 mg m−3) were higher in the black-water river compared to the white-water river (959 inds. m−3; 2.4 mg m−3); however an exceptionally high mesozooplankton density was not observed in the confluence boundary. Nonetheless we found the highest density of ichthyoplankton in the confluence boundary (9.7 inds. m−3), being up to 9-fold higher than in adjacent rivers. The confluence between white and black waters is sandwiched by both environments with low (white water) and high (black water) zooplankton concentrations and by both environments with low (white water) and high (black water) predation pressures for fish larvae, and may function as a boundary layer that offers benefits of both high prey concentrations and low predation risk. This forms a plausible explanation for the high density of ichthyoplankton in the confluence zone of black and white water rivers. PMID:28507821

The density and biomass of mesozooplankton and ichthyoplankton in the Negro and the Amazon Rivers during the rainy season: the ecological importance of the confluence boundary.

PubMed

Nakajima, Ryota; Rimachi, Elvis V; Santos-Silva, Edinaldo N; Calixto, Laura S F; Leite, Rosseval G; Khen, Adi; Yamane, Tetsuo; Mazeroll, Anthony I; Inuma, Jomber C; Utumi, Erika Y K; Tanaka, Akira

2017-01-01

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for consumers by investigating the density, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers during the rainy season. Our results show that mean mesozooplankton density (2,730 inds. m -3 ) and biomass (4.8 mg m -3 ) were higher in the black-water river compared to the white-water river (959 inds. m -3 ; 2.4 mg m -3 ); however an exceptionally high mesozooplankton density was not observed in the confluence boundary. Nonetheless we found the highest density of ichthyoplankton in the confluence boundary (9.7 inds. m -3 ), being up to 9-fold higher than in adjacent rivers. The confluence between white and black waters is sandwiched by both environments with low (white water) and high (black water) zooplankton concentrations and by both environments with low (white water) and high (black water) predation pressures for fish larvae, and may function as a boundary layer that offers benefits of both high prey concentrations and low predation risk. This forms a plausible explanation for the high density of ichthyoplankton in the confluence zone of black and white water rivers.

Rare earth elements in river waters

NASA Technical Reports Server (NTRS)

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

To characterize the input to the oceans of rare earth elements (REE) in the dissolved and the suspended loads of rivers, the REE concentrations were measured in samples of Amazon, Indus, Mississippi, Murray-Darling, and Ohio rivers and in samples of smaller rivers that had more distinct drainage basin lithology and water chemistry. It was found that, in the suspended loads of small rivers, the REE pattern was dependent on drainage basin geology, whereas the suspended loads in major rivers had relatively uniform REE patterns and were heavy-REE depleted relative to the North American Shale composite (NASC). The dissolved loads in the five major rivers had marked relative heavy-REE enrichments, relative to the NASC and the suspended material, with the (La/Yb)N ratio of about 0.4 (as compared with the ratio of about 1.9 in suspended loads).

Mississippi and Louisiana Estuarine Areas. Freshwater Diversion to Lake Pontchartrain Basin and Mississippi Sound. Feasibility Study. Volume 4. Public Views and Responses.

DTIC Science & Technology

1984-04-01

looked at carefully. He said he recognized the dieback in the Louisiana marshes because of levee systems and the displacement of fishermen after seeing...noted these systems were created and Ined by great river systems like the Mississippi and Amazon Rivers. - huition to productivity extends far out to

Novel Henneguya spp. (Cnidaria: Myxozoa) from cichlid fish in the Amazon basin cluster by geographic origin.

PubMed

Zatti, Suellen Aparecida; Atkinson, Stephen D; Maia, Antônio A M; Bartholomew, Jerri L; Adriano, Edson A

2018-03-01

We describe three new Henneguya spp. (Myxobolidae) found parasitizing two species of cichlid fish from the Amazon basin, Brazil: H. tucunarei n. sp. from gill filaments of Cichla monoculus and H. tapajoensis n. sp. from gill filaments of Cichla pinima, both from the Tapajós River, Pará State and H. jariensis n. sp. in the fins of Cichla monoculus from the Jari River, Amapá State. We based descriptions on myxospore morphology and small subunit ribosomal DNA sequences, and used a phylogenetic analysis to compare the new Henneguya species with known relatives. Spores of the three species had similar morphology and morphometrics, but differed molecularly 5-7.5%, and were no more than 94% similar to any other sequence in GenBank. Together with having different hosts, these data supported the diagnosis of the parasites as distinct, novel species. Maximum likelihood and Bayesian analyses showed that H. tucunarei n. sp., H. tapajoensis n. sp., and H. jariensis n. sp. plus Henneguya paraensis (which parasitizes Cichla temensis) formed a well-supported sub-clade of Henneguya parasites of cichlids from the Amazon basin, in a lineage sister to those in characiforms hosts. Our analysis was consistent with previous studies that suggest that aquatic environment and vertebrate host group are the strongest correlates with phylogenetic signals in the Myxobolidae.

Water contamination from oil extraction activities in Northern Peruvian Amazonian rivers.

PubMed

Yusta-García, Raúl; Orta-Martínez, Martí; Mayor, Pedro; González-Crespo, Carlos; Rosell-Melé, Antoni

2017-06-01

Oil extraction activities in the Northern Peruvian Amazon have generated a long-standing socio-environmental conflict between oil companies, governmental authorities and indigenous communities, partly derived from the discharge of produced waters containing high amounts of heavy metals and hydrocarbons. To assess the impact of produced waters discharges we conducted a meta-analysis of 2951 river water and 652 produced water chemical analyses from governmental institutions and oil companies reports, collected in four Amazonian river basins (Marañon, Tigre, Corrientes and Pastaza) and their tributaries. Produced water discharges had much higher concentrations of chloride, barium, cadmium and lead than are typically found in fresh waters, resulting in the widespread contamination of the natural water courses. A significant number of water samples had levels of cadmium, barium, hexavalent chromium and lead that did not meet Peruvian and international water standards. Our study shows that spillage of produced water in Peruvian Amazon rivers placed at risk indigenous population and wildlife during several decades. Furthermore, the impact of such activities in the headwaters of the Amazon extended well beyond the boundaries of oil concessions and national borders, which should be taken into consideration when evaluating large scale anthropogenic impacts in the Amazon. Copyright © 2017 Elsevier Ltd. All rights reserved.

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes

PubMed Central

Silva, Gabriel de Souza da Costa e; Roxo, Fábio Fernandes; Britzke, Ricardo; Oliveira, Claudio

2014-01-01

Abstract A new species of Pseudancistrus is described from the Tapajós Basin, and assigned to the P. barbatus group by having hypertrophied odontodes along the snout and lacking evertible cheek plates. The new species is distinguished from other species in that group (P. barbatus, P. corantijniensis, P. depressus and P. nigrescens) by its pattern of spots, length and color of snout odontodes, greater head depth, cleithral width, anal-fin spine length, peduncle depth and internares width. Molecular phylogenetic results corroborate placement of the new species in the Pseudancistrus barbatus group which is otherwise distributed in the Xingu Basin and rivers draining the Guyana Shield into the Atlantic Ocean. Topology tests strongly reject alternative hypotheses supporting close relationships with Guyanancistrus, Lithoxancistrus or the species Pseudancistrus pectegenitor, P. sidereus and P. genisetiger. Additionally, we propose two hypotheses on the distribution of the new species in the rio Tapajós, a Brazilian Shield drainage. The first one proposes that ancestral stock of the P. barbatus group was widely distributed throughout rivers draining the Guyana and Brazilian shields, and the species P. zawadzkii and Pseudancistrus sp. L17 are in the limit of the distribution for the group in Tapajós and Xingu rivers. The second hypothesis proposes that ancestral stock of the P. barbatus group was restricted to Guyana Shield rivers, and that headwater capture events permitted several dispersal routs through Guyana and Amazon rivers, permitted that the ancestral lineages of Pseudancistrus sp. L17 and P. zawadzkii reached the rivers of Amazon basin. PMID:24843279

Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management.

PubMed

Hegg, Jens C; Giarrizzo, Tommaso; Kennedy, Brian P

2015-01-01

Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world's largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some of the longest freshwater fish migrations in the world, travelling from the Amazon River estuary to the Andes foothills. These species are important apex predators in the main stem rivers of the Amazon Basin and make up the region's largest fishery. They are also the only species to utilize the entire Amazon Basin to complete their life cycle. Studies indicate both that the fisheries may be declining due to overfishing, and that the proposed and completed dams in their upstream range threaten spawning migrations. Despite this, surprisingly little is known about the details of these species' migrations, or their life history. Otolith microchemistry has been an effective method for quantifying and reconstructing fish migrations worldwide across multiple spatial scales and may provide a powerful tool to understand the movements of Amazonian migratory catfish. Our objective was to describe the migratory behaviors of the three most populous and commercially important migratory catfish species, Dourada (Brachyplatystoma rousseauxii), Piramutaba (Brachyplatystoma vaillantii), and Piraíba (Brachyplatystoma filamentosum). We collected fish from the mouth of the Amazon River and the Central Amazon and used strontium isotope signatures ((87)Sr/(86)Sr) recorded in their otoliths to determine the location of early rearing and subsequent. Fish location was determined through discriminant function classification, using water chemistry data from the literature as a training set. Where water chemistry data was unavailable, we successfully in predicted (87)Sr/(86)Sr isotope values using a regression-based approach that related the geology of the upstream watershed to the Sr isotope ratio. Our results provide the first reported otolith microchemical reconstruction of Brachyplatystoma migratory movements in the Amazon Basin. Our results indicate that juveniles exhibit diverse rearing strategies, rearing in both upstream and estuary environments. This contrasts with the prevailing understanding that juveniles rear in the estuary before migrating upstream; however, it is supported by some fisheries data that has indicated the presence of alternate spawning and rearing life-histories. The presence of alternate juvenile rearing strategies may have important implications for conservation and management of the fisheries in the region.

Hydrological Retrospective of floods and droughts: Case study in the Amazon

NASA Astrophysics Data System (ADS)

Wongchuig Correa, Sly; Cauduro Dias de Paiva, Rodrigo; Carlo Espinoza Villar, Jhan; Collischonn, Walter

2017-04-01

Recent studies have reported an increase in intensity and frequency of hydrological extreme events in many regions of the Amazon basin over last decades, these events such as seasonal floods and droughts have originated a significant impact in human and natural systems. Recently, methodologies such as climatic reanalysis are being developed in order to create a coherent register of climatic systems, thus taking this notion, this research efforts to produce a methodology called Hydrological Retrospective (HR), that essentially simulate large rainfall datasets over hydrological models in order to develop a record over past hydrology, enabling the analysis of past floods and droughts. We developed our methodology on the Amazon basin, thus we used eight large precipitation datasets (more than 30 years) through a large scale hydrological and hydrodynamic model (MGB-IPH), after that HR products were validated against several in situ discharge gauges dispersed throughout Amazon basin, given focus in maximum and minimum events. For better HR results according performance metrics, we performed a forecast skill of HR to detect floods and droughts considering in-situ observations. Furthermore, statistical temporal series trend was performed for intensity of seasonal floods and drought in the whole Amazon basin. Results indicate that better HR represented well most past extreme events registered by in-situ observed data and also showed coherent with many events cited by literature, thus we consider viable to use some large precipitation datasets as climatic reanalysis mainly based on land surface component and datasets based in merged products for represent past regional hydrology and seasonal hydrological extreme events. On the other hand, an increase trend of intensity was realized for maximum annual discharges (related to floods) in north-western regions and for minimum annual discharges (related to drought) in central-south regions of the Amazon basin, these features were previously detected by other researches. In the whole basin, we estimated an upward trend of maximum annual discharges at Amazon River. In order to estimate better future hydrological behavior and their impacts on the society, HR could be used as a methodology to understand past extreme events occurrence in many places considering the global coverage of rainfall datasets.

The influence of the Amazonian floodplain ecosystems on the trace element dynamics of the Amazon River mainstem (Brazil).

PubMed

Viers, Jérôme; Barroux, Guénaël; Pinelli, Marcello; Seyler, Patrick; Oliva, Priscia; Dupré, Bernard; Boaventura, Geraldo Resende

2005-03-01

The purpose of this paper is to forecast the role of riverine wetlands in the transfer of trace elements. One of the largest riverine wetlands in the world is the floodplain (várzea) of the Amazon River and its tributaries (Junk and Piedade, 1997). The central Amazon wetlands are constituted by a complex network of lakes and floodplains, named várzeas, that extend over more than 300,000 km2 (Junk, W.J., The Amazon floodplain--a sink or source for organic carbon? In Transport of Carbon and Minerals in Major World Rivers, edited by E.T. Degens, S. Kempe, R. Herrera, SCOPE/UNEP; 267-283, 1985.) and are among the most productive ecosystems in the world due to the regular enrichment in nutrients by river waters In order to understand if the adjacent floodplain of Amazon River have a significant influence on the trace element concentrations and fluxes of the mainstem, the concentrations of selected elements (i.e., Al, Mn, Fe, Co, Cu, Mo, Rb, Sr, Ba, and U) have been measured in the Amazon River water (Manacapuru Station, Amazonas State, Brazil) and in lake waters and plants (leaves) from a várzea(Ilha de Marchantaria, Amazonas State, Brazil) during different periods of the hydrological cycle. Four plant species (two perennial species: Pseudobombax munguba and Salix humboldtiana, and two annual herbaceous plants: Echinochloa polystachya and Eichhornia crassipes) were selected to represent the ecological functioning of the site. Time series obtained for dissolved Mn and Cu (<0.20 microm) in Amazon River water could not be explained by tributary mixing or instream processes only. Therefore, the contribution of the waters transiting the floodplains should be considered. These results suggest that the chemical composition of the waters draining these floodplains is controlled by reactions occurring at sediment-water and plant-water interfaces. Trace elements concentrations in the plants (leaves) vary strongly with hydrological seasonality. Based on the concentration data and the biological productivity of floodplain ecosystems, a first order approximation of trace element storage (permanent or temporary) in the vegetation of these floodplains was made. It was found that floodplain-mainstem elemental fluxes make a significant contribution to the dissolved flux of the Amazon River. This study is part of the Brazilian_French joint research program Hybam (Hydrology and Geochemistry of the Amazonian Basin).

Intercomparison of regional-scale hydrological models and climate change impacts projected for 12 large river basins worldwide—a synthesis

NASA Astrophysics Data System (ADS)

Krysanova, Valentina; Vetter, Tobias; Eisner, Stephanie; Huang, Shaochun; Pechlivanidis, Ilias; Strauch, Michael; Gelfan, Alexander; Kumar, Rohini; Aich, Valentin; Arheimer, Berit; Chamorro, Alejandro; van Griensven, Ann; Kundu, Dipangkar; Lobanova, Anastasia; Mishra, Vimal; Plötner, Stefan; Reinhardt, Julia; Seidou, Ousmane; Wang, Xiaoyan; Wortmann, Michel; Zeng, Xiaofan; Hattermann, Fred F.

2017-10-01

An intercomparison of climate change impacts projected by nine regional-scale hydrological models for 12 large river basins on all continents was performed, and sources of uncertainty were quantified in the framework of the ISIMIP project. The models ECOMAG, HBV, HYMOD, HYPE, mHM, SWAT, SWIM, VIC and WaterGAP3 were applied in the following basins: Rhine and Tagus in Europe, Niger and Blue Nile in Africa, Ganges, Lena, Upper Yellow and Upper Yangtze in Asia, Upper Mississippi, MacKenzie and Upper Amazon in America, and Darling in Australia. The model calibration and validation was done using WATCH climate data for the period 1971-2000. The results, evaluated with 14 criteria, are mostly satisfactory, except for the low flow. Climate change impacts were analyzed using projections from five global climate models under four representative concentration pathways. Trends in the period 2070-2099 in relation to the reference period 1975-2004 were evaluated for three variables: the long-term mean annual flow and high and low flow percentiles Q 10 and Q 90, as well as for flows in three months high- and low-flow periods denoted as HF and LF. For three river basins: the Lena, MacKenzie and Tagus strong trends in all five variables were found (except for Q 10 in the MacKenzie); trends with moderate certainty for three to five variables were confirmed for the Rhine, Ganges and Upper Mississippi; and increases in HF and LF were found for the Upper Amazon, Upper Yangtze and Upper Yellow. The analysis of projected streamflow seasonality demonstrated increasing streamflow volumes during the high-flow period in four basins influenced by monsoonal precipitation (Ganges, Upper Amazon, Upper Yangtze and Upper Yellow), an amplification of the snowmelt flood peaks in the Lena and MacKenzie, and a substantial decrease of discharge in the Tagus (all months). The overall average fractions of uncertainty for the annual mean flow projections in the multi-model ensemble applied for all basins were 57% for GCMs, 27% for RCPs, and 16% for hydrological models.

Shifts in the Budyko curve over the past decade in the Amazon basin

NASA Astrophysics Data System (ADS)

Maeda, E. E.; Ma, X.; Liu, Y.; Huete, A. R.

2017-12-01

The Amazon basin has experienced extensive forest loss during the past decades. These changes can exert significant impact on regional water and energy budget, as well as other environmental processes. Here we evaluated how forest loss in the Madeira and Tapajós River basins, between 2002 and 2015, affected the Budyko relationship. The Budyko framework describes the links between climate and hydrological components, where evapotranspiration (ET) is limited by the supply of either water or energy. The framework is composed by two components, the dryness index (DI) and the evaporative index (EI). The DI determines the type and degree of limitation, with values lower than 1 represent energy-limited condition and values higher than 1, water-limited. The EI describes the partitioning of rainfall (P) into ET and runoff (R), with higher values indicating a larger proportion of ET. In this study, we use a modified version of the Budyko framework, which accounts for intra-annual changes in water storage (dS). Hence, the effective rainfall is represented by P-dS, so that EI=ET/(P-dS) and the DI= PET/(P-dS). We show that the Madeira and Tapajós River basins have lost approximately 60000 km2 and 50000km2 of forested area by 2015, respectively. Our results indicate that these changes caused a subtle shift in the Budyko curve in both basins. At the Madeira basin, a reduction in the DI indicate a shift towards lower water limitation, while decreasing EI indicate that a higher proportion of P is being converted into runoff. At the Tapajós basin, we also observe an overall decrease in the DI, but no significant trends in the evaporative index was observed. We expect that the observed shifts provide a new insight on the Amazon forest responses to changes in climate and land use. Further studies will focus in identifying the biophysical mechanisms driving these shifts, as well as seasonal aspects of the changes.

Using remote sensing for validation of a large scale hydrologic and hydrodynamic model in the Amazon

NASA Astrophysics Data System (ADS)

Paiva, R. C.; Bonnet, M.; Buarque, D. C.; Collischonn, W.; Frappart, F.; Mendes, C. B.

2011-12-01

We present the validation of the large-scale, catchment-based hydrological MGB-IPH model in the Amazon River basin. In this model, physically-based equations are used to simulate the hydrological processes, such as the Penman Monteith method to estimate evapotranspiration, or the Moore and Clarke infiltration model. A new feature recently introduced in the model is a 1D hydrodynamic module for river routing. It uses the full Saint-Venant equations and a simple floodplain storage model. River and floodplain geometry parameters are extracted from SRTM DEM using specially developed GIS algorithms that provide catchment discretization, estimation of river cross-sections geometry and water storage volume variations in the floodplains. The model was forced using satellite-derived daily rainfall TRMM 3B42, calibrated against discharge data and first validated using daily discharges and water levels from 111 and 69 stream gauges, respectively. Then, we performed a validation against remote sensing derived hydrological products, including (i) monthly Terrestrial Water Storage (TWS) anomalies derived from GRACE, (ii) river water levels derived from ENVISAT satellite altimetry data (212 virtual stations from Santos da Silva et al., 2010) and (iii) a multi-satellite monthly global inundation extent dataset at ~25 x 25 km spatial resolution (Papa et al., 2010). Validation against river discharges shows good performance of the MGB-IPH model. For 70% of the stream gauges, the Nash and Suttcliffe efficiency index (ENS) is higher than 0.6 and at Óbidos, close to Amazon river outlet, ENS equals 0.9 and the model bias equals,-4.6%. Largest errors are located in drainage areas outside Brazil and we speculate that it is due to the poor quality of rainfall datasets in these areas poorly monitored and/or mountainous. Validation against water levels shows that model is performing well in the major tributaries. For 60% of virtual stations, ENS is higher than 0.6. But, similarly, largest errors are also located in drainage areas outside Brazil, mostly Japurá River, and in the lower Amazon River. In the latter, correlation with observations is high but the model underestimates the amplitude of water levels. We also found a large bias between model and ENVISAT water levels, ranging from -3 to -15 m. The model provided TWS in good accordance with GRACE estimates. ENS values for TWS over the whole Amazon equals 0.93. We also analyzed results in 21 sub-regions of 4 x 4°. ENS is smaller than 0.8 only in 5 areas, and these are found mostly in the northwest part of the Amazon, possibly due to same errors reported in discharge results. Flood extent validation is under development, but a previous analysis in Brazilian part of Solimões River basin suggests a good model performance. The authors are grateful for the financial and operational support from the brazilian agencies FINEP, CNPq and ANA and from the french observatories HYBAM and SOERE RBV.

Modeling Surface Water Dynamics in the Amazon Basin Using Mosart-Inundation-v1.0: Impacts of Geomorphological Parameters and River Flow Representation

NASA Technical Reports Server (NTRS)

Luo, Xiangyu; Li, Hong-Yi; Leung, Ruby; Tesfa, Teklu K.; Getirana, Augusto; Papa, Fabrice; Hess, Laura L.

2017-01-01

Surface water dynamics play an important role in water, energy and carbon cycles of the Amazon Basin. A macro-scale inundation scheme was integrated with a surface-water transport model and the extended model was applied in this vast basin. We addressed the challenges of improving basin-wide geomorphological parameters and river flow representation for 15 large-scale applications. Vegetation-caused biases embedded in the HydroSHEDS DEM data were alleviated by using a vegetation height map of about 1-km resolution and a land cover dataset of about 90-m resolution. The average elevation deduction from the DEM correction was about 13.2 m for the entire basin. Basin-wide empirical formulae for channel cross-sectional geometry were adjusted based on local information for the major portion of the basin, which could significantly reduce the cross-sectional area for the channels of some subregions. The Manning roughness coefficient of the channel 20 varied with the channel depth to reflect the general rule that the relative importance of riverbed resistance in river flow declined with the increase of river size. The entire basin was discretized into 5395 subbasins (with an average area of 1091.7 km2), which were used as computation units. The model was driven by runoff estimates of 14 years (1994 2007) generated by the ISBA land surface model. The simulated results were evaluated against in situ streamflow records, and remotely sensed Envisat altimetry data and GIEMS inundation data. The hydrographs were reproduced fairly well for the majority of 25 13 major stream gauges. For the 11 subbasins containing or close to 11 of the 13 gauges, the timing of river stage fluctuations was captured; for most of the 11 subbasins, the magnitude of river stage fluctuations was represented well. The inundation estimates were comparable to the GIEMS observations. Sensitivity analyses demonstrated that refining floodplain topography, channel morphology and Manning roughness coefficients, as well as accounting for backwater effects could evidently affect local and upstream inundation, which consequently affected flood waves and inundation of the downstream 30 area. It was also shown that the river stage was sensitive to local channel morphology and Manning roughness coefficients, as well as backwater effects. The understanding obtained in this study could be helpful to improving modeling of surface hydrology in basins with evident inundation, especially at regional or larger scales.

Historical and Present Day Mercury Contamination From Gold Mining in Three Feeding Guilds of Bats From the Peruvian Amazon

NASA Astrophysics Data System (ADS)

Kumar, A.; Divoll, T.

2014-12-01

Miners in many countries use mercury as an amalgam to separate gold from river sediments. In the last twenty years the price of gold has risen and the number of small-scale, artisanal gold mining operations in the Amazon basin have also increased. The influx of mercury into natural river systems has detrimental consequences for the surrounding ecosystem and for organisms, particularly those at higher trophic levels. Toxic mercury levels have been shown to impair reproductive, neurological and behavioral functioning of organisms. I used bats (Chiroptera) as a mammalian model system to study mercury contamination and accumulation due to gold mining from field caught and museum collection specimens in Amazonian Perú and showed that: (1) Total mercury concentrations in Amazonian bat species have increased over time since the 1920's; (2) Bat species from sites with current active mining have higher concentrations of mercury than non-mining sites, with some species having levels exceeding those considered toxic for mammals; (3) Higher trophic levels of bats (piscivores and insectivores) bioaccumulate more mercury than bats of lower trophic levels (frugivores); (4) Bats located in present day uncontaminated sites have the same mercury levels as bats collected in the 1920's from the Amazon basin. The variety of bat feeding guilds allowed for a comparison of how mercury accumulation is affected by diet within one taxonomic order. The novel use of museum specimens allowed for a look back into the historical timeline of mercury contamination in the Amazon basin. Bats represent a new and exciting study system since, like humans, they are mammals and should therefore show similar neurochemical and behavioral responses to this toxic element.

Methane emissions to the troposphere from the Amazon floodplain

NASA Technical Reports Server (NTRS)

Devol, Allen H.; Richey, Jeffrey E.; Clark, Wayne A.; King, Stagg L.; Martinelli, Luiz A.

1988-01-01

The magnitudes of CH4 emissions to the troposphere from the Amazon River floodplain and the mechanism of these emissions were investigated using the data of 94 individual flux measurements made along a 1700-km stretch of the river during July/August 1985. The overall average rate of CH4 emission from wetlands was found to be 390 mg CH4/sq m per day, with the highest emissions (590 mg CH4/sq m per day) attributed to the water surfaces covered by aquatic macrophytes. Ebullition was the dominant mechanism of emission, accounting for 85 percent of the total. Surface-water CH4 concentrations were highly supersaturated, averaging 6.4 micromolar. The annual emission of CH4 from the Amazon Basin to the troposphere, estimated from the area and the known emission rate, is about 10 CH4 Tg/yr, indicating the importance of the area in the global atmospheric CH4 cycle.

An inventory of coastal freshwater fishes from Amapá highlighting the occurrence of eight new records for Brazil

PubMed Central

Melo, Bruno F.; Benine, Ricardo C.; Britzke, Ricardo; Gama, Cecile S.; Oliveira, Claudio

2016-01-01

Abstract The Amazon Basin occupies a vast portion of northern South America and contains some of the highest species richness in the world. The northern Brazilian state of Amapá is delimited by the Amazonas River to the south, the Oyapock River to the northern boundary with French Guyana, and the Atlantic northeastern coast to Amazon estuary. Despite several expeditions to the Amazon in recent decades, little is known about the freshwater ichthyofauna from Amapá, with records limited to local inventories and species descriptions. This paper presents a compilation of the freshwater fish diversity sampled in fifteen sites covering two major Amapá ecoregions during the dry season of 2015. 120 species representing eight orders and 40 families are reported upon in this work. Eight species appear for the first time in the Brazilian territory providing new information for future conservation status evaluations. PMID:27551225

Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning

NASA Astrophysics Data System (ADS)

Victoria, R. L.; Ballester, V. R.; Krushe, A. V.; Richey, J. E.; Aufdenkampe, A. K.; Kavaguishi, N. L.; Gomes, B. M.; Victoria, D. D.; Montebello, A. A.; Niell, C.; Deegan, L.

2004-12-01

In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amazônia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability observed in surface water ions and nutrients concentrations. In small rivers, forest clearing can increase cations, P and C inputs. P and light are the main PPL limiting factors in forested streams, while in pasture streams N becomes limiting. P export to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Pasture streams on Oxisols have very low P export, while on Ultisols P export is increased. Conversions of forest to pasture leads to extensive growth of in channel Paspalum resulting in higher DOC concentrations and respiration rates. Pasture streams have higher DOC fluxes when compared to the forest ones. In pasture areas the soil are compacted, there is less infiltration and higher surface run off, leaching soil superficial layers and caring more DOC to the streams. In forest areas infiltration is deeper into the soils and canopy interaction is higher. Mineralogy and soil properties are key factors determining exports of nutrients to streams. Therefore, land use change effects on nutrient export from terrestrial to aquatic ecosystems and the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Impacts of hydroelectric dams on alluvial riparian plant communities in Eastern Brazilian Amazonian.

PubMed

Ferreira, Leandro Valle; Cunha, Denise A; Chaves, Priscilla P; Matos, Darley C L; Parolin, Pia

2013-09-01

The major rivers of the Amazon River basin and their biota are threatened by the planned construction of large hydroelectric dams that are expected to have strong impacts on floodplain plant communities. The present study presents forest inventories from three floodplain sites colonized by alluvial riparian vegetation in the Tapajós, Xingu and Tocantins River basins in eastern Amazonian. Results indicate that tree species of the highly specialized alluvial riparian vegetation are clearly distinct among the three river basins, although they are not very distinct from each other and environmental constraints are very similar. With only 6 of 74 species occurring in all three inventories, most tree and shrub species are restricted to only one of the rivers, indicating a high degree of local distribution. Different species occupy similar environmental niches, making these fragile riparian formations highly valuable. Conservation plans must consider species complementarily when decisions are made on where to place floodplain forest conservation units to avoid the irreversible loss of unique alluvial riparian vegetation biodiversity.

Distribution of phlebotomine sand fly genotypes (Lutzomyia shannoni, Diptera: Psychodidae) across a highly heterogeneous landscape.

PubMed

Mukhopadhyay, J; Ghosh, K; Ferro, C; Munstermann, L E

2001-03-01

Genetic variability of eight Colombian field populations and two laboratory colonies of a tropical forest sand fly, Lutzomyia shannoni Dyar, was assessed by comparing allozyme frequencies at 20 enzyme loci. Substantial genetic variability was noted in all strains, with mean heterozygosities of 13-21% and alleles per locus of 2.0-2.8. Four loci were monomorphic. Six populations in north and central Colombia showed close genetic similarity (Nei's distances, 0.01-0.09), despite mountainous environment, discontinuous forest habitat, and elevation differences from 125 to 1,220 m. Two samples representing the Orinoco (near Villavicencio) and Amazon (near Leticia) river basins were similar (Nei's distance, 0.08) but diverged substantially from the central six samples (Nei's distances, 0.26-0.40). Although the range of L. shannoni extends from the southeastern United States to northern Argentina, three genetically distinct, geographically discrete, groups were discerned by the current analysis: Orinoco-Amazon river basins, north-central Colombia, and eastern United States.

Oxidative mitigation of aquatic methane emissions in large Amazonian rivers.

PubMed

Sawakuchi, Henrique O; Bastviken, David; Sawakuchi, André O; Ward, Nicholas D; Borges, Clovis D; Tsai, Siu M; Richey, Jeffrey E; Ballester, Maria Victoria R; Krusche, Alex V

2016-03-01

The flux of methane (CH4 ) from inland waters to the atmosphere has a profound impact on global atmospheric greenhouse gas (GHG) levels, and yet, strikingly little is known about the dynamics controlling sources and sinks of CH4 in the aquatic setting. Here, we examine the cycling and flux of CH4 in six large rivers in the Amazon basin, including the Amazon River. Based on stable isotopic mass balances of CH4 , inputs and outputs to the water column were estimated. We determined that ecosystem methane oxidation (MOX) reduced the diffusive flux of CH4 by approximately 28-96% and varied depending on hydrologic regime and general geochemical characteristics of tributaries of the Amazon River. For example, the relative amount of MOX was maximal during high water in black and white water rivers and minimal in clear water rivers during low water. The abundance of genetic markers for methane-oxidizing bacteria (pmoA) was positively correlated with enhanced signals of oxidation, providing independent support for the detected MOX patterns. The results indicate that MOX in large Amazonian rivers can consume from 0.45 to 2.07 Tg CH4 yr(-1) , representing up to 7% of the estimated global soil sink. Nevertheless, climate change and changes in hydrology, for example, due to construction of dams, can alter this balance, influencing CH4 emissions to atmosphere. © 2015 John Wiley & Sons Ltd.

Estimation of erosion and sedimentation yield in the Ucayali river basin, a Peruvian tributary of the Amazon River, using ground and satellite methods

NASA Astrophysics Data System (ADS)

Santini, William; Martinez, Jean-Michel; Guyot, Jean-Loup; Espinoza, Raul; Vauchel, Philippe; Lavado, Waldo

2014-05-01

Since 2003, the works of HYBAM observatory (www.ore-hybam.org) has allowed to quantify with accuracy, precision and over a long period Amazon's main rivers discharges and sediments loads. In Peru, a network of 8 stations is regularly gauged and managed in association with the national meteorological and Hydrological service (SENAMHI), the UNALM (National Agrological University of La Molina) and the National Water Agency (ANA). Nevertheless, some current processes of erosion and sedimentation in the foreland basins are still little known, both in volumes and in localization. The sedimentary contributions of Andean tributaries could be there considerable, masking a very strong sedimentation in subsidence zones localized between the control points of the HYBAM's network. The development of spatial techniques such as the Altimetry and reflectance measurement allows us today to complete the ground's network: HYBAM's works have allowed establishing a relation between surface concentration and reflectance in Amazonian rivers (Martinez et al., 2009, Espinoza et al., 2012) and reconstituting water levels series (Calmant et al., 2006, 2008). If the difficulty of calibration of these techniques increases towards the upstream, their use can allow a first characterization of the tributaries contributions and sedimentation zones. At world level, erosion and sedimentation yields in the upper Ucayali are exceptional, favored by a marked seasonality in this region (Espinoza et al., 2009, Lavado, 2010, Pépin et al., 2010) and the presence of cells of extreme precipitation ("Hotspots") (Johnson et al., 1976, Espinoza et al, 2009a). The upper Ucayali drainage basin is a Piggyback where the River run with a low slope, parallel to the Andean range, deposing by gravity hundred millions a year of sands, silts and clays. In this work, we thus propose an estimation of sedimentation and erosion yield in the Ucayali river basin using ground and satellite methods.

Understanding the Amazon Hydrology for Sustainable Hydropower Development

NASA Astrophysics Data System (ADS)

Pokhrel, Y. N.; Chaudhari, S. N.

2017-12-01

Construction of 147 new hydropower dams, many of which are large, has been proposed in the Amazon river basin, despite the continuous stacking of negative impacts from the existing ones. These dams are continued to be built in a way that disrupts river ecology, causes large-scale deforestation, and negatively affects both the food systems nearby and downstream communities. In this study, we explore the impacts of the existing and proposed hydropower dams on the hydrological fluxes across the Amazonian Basin by incorporating human impact modules in an extensively validated regional hydrological model called LEAF-Hydro-Flood (LHF). We conduct two simulations, one in offline mode, forced by observed meteorological data for the historical period of 2000-2016 and the other in a coupled mode using the Weather Research and Forecasting (WRF) regional climate model. We mainly analyze terrestrial water storage and streamflow changes during the period of dam operations with and without human impacts. It is certain that the Amazon will undergo some major hydrological changes such as decrease in streamflow downstream in the coming decades caused due to these proposed dams. This study helps us understand and represent processes in a predictable manner, and provides the ability to evaluate future scenarios with dams and other major human influences while considering climate change in the basin. It also provides important insights on how to redesign the hydropower systems to make them truly renewable in terms of energy production, hydrology and ecology.

Morphosedimentary dynamics of the Madeira River in Brazil

NASA Astrophysics Data System (ADS)

Bonthius, C.; Latrubesse, E. M.; Abad, J. D.

2012-12-01

The Madeira River, the largest tributary of the Amazon River in terms of water discharge, offers an opportunity to investigate extrinsic and intrinsic controls on channel morphology and pattern. With an average annual discharge of approximately 32,000 m3/s, the Madeira River is a mega-river with a unique anabranching channel pattern, a specific stream power of approximately 20 W/m2, and a width-depth ratio that ranges between 30 and 64 (Latrubesse 2008). Not only of interest for its size and discharge, the Madeira River is also a critical ecological component of the overall Amazon Basin. As the greatest contributor of sediment to the Amazon fluvial system, the Madeira River transports approximately 330 tons/km2 annually, which is about half of the Amazon River's total sediment output (Latrubesse et al 2005). This poster presents analyses of the morphology of the Madeira River and of data collected from a field campaign carried out in summer 2011 on a stretch between Porto Velho and Humaitá in Brazil. Using historical radar and satellite imagery of consistent spatial and temporal resolution, the stability and morphology of in-channel landforms are assessed and quantified. Stretches characterized by vegetated islands demonstrated overall stability; these features were temporally persistent and showed little, if any, change in area over a period of forty years. Sand bars, or un-vegetated sediment, are highly mutable features with numbers that vary between nine and twenty-seven in a same single stretch over time. The main channel also demonstrated stability in its morphology, while the presence and activation of secondary channels varied. Velocity maps and an analysis of secondary currents are presented from data collected from bathymetric surveys and an Acoustic Doppler Current Profiler (ADCP) from Porto Velho and Humaitá. Hydraulic factors in two complex and geologically controlled river reaches, a mainly meandering reach with a tendency to anabranch and a purely anabranching reach, are compared, offering insight into the roles of these intrinsic variables in the fluvial system. Sediment samples collected during the field campaign were analyzed for grain size composition. Connections between median grain size (d50), hydraulic variables, and channel morphology are discussed in context of the resulting channel pattern. These analyses also shed light on differences that exist between the Madeira River and other large fluvial systems. Currently endangered by impoundment with hydroelectric projects expected to be fully operational by January of 2013, the Madeira River is a mega-river that faces irreversible change due to human impact. As a result, the collection and analysis of data of current baseline conditions is of timely and necessary importance to assess geomorphologic and hydrologic changes in the fluvial system, model the river's behavior under a variety of natural and anthropogenic conditions, and inform management plans for the Madeira River and Amazon River basins. References Latrubesse, E.M. 2008. Patterns of anabranching channels: the ultimate end-member adjustment of mega-rivers. Geomorphology, 101, pp. 130-145. Latrubesse, E.M., Stevaux, J.C. and Sinha, R. 2005. Tropical Rivers. Geomorphology, 70, pp. 187-206.

Assessment of the Relationship between Andean Ice Core Precipitation Indicators and Amazon River Discharge

NASA Astrophysics Data System (ADS)

Johnson, N.; Alsdorf, D.; Thompson, L.; Mosley-Thompson, E.; Melack, J.

2006-12-01

Prior to the last 100 years, there is a significant lack of hydrologic knowledge for the Amazon Basin. A 100- year record of discharge from the city of Manaus, located at the confluence of the Solimoes and Negro rivers, is the most complete record for the basin. Inundated wetlands play a key role in carbon out-gassing to the atmosphere whereas discharge from the Amazon River contributes about 20% of the total freshwater flux delivered to the world's oceans. As discharge (Q) and inundation are directly related to precipitation, we are developing a method to extend our understanding of Q and inundation into the 19^{th} century. Using proxy data preserved in Andean glaciers and ice caps and recovered from ice cores, annually resolved histories of δ^{18)O and mass accumulation are available. The latter is a proxy for local precipitation amount whereas δ18O is influenced by continental scale processes (i.e., evaporation, convection) as well as by temperature and hence, by varying climate regimes. We have correlated the accumulation and δ18O records from Core 1 drilled on the Quelccaya ice-cap in the southern Andes of Peru with the Manaus discharge data. As ice core annual layers correspond to the thermal year (in Peru, July to June of the following year) and the discharge records are kept daily (January to December), we averaged 365 days of Q data seeking the optimal correlation for each start and end date. The best statistical relationship between δ18O and Q (r = -0.41, p = < 0.001) is attained when Q is averaged from March 16 to March 15 of the following year. We also correlated 23 years of ENSO events, which are linked to both Amazon River discharge and ice core δ18O (r = -0.60, p = < 0.001). These linear relationships are used to create Amazon discharge for the 20^{th} century and to extrapolate Q into the 19^{th} century. Previously developed relationships between Q and mainstem inundated area are then used to estimate inundated area along the main Amazon channel for the past 200 years. The ice core-derived estimate of inundated area for the past 100 years compares well with the previous and more straightforward estimates based on discharge and remote sensing data.

Proliferation of Hydroelectric Dams in the Andean Amazon and Implications for Andes-Amazon Connectivity

PubMed Central

Finer, Matt; Jenkins, Clinton N.

2012-01-01

Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics. PMID:22529979

Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity.

PubMed

Finer, Matt; Jenkins, Clinton N

2012-01-01

Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics.

New Agricultural Settlement, Meheba River, Zambia, Africa

NASA Technical Reports Server (NTRS)

1990-01-01

This infra-red view of a new settlement along the Meheba River, Zambia, Africa (12.5S, 26.0E) resembles the resettlement clusters in the Amazon basin of Brazil. However, this settlement is on savanna land not a tropical forest region, so relatively little land clearing was required. The familiar pattern of small single family plots, no large commercial fields, along the branches of a herringbone road network is evident.

The influence of changes in lifestyle and mercury exposure in riverine populations of the Madeira River (Amazon Basin) near a hydroelectric project.

PubMed

Hacon, Sandra S; Dórea, José G; Fonseca, Márlon de F; Oliveira, Beatriz A; Mourão, Dennys S; Ruiz, Claudia M V; Gonçalves, Rodrigo A; Mariani, Carolina F; Bastos, Wanderley R

2014-02-26

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.

Testing conceptual and physically based soil hydrology schemes against observations for the Amazon Basin

NASA Astrophysics Data System (ADS)

Guimberteau, M.; Ducharne, A.; Ciais, P.; Boisier, J. P.; Peng, S.; De Weirdt, M.; Verbeeck, H.

2014-06-01

This study analyzes the performance of the two soil hydrology schemes of the land surface model ORCHIDEE in estimating Amazonian hydrology and phenology for five major sub-basins (Xingu, Tapajós, Madeira, Solimões and Negro), during the 29-year period 1980-2008. A simple 2-layer scheme with a bucket topped by an evaporative layer is compared to an 11-layer diffusion scheme. The soil schemes are coupled with a river routing module and a process model of plant physiology, phenology and carbon dynamics. The simulated water budget and vegetation functioning components are compared with several data sets at sub-basin scale. The use of the 11-layer soil diffusion scheme does not significantly change the Amazonian water budget simulation when compared to the 2-layer soil scheme (+3.1 and -3.0% in evapotranspiration and river discharge, respectively). However, the higher water-holding capacity of the soil and the physically based representation of runoff and drainage in the 11-layer soil diffusion scheme result in more dynamic soil water storage variation and improved simulation of the total terrestrial water storage when compared to GRACE satellite estimates. The greater soil water storage within the 11-layer scheme also results in increased dry-season evapotranspiration (+0.5 mm d-1, +17%) and improves river discharge simulation in the southeastern sub-basins such as the Xingu. Evapotranspiration over this sub-basin is sustained during the whole dry season with the 11-layer soil diffusion scheme, whereas the 2-layer scheme limits it after only 2 dry months. Lower plant drought stress simulated by the 11-layer soil diffusion scheme leads to better simulation of the seasonal cycle of photosynthesis (GPP) when compared to a GPP data-driven model based on eddy covariance and satellite greenness measurements. A dry-season length between 4 and 7 months over the entire Amazon Basin is found to be critical in distinguishing differences in hydrological feedbacks between the soil and the vegetation cover simulated by the two soil schemes. On average, the multilayer soil diffusion scheme provides little improvement in simulated hydrology over the wet tropical Amazonian sub-basins, but a more significant improvement is found over the drier sub-basins. The use of a multilayer soil diffusion scheme might become critical for assessments of future hydrological changes, especially in southern regions of the Amazon Basin where longer dry seasons and more severe droughts are expected in the next century.

Isotopic values of the Amazon headwaters in Peru: comparison of the wet upper Río Madre de Dios watershed with the dry Urubamba-Apurimac river system.

PubMed

Lambs, L; Horwath, A; Otto, T; Julien, F; Antoine, P-O

2012-04-15

The Amazon River is a huge network of long tributaries, and little is known about the headwaters. Here we present a study of one wet tropical Amazon forest side, and one dry and cold Atiplano plateau, originating from the same cordillera. The aim is to see how this difference affects the water characteristics. Different kind of water (spring, lake, river, rainfall) were sampled to determine their stable isotopes ratios (oxygen 18/16 and hydrogen 2/1) by continuous flow isotope ratio mass spectrometry (IRMS). These ratios coupled with chemical analysis enabled us to determine the origin of the water, the evaporation process and the water recycling over the Amazon plain forest and montane cloud forest. Our study shows that the water flowing in the upper Madre de Dios basin comes mainly from the foothill humid forest, with a characteristic water recycling process signature, and not from higher glacier melt. On the contrary, the water flowing in the Altiplano Rivers is mainly from glacier melts, with a high evaporation process. This snow and glacier are fed mainly by Atlantic moisture which transits over the large Amazon forest. The Atlantic moisture and its recycling over this huge tropical forest display a progressive isotopic gradient, as a function of distance from the ocean. At the level of the montane cloud forest and on the altiplano, respectively, additional water recycling and evaporation occur, but they are insignificant in the total water discharge. Copyright © 2012 John Wiley & Sons, Ltd.

Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management

PubMed Central

Hegg, Jens C.; Giarrizzo, Tommaso; Kennedy, Brian P.

2015-01-01

Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world’s largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some of the longest freshwater fish migrations in the world, travelling from the Amazon River estuary to the Andes foothills. These species are important apex predators in the main stem rivers of the Amazon Basin and make up the region’s largest fishery. They are also the only species to utilize the entire Amazon Basin to complete their life cycle. Studies indicate both that the fisheries may be declining due to overfishing, and that the proposed and completed dams in their upstream range threaten spawning migrations. Despite this, surprisingly little is known about the details of these species’ migrations, or their life history. Otolith microchemistry has been an effective method for quantifying and reconstructing fish migrations worldwide across multiple spatial scales and may provide a powerful tool to understand the movements of Amazonian migratory catfish. Our objective was to describe the migratory behaviors of the three most populous and commercially important migratory catfish species, Dourada (Brachyplatystoma rousseauxii), Piramutaba (Brachyplatystoma vaillantii), and Piraíba (Brachyplatystoma filamentosum). We collected fish from the mouth of the Amazon River and the Central Amazon and used strontium isotope signatures (87Sr/86Sr) recorded in their otoliths to determine the location of early rearing and subsequent. Fish location was determined through discriminant function classification, using water chemistry data from the literature as a training set. Where water chemistry data was unavailable, we successfully in predicted 87Sr/86Sr isotope values using a regression-based approach that related the geology of the upstream watershed to the Sr isotope ratio. Our results provide the first reported otolith microchemical reconstruction of Brachyplatystoma migratory movements in the Amazon Basin. Our results indicate that juveniles exhibit diverse rearing strategies, rearing in both upstream and estuary environments. This contrasts with the prevailing understanding that juveniles rear in the estuary before migrating upstream; however, it is supported by some fisheries data that has indicated the presence of alternate spawning and rearing life-histories. The presence of alternate juvenile rearing strategies may have important implications for conservation and management of the fisheries in the region. PMID:26153984

Andes Altiplano, South America

NASA Image and Video Library

1991-08-11

STS043-151-159 (2-11 August 1991) --- This photograph looks westward over the high plateau of the southern Peruvian Andes west and north of Lake Titicaca (not in field of view). Lima, Peru lies under the clouds just north of the clear coastal area. Because the high Andes have been uplifted 10,000 to 13,000 feet during the past 20 million years, the rivers which cut down to the Pacific Ocean have gorges almost that deep, such as the Rio Ocona at the bottom of the photograph. The eastern slopes of the Andes are heavily forested, forming the headwaters of the Amazon system. Smoke from burning in the Amazon basin fills river valleys on the right side of the photograph. A Linhof camera was used to take this view.

Amazon Rain Forest Classification Using J-ERS-1 SAR Data

NASA Technical Reports Server (NTRS)

Freeman, A.; Kramer, C.; Alves, M.; Chapman, B.

1994-01-01

The Amazon rain forest is a region of the earth that is undergoing rapid change. Man-made disturbance, such as clear cutting for agriculture or mining, is altering the rain forest ecosystem. For many parts of the rain forest, seasonal changes from the wet to the dry season are also significant. Changes in the seasonal cycle of flooding and draining can cause significant alterations in the forest ecosystem.Because much of the Amazon basin is regularly covered by thick clouds, optical and infrared coverage from the LANDSAT and SPOT satellites is sporadic. Imaging radar offers a much better potential for regular monitoring of changes in this region. In particular, the J-ERS-1 satellite carries an L-band HH SAR system, which via an on-board tape recorder, can collect data from almost anywhere on the globe at any time of year.In this paper, we show how J-ERS-1 radar images can be used to accurately classify different forest types (i.e., forest, hill forest, flooded forest), disturbed areas such as clear cuts and urban areas, and river courses in the Amazon basin. J-ERS-1 data has also shown significant differences between the dry and wet season, indicating a strong potential for monitoring seasonal change. The algorithm used to classify J-ERS-1 data is a standard maximum-likelihood classifier, using the radar image local mean and standard deviation of texture as input. Rivers and clear cuts are detected using edge detection and region-growing algorithms. Since this classifier is intended to operate successfully on data taken over the entire Amazon, several options are available to enable the user to modify the algorithm to suit a particular image.

Hydrological Controls of Riverine Ecosystems of the Napo River (Amazon Basin): Implications for the Management and Conservation of Biodiversity

NASA Astrophysics Data System (ADS)

Celi, J. E.; Hamilton, S. K.

2013-12-01

Scientific understanding of neotropical floodplains comes mainly from work on large rivers with predictable seasonal flooding regimes. Less studied rivers and floodplains on the Andean-Amazon interface are distinct in their hydrology, with more erratic flow regimes, and thus ecological roles of floodplain inundation differ in those ecosystems. Multiple and unpredictable flooding events control inundation of floodplains, with important implications for fish and wildlife, plant communities, and human activities. Wetlands along the river corridor exist across a continuum from strong river control to influence only by local waters, with the latter often lying on floodplain paleoterraces. The goal of this study was to understand the hydrological interactions and habitat diversity of the Napo River, a major Amazon tributary that originates in the Andes and drains exceptionally biodiverse Andean foreland plains. This river system is envisioned by developers as an industrial waterway that would require hydrological alterations and affect floodplain ecosystems. Water level regimes of the Napo River and its associated environments were assessed using networks of data loggers that recorded time under water across transects extending inland from the river across more than 100 sites and for up to 5 years. These networks also included rising stage samplers that collected flood water samples for determination of their origin (i.e., Andean rivers vs. local waters) based on hydrochemical composition. In addition, this work entails a classification of aquatic environments of the Napo Basin using an object-oriented remote sensing approach to simultaneously analyze optical and radar satellite imagery and digital elevation models to better assess the extent and diversity of flooded environments. We found out a continuum of hydrological regimes and aquatic habitats along the Napo River floodplains that are linked to the river hydrology in different degrees. Overall, environments that are proximal or that have high hydrological connectivity are riverine controlled versus systems that are distal or that have less or no connectivity that rely on rainwater or local runoff as a source of flooding. Outcomes of this research gave us insight on the extent and diversity of aquatic habitats of the Napo River, the role that the river has on their ecohydrology, the potential effects of different hydrologic scenarios on these ecosystems, and the management measures that need to be considered to support conservation in the region.

Pre-Columbian urbanism, anthropogenic landscapes, and the future of the Amazon.

PubMed

Heckenberger, Michael J; Russell, J Christian; Fausto, Carlos; Toney, Joshua R; Schmidt, Morgan J; Pereira, Edithe; Franchetto, Bruna; Kuikuro, Afukaka

2008-08-29

The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a "galactic" form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity.

Viruses Surveillance Under Different Season Scenarios of the Negro River Basin, Amazonia, Brazil.

PubMed

Vieira, Carmen Baur; de Abreu Corrêa, Adriana; de Jesus, Michele Silva; Luz, Sérgio Luiz Bessa; Wyn-Jones, Peter; Kay, David; Vargha, Marta; Miagostovich, Marize Pereira

2016-03-01

The Negro River is located in the Amazon basin, the largest hydrological catchment in the world. Its water is used for drinking, domestic activities, recreation and transportation and water quality is significantly affected by anthropogenic impacts. The goals of this study were to determine the presence and concentrations of the main viral etiological agents of acute gastroenteritis, such as group A rotavirus (RVA) and genogroup II norovirus (NoV GII), and to assess the use of human adenovirus (HAdV) and JC polyomavirus (JCPyV) as viral indicators of human faecal contamination in the aquatic environment of Manaus under different hydrological scenarios. Water samples were collected along Negro River and in small streams known as igarapés. Viruses were concentrated by an organic flocculation method and detected by quantitative PCR. From 272 samples analysed, HAdV was detected in 91.9%, followed by JCPyV (69.5%), RVA (23.9%) and NoV GII (7.4%). Viral concentrations ranged from 10(2) to 10(6) GC L(-1) and viruses were more likely to be detected during the flood season, with the exception of NoV GII, which was detected only during the dry season. Statistically significant differences on virus concentrations between dry and flood seasons were observed only for RVA. The HAdV data provides a useful complement to faecal indicator bacteria in the monitoring of aquatic environments. Overall results demonstrated that the hydrological cycle of the Negro River in the Amazon Basin affects the dynamics of viruses in aquatic environments and, consequently, the exposure of citizens to these waterborne pathogens.

[Research Programs Conducted by the University of Virginia]. Part 1; Aquarius

NASA Technical Reports Server (NTRS)

Fuentes, Jose; Garstang, Michael; Macko, Stephen; Swap, Robert

2001-01-01

The hydrological cycle and the source of water vapor within the Amazon River Basin have important implications on questions of global thermal transport and regional ecological and socioeconomic sustainability. A three tiered approach taking advantage of satellite imagery, tipping buckets, and isotopic storm sampling at three basin sites was used to examine different aspects of regional meteoric water. By combining these techniques, it was possible to correlate observed storm structure with rain rates and intrastorm variations.

The role of fluvial sediment supply and river-mouth hydrology in the dynamics of the muddy, Amazon-dominated Amapá-Guianas coast, South America: A three-point research agenda

NASA Astrophysics Data System (ADS)

Anthony, Edward J.; Gardel, Antoine; Proisy, Christophe; Fromard, François; Gensac, Erwan; Peron, Christina; Walcker, Romain; Lesourd, Sandric

2013-07-01

The morphology and sediment dynamics of the 1500 km-long coast of South America between the mouths of the Amazon and the Orinoco Rivers are largely dependent on the massive suspended-sediment discharge of the Amazon, part of which is transported alongshore as mud banks. These mud banks have an overwhelming impact on the geology, the geomorphology, the ecology and the economy of this coast. Although numerous field investigations and remote sensing studies have considerably enhanced our understanding of the dynamics of this coast over the last three decades, much still remains to be understood of the unique functional mechanisms and processes driving its evolution. Among the themes that we deem as requiring further attention three come out as fundamental. The first concerns the mechanisms of formation of individual mud banks from mud streaming on the shelf off the mouth of the Amazon. An unknown quantity of the fluid mud generated by offshore estuarine front activity is transported shoreward and progressively forms mud banks on the Amapá coast, Brazil. The volume of each mud bank can contain from the equivalent of the annual mud supply of the Amazon to several times this annual sediment discharge. The mechanisms by which individual banks are generated from the Amazon turbidity maximum are still to be elucidated. Areas of research include regional mesoscale oceanographic conditions and mud supply from the Amazon. The second theme is that of variations in rates of migration of mud banks, which influence patterns of coastal accretion. Research emphasis needs to be placed on the analysis of both regional meteorological-hydrodynamic forcing and distant Atlantic forcing, as well as on the hydrology of the large rivers draining the Guyana Shield. The rivers appear to generate significant offshore deflection of mud banks in transit alongshore, through a hydraulic-groyne effect. This may favour both muddy accretion on the updrift coast and downdrift mud liquefaction with probably lessened muddy deposition. The third theme concerns sand supply by the Guiana Shield rivers. The rare sand deposits are important in providing sites for human settlements and routes and for nesting by marine turtles. The limited presence of sand bodies on this coast may reflect 'mud blanketing', a hypothesis that requires verification through high-resolution seismic analyses of shelf deposits and coring operations. The large Guiana Shield rivers, especially in Surinam and Guyana, have supplied sand for the construction of significant bands of cheniers, probably enhanced by the afore-mentioned downdrift hydraulic-groyne effect on hindered mud deposition. In all the three themes of this future research agenda, two central elements are the sediment input of the rivers of the Amazon basin, starting with the massive mud supply from the Amazon catchment itself, followed by sand inputs by the Guiana Shield rivers and their river-mouth effects on mud banks.

Landslides Are Common In The Amazon Rainforests Of SE Peru

NASA Astrophysics Data System (ADS)

Khanal, S. P.; Muttiah, R. S.; Janovec, J. P.

2005-12-01

The recent landslides in La Conchita, California, Mumbai, India, Ratnapura, Sri Lanka and Sugozu village, Turkey have dramatically illustrated prolonged rainfall on water induced change in soil shear stress. In these examples, the human footprint may have also erased or altered the natural river drainage from small to large scales. By studying patterns of landslides in natural ecosystems, government officials, policy makers, engineers, geologists and others may be better informed about likely success of prevention or amelioration programs in risk prone areas. Our study area in the Los Amigos basin in Amazon rainforests of Southeastern Peru, has recorded several hundred landslides. The area has no large human settlements. The basin is characterized by heavy rainfall, dense vegetation, river meander and uniform soils. Our objectives were: 1). Determine the spatial pattern of landslides using GIS and Remotely sensed data, 2). Model the statistical relationship between environmental variables and, 3). Evaluate influence of drainage on landscape and soil loss. GIS layers consisted of: 50cm aerial imagery, DEMs, digitized streams, soils, geology, rainfall from the TRMM satellite, and vegetation cover from the LANDSAT and MODIS sensors.

Projected increases in the annual flood pulse of the western Amazon

NASA Astrophysics Data System (ADS)

Zulkafli, Zed; Buytaert, Wouter; Manz, Bastian; Veliz Rosas, Claudia; Willems, Patrick; Lavado-Casimiro, Waldo; Guyot, Jean-Loup; Santini, William

2016-04-01

The impact of a changing climate on the Amazon basin is a subject of intensive research due to its rich biodiversity and the significant role of rain forest in carbon cycling. Climate change has also direct hydrological impact, and there have been increasing efforts to understand such dynamics at continental and subregional scales such as the scale of the western Amazon. New projections from the Coupled Model Inter- comparison Project Phase 5 (CMIP5) ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the river. Using extremes value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 years. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100- year return floods). These findings are in agreement with previously projected increases in high extremes under the Special Report on Emissions Scenarios (SRES) climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amid a growing literature that more strongly emphasises future droughts and their impact on the viability of the rain forest system over the greater Amazonia.

The Influence of Changes in Lifestyle and Mercury Exposure in Riverine Populations of the Madeira River (Amazon Basin) near a Hydroelectric Project

PubMed Central

Hacon, Sandra S.; Dórea, José G.; Fonseca, Márlon de F.; Oliveira, Beatriz A.; Mourão, Dennys S.; Ruiz, Claudia M. V.; Gonçalves, Rodrigo A.; Mariani, Carolina F.; Bastos, Wanderley R.

2014-01-01

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. PMID:24577285

Export of Nitrogen From the Yukon River Basin to the Bering Sea

NASA Astrophysics Data System (ADS)

Dornblaser, M. M.; Striegl, R. G.

2005-12-01

The US Geological Survey measured nitrogen export from the 831,400 km2 Yukon River basin during 2001-04 as part of a five year water quality study of the Yukon River and its major tributaries. Concentrations of NO2+NO3, NH4+DON, and particulate N were measured ~6 times annually during open water and once under ice cover at three locations on the Yukon River, and on the Porcupine and Tanana Rivers. Concentration and continuous flow data were used to generate daily and annual loads of N species. NH4 concentration was generally negligible when compared to DON concentration, allowing for comparison of the relative importance of DIN vs. DON export at various watershed scales. NO2 concentration was also small compared to NO3. At Pilot Station, the last site on the Yukon before it flows into the Yukon Delta and the Bering Sea, DIN, DON, and particulate N loads averaged 19.3 × 106 kg/yr, 52.6 × 106 kg/yr, and 39.1 × 106 kg/yr, respectively. Normalized for the watershed area at Pilot Station, corresponding N yields were 1.65, 4.52, and 3.35 mmol/m2/yr. DIN yield for the Yukon at Pilot Station is substantially less than the NO3 flux reported for tropical/temperate rivers such as the Amazon, the Yangtze, and the Mississippi. DIN yield in the upper Yukon River basin is similar to that of the Mackenzie and other arctic rivers, but increases substantially downstream. This is likely due to development around Fairbanks in the Tanana River basin. When compared to other headwater basins in the upper Yukon, the Tanana basin yields about four times more DIN and two times more particulate N, while DON yields are only slightly elevated.

Preliminary Characterization of Organic Geochemistry in the Fly-Strickland River System, Papua New Guinea

NASA Astrophysics Data System (ADS)

Alin, S. R.; Aalto, R.; Remington, S. M.; Richey, J. E.

2003-12-01

The Fly-Strickland fluvial dispersal system comprises one of the largest river basins in tropical Oceania, ranking among the top 20 rivers in the world for water and sediment discharge. From the New Guinea highlands, these rivers flow >1000 km across lowland tropical floodplains to the Gulf of Papua, with an average annual depth of runoff 100 times that of the Amazon. Within the system, the Strickland has greater sediment discharge and a steeper gradient than the Fly, providing an opportunity to investigate biogeochemical differences associated with particulate flux. For eight lowland sites across the Fly-Strickland river system, we analyzed water and suspended sediment (SS) samples for an initial survey of various carbon cycle parameters. Both the Fly and Strickland Rivers were strongly supersaturated with carbon dioxide (2008-10,479 uatm CO2) and undersaturated with oxygen (1.10-5.48 mg/l O2), with the Fly having higher CO2 and lower O2 concentrations than the Strickland River. These pCO2 and O2 concentrations are comparable to and lower than (respectively) typical values in the Amazon. Measured Fly-Strickland alkalinity values fell in the range of 0.893-1.888 meq, and pH measurements were neutral to slightly alkaline (6.916-7.852). In a sample from a sediment-impoverished tributary from Lake Murray to the Strickland (Herbert R.), pH was neutral (7.060), and alkalinity and pCO2 had their lowest observed values at 0.234 meq and 1407 uatm, respectively. Nutrient concentrations were generally higher in the Strickland ([NO3]=3.36+/-0.69 uM, [PO4]=0.09+/-0.10 uM, and [Si(OH)4]=176.6+/-41.7 uM) than in the Fly River ([NO3]=1.09+/-0.04 uM, [PO4]=0.01+/-0.01 uM, and [Si(OH)4]=110.6+/-4.8 uM). NO3 and PO4 concentrations in the Fly-Strickland river system were lower than in the Amazon, and silicate was comparable. SS concentrations were higher in the Strickland than in the Fly (49.4-231.1 mg/l vs. 19.5-59.6 mg/l). Coarse particulates were organic-poor in the Fly and Strickland rivers, with <1% organic carbon (OC). Fine particulates contained more OC in the Fly (2.32-9.03%) than in the Strickland (0.99-3.08%). In aggregate, the average OC concentration of Fly-Strickland river SS samples is 3.75+/-3.07%, which is substantially higher than %OC values measured in fine particulates in the Amazon. C/N ratios for fine particulate organic matter (FPOM) are higher in the Fly (13.0-24.1) than in the Strickland (9.5-14.4), suggesting a greater contribution of N-poor, terrestrial organics to the Fly River. FPOM δ 13C values in the Fly are more depleted (-31.1--30.3‰ ) than in the Strickland River (-29.6--28.4‰ ). We intend to estimate the total biogeochemical fluxes associated with these reported concentrations. Collectively, these preliminary data on carbon cycling in the Fly and Strickland rivers suggest that this fluvial dispersal system outgases a substantial volume of CO2 each year relative to its area, much like the Amazon River. However, in contrast to the Amazon, where the majority of the sediment from the Andes is trapped in sub-aerial, intra-cratonal basins, most fluviatile sediment is advected beyond the Fly River mouth. Therefore, due to the higher organic content of the fine suspended sediment in this river system, it seems probable that a relatively greater export and burial flux of organic carbon may occur within the delta and shelf deposits of the Gulf of Papua.

Historical and potential future impacts of extreme hydrological events on the Amazonian floodplain hydrology and inundation dynamics

NASA Astrophysics Data System (ADS)

Macedo, M.; Panday, P. K.; Coe, M. T.; Lefebvre, P.; Castello, L.

2015-12-01

The Amazonian floodplains and wetlands cover one fifth of the basin and are highly productive promoting diverse biological communities and sustaining human populations with fisheries. Seasonal inundation of the floodplains fluctuates in response to drought or extreme rainfall as observed in the recent droughts of 2005 and 2010 where river levels dropped to among the lowest recorded. We model and evaluate the historical (1940-2010) and projected future (2010-2100) impacts of droughts and floods on the floodplain hydrology and inundation dynamics in the central Amazon using the Integrated Biosphere Simulator (IBIS) and the Terrestrial Hydrology Model and Biogeochemistry (THMB). Simulated discharge correlates well with observed discharges for tributaries originating in Brazil but underestimates basins draining regions in the non-Brazilian Amazon (Solimões, Japuŕa, Madeira, and Negro) by greater than 30%. A volume bias-correction from the simulated and observed runoff was used to correct the input precipitation across the major tributaries of the Amazon basin that drain the Andes. Simulated hydrological parameters (discharge, inundated area and river height) using corrected precipitation has a strong correlation with field measured discharge at gauging stations, surface water extent data (Global Inundation Extent from Multi-Satellites (GIEMS) and NASA Earth System Data Records (ESDRs) for inundation), and satellite radar altimetry (TOPEX/POSEIDON altimeter data for 1992-1998 and ENVISAT data for 2002-2010). We also used an ensemble of model outputs participating in the IPCC AR5 to drive two sets of simulations with and without carbon dioxide fertilization for the 2006-2100 period, and evaluated the potential scale and variability of future changes in discharge and inundation dynamics due to the influences of climate change and vegetation response to carbon dioxide fertilization. Preliminary modeled results for future scenarios using Representative Concentration Pathways (RCP) 4.5 indicate decreases in projected discharge and extent of inundated area on the mainstem Amazon by the late 21st century owing to influences of future climate change only.

Simulating C fluxes along the terrestrial-aquatic continuum of the Amazon basin from 1861-2100

NASA Astrophysics Data System (ADS)

Lauerwald, R.; Regnier, P. A. G.; Ciais, P.

2017-12-01

To date, Earth System Models (ESM) ignore the lateral transfers of carbon (C) along the terrestrial-aquatic continuum down to the oceans and thus overestimate the terrestrial C storage. Here, we present the implementation of fluvial transport of dissolved organic carbon (DOC) and CO2 into ORCHIDEE, the land surface scheme of the Institut Pierre-Simon Laplace ESM. This new model branch, called ORCHILEAK, represents DOC production from canopy and soils, DOC and CO2 leaching from soils to streams, DOC decomposition and CO2 evasion to the atmosphere during its lateral transport in rivers, as well as exchange with the soil carbon and litter stocks in riparian wetlands. The model is calibrated and applied to the Amazon basin, including historical simulations starting from 1861 and future projections to the end of the 21st century. The model is found to reproduce well the observed dynamics in lateral DOC fluxes and CO2 evasion from the water surface. According to the simulations, half of the evading CO2 and 2/3 of the DOC transported in the rivers are produced within the water column or in flooded wetlands. We predict an increase in fluvial DOC exports to the coast and CO2 evasion to the atmosphere of about 1/4 over the 21st century (RCP 6.0). These long-term trends are mainly controlled by increasing atmospheric CO2 concentration and its fertilizing effect on terrestrial primary production in the model, while the effects of land-use change and increasing air temperature are minor. Interannual variations and seasonality of CO2 evasion and DOC transported by the river are however mainly controlled by hydrology. Over the simulation period, the actual land C sink represents less than half of the balance between terrestrial production and respiration in the Amazon basin, while the larger proportion is exported through the terrestrial-aquatic interface. These results highlight the importance of the terrestrial-aquatic continuum in the global C cycle.

Patterns of diversification in the discus fishes (Symphysodon spp. Cichlidae) of the Amazon basin.

PubMed

Farias, Izeni Pires; Hrbek, Tomas

2008-10-01

We carried out a phylogeograhic and population genetic analysis of fishes of the taxonomically contentious genus Symphysodon from the Amazon basin in order to test hypotheses of relationships among taxonomic units, and potential processes driving diversification within this genus. We sampled 334 individuals of the genus Symphysodon from 24 localities that span the complete geographic distribution of this genus. The sampling scheme included all known phenotypic groups, species and subspecies. Analyses were based on 474 bp of the mitochondrial control region and 1443 bp of the exon 3 of RAG1 gene. We observed 102 mtDNA haplotypes defined by 89 segregating sites, and 5 nuDNA alleles defined by three segregating sites. Maximum-likelihood, Bayesian-inference and statistical parsimony analyses revealed three well defined monophyletic groups. These clades corresponded to the 'green' and 'blue' groups of Symphysodon aequifasciatus, and to a previously morphologically unrecognized clade from the Xingu River drainage. These three clades were nested within a paraphyletic assemblage consisting of the 'brown' group of S. aequifasciatus and of both described subspecies of S. discus, the 'Heckel' and the 'abacaxi' discus. Nuclear allele sharing was observed among groups, but there were significant differences in frequencies. We inferred several processes including past fragmentation among groups, and restricted gene flow with isolation by distance within the paraphyletic 'brown+Heckel+abacaxi' groups, and suggest that differences among the 'blue', 'Heckel' and 'brown' groups are potentially maintained by differences in water chemistry preferences. We further inferred colonization of the western Amazon basin by an ancestor of the 'green' clade. The 'green' group was the only group with a pattern of haplotype distribution consistent of a demographic expansion, and the divergence of this clade from other groups of discus was consistent with recent geologic evidence on the breach of the Purus Arch which separates western Amazon from eastern Amazon. We further hypothesized that the differentiation of the 'Xingu' clade could be due to vicariance events resulting from Pleistocene sea level, and thus Amazon River level fluctuations. We discuss the bearings of our results on the current taxonomy of this group, and on the biological reality of the different forms, subspecies and species of Symphysodon concluding that we are probably observing a process of diversification, and therefore taxonomy will remain contentious.

Assessment of Anthropogenic Impacts in La Plata River Basin

NASA Astrophysics Data System (ADS)

Garcia, N. O.; Venencio, M.

2006-12-01

An assessment of the variability of the streamflows in La Plata Basin (LPB), particularly in its major tributaries Paraná and Uruguay, is presented in this work. The La Plata Basin, the fifth largest basin in the world and second only to the Amazon in South America, is 3.6 million km2 and covers portions of 5 countries: Argentina, Brazil, Bolivia, Paraguay, and Uruguay. Sub-basins include the Bermejo, Paraná, Paraguay, Pilcomayo, and Uruguay. Major rivers of the basin are the Paraguay, the Uruguay and the Paraná. Streamflows in the LPB have been above normal in the last decades, e.g. the mean flow in the Paraná river during the 1971-1994 period was 34% higher than the mean flow during the 1931-1970 period. A similar analysis carried out on the precipitation records for the La Plata basin showed only a 14% increase during the same periods for the Upper Paraná basin and a 20% increase for the Uruguay basin. In this paper it is postulated that the increase in the streamflows, not explained by precipitation increases, is due to the changes in cultivation patterns in the upper basins of the Paraná and Uruguay. Particularly, the substitution of coffee plantations for annual crops, mainly soybeans, has produced a change in the infiltration patterns that influenced the discharges.

Climate change increases riverine carbon outgassing, while export to the ocean remains uncertain

NASA Astrophysics Data System (ADS)

Langerwisch, F.; Walz, A.; Rammig, A.; Tietjen, B.; Thonicke, K.; Cramer, W.

2016-07-01

Any regular interaction of land and river during flooding affects carbon pools within the terrestrial system, riverine carbon and carbon exported from the system. In the Amazon basin carbon fluxes are considerably influenced by annual flooding, during which terrigenous organic material is imported to the river. The Amazon basin therefore represents an excellent example of a tightly coupled terrestrial-riverine system. The processes of generation, conversion and transport of organic carbon in such a coupled terrigenous-riverine system strongly interact and are climate-sensitive, yet their functioning is rarely considered in Earth system models and their response to climate change is still largely unknown. To quantify regional and global carbon budgets and climate change effects on carbon pools and carbon fluxes, it is important to account for the coupling between the land, the river, the ocean and the atmosphere. We developed the RIVerine Carbon Model (RivCM), which is directly coupled to the well-established dynamic vegetation and hydrology model LPJmL, in order to account for this large-scale coupling. We evaluate RivCM with observational data and show that some of the values are reproduced quite well by the model, while we see large deviations for other variables. This is mainly caused by some simplifications we assumed. Our evaluation shows that it is possible to reproduce large-scale carbon transport across a river system but that this involves large uncertainties. Acknowledging these uncertainties, we estimate the potential changes in riverine carbon by applying RivCM for climate forcing from five climate models and three CO2 emission scenarios (Special Report on Emissions Scenarios, SRES). We find that climate change causes a doubling of riverine organic carbon in the southern and western basin while reducing it by 20 % in the eastern and northern parts. In contrast, the amount of riverine inorganic carbon shows a 2- to 3-fold increase in the entire basin, independent of the SRES scenario. The export of carbon to the atmosphere increases as well, with an average of about 30 %. In contrast, changes in future export of organic carbon to the Atlantic Ocean depend on the SRES scenario and are projected to either decrease by about 8.9 % (SRES A1B) or increase by about 9.1 % (SRES A2). Such changes in the terrigenous-riverine system could have local and regional impacts on the carbon budget of the whole Amazon basin and parts of the Atlantic Ocean. Changes in riverine carbon could lead to a shift in the riverine nutrient supply and pH, while changes in the exported carbon to the ocean lead to changes in the supply of organic material that acts as a food source in the Atlantic. On larger scales the increased outgassing of CO2 could turn the Amazon basin from a sink of carbon to a considerable source. Therefore, we propose that the coupling of terrestrial and riverine carbon budgets should be included in subsequent analysis of the future regional carbon budget.

The changing hydrology of a dammed Amazon

PubMed Central

Timpe, Kelsie; Kaplan, David

2017-01-01

Developing countries around the world are expanding hydropower to meet growing energy demand. In the Brazilian Amazon, >200 dams are planned over the next 30 years, and questions about the impacts of current and future hydropower in this globally important watershed remain unanswered. In this context, we applied a hydrologic indicator method to quantify how existing Amazon dams have altered the natural flow regime and to identify predictors of alteration. The type and magnitude of hydrologic alteration varied widely by dam, but the largest changes were to critical characteristics of the flood pulse. Impacts were largest for low-elevation, large-reservoir dams; however, small dams had enormous impacts relative to electricity production. Finally, the “cumulative” effect of multiple dams was significant but only for some aspects of the flow regime. This analysis is a first step toward the development of environmental flows plans and policies relevant to the Amazon and other megadiverse river basins. PMID:29109972

Weather For Aircrews - Air Force Handbook 11-203, Volume 1

DTIC Science & Technology

1997-03-01

I S-X. Aurora Borealis...combinations of these factors produce tropical weather ranging from the hot, humid climate of the Amazon and Congo river basins, to the arid Sahara Desert... Aurora . Disturbances on the sun spew out bursts of energy particles, a portion of which eventually reach the earth. The high-energy particles strike

Metagenomics of the Water Column in the Pristine Upper Course of the Amazon River

PubMed Central

McMahon, Katherine D.; Toyama, Danyelle; Rinke, Raquel; Cristina Souza de Oliveira, Tereza; Wagner Garcia, José; Pellon de Miranda, Fernando; Henrique-Silva, Flavio

2011-01-01

River water is a small percentage of the total freshwater on Earth but represents an essential resource for mankind. Microbes in rivers perform essential ecosystem roles including the mineralization of significant quantities of organic matter originating from terrestrial habitats. The Amazon river in particular is famous for its size and importance in the mobilization of both water and carbon out of its enormous basin. Here we present the first metagenomic study on the microbiota of this river. It presents many features in common with the other freshwater metagenome available (Lake Gatun in Panama) and much less similarity with marine samples. Among the microbial taxa found, the cosmopolitan freshwater acI lineage of the actinobacteria was clearly dominant. Group I Crenarchaea and the freshwater sister group of the marine SAR11 clade, LD12, were found alongside more exclusive and well known freshwater taxa such as Polynucleobacter. A metabolism-centric analysis revealed a disproportionate representation of pathways involved in heterotrophic carbon processing, as compared to those found in marine samples. In particular, these river microbes appear to be specialized in taking up and mineralizing allochthonous carbon derived from plant material. PMID:21915244

Understanding Hydrological Regime Alterations Caused by dams: the Santiago River case in the Andean Region of the Amazon Basin.

NASA Astrophysics Data System (ADS)

Rosero-Lopez, D.; Flecker, A.; Walter, M. T.

2016-12-01

Water resources in South America have been clearly targeted as key sources for hydropower expansion over the next 30 years. Ecuador, among the most biologically diverse countries in the world, has the highest density of hydropower dams, either operational, under construction, or planned, in the Amazon Basin. Ecuador's ambitious plan to change its energy portfolio is conceived to satisfy the country's demand and to empower the country to be the region's first hydroelectric energy exporter. The Santiago watershed located in the southeast part of the country has 39 facilities either under construction or in operation. The Santiago River and its main tributaries (Zamora and Upano) are expected to be impounded by large dams over the next 10 years. In order to understand the magnitude and potential impacts of regional dam development on hydrological regimes, a 35-year historical data set of stream discharge was analyzed. We examined flow regimes for time series between the construction of each dam, starting with the oldest and largest built in 1982 up until the most recent dam built in 2005. Preliminary results indicate a systematic displacement in flow seasonality following post-dam compared to pre-dam conditions. There are also notable differences in the distributions of peaks and pulses in post-dam flows. The range of changes from these results shows that punctuated and cumulative impacts are related to the size of each new impoundment. These observations and their implications to the livelihoods, biota, and ecosystems services in the Santiago watershed need to be incorporated into a broader cost-benefit analysis of hydropower generation in the western Amazon Basin.

DNA Barcoding in Pencilfishes (Lebiasinidae: Nannostomus) Reveals Cryptic Diversity across the Brazilian Amazon

PubMed Central

Benzaquem, Denise Corrêa; Oliveira, Claudio; da Silva Batista, Jaqueline; Zuanon, Jansen; Porto, Jorge Ivan Rebelo

2015-01-01

Nannostomus is comprised of 20 species. Popularly known as pencilfishes the vast majority of these species lives in the flooded forests of the Amazon basin and are popular in the ornamental trade. Among the lebiasinids, it is the only genus to have undergone more than one taxonomic revision. Even so, it still possesses poorly defined species. Here, we report the results of an application of DNA barcoding to the identification of pencilfishes and highlight the deeply divergent clades within four nominal species. We surveyed the sequence variation in the mtDNA cytochrome c oxidase subunit I gene among 110 individuals representing 14 nominal species that were collected from several rivers along the Amazon basin. The mean Kimura-2-parameter distances within species and genus were 2% and 19,0%, respectively. The deep lineage divergences detected in N. digrammus, N. trifasciatus, N. unifasciatus and N. eques suggest the existence of hidden diversity in Nannostomus species. For N. digrammus and N. trifasciatus, in particular, the estimated divergences in some lineages were so high that doubt about their conspecific status is raised. PMID:25658694

Earth Observation taken by the Expedition 20 crew

NASA Image and Video Library

2009-10-06

ISS020-E-047807 (6 Oct. 2009) --- Thunderstorms on the Brazilian horizon are featured in this image photographed by an Expedition 20 crew member on the International Space Station. A picturesque line of thunderstorms and numerous circular cloud patterns filled the view as the station crew members looked out at the limb and atmosphere (blue line on the horizon) of Earth. This region displayed in the photograph (top) includes an unstable, active atmosphere forming a large area of cumulonimbus clouds in various stages of development. The crew was looking west southwestward from the Amazon Basin, along the Rio Madeira, toward Bolivia when the image was taken. The distinctive circular patterns of the clouds in this view are likely caused by the aging of thunderstorms. Such ring structures often form during the final stages of a storm?s development as their centers collapse. Sunglint is visible on the waters of the Rio Madeira and Lago Acara in the Amazon Basin. Widespread haze over the basin gives the reflected light an orange hue. The Rio Madeira flows northward and joins the Amazon River on its path to the Atlantic Ocean. Scientists believe that a large smoke plume near the bottom center of the image may explain one source of the haze.

Chemodiversity of dissolved organic matter in the Amazon Basin

NASA Astrophysics Data System (ADS)

Gonsior, Michael; Valle, Juliana; Schmitt-Kopplin, Philippe; Hertkorn, Norbert; Bastviken, David; Luek, Jenna; Harir, Mourad; Bastos, Wanderley; Enrich-Prast, Alex

2016-07-01

Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajós River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur- and nitrogen-containing molecules in this white water river system. Waters from the Tapajós main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.

Nonlinear interactions between the Amazon River basin and the Tropical North Atlantic at interannual timescales

NASA Astrophysics Data System (ADS)

Builes-Jaramillo, Alejandro; Marwan, Norbert; Poveda, Germán; Kurths, Jürgen

2018-04-01

We study the physical processes involved in the potential influence of Amazon (AM) hydroclimatology over the Tropical North Atlantic (TNA) Sea Surface Temperatures (SST) at interannual timescales, by analyzing time series of the precipitation index (P-E) over AM, as well as the surface atmospheric pressure gradient between both regions, and TNA SSTs. We use a recurrence joint probability based analysis that accounts for the lagged nonlinear dependency between time series, which also allows quantifying the statistical significance, based on a twin surrogates technique of the recurrence analysis. By means of such nonlinear dependence analysis we find that at interannual timescales AM hydrology influences future states of the TNA SSTs from 0 to 2 months later with a 90-95% statistical confidence. It also unveils the existence of two-way feedback mechanisms between the variables involved in the processes: (1) precipitation over AM leads the atmospheric pressure gradient between TNA and AM from 0 to 2 month lags, (2) the pressure gradient leads the trade zonal winds over the TNA from 0 to 3 months and from 7 to 12 months, (3) the zonal winds lead the SSTs from 0 to 3 months, and (4) the SSTs lead precipitation over AM by 1 month lag. The analyses were made for time series spanning from 1979 to 2008, and for extreme precipitation events in the AM during the years 1999, 2005, 2009 and 2010. We also evaluated the monthly mean conditions of the relevant variables during the extreme AM droughts of 1963, 1980, 1983, 1997, 1998, 2005, and 2010, and also during the floods of 1989, 1999, and 2009. Our results confirm that the Amazon River basin acts as a land surface-atmosphere bridge that links the Tropical Pacific and TNA SSTs at interannual timescales. The identified mutual interactions between TNA and AM are of paramount importance for a deeper understanding of AM hydroclimatology but also of a suite of oceanic and atmospheric phenomena over the TNA, including recently observed trends in SSTs, as well as future occurrences and impacts on tropical storms and hurricanes throughout the TNA region, but also on fires, droughts, deforestation and dieback of the tropical rain forest of the Amazon River basin.

Regional nitrogen budgets and riverine N & P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences

USGS Publications Warehouse

Howarth, R.W.; Billen, G.; Swaney, D.; Townsend, A.; Jaworski, N.; Lajtha, K.; Downing, J.A.; Elmgren, Ragnar; Caraco, N.; Jordan, T.; Berendse, F.; Freney, J.; Kudeyarov, V.; Murdoch, P.; Zhu, Z.-L.

1996-01-01

We present estimates of total nitrogen and total phosphorus fluxes in rivers to the North Atlantic Ocean from 14 regions in North America, South America, Europe, and Africa which collectively comprise the drainage basins to the North Atlantic. The Amazon basin dominates the overall phosphorus flux and has the highest phosphorus flux per area. The total nitrogen flux from the Amazon is also large, contributing 3.3 Tg yr-1 out of a total for the entire North Atlantic region of 13.1 Tg yr-1. On a per area basis, however, the largest nitrogen fluxes are found in the highly disturbed watersheds around the North Sea, in northwestern Europe, and in the northeastern U.S., all of which have riverine nitrogen fluxes greater than 1,000 kg N km-2 yr-1. Non-point sources of nitrogen dominate riverine fluxes to the coast in all regions. River fluxes of total nitrogen from the temperate regions of the North Atlantic basin are correlated with population density, as has been observed previously for fluxes of nitrate in the world's major rivers. However, more striking is a strong linear correlation between river fluxes of total nitrogen and the sum of anthropogenically-derived nitrogen inputs to the temperate regions (fertilizer application, human-induced increases in atmospheric deposition of oxidized forms of nitrogen, fixation by leguminous crops, and the import/export of nitrogen in agricultural products). On average, regional nitrogen fluxes in rivers are only 25% of these anthropogenically derived nitrogen inputs. Denitrification in wetlands and aquatic ecosystems is probably the dominant sink, with storage in forests perhaps also of importance. Storage of nitrogen in groundwater, although of importance in some localities, is a very small sink for nitrogen inputs in all regions. Agricultural sources of nitrogen dominate inputs in many regions, particularly the Mississippi basin and the North Sea drainages. Deposition of oxidized nitrogen, primarily of industrial origin, is the major control over river nitrogen export in some regions such as the northeastern U.S. Using data from relatively pristine areas as an index of change, we estimate that riverine nitrogen fluxes in many of the temperate regions have increased from pre-industrial times by 2 to 20 fold, although some regions such as northern Canada are relatively unchanged. Fluxes from the most disturbed region, the North Sea drainages, have increased by 6 to 20 fold. Fluxes from the Amazon basin are also at least 2 to 5 fold greater than estimated fluxes from undisturbed temperate-zone regions, despite low population density and low inputs of anthropogenic nitrogen to the region. This suggests that natural riverine nitrogen fluxes in the tropics may be significantly greater than in the temperate zone. However, deforestation may be contributing to the tropical fluxes. In either case, projected increases in fertilizer use and atmospheric deposition in the coming decades are likely to cause dramatic increases in nitrogen loading to many tropical river systems. ?? 1996 Kluwer Academic Publishers.

Acoustic characteristics of biosonar sounds of free-ranging botos (Inia geoffrensis) and tucuxis (Sotalia fluviatilis) in the Negro River, Amazon, Brazil.

PubMed

Yamamoto, Yukiko; Akamatsu, Tomonari; da Silva, Vera M F; Yoshida, Yayoi; Kohshima, Shiro

2015-08-01

Odontoceti emit broadband high-frequency clicks on echolocation for orientation or prey detection. In the Amazon Basin, two odontoceti species, boto (Amazon River dolphin, Inia geoffrensis) and tucuxi (Sotalia fluviatilis), live sympatrically. The acoustic characteristics of the echolocation clicks of free-ranging botos and tucuxis were measured with a hydrophone array consisting of a full-band and an acoustic event recorder (A-tag). The clicks of the two species were short-duration broadband signals. The apparent source level was 201 dB 1 μPa peak-to-peak at 1 m in the botos and 181 dB 1 μPa peak-to-peak at 1 m in the tucuxis, and the centroid frequency was 82.3 kHz in the botos and 93.1 kHz in the tucuxis. The high apparent source level and low centroid frequency are possibly due to the difference in body size or sound production organs, especially the nasal structure, the sound source of clicks in odontoceti.

From drought to flooding: understanding the abrupt 2010-11 hydrological annual cycle in the Amazonas River and tributaries

NASA Astrophysics Data System (ADS)

Carlo Espinoza, Jhan; Ronchail, Josyane; Loup Guyot, Jean; Junquas, Clementine; Drapeau, Guillaume; Martinez, Jean Michel; Santini, William; Vauchel, Philippe; Lavado, Waldo; Ordoñez, Julio; Espinoza, Raúl

2012-06-01

In this work we document and analyze the hydrological annual cycles characterized by a rapid transition between low and high flows in the Amazonas River (Peruvian Amazon) and we show how these events, which may impact vulnerable riverside residents, are related to regional climate variability. Our analysis is based on comprehensive discharge, rainfall and average suspended sediment data sets. Particular attention is paid to the 2010-11 hydrological year, when an unprecedented abrupt transition from the extreme September 2010 drought (8300 m3 s-1) to one of the four highest discharges in April 2011 (49 500 m3 s-1) was recorded at Tamshiyacu (Amazonas River). This unusual transition is also observed in average suspended sediments. Years with a rapid increase in discharge are characterized by negative sea surface temperature anomalies in the central equatorial Pacific during austral summer, corresponding to a La Niña-like mode. It originates a geopotential height wave train over the subtropical South Pacific and southeastern South America, with a negative anomaly along the southern Amazon and the southeastern South Atlantic convergence zone region. As a consequence, the monsoon flux is retained over the Amazon and a strong convergence of humidity occurs in the Peruvian Amazon basin, favoring high rainfall and discharge. These features are also reported during the 2010-11 austral summer, when an intense La Niña event characterized the equatorial Pacific.

(210)Pb and compositional data of sediments from Rondonian lakes, Madeira River basin, Brazil.

PubMed

Bonotto, Daniel Marcos; Vergotti, Marcelo

2015-05-01

Gold exploration has been intensive in Brazilian Amazon over the last 40 years, where the use of mercury as an amalgam has caused abnormal Hg concentrations in water bodies. Special attention has been directed to Madeira River due to fact it is a major tributary of Amazon River and that since 1986, gold exploration has been officially permitted along a 350km sector of the river. The (21)(0)Pb method has been used to date sediments taken from nine lakes situated in Madeira River basin, Rondônia State, and to verify where anthropogenic Hg might exist due to gold exploitation in Madeira River. Activity profiles of excess (21)(0)Pb determined in the sediment cores provided a means to evaluate the sedimentation rates using a Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported/excess (21)(0)Pb models. A significant relationship was found between the CF:CS sedimentation rates and the mean values of the CRS sedimentation rates (Pearson correlation coefficient r=0.59). Chemical data were also determined in the sediments for identifying possible relationships with Hg occurring in the area. Significant values were found in statistical correlation tests realized among the Hg, major oxides and Total Organic Carbon (TOC) content in the sediments. The TOC increased in the sediment cores accompanied by a loss on ignition (LOI) increment, whereas silica decreased following a specific surface area raising associated to the TOC increase. The CRS model always provided ages within the permitted range of the (21)(0)Pb-method in the studied lakes, whereas the CF:CS model predicted two values above 140 years. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tracing oxidative weathering from the Andes to the lowland Amazon Basin using dissoved rhenium

NASA Astrophysics Data System (ADS)

Dellinger, M.; Hilton, R. G.; West, A. J.; Torres, M.; Burton, K. W.; Clark, K. E.; Baronas, J. J.

2016-12-01

Over long timescales (>105 yrs), the abundance of carbon dioxide (CO2) in the atmosphere is determined by the balance of the major carbon sources and sinks. Among the major carbon sources, the oxidation of organic carbon contained within sedimentary rocks ("petrogenic" carbon, or OCpetro) is thought to result in CO2 emission of similar magnitude to that released by volcanism. Rhenium (Re) has been proposed as a proxy for tracing OCpetro oxidation. Here we investigate the source, behavior and flux of dissolved and particulate rhenium (Re) in the Madre de Dios watershed (a major Andean tributary of the Amazon River) and the lowlands, aiming to characterize the behavior of Re in river water and quantify the flux of CO2 released by OCpetro oxidation. Measured Re concentrations in Andean rivers range from 0.07 to 1.55 ppt. In the Andes, Re concentration do not change significantly with water discharge, whereas in the lowlands, Re concentration decrease at high water discharge. Mass balance calculation show that more than 70% of the dissolved Re is sourced from the oxidation of OCpetro the Andes-floodplain system. We calculate dissolved Re flux over a hydrological year to estimate the rates of oxidative weathering, and the associated CO2 release from OCpetro. Rates are high in the Andean headwaters, consistent with estimates from other mountain rivers with similar rates of physical erosion. We find evidence that a significant amount of additional oxidation (Re flux) happens during floodplain transport. These results have important implications for improving our understanding of the source and processes controlling Re in rivers, and allowing us to quantify long-term OCpetro cycling in large river basins.

Automatic Calibration of Global Flow Routing Model Parameters in the Amazon Basin Using Virtual SWOT Data

NASA Astrophysics Data System (ADS)

Mouffe, Melodie; Getirana, Augusto; Ricci, Sophie; Lion, Christine; Biancamaria, Sylvian; Boone, Aaron; Mognard, Nelly; Rogel, Philippe

2013-09-01

The Surface Water and Ocean Topography (SWOT) wide swath altimetry mission will provide measurements of water surface elevations (WSE) at a global scale. The aim of this study is to investigate the potential of these satellite data for the calibration of the hydrological model HyMAP, over the Amazon river basin. Since SWOT has not yet been launched, synthetical observations are used to calibrate the river bed depth and width, the Manning coefficient and the baseflow concentration time. The calibration process stands in the minimization of a cost function using an evolutionnary, global and multi-objective algorithm that describes the difference between the simulated and the observed WSE. We found that the calibration procedure is able to retrieve an optimal set of parameters such that it brings the simulated WSE closer to the observation. Still with a global calibration procedure where a uniform correction is applied, the improvement is limited to a mean correction over the catchment and the simulation period. We conclude that in order to benefit from the high resolution and complete coverage of the SWOT mission, the calibration process should be achieved sequentially in time over sub-domains as observations become available.

Tree-Ring Reconstruction of Wet Season Rainfall Totals in the Amazon

NASA Astrophysics Data System (ADS)

Stahle, D. W.; Lopez, L.; Granato-Souza, D.; Barbosa, A. C. M. C.; Torbenson, M.; Villalba, R.; Pereira, G. D. A.; Feng, S.; Schongart, J.; Cook, E. R.

2017-12-01

The Amazon Basin is a globally important center of deep atmospheric convection, energy balance, and biodiversity, but only a handful of weather stations in this vast Basin have recorded rainfall measurements for at least 50 years. The available rainfall and river level observations suggest that the hydrologic cycle in the Amazon may have become amplified in the last 40-years, with more extreme rainfall and streamflow seasonality, deeper droughts, and more severe flooding. These changes in the largest hydrological system on earth may be early evidence of the expected consequences of anthropogenic climate change and deforestation in the coming century. Placing these observed and simulated changes in the context of natural climate variability during the late Holocene is a significant challenge for high-resolution paleoclimatology. We have developed exactly dated and well-replicated annual tree-ring chronologies from two native Amazonian tree species (Cedrela sp and Centrolobium microchaete). These moisture sensitive chronologies have been used to compute two reconstructions of wet season rainfall totals, one in the southern Amazon based on Centrolobium and another in the eastern equatorial Amazon using Cedrela. Both reconstructions are over 200-years long and extend the available instrumental observations in each region by over 150-years. These reconstructions are well correlated with the same regional and large-scale climate dynamics that govern the inter-annual variability of the instrumental wet season rainfall totals. Increased multi-decadal variability is reconstructed after 1950 with the Centrolobium chronologies in the southern Amazon. The Cedrela reconstruction from the eastern Amazon exhibits changes in the spatial pattern of correlation with regional rainfall stations and the large-scale sea surface temperature field after 1990 that may be consistent with recent changes in the mean position of the Inter-Tropical Convergence Zone in March over the western Atlantic and South American sector.

Particulate Organic Matter Distribution along the Lower Amazon River: Addressing Aquatic Ecology Concepts Using Fatty Acids

PubMed Central

Mortillaro, Jean-Michel; Rigal, François; Rybarczyk, Hervé; Bernardes, Marcelo; Abril, Gwenaël; Meziane, Tarik

2012-01-01

One of the greatest challenges in understanding the Amazon basin functioning is to ascertain the role played by floodplains in the organic matter (OM) cycle, crucial for a large spectrum of ecological mechanisms. Fatty acids (FAs) were combined with environmental descriptors and analyzed through multivariate and spatial tools (asymmetric eigenvector maps, AEM and principal coordinates of neighbor matrices, PCNM). This challenge allowed investigating the distribution of suspended particulate organic matter (SPOM), in order to trace its seasonal origin and quality, along a 800 km section of the Amazon river-floodplain system. Statistical analysis confirmed that large amounts of saturated FAs (15:0, 18:0, 24:0, 25:0 and 26:0), an indication of refractory OM, were concomitantly recorded with high pCO2 in rivers, during the high water season (HW). Contrastingly, FAs marker which may be attributed in this ecosystem to aquatic plants (18:2ω6 and 18:3ω3) and cyanobacteria (16:1ω7), were correlated with higher O2, chlorophyll a and pheopigments in floodplains, due to a high primary production during low waters (LW). Decreasing concentrations of unsaturated FAs, that characterize labile OM, were recorded during HW, from upstream to downstream. Furthermore, using PCNM and AEM spatial methods, FAs compositions of SPOM displayed an upstream-downstream gradient during HW, which was attributed to OM retention and the extent of flooded forest in floodplains. Discrimination of OM quality between the Amazon River and floodplains corroborate higher autotrophic production in the latter and transfer of OM to rivers at LW season. Together, these gradients demonstrate the validity of FAs as predictors of spatial and temporal changes in OM quality. These spatial and temporal trends are explained by 1) downstream change in landscape morphology as predicted by the River Continuum Concept; 2) enhanced primary production during LW when the water level decreased and its residence time increased as predicted by the Flood Pulse Concept. PMID:23029412

Geographical origin of Amazonian freshwater fishes fingerprinted by ⁸⁷Sr/⁸⁶Sr ratios on fish otoliths and scales.

PubMed

Pouilly, Marc; Point, David; Sondag, Francis; Henry, Manuel; Santos, Roberto V

2014-08-19

Calcified structures such as otoliths and scales grow continuously throughout the lifetime of fishes. The geochemical variations present in these biogenic structures are particularly relevant for studying fish migration and origin. In order to investigate the potential of the (87)Sr/(86)Sr ratio as a precise biogeochemical tag in Amazonian fishes, we compared this ratio between the water and fish otoliths and scales of two commercial fish species, Hoplias malabaricus and Schizodon fasciatus, from three major drainage basins of the Amazon: the Madeira, Solimões, and Tapajós rivers, displaying contrasted (87)Sr/(86)Sr ratios. A comparison of the (87)Sr/(86)Sr ratios between the otoliths and scales of the same individuals revealed similar values and were very close to the Sr isotopic composition of the local river where they were captured. This indicates, first, the absence of Sr isotopic fractionation during biological uptake and incorporation into calcified structures and, second, that scales may represent an interesting nonlethal alternative for (87)Sr/(86)Sr ratio measurements in comparison to otoliths. Considering the wide range of (87)Sr/(86)Sr variations that exist across Amazonian rivers, we used variations of (87)Sr/(86)Sr to discriminate fish origin at the basin level, as well as at the sub-basin level between the river and savannah lakes of the Beni River (Madeira basin).

Amazon River carbon dioxide outgassing fuelled by wetlands.

PubMed

Abril, Gwenaël; Martinez, Jean-Michel; Artigas, L Felipe; Moreira-Turcq, Patricia; Benedetti, Marc F; Vidal, Luciana; Meziane, Tarik; Kim, Jung-Hyun; Bernardes, Marcelo C; Savoye, Nicolas; Deborde, Jonathan; Souza, Edivaldo Lima; Albéric, Patrick; Landim de Souza, Marcelo F; Roland, Fabio

2014-01-16

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world's flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.

Reactive and dissolved meteoric 10Be/9Be ratios in the Amazon basin

NASA Astrophysics Data System (ADS)

Wittmann, Hella; Dannhaus, Nadine; von Blanckenburg, Friedhelm; Bouchez, Julien; Suessenberger, Annette; Guyot, Jean-Loup; Maurice, Laurence; Filizola, Naziano; Gaillardet, Jerome; Christl, Marcus

2014-05-01

Recently, the ratio of the meteoric cosmogenic nuclide 10Be to stable 9Be has been established as a weathering and erosion proxy where meteoric 10Be/9Be ratios in reactive phases of secondary weathering products leached from detrital Amazonian river sediment were measured[1]. For this dataset, we derived a new 10Be-based mass balance, which compares the fluxes exported during erosion and weathering, Fout, calculated by the sum of [10Be]reac multiplied by gauging-derived sediment discharge and [10Be]dissmultiplied by water discharge, to the meteoric depositional flux Fin. This assessment allows evaluating the weathering state of the Amazon basin. Further, in order to assess equilibration of reactive phases in the water column, we measured (10Be/9Be)reac ratios leached from suspended sediments for two depth profiles of the Amazon (55m depth) and Madeira (12m depth) Rivers, their corresponding surface dissolved 10Be/9Be ratios, as well as dissolved ratios of smaller Amazon tributaries (Beni, Madre de Dios) to compare with published reactive ratios[1]. In these rivers, modest pH and salinity fluctuations help to constrain a 'simple' system that might however still be affected by seasonally changing isotopic compositions between water and suspended sediment[2] and seasonal fluctuations of TSS and TDS[3]. The 10Be-based mass balance shows that in Andean source areas Fout/Fin ≡1, indicating a balance between ingoing and exported flux, whereas in the Shield headwaters, Fout/Fin=0.3, indicating a combination of decay of 10Be during storage and little export of 10Be associated with particulate and dissolved loads. In central Amazonia, the export of 10Be decreases slightly relative to its atmospheric flux as evidenced by Fout/Fin=0.8 for the Amazon and Madeira Rivers. This value is interpreted as being close to steady state, but its modification could be due to additions of Shield-derived sediment to sediment carried in the main river[4]. Regarding the depth profiles, our preliminary findings stress that the (10Be/9Be)reac for the Amazon River (n=3, Avg.= 5.4x10-10with SD=3.7x10-11) and the Madeira River (n=3, Avg.= 4x10-10with SD=2.1x10-11) do not change significantly within the water column. These depth-dependent reactive ratios compare well with 10Be/9Be ratios of surface waters and sediments and with published data available for the Negro and Orinoco[5]: For all these large rivers, surface (10Be/9Be)reac vs. (10Be/9Be)dissagree very well (R2 ≡1). For smaller tributaries like the Apure, La Tigra, Beni and Madre de Dios, (10Be/9Be)reacare 2-3 times lower than (10Be/9Be)diss. As pH values are similar for all these rivers, one possibility is that in smaller river systems mixing of sediment and water between the channel and the floodplain is less thorough, potentially resulting in reactive and dissolved phases that are not fully equilibrated. For large rivers, however, our depth-invariant (10Be/9Be)reac data indicate consistent and probably early equilibration of Be with depth. We also do not observe potentially divergent 10Be/9Be ratios due to e.g. floodplain remobilization or different erosion rates in the source area. From this, we infer a thorough mixing of the clay/silt fraction within large rivers, with the different 10Be/9Be ratios of Madeira and Amazon Rivers fingerprinting the different prevailing denudation rates of the source areas (Andes and Brazilian Shield). The here presented results suggest that one surface sample, either reactive or dissolved, would be sufficient to determine denudation rates of an entire catchment. [1] F. von Blanckenburg et al., EPSL, 351-352 (2012) 295-305. [2] J. Viers, et al., EPSL, 274 (2008) 511-523. [3] J. Bouchez, et al., Geochem. Geophys. Geosys. 12 (2011) Q03008. [4] H. Wittmann et al., Geology 39 (2011) 467-470. [5] E. T. Brown et al., GCA 56 (1992) 1607-1624.

Metagenomics Analysis of Microorganisms in Freshwater Lakes of the Amazon Basin.

PubMed

Toyama, Danyelle; Kishi, Luciano Takeshi; Santos-Júnior, Célio Dias; Soares-Costa, Andrea; de Oliveira, Tereza Cristina Souza; de Miranda, Fernando Pellon; Henrique-Silva, Flávio

2016-12-22

The Amazon Basin is the largest hydrographic basin on the planet, and the dynamics of its aquatic microorganisms strongly impact global biogeochemical cycles. However, it remains poorly studied. This metagenome project was performed to obtain a snapshot of prokaryotic microbiota from four important lakes in the Amazon Basin. Copyright © 2016 Toyama et al.

Global scale modeling of riverine sediment loads: tropical rivers in a global context

NASA Astrophysics Data System (ADS)

Cohen, Sagy; Syvitski, James; Kettner, Albert

2015-04-01

A global scale riverine sediment flux model (termed WBMsed) is introduced. The model predicts spatially and temporally explicit water, suspended sediment and nutrients flux in relatively high resolutions (6 arc-min and daily). Modeled riverine suspended sediment flux through global catchments is used in conjunction with observational data for 35 tropical basins to highlight key basin scaling relationships. A 50 year, daily model simulation illuminates how precipitation, relief, lithology and drainage basin area affect sediment load, yield and concentration. Tropical river systems, wherein much of a drainage basin experiences tropical climate are strongly influenced by the annual and inter-annual variations of the Inter-tropical Convergence Zone (ITCZ) and its derivative monsoonal winds, have comparatively low inter-annual variation in sediment yield. Rivers draining rainforests and those subjected to tropical monsoons typically demonstrate high runoff, but with notable exceptions. High rainfall intensities from burst weather events are common in the tropics. The release of rain-forming aerosols also appears to uniquely increase regional rainfall, but its geomorphic manifestation is hard to detect. Compared to other more temperate river systems, climate-driven tropical rivers do not appear to transport a disproportionate amount of particulate load to the world's oceans, and their warmer, less viscous waters are less competent. Multiple-year hydrographs reveal that seasonality is a dominant feature of most tropical rivers, but the rivers of Papua New Guinea are somewhat unique being less seasonally modulated. Local sediment yield within the Amazon is highest near the Andes, but decreases towards the ocean as the river's discharge is diluted by water influxes from sediment-deprived rainforest tributaries

A Paleoecological View of the Anthropocene in Tropical South America

NASA Astrophysics Data System (ADS)

Bush, M. B.; McMichael, C. H.; Piperno, D. R.

2015-12-01

Many potential events could define the onset of the Anthropocene in the Neotropics. The first effects caused by humans included the final extinction of megafauna around 10,000 years ago, and changes in fire frequency, particularly after about 8000 years ago. The first agriculture (squash) is evident in northwestern regions at 9000 BP, and in the Amazon Basin maize is cultivated by 6300 BP. But these events have not been widely documented on the continent and if some chronological uniformity is sought as a guide to defining the onset of the Anthropocene, they would fail that test. Coming forward through time, increasing societal complexity is evident beginning about 3000 BP in both the Amazon and the Andes, but again the development was patchy. Some archaeologists are arguing that between c. 2000 BP and 500 BP the Amazon Basin became a manufactured landscape. While major river corridors were very likely influenced by human populations, the level of use in the great interfluvial areas (c. 90% of Amazonia) remains a matter of debate. The empirical data that exist for human presence in these areas point to sparse occupation, both in space and time, and the assertion that most of prehistoric Amazonia was manipulated by humans is unsupported. Following European contact, indigenous populations were reduced probably 90-95% within 200 years, which interrupted the cultural trajectory of the Neotropics. The next possible contender for the local onset of the Anthropocene was the Rubber Boom (1879-1912). The Rubber Boom greatly increased human populations along many of the Amazon's major rivers and tributaries. Hunting and deforestation picked up pace, and the growing presence of steamships allowed exportation of a wide range of Amazonian products beyond rubber, e.g. plumes, timber, and turtle oil. In addition to these local effects, the global effects that came with increased fossil fuel use and industrialization, would also have influenced all of South America. Even so, the influence of the Rubber Boom would have been strongest in the Amazon Basin and far milder in the Andes or along the Pacific coastline. In the 1950s-1970s the green revolutions and fossil-fuel based agriculture caused an increase in global NOx. Increased NOx deposition and the appearance of plastics may be defining markers of the Anthropocene in South America.

Understanding the Impacts of Climate and Hydrologic Extremes on Diarrheal Diseases in Southwestern Amazon

NASA Astrophysics Data System (ADS)

Fonseca, P. A. M.

2015-12-01

Bacterial diarrheal diseases have a high incidence rate during and after flooding episodes. In the Brazilian Amazon, flood extreme events have become more frequent, leading to high incidence rates for infant diarrhea. In this study we aimed to find a statistical association between rainfall, river levels and diarrheal diseases in children under 5, in the river Acre basin, in the State of Acre (Brazil). We also aimed to identify the time-lag and annual season of extreme rainfall and flooding in different cities in the water basin. The results using Tropical Rainfall Measuring Mission (TRMM) Satellite rainfall data show robustness of these estimates against observational stations on-ground. The Pearson coefficient correlation results (highest 0.35) indicate a time-lag, up to 4 days in three of the cities in the water-basin. In addition, a correlation was also tested between monthly accumulated rainfall and the diarrheal incidence during the rainy season (DJF). Correlation results were higher, especially in Acrelândia (0.7) and Brasiléia and Epitaciolândia (0.5). The correlation between water level monthly averages and diarrheal diseases incidence was 0.3 and 0.5 in Brasiléia and Epitaciolândia. The time-lag evidence found in this paper is critical to inform stakeholders, local populations and civil defense authorities about the time available for preventive and adaptation measures between extreme rainfall and flooding events in vulnerable cities. This study was part of a pilot application in the state of Acre of the PULSE-Brazil project (http://www.pulse-brasil.org/tool/), an interface of climate, environmental and health data to support climate adaptation. The next step of this research is to expand the analysis to other climate variables on diarrheal diseases across the whole Brazilian Amazon Basin and estimate the relative risk (RR) of a child getting sick. A statistical model will estimate RR based on the observed values and seasonal forecasts (higher accuracy for the Amazon region) will be used so the government can be prepared for extreme climate events forecasted. It is expected that these results can be helpful during and post extreme events to improve health surveillance preparedness and better allocate available results in adapting vulnerable cities to climate extreme events.

Confluence of the Amazon and Topajos Rivers, Brazil, South America

NASA Image and Video Library

1991-08-11

This view shows the confluence of the Amazon and the Topajos Rivers at Santarem, Brazil (2.0S, 55.0W). The Am,azon flows from lower left to upper right of the photo. Below the river juncture of the Amazon and Tapajos, there is considerable deforestation activity along the Trans-Amazon Highway.

Spatial analysis from remotely sensed observations of Congo basin of East African high Land to drain water using gravity for sustainable management of low laying Chad basin of Central Africa

NASA Astrophysics Data System (ADS)

Modu, B.; Herbert, B.

2014-11-01

The Chad basin which covers an area of about 2.4 million kilometer square is one of the largest drainage basins in Africa in the centre of Lake Chad .This basin was formed as a result of rifting and drifting episode, as such it has no outlet to the oceans or seas. It contains large area of desert from the north to the west. The basin covers in part seven countries such as Chad, Nigeria, Central African Republic, Cameroun, Niger, Sudan and Algeria. It is named Chad basin because 43.9% falls in Chad republic. Since its formation, the basin continues to experienced water shortage due to the activities of Dams combination, increase in irrigations and general reduction in rainfall. Chad basin needs an external water source for it to be function at sustainable level, hence needs for exploitation of higher east African river basin called Congo basin; which covers an area of 3.7 million square km lies in an astride the equator in west-central Africa-world second largest river basin after Amazon. The Congo River almost pans around republic of Congo, the democratic republic of Congo, the Central African Republic, western Zambia, northern Angola, part of Cameroun, and Tanzania. The remotely sensed imagery analysis and observation revealed that Congo basin is on the elevation of 275 to 460 meters and the Chad basin is on elevation of 240 meters. This implies that water can be drained from Congo basin via headrace down to the Chad basin for the water sustainability.

Source to sink: Evolution of lignin composition in the Madre de Dios River system with connection to the Amazon basin and offshore

NASA Astrophysics Data System (ADS)

Feng, Xiaojuan; Feakins, Sarah J.; Liu, Zongguang; Ponton, Camilo; Wang, Renée. Z.; Karkabi, Elias; Galy, Valier; Berelson, William M.; Nottingham, Andrew T.; Meir, Patrick; West, A. Joshua

2016-05-01

While lignin geochemistry has been extensively investigated in the Amazon River, little is known about lignin distribution and dynamics within deep, stratified river channels or its transformations within soils prior to delivery to rivers. We characterized lignin phenols in soils, river particulate organic matter (POM), and dissolved organic matter (DOM) across a 4 km elevation gradient in the Madre de Dios River system, Peru, as well as in marine sediments to investigate the source-to-sink evolution of lignin. In soils, we found more oxidized lignin in organic horizons relative to mineral horizons. The oxidized lignin signature was maintained during transfer into rivers, and lignin was a relatively constant fraction of bulk organic carbon in soils and riverine POM. Lignin in DOM became increasingly oxidized downstream, indicating active transformation of dissolved lignin during transport, especially in the dry season. In contrast, POM accumulated undegraded lignin downstream during the wet season, suggesting that terrestrial input exceeded in-river degradation. We discovered high concentrations of relatively undegraded lignin in POM at depth in the lower Madre de Dios River in both seasons, revealing a woody undercurrent for its transfer within these deep rivers. Our study of lignin evolution in the soil-river-ocean continuum highlights important seasonal and depth variations of river carbon components and their connection to soil carbon pools, providing new insights into fluvial carbon dynamics associated with the transfer of lignin biomarkers from source to sink.

Simulating Spatial Variability of Fluvial Sediment Fluxes Within the Magdalena Drainage Basin, Colombia.

NASA Astrophysics Data System (ADS)

Kettner, A. J.; Syvitski, J. P.; Restrepo, J. D.

2008-12-01

This study explores the application of an empirical sediment flux model BQART, to simulate long-term sediment fluxes of major tributaries of a river system based on a limited number of input parameters. We validate model results against data of the 1612 km long Magdalena River, Colombia, South America, which is well monitored. The Magdalena River, draining a hinterland area of 257,438 km2, of which the majority lies in the Andes before reaching the Atlantic coast, is known for its high sediment yield, 560 t kg- 2 yr-1; higher than nearby South American rivers like the Amazon or the Orinoco River. Sediment fluxes of 32 tributary basins of the Magdalena River were simulated based on the following controlling factors: geomorphic influences (tributary-basin area and relief) derived from high-resolution Shuttle Radar Topography Mission data, tributary basin-integrated lithology based on GIS analysis of lithology data, 30year temperature data, and observed monthly mean discharge data records (varying in record length of 15 to 60 years). Preliminary results indicate that the simulated sediment flux of all 32 tributaries matches the observational record, given the observational error and the annual variability. These simulations did not take human influences into account yet, which often increases sediment fluxes by accelerating erosion, especially in steep mountainous area similar to the Magdalena. Simulations indicate that, with relatively few input parameters, mostly derived from remotely-sensed data or existing compiled GIS datasets, it is possible to predict: which tributaries in an arbitrary river drainage produce relatively high contributions to sediment yields, and where in the drainage basin you might expect conveyance loss.

Recovery of Methane Consumption by Secondary Forests in the Amazon River Basin

NASA Astrophysics Data System (ADS)

Webster, K. D.; Meredith, L. K.; Piccini, W.; Pedrinho, A.; Nüsslein, K.; Van Haren, J. L. M.; Camargo, P. B. D.; Mui, T. S.; Saleska, S. R.

2017-12-01

Methane (CH4) is a major greenhouse gas in Earth's atmosphere and its atmospheric global mole fraction has roughly doubled since the start of the industrial revolution. The tropics are thought to be a major CH4 emitter, with the Amazon River Basin estimated to contribute 7 % of the annual flux to the atmosphere. The Amazon has experienced extensive land use change during the past 30 years, but we lack an understanding of the qualitative and quantitative effects of land use change on CH4 flux from the Amazon and the associated reasons. To illuminate the factors controlling CH4 flux across land use gradients in the Amazon we measured the CH4 fluxes and will measure the associated stable isotopic composition from pastures, primary forests, and secondary forests, at Ariquemes (Western Amazon, more deforested), and Santarem (Eastern Amazon, less deforested), Brazil. The sites near Santarem were sampled in June of 2016 and the sites near Ariquemes were sampled in March and April of 2017, both at the end of the wet season. Little difference was observed between land use types in Santarem with each land use type slightly consuming atmospheric CH4. However, pasture fluxes at Ariquemes were higher (+520 μg-C m-2 hr-1) than in primary (0 μg-C m-2 hr-1) and secondary forests (-20 μg-C m-2 hr-1; p = 6*10-4). CH4 flux from individual Santarem sites was not correlated with environmental variables. CH4 flux from Airquemes was correlated with several parameters across all samples including soil temperature (p = 7*10-4), and soil humidity (p = 0.02). Despite the fact that pastures experienced higher soil temperatures than forest soils this appears to be a low predictor of CH4 flux from these environments as it was seen at both Santarem and Ariquemes. The analysis of the stable isotopic composition of CH4 from these chambers will aid in understanding the competing processes of microbial CH4 consumption and production in these soils and why pastures may become CH4 sources and secondary forests are able to regain the function as a CH4 sink in some instances. Support: NSF, FAPESP-Biota, CNPq, CAPES.

How Pecten Brazil drilled the Amazon basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bleakley, W.B.

1983-09-01

Pecten Brazil overcame numerous obstacles to drill two exploratory wells in the Amazon Basin last year. These included: The threat of low water in normally navigable rivers. Dense jungle growth at both locations. Lack of suitable roads for heavy hauling. Inconvenient distances from supply points. An unusual basalt formation responsible for unique drilling problems. Hundreds of helicopter lifts to move drilling rigs, supplies, and personnel. Pecten contracted with Petrobras, the Brazilian national oil company, to evaluate three blocks in the Amazon jungle, each about 68 miles (110 km) on a side, through seismic study and ultimate drilling. Planning for themore » drilling phase got started on March 17, 1981 with December 1 targeted as spud date for the first well. Actual spud date was November 25, 5 days ahead of schedule, in spite of all obstacles. Pecten has a mid-Amazonas block now under seismic investigation for possible exploratory drilling. Logistics problems in this one provide new difficulties, as the area is extremely wet. Most work is carried on by boat. The company is also looking offshore Bahia, testing the possible extension of the Renconcavo basin. Two wells have already provided good shows of a high pour point oil, with flow rates from 400 to 1,000 b/d. Another area of interest to Pecten is offshore Rio Grande do Norte.« less

Forest Canopy Heights in Amazon River Basin Forests as Estimated with the Geoscience Laser Altimeter System (GLAS)

Treesearch

E. H. Helmer; M. A. Lefsky

2006-01-01

Land-use change, mainly forest burning, harvest, or clearing for agriculture, may compose 15 to 40 percent of annual human-caused emissions of carbon (C) to the atmosphere. Spatially extensive data on forest C pools can validate and parameterize atmospheric and ecosystem models of those fluxes and quantify fluxes from forest change. Excellent evidence exists that light...

Oil pollution in soils and sediments from the Northern Peruvian Amazon.

PubMed

Rosell-Melé, Antoni; Moraleda-Cibrián, Núria; Cartró-Sabaté, Mar; Colomer-Ventura, Ferran; Mayor, Pedro; Orta-Martínez, Martí

2018-01-01

Oil has been extracted from the Northern Peruvian Amazon for over four decades. However, few scientific studies have assessed the impacts of such activities in the environment and health of indigenous communities in the region. We have investigated the occurrence of petrogenic hydrocarbon pollution in soils and sediments from areas favoured as hunting or fishing grounds by local indigenous inhabitants. The study was conducted in one of the most productive oil blocks in Peru, located in the headwaters of the Amazon river. Soils and river sediments, in the vicinity of oil extraction and processing infrastructure, contained an oil pollution signature as attested by the occurrence of hopanes and steranes. Given the lack of any other significant source of oil pollution in the region, the sources of hydrocarbons are likely to be the activities of the oil industry in the oil block, from voluntary discharges or accidental spills. Spillage of produced water was commonplace until 2009. Moreover, petrogenic compounds were absent in control samples in sites far removed from any oil infrastructure in the oil block. Our findings suggest that wildlife and indigenous populations in this region of the Amazon are exposed to the ingestion of oil polluted soils and sediments. The data obtained supports previous claims that the local spillage of oil and produced waters in the water courses in the Corrientes and Pastaza basins could have eventually reached the main water course of the Amazon. Copyright © 2017 Elsevier B.V. All rights reserved.

River Mixing in the Amazon as a Driver of Concentration-Discharge Relationships

NASA Astrophysics Data System (ADS)

Bouchez, Julien; Moquet, Jean-Sébastien; Espinoza, Jhan Carlo; Martinez, Jean-Michel; Guyot, Jean-Loup; Lagane, Christelle; Filizola, Naziano; Noriega, Luis; Hidalgo Sanchez, Liz; Pombosa, Rodrigo

2017-11-01

Large hydrological systems aggregate compositionally different waters derived from a variety of pathways. In the case of continental-scale rivers, such aggregation occurs noticeably at confluences between tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We build up a simple model for tributary mixing to predict the behavior of C-Q relationships during aggregation. We test a set of predictions made in the context of the largest world's river, the Amazon. In particular, we predict that the C-Q relationships of the rivers draining heterogeneous catchments should be the most "dilutional" and should display the widest hysteresis loops. To check these predictions, we compute 10 day-periodicity time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations located throughout the Amazon basin. In agreement with the model predictions, C-Q relationships of most solutes shift from a fairly "chemostatic" behavior (nearly constant C) at the Andean mountain front and in pure lowland areas, to more "dilutional" patterns (negative C-Q relationship) toward the system mouth. More prominent C-Q hysteresis loops are also observed at the most downstream stations. Altogether, this study suggests that mixing of water and solutes between different flowpaths exerts a strong control on C-Q relationships of large-scale hydrological systems.

ERS-ENVISAT radar altimetry over the Amazon basin

NASA Astrophysics Data System (ADS)

Santos da Silva, J.; Calmant, S.; Rotunno Filho, O. C.; Seyler, F.; Mansur, W. J.; Cochonneau, G.

2009-12-01

Since the launch of satellite embarking radar altimeters in the late 80’s, scientists have investigated the feasibility of using these ocean-dedicated data over the continental waters. In fact, satellite radar altimetry is being recognized as a powerful tool to obtain time series of water stage consistent to those obtained by conventional in situ gauge stations. In addition, this technology has been proved to provide reliable information about the dynamics of large water bodies such as lakes and inner seas. However, the results should be deeply examined as we shift the analysis to water levels acquired during satellite crosses over rivers. Yet, hydrologists are still reluctant in using these data, as neither the neces¬sary time sampling nor accuracy is achieved, leading to endless debates in specialized workshops. Noteworthy to highlight, few published studies are dedicated to an in depth assessment of the radar altimetry over rivers, in¬cluding comparisons with water levels at fluviometric gauges. In this work, we present an extensive analysis of the quality of times series of river stages that we have constructed in the Amazon basin for a variety of water bodies such as large rivers, narrow stems, lakes and flooded areas using radar altimeters embarked on¬board ERS-2 and ENVISAT. The approach includes the sensitivity to the raw data processing methodology such as the tracking algorithm, the data selection at the crossings between satellite track and river bed (so-called virtual stations) and correction for off-nadir effects. The VALS toolbox was developed to process altimetry data at virtual stations under the framework of this study. Results of internal validation at cross-overs and external validation by comparison with in situ gauges are presented.

How important and different are tropical rivers? - An overview

NASA Astrophysics Data System (ADS)

Syvitski, James P. M.; Cohen, Sagy; Kettner, Albert J.; Brakenridge, G. Robert

2014-12-01

Tropical river systems, wherein much of the drainage basin experiences tropical climate are strongly influenced by the annual and inter-annual variations of the Inter-tropical Convergence Zone (ITCZ) and its derivative monsoonal winds. Rivers draining rainforests and those subjected to tropical monsoons typically demonstrate high runoff, but with notable exceptions. High rainfall intensities from burst weather events are common in the tropics. The release of rain-forming aerosols also appears to uniquely increase regional rainfall, but its geomorphic manifestation is hard to detect. Compared to other more temperate river systems, climate-driven tropical rivers do not appear to transport a disproportionate amount of particulate load to the world's oceans, and their warmer, less viscous waters are less competent. Tropical biogeochemical environments do appear to influence the sedimentary environment. Multiple-year hydrographs reveal that seasonality is a dominant feature of most tropical rivers, but the rivers of Papua New Guinea are somewhat unique being less seasonally modulated. Modeled riverine suspended sediment flux through global catchments is used in conjunction with observational data for 35 tropical basins to highlight key basin scaling relationships. A 50 year, daily model simulation illuminates how precipitation, relief, lithology and drainage basin area affect sediment load, yield and concentration. Local sediment yield within the Amazon is highest near the Andes, but decreases towards the ocean as the river's discharge is diluted by water influxes from sediment-deprived rainforest tributaries. Bedload is strongly affected by the hydraulic gradient and discharge, and the interplay of these two parameters predicts foci of net bedload deposition or erosion. Rivers of the tropics have comparatively low inter-annual variation in sediment yield.

The Amazon hydrometeorology: Climatology, variability and links to changes in weather patterns

NASA Astrophysics Data System (ADS)

Fernandes, Katia De Avila

My thesis focuses on improving the quantification of the hydrological cycle and understanding the atmospheric processes that link weather to climate in the Amazon River basin. By using ERA40 and independent observations, I assess how well we can estimate the surface water budget in the Amazon River basin. I find that ERA40 basin wide annual precipitation (P) overall agrees with observations showing a slight underestimation of 10% in average, whereas runoff (R) is underestimated by a larger margin (˜25%). Observed residual of precipitation and runoff (denoted as P-R) is better estimated by ERA40 P-R than actual ET which includes soil moisture nudging. The causes for said discrepancies were found to partly relate to soil moisture nudging that needs to be applied during the dry season to produce realistic ET and compensate for the low soil moisture recharge during the previous wet season. Insufficient recharge may in part be caused by underestimation of rainfall amount and intensity; moreover the shallow root layer in the model does not represent the deep soil water reservoir characteristic of the Amazonian forest. Whether the hydrological cycle and weather patterns in the Amazon have changed during the past few decades is a highly debatable but central question for detecting climate change in the region. The second part of my thesis focus on the physical links between rainfall changes detected in observations, and changes of synoptic scale systems as represented by ERA40. My results suggest that an observed delayed wet season onset is consistent with a decreasing number of cold air incursion (CAI) days in southern Amazon for the period 1979--2001. The variability of CAI into southern Amazon is related to the variability of SST upstream of South America in the tropical Pacific and Indian Oceans. A Singular Value Decomposition Analysis (SVD) between CAI days and global SST reveal three main modes of co-variability. The first mode describes the effect of the El Nino-Southern Oscillation. During El Nino (La Nina) a strong (weak) subtropical jet stream over South America tends to prevent transient systems from moving to southern Amazon, resulting in decreased (increased) CAI days during SON. The second mode of co-variability shows an anomalously warm western Indian Ocean also related to strong subtropical jet stream, except the jet is positioned farther north in South America, which along with the absence of a well defined subpolar jet stream, favors the northward displacement of transient waves into central South America, but show little response in southern Amazon. The CAI days reconstructed from the first and second modes do not present any significant trend in southern Amazon. CAI days reconstructed from the third mode of co-variability on the other hand, reproduces the SON observed trend in almost its entirety. The third mode of co-variability describes negative (positive) anomalies in CAI days associated with cold (warm) SST anomalies in the eastern tropical Pacific, anomalous wavetrain in the Southern Hemisphere and Walker Cell displacement that are unfavorable (favorable) to the incursion of CAI into southern Amazon. The temporal evolution of this mode correlates negatively with the Pacific Decadal Oscillation, suggesting that the recent gradual shift in PDO polarity reflected on the interannual response of Southern Pacific atmospheric patterns, hence on the behavior of transients propagation. The negative PDO index and its related atmospheric patterns are in agreement with the reduced observed CAI days, which also related to a delayed wet season onset in the southern Amazon.

Disease Vector Ecology Profile: Colombia

DTIC Science & Technology

1998-12-01

the Amazon Basin. Unknown. Unknown. Culex gnomatus VEE (Ecuador, Peru ) Many mammals and birds, but equines are key reservoirs with high...Arboviruses other than Dengue or Yellow Fever in the Amazon Basin and Associated Northwestern Regions of South America...widespread (Amazonia, Orinoquia, Cauca Valley, Caribbean regions), and to mefloquine and amodiaquine ( Amazon Basin). Plasmodium vivax resistance

A new genus and species of proteocephalidean tapeworm (Cestoda), first parasite found in the driftwood catfish Tocantinsia piresi (Siluriformes: Auchenipteridae) from Brazil.

PubMed

Alves, Philippe Vieira; Chambrier, Alain de; Scholz, Tomas; Luque, Jose Luis

2015-01-01

Frezella gen. n. is proposed to accommodate Frezella vaucheri sp. n. from poorly known auchenipterid fish, Tocantinsia piresi (Miranda Ribeiro), from the Xingú River, one of the principal tributaries of the lower Amazon River in Brazil. The new genus belongs to the Proteocephalinae because of the medullary position of the testes, ovary (yet some follicles penetrate to the cortex on the dorsal side), vitelline follicles and uterus. It differs from other proteocephaline genera in the morphology of the scolex, which includes a metascolex composed of two distinct zones: anterior, strongly wrinkled part posterior to the suckers, and posterior, sparsely folded zone. Frezella can also be differentiated by having the internal longitudinal musculature hypertrophied laterally on both sides, the presence of some ovarian follicles in the cortex on the dorsal side and the presence of additional pair of tiny, thin-walled osmoregulatory canals situated slightly dorsomedian to ventral canals. Frezella vaucheri is the first helminth parasite reported from T. piresi, which occurs in the lower reaches of the Amazon and Tocantins River basins in Brazil.

Simulating hydrologic and hydraulic processes throughout the Amazon River Basin

USGS Publications Warehouse

Beighley, R.E.; Eggert, K.G.; Dunne, T.; He, Y.; Gummadi, V.; Verdin, K.L.

2009-01-01

Presented here is a model framework based on a land surface topography that can be represented with various degrees of resolution and capable of providing representative channel/floodplain hydraulic characteristics on a daily to hourly scale. The framework integrates two models: (1) a water balance model (WBM) for the vertical fluxes and stores of water in and through the canopy and soil layers based on the conservation of mass and energy, and (2) a routing model for the horizontal routing of surface and subsurface runoff and channel and floodplain waters based on kinematic and diffusion wave methodologies. The WBM is driven by satellite-derived precipitation (TRMM_3B42) and air temperature (MOD08_M3). The model's use of an irregular computational grid is intended to facilitate parallel processing for applications to continental and global scales. Results are presented for the Amazon Basin over the period Jan 2001 through Dec 2005. The model is shown to capture annual runoff totals, annual peaks, seasonal patterns, and daily fluctuations over a range of spatial scales (>1, 000 to < 4·7M km2). For the period of study, results suggest basin-wide total water storage changes in the Amazon vary by approximately + /− 5 to 10 cm, and the fractional components accounting for these changes are: root zone soil moisture (20%), subsurface water being routed laterally to channels (40%) and channel/floodplain discharge (40%). Annual variability in monthly water storage changes by + /− 2·5 cm is likely due to 0·5 to 1 month variability in the arrival of significant rainfall periods throughout the basin.

Metalloproteomics Approach to Analyze Mercury in Breast Milk and Hair Samples of Lactating Women in Communities of the Amazon Basin, Brazil.

PubMed

Cerbino, M R; Vieira, José Cavalcante Souza; Braga, C P; Oliveira, G; Padilha, I F; Silva, T M; Zara, L F; Silva, N J; Padilha, P M

2018-02-01

Mercury is a potentially toxic element that is present in the environment of the Brazilian Amazon and is responsible for adverse health effects in humans. This study sought to assess possible protein biomarkers of mercury exposure in breast milk samples from lactating women in the Madeira and Negro Rivers in the Brazilian Amazon. The mercury content of hair samples of lactating women was determined, and the proteome of breast milk samples was obtained using two-dimensional electrophoresis after protein precipitation with acetone. Mercury measurements of protein spots obtained via protein fractionation were performed by graphite furnace atomic absorption spectrometry (GFAAS), and it was observed that mercury is linked to proteins with molecular masses in the range of 14-26 kDa. The total mercury concentration was also determined by GFAAS in unprocessed milk, lyophilized milk, and protein pellets, with the purpose of determining the mercury mass balance in relation to the concentration of this element in milk and pellets. Approximately 85 to 97% of mercury present in the lyophilized milk from samples of lactating women of the Madeira River is bound in the protein fraction. From lactating women of the Negro River, approximately 49% of the total mercury is bound in the protein fraction, and a difference of 51% is bound in the lipid fraction.

Global Physiographic and Climatic Maps to Support Revision of Environmental Testing Guidelines

DTIC Science & Technology

2009-07-06

precipitation and boarded by High and Low Relief Mountains or Interior Plains and Plateaus, such as the Amazon River Basin in South America and the Congo...taxonomy system. These form in hot climates with continual moisture availability, typically thought to occur only beneath tropical rainforests , though...Montane Tropical Forest Tropical Degraded Forest Seasonal Tropical Forest Rain Green Tropical Forest Tropical Rainforest FIGURE 6-1 DATE: 6-02

The price of gold: mercury exposure in the Amazonian rain forest.

PubMed

Branches, F J; Erickson, T B; Aks, S E; Hryhorczuk, D O

1993-01-01

Concern has surfaced over the recent discovery of human mercury exposure throughout the tropical rain forest of South America's Amazon River Basin. The probable source of mercury has been traced to gold mines located within the interior. The mining process involves the extraction of gold from ore by burning off a mercury additive, resulting in vaporization of elemental mercury into the surrounding environment. The purpose of this case series is to document mercury levels in miners and local villagers presenting with a history of exposure, or signs and symptoms consistent with mercury toxicity. Over a five year period (1986-91), the whole blood and urine mercury levels of 55 Brazilian patients demonstrating signs and symptoms consistent with mercury exposure were collected. Thirty-three (60%) of the subjects had direct occupational exposure to mercury via gold mining and refining. Whole blood mercury levels ranged from 0.4-13.0 micrograms/dL (mean 3.05 micrograms/dL). Spot urine levels ranged 0-151 micrograms/L (mean = 32.7 micrograms/L). Occupational mercury exposure is occurring in the Amazon River Basin. Interventions aimed at altering the gold mining process while protecting the workers and surrounding villagers from the source of exposure are essential. The impact of the gold mining industry on general environmental contamination has not been investigated.

Response of the Amazon rainforest to late Pleistocene climate variability

NASA Astrophysics Data System (ADS)

Häggi, Christoph; Chiessi, Cristiano M.; Merkel, Ute; Mulitza, Stefan; Prange, Matthias; Schulz, Michael; Schefuß, Enno

2017-12-01

Variations in Amazonian hydrology and forest cover have major consequences for the global carbon and hydrological cycles as well as for biodiversity. Yet, the climate and vegetation history of the lowland Amazon basin and its effect on biogeography remain debated due to the scarcity of suitable high-resolution paleoclimate records. Here, we use the isotopic composition (δD and δ13C) of plant-waxes from a high-resolution marine sediment core collected offshore the Amazon River to reconstruct the climate and vegetation history of the integrated lowland Amazon basin for the period from 50,000 to 12,800 yr before present. Our results show that δD values from the Last Glacial Maximum were more enriched than those from Marine Isotope Stage (MIS) 3 and the present-day. We interpret this trend to reflect long-term changes in precipitation and atmospheric circulation, with overall drier conditions during the Last Glacial Maximum. Our results thus suggest a dominant glacial forcing of the climate in lowland Amazonia. In addition to previously suggested thermodynamic mechanisms of precipitation change, which are directly related to temperature, we conclude that changes in atmospheric circulation are crucial to explain the temporal evolution of Amazonian rainfall variations, as demonstrated in climate model experiments. Our vegetation reconstruction based on δ13C values shows that the Amazon rainforest was affected by intrusions of savannah or more open vegetation types in its northern sector during Heinrich Stadials, while it was resilient to glacial drying. This suggests that biogeographic patterns in tropical South America were affected by Heinrich Stadials in addition to glacial-interglacial climate variability.

Epidemiology of Spotted Fever Group and Typhus Group Rickettsial Infection in the Amazon Basin of Peru

DTIC Science & Technology

2010-01-01

MediCine and Hyg1cne Epidemiology of Spotted Fever Group and Typhus Group Rickettsial Infection in the Amazon Basin of Peru Brett M. Forshey, Allison...approximately 4% of acute febrile episodes detected in Iquitos, a city located in the Amazon region of northeast- ern Peru , could be attributed to SFGR...2010 to 00-00-2010 4. TITLE AND SUBTITLE Epidemiology Of Spotted Fever Group And Typhus Group Rickettsial Infection In The Amazon Basin Of Peru 5a

Detrital Zircon Provenance Record of Pre-Andean to Modern Tectonics in the Northern Andes: Examples from Peru, Ecuador, and Colombia

NASA Astrophysics Data System (ADS)

George, S. W. M.; Jackson, L. J.; Horton, B. K.

2015-12-01

Detrital zircon U-Pb age distributions from modern rivers and Mesozoic-Cenozoic basin fill in the northern Andes provide insights into pre-Andean, Andean, and active uplift and exhumation of distinctive sediment source regions. Diagnostic age signatures enable straightforward discrimination of competing sediment sources within the Andean magmatic arc (Western Cordillera-Central Cordillera), retroarc fold-thrust belt (Eastern Cordillera-Subandean Zone), and Amazonian craton (composed of several basement provinces). More complex, however, are the mid/late Cenozoic provenance records generated by recycling of basin fill originally deposited during early/mid Mesozoic extension, late Mesozoic thermal subsidence, and early Cenozoic shortening. Although subject to time-transgressive trends, regionally significant provenance patterns in Peru, Ecuador, and Colombia reveal: (1) Triassic-Jurassic growth of extensional subbasins fed by local block uplifts (with commonly unimodal 300­-150 Ma age peaks); (2) Cretaceous deposition in an extensive postrift setting fed by principally cratonic sources (with common 1800-900 Ma ages); and (3) Cenozoic growth of a broad flexural basin fed initially fed by magmatic-arc rocks (100-0 Ma), then later dominance by thrust-belt sedimentary rocks with progressively greater degrees of basin recycling (yielding diverse and variable age populations from the aforementioned source regions). U-Pb results from modern rivers and smaller subbasins prove useful in evaluating source-to-sink relationships, downstream mixing relationships, hinterland-foreland basin connectivity, paleodrainage integration, and tectonic/paleotopographic reconstructions. Most but not all of the elevated intermontane basins in the modern hinterland of the northern Andes contain provenance records consistent with genesis in a broader foreland basin developed at low elevation. Downstream variations within modern axial rivers and Cenozoic axial basins inform predictive models of Andean contributions from the >1500 km Marañon river to the broader Amazon drainage system, and help pinpoint the late Miocene birth of the >1500 km Magdalena river and associated submarine fan along the southern Caribbean margin.

Improving the Amazonian Hydrologic Cycle in a Coupled Land-Atmosphere, Single Column Model

NASA Astrophysics Data System (ADS)

Harper, A. B.; Denning, S.; Baker, I.; Prihodko, L.; Branson, M.

2006-12-01

We have coupled a land-surface model, the Simple Biosphere Model (SiB3), to a single column of the Colorado State University General Circulation Model (CSU-GCM) in the Amazon River Basin. This is a preliminary step in the broader goal of improved simulation of Basin-wide hydrology. A previous version of the coupled model (SiB2) showed drought and catastrophic dieback of the Amazon rain forest. SiB3 includes updated soil hydrology and root physiology. Our test area for the coupled single column model is near Santarem, Brazil, where measurements from the km 83 flux tower in the Tapajos National Forest can be used to evaluate model output. The model was run for 2001 using NCEP2 Reanalysis as driver data. Preliminary results show that the updated biosphere model coupled to the GCM produces improved simulations of the seasonal cycle of surface water balance and precipitation. Comparisons of the diurnal and seasonal cycles of surface fluxes are also being made.

Measuring Water Storage in the Amazon

NASA Image and Video Library

2010-07-07

This image is from data taken by NASA Gravity Recovery and Climate Experiment showing the Amazon basin in South America. The amount of water stored in the Amazon basin varies from month to month. Animations are available at the Photojournal.

Two sides of a coin: Effects of climate change on the native and non-native distribution of Colossoma macropomum in South America.

PubMed

Lopes, Taise M; Bailly, Dayani; Almeida, Bia A; Santos, Natália C L; Gimenez, Barbara C G; Landgraf, Guilherme O; Sales, Paulo C L; Lima-Ribeiro, Matheus S; Cassemiro, Fernanda A S; Rangel, Thiago F; Diniz-Filho, José A F; Agostinho, Angelo A; Gomes, Luiz C

2017-01-01

Climate change and species invasions interact in nature, disrupting biological communities. Based on this knowledge, we simultaneously assessed the effects of climate change on the native distribution of the Amazonian fish Colossoma macropomum as well as on its invasiveness across river basins of South America, using ecological niche modeling. We used six niche models within the ensemble forecast context to predict the geographical distribution of C. macropomum for the present time, 2050 and 2080. Given that this species has been continuously introduced into non-native South American basins by fish farming activities, we added the locations of C. macropomum farms into the modeling process to obtain a more realistic scenario of its invasive potential. Based on modelling outputs we mapped climate refuge areas at different times. Our results showed that a plenty of climatically suitable areas for the occurrence of C. macropomum occurrence are located outside the original basins at the present time and that its invasive potential is greatly amplified by fish farms. Simulations of future geographic ranges revealed drastic range contraction in the native region, implying concerns not only with respect to the species conservation but also from a socio-economic perspective since the species is a cornerstone of artisanal and commercial fisheries in the Amazon. Although the invasive potential is projected to decrease in the face of climate change, climate refugia will concentrate in Paraná River, Southeast Atlantic and East Atlantic basins, putting intense, negative pressures on the native fish fauna these regions. Our findings show that short and long-term management actions are required for: i) the conservation of natural stocks of C. macropomum in the Amazon, and ii) protecting native fish fauna in the climate refuges of the invaded regions.

Two sides of a coin: Effects of climate change on the native and non-native distribution of Colossoma macropomum in South America

PubMed Central

Lopes, Taise M.; Bailly, Dayani; Almeida, Bia A.; Santos, Natália C. L.; Gimenez, Barbara C. G.; Landgraf, Guilherme O.; Sales, Paulo C. L.; Lima-Ribeiro, Matheus S.; Cassemiro, Fernanda A. S.; Rangel, Thiago F.; Diniz-Filho, José A. F.; Agostinho, Angelo A.; Gomes, Luiz C.

2017-01-01

Climate change and species invasions interact in nature, disrupting biological communities. Based on this knowledge, we simultaneously assessed the effects of climate change on the native distribution of the Amazonian fish Colossoma macropomum as well as on its invasiveness across river basins of South America, using ecological niche modeling. We used six niche models within the ensemble forecast context to predict the geographical distribution of C. macropomum for the present time, 2050 and 2080. Given that this species has been continuously introduced into non-native South American basins by fish farming activities, we added the locations of C. macropomum farms into the modeling process to obtain a more realistic scenario of its invasive potential. Based on modelling outputs we mapped climate refuge areas at different times. Our results showed that a plenty of climatically suitable areas for the occurrence of C. macropomum occurrence are located outside the original basins at the present time and that its invasive potential is greatly amplified by fish farms. Simulations of future geographic ranges revealed drastic range contraction in the native region, implying concerns not only with respect to the species conservation but also from a socio-economic perspective since the species is a cornerstone of artisanal and commercial fisheries in the Amazon. Although the invasive potential is projected to decrease in the face of climate change, climate refugia will concentrate in Paraná River, Southeast Atlantic and East Atlantic basins, putting intense, negative pressures on the native fish fauna these regions. Our findings show that short and long-term management actions are required for: i) the conservation of natural stocks of C. macropomum in the Amazon, and ii) protecting native fish fauna in the climate refuges of the invaded regions. PMID:28654663

Insights into iron sources and pathways in the Amazon River provided by isotopic and spectroscopic studies

NASA Astrophysics Data System (ADS)

Mulholland, Daniel Santos; Poitrasson, Franck; Boaventura, Geraldo Resende; Allard, Thierry; Vieira, Lucieth Cruz; Santos, Roberto Ventura; Mancini, Luiz; Seyler, Patrick

2015-02-01

The present study investigated the weathering and transport mechanisms of Fe in the Amazon River. A particular emphasis was placed on Fe partitioning, speciation, and isotopic fractionation in the contrasting waters of the Solimões and Negro rivers and their mixing zone at the beginning of the Amazon River. Samples collected in the end-member rivers and thirteen sites distributed throughout the mixing zone were processed through frontal vacuum filtration and tangential-flow ultrafiltration to separate the different suspended solid fractions, i.e., particulate (P > 0.45 μm and P > 0.22 μm), colloidal (0.22 μm > C > 5 kDa) and truly dissolved elements (TD < 5 kDa). The Fe isotopic composition and electron paramagnetic resonance (EPR) species were measured on these different pore-sized fractions. The acidic and organo-Fe-rich waters of the Negro River displayed dissolved and colloidal fractions enriched in heavy isotopes (∼1.2‰, in δ57Fe values relative to IRMM-14), while the particulate fractions yielded light isotopic compositions of -0.344‰ for P > 0.22 μm and -0.104‰ for P > 0.45 μm fractions). The mineral particulate-rich waters of the Solimões River had dissolved and colloidal fractions with light isotopic composition (-0.532‰ and -0.176‰, respectively), whereas the particulate fractions yielded δ57Fe values close to those of the continental crust (i.e., -0.029‰ for P > 0.22 μm and 0.028‰ for P > 0.45 μm). Ten kilometers downstream from the Negro and Solimões junction, the concentrations of colloidal and dissolved Fe species deviate markedly from conservative mixing. A maximum Fe loss of 43 μg/L (i.e., 50% of the dissolved and colloidal Fe) is observed 110 km downstream from the rivers junction. The contrasting Negro and Solimões Rivers isotopic compositions along the pore-sized water fractions is attributable to the biogeochemical processes involving different types of upland soils and parental materials. For instance, the isotopic composition of colloidal and dissolved Fe from the Negro River are consistent with Fe oxidation and complexation mechanisms at the interface between waterlogged podzols and river networks, as supported by strong organo-Fe complexes signals observed by EPR. Conversely, the particulate and colloidal fractions from the Solimões River have δ57Fe consistent with strong mechanical erosion in the Andean Cordillera and upland soils, as evidenced by high concentrations of Fe3+-oxides sensu lato measured by EPR. The massive dissolved and colloidal Fe removal is associated with the evolution of the physical and chemical composition of the waters (i.e., ionic strength) during mixing, which influences organo-Fe3+ and Fe3+-oxyhydroxides stability. Several models are discussed to explain Fe non-conservative behavior, including dissociation of organo-Fe complexes and the subsequent formation of solid Fe3+-oxyhydroxides and semiquinone free radicals, as evidenced by EPR spectra demonstrating that organo-Fe signals decrease as Fe3+-oxyhydroxides and free radicals signals increase. As in estuarine regions, the mechanisms involving Fe transfer and loss in the mixing zone has a negligible effect on the bulk water Fe isotopic composition. This result suggests that a tropical basin similar to the Amazon River Basin delivers to the ocean waters with an Fe isotopic composition similar to that of the Earth's continental crust.

Vulnerability associated with "symptoms similar to those of mercury poisoning" in communities from Xingu River, Amazon basin.

PubMed

Da Silva-Junior, Flávio Mnaoel Rodrigues; Oleinski, Ritta M; Azevedo, Antonia E S; Monroe, Kátia C M C; Dos Santos, Marina; Da Silveira, Tatiane Britto; De Oliveira, Adrianne Maria Netto; Soares, Maria Cristina Flores; Pereira, Tatiana Da Silva

2018-06-01

The Brazilian Amazon is known to be a region with high levels of mercury (Hg) in the environment and studies point to an association between high levels of natural mercury in the mother rock and the vast number of clandestine gold mines. Other studies already report the contamination of fish in this region, as well as high levels of Hg in biological material from environmentally exposed populations. On the other hand, this is one of the least developed regions of the planet and it is necessary to understand the vulnerability factors in these populations that may be intoxicated by this element. The purpose of the present study was to investigate the vulnerability factors in communities from Xingu River-Amazon basin probably exposed to Hg. A cross-selection study in two cities localized in Xingu River was conducted, and the sample contained was 268 individuals. sociodemographic questions, lifestyle, diet habits and health conditions were collated. The majority of the sample was female, between 30 and 59 years old, had less than 3 years of educational level and lived in the local of study more than 240 months. There was regular fish consumption (95.9%), principally carnivorous species (80.5%). The visual problem has a highest prevalence (43.3%) between the health problems and about the symptoms of Hg intoxication, memory loss (42.9%), weakness (35.1%), fatigue (34.3%), mood changes (28.7%) and difficulties in concentration (27.2%) was most reported. The female sex, age over 60, educational level below 3 years of study, did not had flush toilet, smoke and least one chronic non-communicable disease represent higher probability to had symptoms of Hg intoxication. Lack of access to health services, low education level and income evidence the susceptibility of this community to diseases and injuries. The vulnerable groups identified in this study should be a priority in public health and environmental health policies.

How Do Morphodynamic Signatures Vary Along the Ucayali, a Large Transitional River?

NASA Astrophysics Data System (ADS)

Dauer, K.; Frias, C. E.; Abad, J. D.; Paredes, J.; Vizcarra, J.; Holguin, C.

2013-12-01

The Ucayali River, with an average discharge of 11, 260 m3 ● s-1 at the Requena station, is one of the largest rivers in Peru, and at its confluence with the Maranon River, the Amazon River is born. The Ucayali River transitions from purely meandering to quasi-anabranching planform near the confluence with the Marañon River. In addition, it carries large amounts of suspended sediment and has been shown to display high rates of migration. Prompted by evidence of changing trends in rainfall and discharge in the Amazon basin, where the Ucayali is located, we have performed a baseline characterization of the planform metrics, thus to determine if effects of climatic change on the morphodynamics are happening in this transitional river, which is a vital transportation route for cities in the jungle such as Iquitos, Peru. Herein, the morphodynamics of the Ucayali River are characterized from its upstream end in Atalaya, Peru to its confluence with the Marañon near Nauta City. First, the migration rates along the Ucayali River are calculated from temporal Landsat images. Then migration rates and planform characteristics, such as wavelength and sinuosity, along the river are compared with the slope along the river to distinguish spatial dominant scales. In addition, bathymetry and velocity measurements taken in 2013 along the Ucayali River help us to understand the complex morphodynamics of the river. Specific case studies have been done at Pucallpa and Jenaro-Herrera, Peru using hydrodynamic and bathymetric measurements complemented with high-resolution shallow water modeling to understand the process of cutoff formation in different locations along the river. This study discusses the frequency at which meanders along the Ucayali River shift from low sinuosity to complete maturity in order to produce cutoffs.

Neogene vegetation development in the Amazon Basin: evidence from marine well-2, Foz do Amazonas (Brazil)

NASA Astrophysics Data System (ADS)

Bogota-Angel, Raul; Chemale Junior, Farid; Davila, Roberto; Soares, Emilson; Pinto, Ricardo; Do Carmo, Dermeval; Hoorn, Carina

2014-05-01

Origen and development of the highly diverse Amazon tropical forest has mostly been inferred from continental sites. However, sediment records in the marine Foz do Amazonas Basin can provide important information to better understand the influence of the Andes uplift and climate change on its plant biomes evolution since the Neogene. Sediment analyses of samples from BP-Petrobras well 1 and 2, drilled in the Amazon Fan, allowed to infer the onset of the transcontinental Amazon river and the fan phase during the middle to late Miocene (c. 10.5 Ma). As part of the CLIMAMAZON research programme we performed pollen analysis on the 10.5 to 0.4 Ma time interval. 76 ditch cutting samples of the upper 4165 m sediments of well 2 permitted us to infer changes in floral composition in the Amazon Basin. The palynological spectra across this interval (nannofossil based age model) include pollen, fern spores, dinocysts and foram lignings. When possible pollen and fern spores were grouped in four vegetation types: estuarine, tropical, mountain forest and high mountain open treeless vegetation. Pollen is generally corroded and reflects the effects of sediment transportation while reworked material is also common. Good pollen producers such as Poaceae, Asteraceae and Cyperaceae are common and reflect indistinctive vegetation types particularly those associated to riverine systems. Rhizophora/Zonocostites spp. indicate "close-distance" mangrove development. Tropical forest biomes are represented by pollen that resemble Moraceae-Urticaceae, Melastomataceae-Combretaceae, Sapotaceae, Alchornea, Euphorbiaceae, Rubiaceae, Bignoniaceae, Mauritia and Arecaceae. Myrica, and particularly sporadic occurrences of fossil fern spores like Lophosoria, and Cyathea suggest the development of a moist Andean forest in areas above 1000 m. First indicators of high altitudes appear in the last part of late Miocene with taxa associated to current Valeriana and particularly Polylepis, a neotropical taxon currently growing along the Andean fluvial system on altitudes between c. 2000 up to c. 4800 m. Alnus is an important Andean forest taxa since Pliocene. In summary, the Neogene palynological record of the Amazon Fan strongly reflects and confirms the influence of the uplift of the Andes and its transcontinental character from late Miocene onwards.

Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved

PubMed Central

Khoury, Eliana Dirce Torres; Souza, Givago da Silva; da Costa, Carlos Araújo; de Araújo, Amélia Ayako Kamogari; de Oliveira, Cláudia Simone Baltazar; Silveira, Luiz Carlos de Lima; Pinheiro, Maria da Conceição Nascimento

2015-01-01

The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13–53 years old. Mercury analysis was performed in head hair samples weighting 0.1–0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age—mercury-exposed and non-exposed—the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population. PMID:26658153

Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved.

PubMed

Khoury, Eliana Dirce Torres; Souza, Givago da Silva; da Costa, Carlos Araújo; de Araújo, Amélia Ayako Kamogari; de Oliveira, Cláudia Simone Baltazar; Silveira, Luiz Carlos de Lima; Pinheiro, Maria da Conceição Nascimento

2015-01-01

The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13-53 years old. Mercury analysis was performed in head hair samples weighting 0.1-0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age-mercury-exposed and non-exposed-the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population.

Genetic differentiation and trade among populations of peach palm ( Bactris gasipaes Kunth) in the Peruvian Amazon-implications for genetic resource management.

PubMed

Adin, A; Weber, J C; Sotelo Montes, C; Vidaurre, H; Vosman, B; Smulders, M J M

2004-05-01

Peach palm ( Bactris gasipaes Kunth) is cultivated for fruit and 'heart of palm', and is an important component of agroforestry systems in the Peruvian Amazon. In this study, AFLP was used to compare genetic diversity among domesticated populations along the Paranapura and Cuiparillo rivers, which are managed by indigenous and colonist farming communities, respectively. Gene diversity was 0.2629 for the populations in indigenous communities and 0.2534 in colonist communities. Genetic differentiation among populations ( G(st)) was 0.0377-0.0416 ( P<0.01) among populations along both rivers. There was no relation between genetic differentiation and the geographical location of populations along the rivers. Since natural seed dispersal by birds and rodents is thought to occur only across relatively short distances (100-200 m), it is likely that exchange of material by farmers and commercial traders is responsible for most of the 'long-distance' (over more than 20 km) gene flow among populations along the two rivers studied. This exchange of material may be important to counteract the effects of selection as well as genetic drift in small groups of trees in farmers' fields, much as in a metapopulation, and may account for the weak genetic differentiation between the two rivers ( G(st)=0.0249, P<0.01). A comparison with samples from other landraces in Peru and Brazil showed the existence of an isolation-by-distance structure up to 3,000 km, consistent with gene flow on a regional scale, likely mediated by trade in the Amazon Basin. Results are discussed with regard to practical implications for the management of genetic resources with farming communities.

The effect of the 2011 flood on agricultural chemical and sediment movement in the lower Mississippi River Basin

NASA Astrophysics Data System (ADS)

Welch, H.; Coupe, R.; Aulenbach, B.

2012-04-01

Extreme hydrologic events, such as floods, can overwhelm a surface water system's ability to process chemicals and can move large amounts of material downstream to larger surface water bodies. The Mississippi River is the 3rd largest River in the world behind the Amazon in South America and the Congo in Africa. The Mississippi-Atchafalaya River basin grows much of the country's corn, soybean, rice, cotton, pigs, and chickens. This is large-scale modern day agriculture with large inputs of nutrients to increase yields and large applied amounts of crop protection chemicals, such as pesticides. The basin drains approximately 41% of the conterminous United States and is the largest contributor of nutrients to the Gulf of Mexico each spring. The amount of water and nutrients discharged from the Mississippi River has been related to the size of the low dissolved oxygen area that forms off of the coast of Louisiana and Texas each summer. From March through April 2011, the upper Mississippi River basin received more than five times more precipitation than normal, which combined with snow melt from the Missouri River basin, created a historic flood event that lasted from April through July. The U.S. Geological Survey, as part of the National Stream Quality Accounting Network (NASQAN), collected samples from six sites located in the lower Mississippi-Atchafalaya River basin, as well as, samples from the three flow-diversion structures or floodways: the Birds Point-New Madrid in Missouri and the Morganza and Bonnet Carré in Louisiana, from April through July. Samples were analyzed for nutrients, pesticides, suspended sediments, and particle size; results were used to determine the water quality of the river during the 2011 flood. Monthly loads for nitrate, phosphorus, pesticides (atrazine, glyphosate, fluometuron, and metolachlor), and sediment were calculated to quantify the movement of agricultural chemicals and sediment into the Gulf of Mexico. Nutrient loads were compared to historic loads to assess the effect of the flood on the zone of hypoxia that formed in the Gulf of Mexico during the spring of 2011.

Amazon River investigations, reconnaissance measurements of July 1963

USGS Publications Warehouse

Oltman, Roy Edwin; Sternberg, H. O'R.; Ames, F.C.; Davis, L.C.

1964-01-01

The first measurements of the flow of the Amazon River were made in July 1963 as a joint project of the University of Brazil, the Brazilian Navy, and the U.S. Geological Survey. The discharge of the Amazon River at Obidos was 7,640,000 cfs at an annual flood stage somewhat lower than the average. For comparison the maximum known discharge of the Mississippi River at Vicksburg is about 2,300,000 cfs. Dissolved-solids concentrations and sediment loads of the Amazon River and of several major tributaries were found to be low.

Impacts of future deforestation and climate change on the hydrology of the Amazon Basin: a multi-model analysis with a new set of land-cover change scenarios

NASA Astrophysics Data System (ADS)

Guimberteau, Matthieu; Ciais, Philippe; Ducharne, Agnès; Boisier, Juan Pablo; Dutra Aguiar, Ana Paula; Biemans, Hester; De Deurwaerder, Hannes; Galbraith, David; Kruijt, Bart; Langerwisch, Fanny; Poveda, German; Rammig, Anja; Andres Rodriguez, Daniel; Tejada, Graciela; Thonicke, Kirsten; Von Randow, Celso; Von Randow, Rita C. S.; Zhang, Ke; Verbeeck, Hans

2017-03-01

Deforestation in Amazon is expected to decrease evapotranspiration (ET) and to increase soil moisture and river discharge under prevailing energy-limited conditions. The magnitude and sign of the response of ET to deforestation depend both on the magnitude and regional patterns of land-cover change (LCC), as well as on climate change and CO2 levels. On the one hand, elevated CO2 decreases leaf-scale transpiration, but this effect could be offset by increased foliar area density. Using three regional LCC scenarios specifically established for the Brazilian and Bolivian Amazon, we investigate the impacts of climate change and deforestation on the surface hydrology of the Amazon Basin for this century, taking 2009 as a reference. For each LCC scenario, three land surface models (LSMs), LPJmL-DGVM, INLAND-DGVM and ORCHIDEE, are forced by bias-corrected climate simulated by three general circulation models (GCMs) of the IPCC 4th Assessment Report (AR4). On average, over the Amazon Basin with no deforestation, the GCM results indicate a temperature increase of 3.3 °C by 2100 which drives up the evaporative demand, whereby precipitation increases by 8.5 %, with a large uncertainty across GCMs. In the case of no deforestation, we found that ET and runoff increase by 5.0 and 14 %, respectively. However, in south-east Amazonia, precipitation decreases by 10 % at the end of the dry season and the three LSMs produce a 6 % decrease of ET, which is less than precipitation, so that runoff decreases by 22 %. For instance, the minimum river discharge of the Rio Tapajós is reduced by 31 % in 2100. To study the additional effect of deforestation, we prescribed to the LSMs three contrasted LCC scenarios, with a forest decline going from 7 to 34 % over this century. All three scenarios partly offset the climate-induced increase of ET, and runoff increases over the entire Amazon. In the south-east, however, deforestation amplifies the decrease of ET at the end of dry season, leading to a large increase of runoff (up to +27 % in the extreme deforestation case), offsetting the negative effect of climate change, thus balancing the decrease of low flows in the Rio Tapajós. These projections are associated with large uncertainties, which we attribute separately to the differences in LSMs, GCMs and to the uncertain range of deforestation. At the subcatchment scale, the uncertainty range on ET changes is shown to first depend on GCMs, while the uncertainty of runoff projections is predominantly induced by LSM structural differences. By contrast, we found that the uncertainty in both ET and runoff changes attributable to uncertain future deforestation is low.

The spatial extent of change in tropical forest ecosystem services in the Amazon delta

NASA Astrophysics Data System (ADS)

de Araujo Barbosa, C. C.; Atkinson, P.; Dearing, J.

2014-12-01

Deltas hold major economic potential due their strategic location, close to seas and inland waterways, thereby supporting intense economic activity. The increasing pace of human development activities in coastal deltas over the past five decades has also strained environmental resources and produced extensive economic and sociocultural impacts. The Amazon delta is located in the Amazon Basin, North Brazil, the largest river basin on Earth and also one of the least understood. A considerable segment of the population living in the Amazon delta is directly dependent on the local extraction of natural resources for their livelihood. Areas sparsely inhabited may be exploited with few negative consequences for the environment. However, increasing pressure on ecosystem services is amplified by large fluxes of immigrants from other parts of the country, especially from the semi-arid zone in Northeast Brazil to the lowland forests of the Amazon delta. Here we present partial results from a bigger research project. Therefore, the focus will be on presenting an overview of the current state, and the extent of changes on forest related ecosystem services in the Amazon delta over the last three decades. We aggregated a multitude of datasets, from a variety of sources, for example, from satellite imagery such as the Advanced Very High Resolution Radiometer (AVHRR), the Global Inventory Modelling and Mapping Studies (GIMMS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and climate datasets at meteorological station level from the Brazilian National Institute of Meteorology (INMET) and social and economic statistics data from the Brazilian Institute of Geography and Statistics (IBGE) and from the Brazilian Institute of Applied Economic Research (IPEA). Through analysis of socioeconomic and satellite earth observation data we were able to produce and present spatially-explicit information with the current state and transition in forest cover and its impacts to forest ecosystem services providing units in the Amazon delta.

Regional controls on geomorphology, hydrology, and ecosystem integrity in the Orinoco Delta, Venezuela

USGS Publications Warehouse

Warne, A.G.; Meade, R.H.; White, W.A.; Guevara, E.H.; Gibeaut, J.; Smyth, R.C.; Aslan, A.; Tremblay, T.

2002-01-01

Interacting river discharge, tidal oscillation, and tropical rainfall across the 22,000 km2 Orinoco delta plain support diverse fresh and brackish water ecosystems. To develop environmental baseline information for this largely unpopulated region, we evaluate major coastal plain, shallow marine, and river systems of northeastern South America, which serves to identify principal sources and controls of water and sediment flow into, through, and out of the Orinoco Delta. The regional analysis includes a summary of the geology, hydrodynamics, sediment dynamics, and geomorphic characteristics of the Orinoco drainage basin, river, and delta system. Because the Amazon River is a major source of sediment deposited along the Orinoco coast, we summarize Amazon water and sediment input to the northeastern South American littoral zone. We investigate sediment dynamics and geomorphology of the Guiana coast, where marine processes and Holocene history are similar to the Orinoco coast. Major factors controlling Orinoco Delta water and sediment dynamics include the pronounced annual flood discharge; the uneven distribution of water and sediment discharge across the delta plain; discharge of large volumes of water with low sediment concentrations through the Rio Grande and Araguao distributaries; water and sediment dynamics associated with the Guayana littoral current along the northeastern South American coast; inflow of large volumes of Amazon sediment to the Orinoco coast; development of a fresh water plume seaward of Boca Grande; disruption of the Guayana Current by Trinidad, Boca de Serpientes, and Gulf of Paria; and the constriction at Boca de Serpientes. ?? 2002 Elsevier Science B.V. All rights reserved.

DDT AND ITS METABOLITES IN BREAST MILK FROM THE MADEIRA RIVER BASIN IN THE AMAZON, BRAZIL

PubMed Central

Azeredo, Antonio; Torres, João P. M.; de Freitas Fonseca, Márlon; Britto, José Lailson; Bastos, Wanderley Rodrigues; Azevedo e Silva, Cláudio E.; Cavalcanti, Giselle; Meire, Rodrigo Ornellas; Sarcinelli, Paula N.; Claudio, Luz; Markowitz, Steven; Malm, Olaf

2008-01-01

Until the 1990’s the 1,1,1-trichloro-bis-2,2′-(4chlorophenyl) ethane (DDT) was sprayed in the walls of the house in the along the Madeira River basin, Brazilian Amazon, a region well known by its large number of malaria cases. In the 1910, the relate of Oswaldo Cruz about health conditions in Madeira River region describes the presence of malaria in rates ranging until 100% of infected people in some localities. Data available in the literature points to the DDT contamination in fishes captured in Madeira River region. Fish is the major source of dietary protein to this people. DDT tends to accumulate in lipid rich tissues being eliminated by different events, including lactation. Considering the importance of the breast milk to the children feeding, the associated risks of DDT exposure via breast milk intake to children must be assessed. This is the main objective of this work: to analyse the presence of the p,p′-DDT and its metabolites p,p′-DDE and p,p′-DDD in 69 human milk samples and to estimate the intake of DDT and its metabolite in terms of total DDT (total DDT = p,p′-DDE+ p,p′-DDD+ p,p′-DDT). All sample showed contamination with DDT and its metabolites ranging from 25.4 to 9361.9 ng of total DDT / g of lipid (median=369.6 ng of total DDT / g of lipid) and 8.7 % of the Estimated Daily Intake (EDI), in terms of total DDT, was higher than the Acceptable Daily Intake proposed by the WHO. Key words: DDT, breast milk, children, organochlorine pesticide, fish. PMID:18495200

Deforestation, Rondonia, Brazil

NASA Technical Reports Server (NTRS)

1992-01-01

This view of deforestation in Rondonia, far western Brazil, (10.0S, 63.0W) is part of an agricultural resettlement project which ultimately covers an area about 80% the size of France. The patterns of deforestation in this part of the Amazon River Basin are usually aligned adjacent to highways, secondary roads, and streams for ease of access and transportation. Compare this view with the earlier 51G-37-062 for a comparison of deforestation in the region.

Deforestation, Rondonia, Brazil

NASA Image and Video Library

1992-08-08

This view of deforestation in Rondonia, far western Brazil, (10.0S, 63.0W) is part of an agricultural resettlement project which ultimately covers an area about 80% the size of France. The patterns of deforestation in this part of the Amazon River Basin are usually aligned adjacent to highways, secondary roads, and streams for ease of access and transportation. Compare this view with the earlier 51G-37-062 for a comparison of deforestation in the region.

Boundary layer ozone - An airborne survey above the Amazon Basin

NASA Technical Reports Server (NTRS)

Gregory, Gerald L.; Browell, Edward V.; Warren, Linda S.

1988-01-01

Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.

Mouths of the Amazon River, Brazil, South America

NASA Technical Reports Server (NTRS)

1992-01-01

In this view of the Amazon River Mouth (0.0, 51.0W), a large sediment plume can be seen expanding outward into the Atlantic Ocean. The sediment plume can be seen hugging the coast north of the delta as a result of the northwest flowing coastal Guyana Current. In recent years, the flow of the Amazon has become heavily laden with sediment as soil runoff from the denuded landscape of the interior enters the Amazon River (and other rivers) drainage system.

Science and Technology Review March 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aufderheide, M B

2006-01-18

This month's issue has the following articles: (1) Without Fanfare, Technicians Safely Keep the Laboratory Humming--Commentary by Bruce T. Goodwin; (2) These People Make Things Happen--Technicians at Lawrence Livermore, comprising more than 20 percent of the workforce, are essential to research efforts. March 2006; (3) The Shocking Truth about Detonations and Metals--The multichannel x-ray system Hydra records the changes in metals undergoing a high-explosives shock, revealing phenomena not predicted by material models; (4) Floating into Thin Air--High-flying balloon gathers images from x-ray sources that are out of this world; and (5) Carbon Goes Full Cycle in the Amazon--Recent measurements indicatemore » that the Amazon River basin returns carbon to the atmosphere in only 5 years.« less

Evaluation of organic compounds and trace elements in Amazon Creek Basin, Oregon, September 1990

USGS Publications Warehouse

Rinella, F.A.

1993-01-01

Water and bottom sediment were collected from Amazon Creek, Oregon during a summer low-flow condition and analyzed for different classes of organic compounds, including many from the U.S. Environmental Protection Agency's priority pollutant list. Bottom sediment also was analyzed for trace elements typically associated with urban runoff. Trace-element concentrations in the less than 63 micrometer fraction of Amazon Creek bottom-sediment samples were compared with baseline concentrations (expected 95 percent confidence range) for soils from the Western United States and with concen- trations found in bottom sediment from the Willamette River Basin. Total-digestion concentrations of antimony, arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, silver, titanium, and zinc were enriched at some or all sites sampled. Whole-water samples from some sites contained concentrations of several chlorophenoxy-acid herbicides, the organophosphorus insecticide diazinon, and several semivolatile priority pollutants. Classes of compounds not detected in whole-water samples included carbamate insecticides, triazine and other nitrogen-containing herbicides, and purgeable organic compounds. Bottom-sediment samples contained many organochlorine compounds, including chlordane, DDT plus metabolites, dieldrin, endrin, heptachlor epoxide (a metabolite of heptachlor), and PCBs at some or all sites sampled. Twenty-four of 54 semivolatile compounds were detected in bottom- sediment samples at some or all sites sampled.

The extreme 2014 flood in south-western Amazon basin: the role of tropical-subtropical South Atlantic SST gradient

NASA Astrophysics Data System (ADS)

Carlo Espinoza, Jhan; Marengo, José Antonio; Ronchail, Josyane; Molina Carpio, Jorge; Noriega Flores, Luís; Loup Guyot, Jean

2014-12-01

Unprecedented wet conditions are reported in the 2014 summer (December-March) in South-western Amazon, with rainfall about 100% above normal. Discharge in the Madeira River (the main southern Amazon tributary) has been 74% higher than normal (58 000 m3 s-1) at Porto Velho and 380% (25 000 m3 s-1) at Rurrenabaque, at the exit of the Andes in summer, while levels of the Rio Negro at Manaus were 29.47 m in June 2014, corresponding to the fifth highest record during the 113 years record of the Rio Negro. While previous floods in Amazonia have been related to La Niña and/or warmer than normal tropical South Atlantic, the 2014 rainfall and flood anomalies are associated with warm condition in the western Pacific-Indian Ocean and with an exceptionally warm Subtropical South Atlantic. Our results suggest that the tropical and subtropical South Atlantic SST gradient is a main driver for moisture transport from the Atlantic toward south-western Amazon, and this became exceptionally intense during summer of 2014.

Chain of commercialization of Podocnemis spp. turtles (Testudines: Podocnemididae) in the Purus River, Amazon basin, Brazil: current status and perspectives.

PubMed

Pantoja-Lima, Jackson; Aride, Paulo H R; de Oliveira, Adriano T; Félix-Silva, Daniely; Pezzuti, Juarez C B; Rebêlo, George H

2014-01-27

Consumption of turtles by natives and settlers in the Amazon and Orinoco has been widely studied in scientific communities. Accepted cultural customs and the local dietary and monetary needs need to be taken into account in conservation programs, and when implementing federal laws related to consumption and fishing methods. This study was conducted around the Purus River, a region known for the consumption and illegal trade of turtles. The objective of this study was to quantify the illegal turtle trade in Tapauá and to understand its effect on the local economy. This study was conducted in the municipality of Tapauá in the state of Amazonas, Brazil. To estimate turtle consumption, interviews were conducted over 2 consecutive years (2006 and 2007) in urban areas and isolated communities. The experimental design was randomized with respect to type of household. To study the turtle fishery and trade chain, we used snowball sampling methodology. During our study period, 100% of respondents reported consuming at least three species of turtles (Podocnemis spp.). Our estimates indicate that about 34 tons of animals are consumed annually in Tapauá along the margins of a major fishing river in the Amazon. At least five components related to the chain of commercialization of turtles on the Purus River are identified: Indigenous Apurinã and (2) residents of bordering villages (communities); (3) of local smugglers buy and sell turtles to the community in exchange for manufactured goods, and (4) regional smugglers buy in Tapauá, Lábrea, and Beruri to sell in Manaus and Manacapuru; Finally, (5) there are professional fishermen. We quantify the full impact of turtle consumption and advocate the conservation of the region's turtle populations. The Brazilian government should initiate a new turtle consumption management program which involves the opinions of consumers. With these measures the conservation of freshwater turtles in the Brazilian Amazon, is possible.

Chain of commercialization of Podocnemis spp. turtles (Testudines: Podocnemididae) in the Purus River, Amazon basin, Brazil: current status and perspectives

PubMed Central

2014-01-01

Background Consumption of turtles by natives and settlers in the Amazon and Orinoco has been widely studied in scientific communities. Accepted cultural customs and the local dietary and monetary needs need to be taken into account in conservation programs, and when implementing federal laws related to consumption and fishing methods. This study was conducted around the Purus River, a region known for the consumption and illegal trade of turtles. The objective of this study was to quantify the illegal turtle trade in Tapauá and to understand its effect on the local economy. Methods This study was conducted in the municipality of Tapauá in the state of Amazonas, Brazil. To estimate turtle consumption, interviews were conducted over 2 consecutive years (2006 and 2007) in urban areas and isolated communities. The experimental design was randomized with respect to type of household. To study the turtle fishery and trade chain, we used snowball sampling methodology. Results During our study period, 100% of respondents reported consuming at least three species of turtles (Podocnemis spp.). Our estimates indicate that about 34 tons of animals are consumed annually in Tapauá along the margins of a major fishing river in the Amazon. At least five components related to the chain of commercialization of turtles on the Purus River are identified: Indigenous Apurinã and (2) residents of bordering villages (communities); (3) of local smugglers buy and sell turtles to the community in exchange for manufactured goods, and (4) regional smugglers buy in Tapauá, Lábrea, and Beruri to sell in Manaus and Manacapuru; Finally, (5) there are professional fishermen. Conclusions We quantify the full impact of turtle consumption and advocate the conservation of the region’s turtle populations. The Brazilian government should initiate a new turtle consumption management program which involves the opinions of consumers. With these measures the conservation of freshwater turtles in the Brazilian Amazon, is possible. PMID:24467796

Aqua-planet simulations of the formation of the South Atlantic convergence zone

NASA Technical Reports Server (NTRS)

Nieto Ferreira, Rosana; Chao, Winston C.

2013-01-01

The impact of Amazon Basin convection and cold fronts on the formation and maintenance of the South Atlantic convergence zone (SACZ) is studied using aqua-planet simulations with a general circulation model. In the model, a circular patch of warm sea-surface temperature (SST) is used to mimic the effect of the Amazon Basin on South American monsoon convection. The aqua-planet simulations were designed to study the effect of the strength and latitude of Amazon Basin convection on the formation of the SACZ. The simulations indicate that the strength of the SACZ increases as the Amazon convection intensifies and is moved away from the equator. Of the two controls studied here, the latitude of the Amazon convection exerts the strongest effect on the strength of the SACZ. An analysis of the synoptic-scale variability in the simulations shows the importance of frontal systems in the formation of the aqua-planet SACZ. Composite time series of frontal systems that occurred in the simulations show that a robust SACZ occurs when fronts penetrate into the subtropics and become stationary there as they cross eastward of the longitude of the Amazon Basin. Moisture convergence associated with these frontal systems produces rainfall not along the model SACZ region and along a large portion of the northern model Amazon Basin. Simulations in which the warm SST patch was too weak or too close to the equator did not produce frontal systems that extended into the tropics and became stationary, and did not form a SACZ. In the model, the SACZ forms as Amazon Basin convection strengthens and migrates far enough southward to allow frontal systems to penetrate into the tropics and stall over South America. This result is in agreement with observations that the SACZ tends to form after the onset of the monsoon season in the Amazon Basin.

Identifiability of altimetry-based rating curve parameters in function of river morphological parameters

NASA Astrophysics Data System (ADS)

Paris, Adrien; André Garambois, Pierre; Calmant, Stéphane; Paiva, Rodrigo; Walter, Collischonn; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Bonnet, Marie-Paule; Seyler, Frédérique; Monnier, Jérôme

2016-04-01

Estimating river discharge for ungauged river reaches from satellite measurements is not straightforward given the nonlinearity of flow behavior with respect to measurable and non measurable hydraulic parameters. As a matter of facts, current satellite datasets do not give access to key parameters such as river bed topography and roughness. A unique set of almost one thousand altimetry-based rating curves was built by fit of ENVISAT and Jason-2 water stages with discharges obtained from the MGB-IPH rainfall-runoff model in the Amazon basin. These rated discharges were successfully validated towards simulated discharges (Ens = 0.70) and in-situ discharges (Ens = 0.71) and are not mission-dependent. The rating curve writes Q = a(Z-Z0)b*sqrt(S), with Z the water surface elevation and S its slope gained from satellite altimetry, a and b power law coefficient and exponent and Z0 the river bed elevation such as Q(Z0) = 0. For several river reaches in the Amazon basin where ADCP measurements are available, the Z0 values are fairly well validated with a relative error lower than 10%. The present contribution aims at relating the identifiability and the physical meaning of a, b and Z0given various hydraulic and geomorphologic conditions. Synthetic river bathymetries sampling a wide range of rivers and inflow discharges are used to perform twin experiments. A shallow water model is run for generating synthetic satellite observations, and then rating curve parameters are determined for each river section thanks to a MCMC algorithm. Thanks to twin experiments, it is shown that rating curve formulation with water surface slope, i.e. closer from Manning equation form, improves parameter identifiability. The compensation between parameters is limited, especially for reaches with little water surface variability. Rating curve parameters are analyzed for riffle and pools for small to large rivers, different river slopes and cross section shapes. It is shown that the river bed elevation Z0is systematically well identified with relative errors on the order of a few %. Eventually, these altimetry-based rating curves provide morphological parameters of river reaches that can be used as inputs into hydraulic models and a priori information that could be useful for SWOT inversion algorithms.

Strengthening Adaptation to Extreme Climate Events in Southwestern Amazonia: an Example from the Trinational Acre River Basin in the Madre de Dios/Peru - Acre/Brazil - Pando/Bolivia (MAP) Region.

NASA Astrophysics Data System (ADS)

Brown, I. F.

2015-12-01

Southwestern Amazonia, where Bolivia, Brazil and Peru meet, faces numerous challenges to the sustainable utilization of land and water resources as the region experiences rapid population and economic growth, expanding agriculture, transportation and energy sectors, along with frequent flooding and droughts. It is also predicted to be one of the most susceptible areas for climate change in the coming decade. The Acre River Basin, one of the few trinational basins in Amazonia, lies at the center of the Madre de Dios Region (Peru), Acre State (Brazil) and Pando Department (Bolivia) or MAP Region. It covers approximately 7,500 km2 and its inhabitants range from indigenous groups avoiding contact with industrial society to more than 60,000 dwellers of a binational urban center. The basin incorporates most the challenges facing the region and this paper discusses steps underway to address the basin's vulnerability to climate-related threats. A trinational group of professionals used GIS databases and local knowledge to classify these threats and possible societal responses. To prioritize threats and to propose responses, this group adapted a method proposed by the Queensland Climate Change Centre of Excellence of Australia to develop climate risk matrices for assessing impacts, adaptation, risk and vulnerability. The three priority climate variables were prolonged and more frequent droughts, more intense flooding, and more days with temperatures > 35oC. The final matrix proposed two areas of concentration - 1) Reduce the vulnerability of communities to hydro-meteorological extreme events and 2) Protect and restore ecosystems that maintain critical water-related resources with actions in public policy, capacity-building, and immediate activities. These results are being incorporated into the Amazon Project of the Global Environment Fund of the United Nations Environment Program, administered by the Amazon Cooperation Treaty Organization (ACTO).

Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin.

PubMed

Fernandes, Itanna O; de Souza, Jorge L P

2018-01-01

Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth's natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six plots (transects) each, totaling 30 sampling plots. The transects were distributed with 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, the study used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9,165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera and 324 species/morphospecies. The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna. Until recently, most studies conducted on hydroelectric plants, located in the Amazon Basin, were carried out after the implementation of dams in order to assess their impacts on the environment and biodiversity (Benchimol and Peres 2015, Latrubesse et al. 2017, Sá-Oliveira et al. 2015). Recent studies on dam impacts have begun to be conducted prior to dam implementation (e.g. Bobrowiec and Tavares 2017, Fraga et al. 2014, Moser et al. 2014), thus providing a better overview of the impact and a better assessment of its magnitude.

Multispecies Fisheries in the Lower Amazon River and Its Relationship with the Regional and Global Climate Variability

PubMed Central

Buss de Souza, Ronald; Freire, Juan; Isaac, Victoria Judith

2016-01-01

This paper aims to describe the spatial-temporal variability in catch of the main fishery resources of the Amazon River and floodplain lakes of the Lower Amazon, as well as relating the Catch per Unit of Effort with anomalies of some of the Amazon River, atmosphere and Atlantic Ocean system variables, determining the influence of the environment on the Amazonian fishery resources. Finfish landings data from the towns and villages of the Lower Amazon for the fisheries of three sites (Óbidos, Santarém and Monte Alegre), were obtained for the period between January 1993 and December 2004. Analysis of variance, detrended correspondence analysis, redundancy analysis and multiple regression techniques were used for the statistical analysis of the distinct time series. Fisheries production in the Lower Amazon presents differences between the Amazon River and the floodplain lakes. Production in the Amazon River is approximately half of the one of the floodplain lakes. This variability occurs both along the Lower Amazon River region (longitudinal gradient) and laterally (latitudinal gradient) for every fishing ground studied here. The distinct environmental variables alone or in association act differently on the fishery stocks and the success of catches in each fishery group studied here. Important variables are the flooding events; the soil the sea surface temperatures; the humidity; the wind and the occurence of El Niño-Southern Oscillation events. Fishery productivity presents a large difference in quantity and distribution patterns between the river and floodplain lakes. This variability occurs in the region of the Lower Amazon as well as laterally for each fishery group studied, being dependent on the ecological characteristics and life strategies of each fish group considered here. PMID:27314951

The Amazon, measuring a mighty river

USGS Publications Warehouse

,

1967-01-01

The Amazon, the world's largest river, discharges enough water into the sea each day to provide fresh water to the City of New York for over 9 years. Its flow accounts for about 15 percent of all the fresh water discharged into the oceans by all the rivers of the world. By comparison, the Amazon's flow is over 4 times that of the Congo River, the world's second largest river. And it is 10 times that of the Mississippi, the largest river on the North American Continent.

Geographical genetics of Pseudoplatystoma punctifer (Castelnau, 1855) (Siluriformes, Pimelodidae) in the Amazon Basin.

PubMed

Telles, M P C; Collevatti, R G; Braga, R S; Guedes, L B S; Castro, T G; Costa, M C; Silva-Júnior, N J; Barthem, R B; Diniz-Filho, J A F

2014-05-09

Geographical genetics allows the evaluation of evolutionary processes underlying genetic variation within and among local populations and forms the basis for establishing more effective strategies for biodiversity conservation at the population level. In this study, we used explicit spatial analyses to investigate molecular genetic variation (estimated using 7 microsatellite markers) of Pseudoplatystoma punctifer, by using samples obtained from 15 localities along the Madeira River and Solimões, Amazon Basin. A high genetic diversity was observed associated with a relatively low FST (0.057; P < 0.001), but pairwise FST values ranged from zero up to 0.21 when some pairs of populations were compared. These FST values have a relatively low correlation with geographic distances (r = 0.343; P = 0.074 by Mantel test), but a Mantel correlogram revealed that close populations (up to 80 km) tended to be more similar than expected by chance (r = 0.360; P = 0.015). The correlogram also showed a exponential-like decrease of genetic similarity with distance, with a patch-size of around 200 km, compatible with isolation-by-distance and analogous processes related to local constraints of dispersal and spatially structured levels of gene flow. The pattern revealed herein has important implications for establishing strategies to maintain genetic diversity in the species, especially considering the threats due to human impacts caused by building large dams in this river system.

A Combined Infrared and Microwave Technique for Studying the Diurnal Variation of Rainfall over Amazonia

NASA Technical Reports Server (NTRS)

Negri, Andrew J.; Anagnostou, Emmanouil; Adler, Robert F.

1999-01-01

Over 10 years of continuous data from the Special Sensor microwave Imager (SSM/I) aboard a series of Defense Department satellites has made it possible to construct regional rainfall climatologies at high spatial resolution. Using the Goddard Profiling Algorithm (GPROF), monthly estimates of precipitation were made over the region of northern Brazil, including the Amazon Basin, for 1987 to 1998. GPROF is a physical approach to passive microwave precipitation retrieval, which uses the Goddard Cumulus Ensemble (cloud) model to establish prior probability densities of precipitation structures. Precipitation fields from GPROF were stratified into morning and evening satellite overpasses, and accumulated at monthly intervals at 0.5 degree spatial resolution. Important diurnal effects were noted in the analysis, the most pronounced being a land/sea breeze circulation along the northern coast of Brazil and a mountain/valley circulation along the Andes. There were also indications of morning rainfall maxima along the major rivers, and evening maxima between the rivers. The addition of simultaneous geosynchronous infrared (IR) data leads to the current technique, which takes advantage of the 30 minute sampling and 4 km spatial resolution of the infrared channel and the better physics of the microwave retrieval. The resultant IR method is subsequently used to derive the diurnal variability of rainfall over the Amazon basin, and further, to investigate the relative contribution from its convective and stratiform components.

Assessment of an improved hydrological loading model from space geodesy: case study in South America

NASA Astrophysics Data System (ADS)

Nicolas, Joëlle; Boy, Jean-Paul; Durand, Frédéric; Mémin, Anthony

2017-04-01

Loading effects are crustal deformations induced by ocean, atmosphere and continental water mass redistributions. In this study we focus on hydrological loading effect monitored by space geodesy and in particular by GNSS and GRACE. Classically, hydrological loading models take into account snow and soil-moisture but don't consider surface waters (rivers, lakes…). As a result, huge discrepancies between GPS observations and those models arise around large rivers such as the Amazon where nearly half of the vertical signal cannot be explained by the combination of atmospheric, oceanic and hydrological loading models. To better resolve the hydrological signal, we improve the continental water storage models computed from soil-moisture and snow GLDAS/Noah or MERRA data sets by including surface water runoff. We investigate how continental water storage model improvements are supported by GNSS and GRACE observations in South America main river basins: Amazon, Orinoco and Parana. In this area the hydrological effects are among the largest in the world mainly due to the river level variations. We present the results of time series analyses with spectral and principal component analysis (PCA) methods. We extract the dominant spatio-temporal annual mode. We also identify and characterize the spatio-temporal changes in the annual hydrology signal, which is the key to a better understanding of the water cycle variations of those major rivers. We demonstrate that it is crucial to take into account the river contribution in fluid signatures before investigating high-frequency variability and episodic events.

Susceptibility of Peruvian Mosquitoes to Eastern Equine Encephalitis virus

DTIC Science & Technology

2008-07-01

the Amazon Basin, near Iquitos, Peru , and used in experimental studies to evaluate their susceptibility to strains of eastern equine encephalitis virus...the repeated isolation of strains of EEEV from Cx. pedroi captured in the Amazon Basin region of Peru , suggests that Cx. pedroi may be the primary...in the Amazon Basin region in Peru , mosquitoes were cap- tured and identiÞed and tested for arboviruses (Pecor et al. 2000, Jones et al. 2004, Turell

Seasonal Distribution, Biology, and Human Attraction Patterns of Mosquitoes (Diptera: Culicidae) in a Rural Village and Adjacent Forested Site Near Iquitos, Peru

DTIC Science & Technology

2008-11-01

and malarial activity in the Amazon Basin, Loreto Department, Peru , to determine the relative abundance, species diversity, and seasonal and vertical...populations. KEY WORDS Anopheles, bionomics, mosquito ecology, Amazon Basin, Peru Malaria and other arthropod-vectored diseases are on the increase...in the Amazon Basin region of Peru to date. The Puerto Almendra area was selected because human cases of dengue, malaria, Mayaro, Oropouche

Integrating Disciplines, Sectors, and Societies to Improve the Definition and Implementation of Environmental Flows for Dammed Amazonian Rivers

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Livino, A.; Arias, M. E.; Crouch, T. D.; Anderson, E.; Marques, E.; Dutka-Gianelli, J.

2017-12-01

The Amazon River watershed is the world's largest river basin and provides US$30 billion/yr in ecosystem services to local populations, national societies, and humanity at large. The Amazon is also a relatively untapped source of hydroelectricity for Latin America, and construction of >30 large hydroelectric dams and >170 small dams is currently underway. Hydropower development will have a cascade of physical, ecological, and social effects at local to global scales. While Brazil has well-defined environmental impact assessment and mitigation programs, these efforts often fail to integrate data and knowledge across disciplines, sectors, and societies throughout the dam planning process. Resulting failures of science, policy, and management have had widespread environmental, economic, and social consequences, highlighting the need for an improved theoretical and practical framework for understanding the impacts of Amazon dams and guiding improved management that respects the needs and knowledge of diverse set of stakeholders. We present a conceptual framework that links four central goals: 1) connecting research in different disciplines (interdisciplinarity); 2) incorporating new knowledge into decision making (adaptive management); 3) including perspectives and participation of non-academic participants in knowledge generation (transdisciplinarity); and 4) extending the idea of environmental flows ("how much water does a river need?") to better consider human uses and users through the concept of fluvial anthropology ("how much water does a society need?"). We use this framework to identify opportunities for improved integration strategies within the (Brazilian) hydroelectric power plant planning and implementation "lifecycle." We applied this approach to the contentious Belo Monte dam, where compliance with regulatory requirements, including monitoring for environmental flows, exemplifies the opportunity for applying adaptive management, but also highlights an urgent need for much improved communication with and participation of affected communities.

Aquatic Biodiversity in the Amazon: Habitat Specialization and Geographic Isolation Promote Species Richness.

PubMed

Albert, James S; Carvalho, Tiago P; Petry, Paulo; Holder, Meghan A; Maxime, Emmanuel L; Espino, Jessica; Corahua, Isabel; Quispe, Roberto; Rengifo, Blanca; Ortega, Hernan; Reis, Roberto E

2011-04-29

The Neotropical freshwater ichthyofauna has among the highest species richness and density of any vertebrate fauna on Earth, with more than 5,600 species compressed into less than 12% of the world's land surface area, and less than 0.002% of the world's total liquid water supply. How have so many species come to co-exist in such a small amount of total habitat space? Here we report results of an aquatic faunal survey of the Fitzcarrald region in southeastern Peru, an area of low-elevation upland (200-500 m above sea level) rainforest in the Western Amazon, that straddles the headwaters of four large Amazonian tributaries; the Juruá (Yurúa), Ucayali, Purús, and Madre de Dios rivers. All measures of fish species diversity in this region are high; there is high alpha diversity with many species coexisting in the same locality, high beta diversity with high turnover between habitats, and high gamma diversity with high turnover between adjacent tributary basins. Current data show little species endemism, and no known examples of sympatric sister species, within the Fitzcarrald region, suggesting a lack of localized or recent adaptive divergences. These results support the hypothesis that the fish species of the Fitzcarrald region are relatively ancient, predating the Late Miocene-Pliocene (c. 4 Ma) uplift that isolated its several headwater basins. The results also suggest that habitat specialization (phylogenetic niche conservatism) and geographic isolation (dispersal limitation) have contributed to the maintenance of high species richness in this region of the Amazon Basin.

Distribution and availability of mercury and methylmercury in different waters from the Rio Madeira Basin, Amazon.

PubMed

Vieira, Miguel; Bernardi, José V E; Dórea, José G; Rocha, Bruno C P; Ribeiro, Romulo; Zara, Luis F

2018-04-01

Waters from the Amazon Basin have distinct physicochemical characteristics that can be optically classified as "black", "clear" and "white". We studied the distribution of total-Hg (THg) and methyl-Hg (MeHg) in these waters and respective suspended solids, sediment, phytoplankton, zooplankton, and benthic macroinvertebrates (BM) in the Madeira River Basin. Compared with the other types of water, the more acidic "black" kind had the highest THg and MeHg concentrations. The trend (black > clear > white) occurred for the concentrations of THg and MeHg in sediments and in the biotic compartment (plankton, macroinvertebrates). Organic Hg accounted for a small percentage (0.6-0.4%) of the THg in sediments but was highest in water (17-15%). For plankton and BM, the biota sediment accumulation factor (BSAFs) of MeHg (53-125) were greater than those of THg (4.5-15); however, the BSAF trend according to water type (black > clear > white) was only significant for MeHg. Sediment THg is correlated with all forms of Hg in biotic and abiotic matrices. The results indicate that water acidity in the Amazon is an important chemical characteristic in assessing Hg contamination of sediments and bioaccumulation in the aquatic food web. The differences in the BSAFs between THg and MeHg support the use of this factor for evaluating the bioaccumulation potential of sediment-bound Hg. The results add information critical to assessing environmental and health risks related to Hg methylation and potential fish-MeHg contamination, especially in tropical aquatic environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Global determination of rating curves in the Amazon basin from satellite altimetry

NASA Astrophysics Data System (ADS)

Paris, Adrien; Paiva, Rodrigo C. D.; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stéphane; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frédérique

2014-05-01

The Amazonian basin is the largest hydrological basin all over the world. Over the past few years, it has experienced an unusual succession of extreme droughts and floods, which origin is still a matter of debate. One of the major issues in understanding such events is to get discharge series distributed over the entire basin. Satellite altimetry can be used to improve our knowledge of the hydrological stream flow conditions in the basin, through rating curves. Rating curves are mathematical relationships between stage and discharge at a given place. The common way to determine the parameters of the relationship is to compute the non-linear regression between the discharge and stage series. In this study, the discharge data was obtained by simulation through the entire basin using the MGB-IPH model with TRMM Merge input rainfall data and assimilation of gage data, run from 1998 to 2009. The stage dataset is made of ~900 altimetry series at ENVISAT and Jason-2 virtual stations, sampling the stages over more than a hundred of rivers in the basin. Altimetry series span between 2002 and 2011. In the present work we present the benefits of using stochastic methods instead of probabilistic ones to determine a dataset of rating curve parameters which are hydrologicaly meaningful throughout the entire Amazon basin. The rating curve parameters have been computed using an optimization technique based on Markov Chain Monte Carlo sampler and Bayesian inference scheme. This technique provides an estimate of the best value for the parameters together with their posterior probability distribution, allowing the determination of a credibility interval for calculated discharge. Also the error over discharges estimates from the MGB-IPH model is included in the rating curve determination. These MGB-IPH errors come from either errors in the discharge derived from the gage readings or errors in the satellite rainfall estimates. The present experiment shows that the stochastic approach is more efficient than the determinist one. By using for the parameters prior credible intervals defined by the user, this method provides an estimate of best rating curve estimate without any unlikely parameter. Results were assessed trough the Nash Sutcliffe efficiency coefficient. Ens superior to 0.7 is found for most of the 920 virtual stations . From these results we were able to determinate a fully coherent map of river bed height, mean depth and Manning's roughness coefficient, information that can be reused in hydrological modeling. Bad results found at a few virtual stations are also of interest. For some sub-basins in the Andean piemont, the bad result confirms that the model failed to estimate discharges overthere. Other are found at tributary mouths experiencing backwater effects from the Amazon. Considering mean monthly slope at the virtual station in the rating curve equation, we obtain rated discharges much more consistent with modeled and measured ones, showing that it is now possible to obtain a meaningful rating curve in such critical areas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Getirana, Augusto; Dutra, Emanuel; Guimberteau, Matthieu

Despite recent advances in modeling and remote sensing of land surfaces, estimates of the global water budget are still fairly uncertain. The objective of this study is to evaluate the water budget of the Amazon basin based on several state-of-the-art land surface model (LSM) outputs. Water budget variables [total water storage (TWS), evapotranspiration (ET), surface runoff (R) and baseflow (B)] are evaluated at the basin scale using both remote sensing and in situ data. Fourteen LSMs were run using meteorological forcings at a 3-hourly time step and 1-degree spatial resolution. Three experiments are performed using precipitation which has been rescaledmore » to match monthly global GPCP and GPCC datasets and the daily HYBAM dataset for the Amazon basin. R and B are used to force the Hydrological Modeling and Analysis Platform (HyMAP) river routing scheme and simulated discharges are compared against observations at 165 gauges. Simulated ET and TWS are compared against FLUXNET and MOD16A2 evapotranspiration, and GRACE TWS estimates in different catchments. At the basin scale, simulated ET ranges from 2.39mm.d-1 to 3.26mm.d-1 and a low spatial correlation between ET and P indicates that evapotranspiration does not depend on water availability over most of the basin. Results also show that other simulated water budget variables vary significantly as a function of both the LSM and precipitation used, but simulated TWS generally agree at the basin scale. The best water budget simulations resulted from experiments using the HYBAM dataset, mostly explained by a denser rainfall gauge network the daily rescaling.« less

Forest-rainfall cascades buffer against drought across the Amazon

NASA Astrophysics Data System (ADS)

Staal, Arie; Tuinenburg, Obbe A.; Bosmans, Joyce H. C.; Holmgren, Milena; van Nes, Egbert H.; Scheffer, Marten; Zemp, Delphine Clara; Dekker, Stefan C.

2018-06-01

Tree transpiration in the Amazon may enhance rainfall for downwind forests. Until now it has been unclear how this cascading effect plays out across the basin. Here, we calculate local forest transpiration and the subsequent trajectories of transpired water through the atmosphere in high spatial and temporal detail. We estimate that one-third of Amazon rainfall originates within its own basin, of which two-thirds has been transpired. Forests in the southern half of the basin contribute most to the stability of other forests in this way, whereas forests in the south-western Amazon are particularly dependent on transpired-water subsidies. These forest-rainfall cascades buffer the effects of drought and reveal a mechanism by which deforestation can compromise the resilience of the Amazon forest system in the face of future climatic extremes.

Vector Competence of Peruvian Mosquitoes (Diptera:Culicidae) for a Subtype IIIC Strain in the Venezuelan Equine Encephalomyelitis Complex Isolated from Mosquitoes Captured in Peru

DTIC Science & Technology

2006-03-01

Amazon Basin, near Iquitos, Peru , for their suscep- tibility to a subtype IIIC strain of the Venezuelan equine encephalomyelitis complex. This virus...As part of a field ecology study of mosquitoes in the Amazon Basin region of Peru (Jones et al. 2004), over 160 virus isolations were made from...distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT We evaluated mosquitoes collected in the Amazon Basin, near Iquitos, Peru , for their

Taxonomic revision of the South American catfish genus Ageneiosus (Siluriformes: Auchenipteridae) with the description of four new species

USGS Publications Warehouse

Ribeiro, Frank R.V.; Rapp Py-Daniel, Lúcia H.; Walsh, Stephen J.

2017-01-01

The catfish genus Ageneiosus in the exclusively Neotropical family Auchenipteridae is revised. Species of Ageneiosus are widely distributed in all major South American continental drainages except the São Francisco River basin and small rivers along the Brazilian east coast. The taxonomic revision was based on examination of available type specimens, additional museum material and comparisons of original descriptions. A suite of morphometric, meristic and qualitative characters of internal and external anatomy were used to diagnose valid species and determine synonyms. Thirteen valid species are recognized in the genus Ageneiosus, some of which are widely distributed across South America. Ageneiosus pardalis is the only trans-Andean species in the genus. Ageneiosus polystictus and Ageneiosus uranophthalmus are more widely distributed than previously reported. Ageneiosus marmoratus is a junior synonym of Ageneiosus inermis. Ageneiosus dentatus is a valid species and its name is removed from the synonymy of Ageneiosus ucayalensis. Four new species are described: Ageneiosus akamai, Ageneiosus apiaka, Ageneiosus intrusus and Ageneiosus lineatus, all from the Amazon River basin. A dichotomous key for all 13 valid species of Ageneiosus species is provided.

United States Naval Hospital Ship Program: History, Evolution, and Configuration Management.

DTIC Science & Technology

1987-12-01

named the CARLOS CHAGAS and was built in Rio de Janeiro in 1984. The basic ship configuration characteristics are as follows: dimension, in ’ feet: 154.2...of 2,500 cubic feet. The ship’s medical missions include trips to countries in the Caribbean Basin and the Amazon River in Brazil . In contrast to...20 D;S’RIBUTION , AVAILABILITY OF ABSTRACT 2’ ABSTRACT SE RITY CASSIFICATION CXNCLASSIVIEDUNLMFi’ED - SAME AS RPT - Z)TIC USERS UNCL 22a NAME O

Central Brazil

NASA Technical Reports Server (NTRS)

2002-01-01

This Moderate resolution Imaging Spectroradiometer (MODIS) true-color image was acquired on October 19, 2000, over a region in Brazil large enough to show much of the country's diverse landscape. Spanning some 8.5 million square kilometers (3.2 million square miles), Brazil is by far the largest South American nation--both in terms of land and population. The region known as the Amazon Basin lies to the northwest (upper left) and extends well beyond the northern and western edges of this scene. Typically, from this perspective Amazonia appears as a lush, dark green carpet due to the thick canopy of vegetation growing there. Some of the Amazon Basin is visible in this image, but much is obscured by clouds (bright white pixels), as is the Amazon River. This region is home to countless plant and animal species and some 150,000 native South Americans. The clusters of square and rectangular patterns toward the center of the image (light green or reddish-brown pixels) are where people have cleared away trees and vegetation to make room for development and agriculture. Toward the western side of the scene there is considerable haze and smoke from widespread biomass burning in parts of Brazil and Bolivia, which shares its eastern border with Brazil. Toward the east in this image is the highland, or 'cerrado,' region, which is more sparsely vegetated and has a somewhat drier climate than the Amazon Basin. The capital city, Brasilia, lies within this region just southwest of the Geral de Goias Mountains (orangish pixels running north-south). There are two large water reservoirs visible in this scene--the Sobradinho Reservoir about 800 km (500 miles) northeast of Brasilia, and the Paranaiba about 500 km (300 miles) southwest of Brasilia. MODIS flies aboard NASA's Terra spacecraft. Image courtesy Brian Montgomery, Reto Stockli, and Robert Simmon, based on data from the MODIS Science Team.

Towards SWOT data assimilation for hydrology : automatic calibration of global flow routing model parameters in the Amazon basin

NASA Astrophysics Data System (ADS)

Mouffe, M.; Getirana, A.; Ricci, S. M.; Lion, C.; Biancamaria, S.; Boone, A.; Mognard, N. M.; Rogel, P.

2011-12-01

The Surface Water and Ocean Topography (SWOT) mission is a swath mapping radar interferometer that will provide global measurements of water surface elevation (WSE). The revisit time depends upon latitude and varies from two (low latitudes) to ten (high latitudes) per 22-day orbit repeat period. The high resolution and the global coverage of the SWOT data open the way for new hydrology studies. Here, the aim is to investigate the use of virtually generated SWOT data to improve discharge simulation using data assimilation techniques. In the framework of the SWOT virtual mission (VM), this study presents the first results of the automatic calibration of a global flow routing (GFR) scheme using SWOT VM measurements for the Amazon basin. The Hydrological Modeling and Analysis Platform (HyMAP) is used along with the MOCOM-UA multi-criteria global optimization algorithm. HyMAP has a 0.25-degree spatial resolution and runs at the daily time step to simulate discharge, water levels and floodplains. The surface runoff and baseflow drainage derived from the Interactions Sol-Biosphère-Atmosphère (ISBA) model are used as inputs for HyMAP. Previous works showed that the use of ENVISAT data enables the reduction of the uncertainty on some of the hydrological model parameters, such as river width and depth, Manning roughness coefficient and groundwater time delay. In the framework of the SWOT preparation work, the automatic calibration procedure was applied using SWOT VM measurements. For this Observing System Experiment (OSE), the synthetical data were obtained applying an instrument simulator (representing realistic SWOT errors) for one hydrological year to HYMAP simulated WSE using a "true" set of parameters. Only pixels representing rivers larger than 100 meters within the Amazon basin are considered to produce SWOT VM measurements. The automatic calibration procedure leads to the estimation of optimal parametersminimizing objective functions that formulate the difference between SWOT observations and modeled WSE using a perturbed set of parameters. Different formulations of the objective function were used, especially to account for SWOT observation errors, as well as various sets of calibration parameters.

Paleo-environment in the upper amazon basin during early to middle Miocene times

NASA Astrophysics Data System (ADS)

van Soelen, Els; Hoorn, Carina; Santos, Roberto V.; Dantas, Elton L.; Sinninghe Damsté, Jaap S.; Kim, Jung-Hyun

2014-05-01

The Amazon River has the largest catchment in the world and is responsible for the largest water discharge from land to the ocean. The river system that flows from the Andes to the Atlantic Equatorial Margin exists since the late Miocene, and results from Andean uplift which strongly affected erosion/deposition and major flow patterns in northern South-America. Two outcrop sites from the Solimões basin, Mariñame (17.7-16.1 Ma) and Los Chorros (14.2-12.7 Ma), may shed light on the inland paleo-environmental conditions during a period of active Andean uplift in the early to middle Miocene. Earlier works revealed the Mariñame outcrops to represent a river born in Amazonia. Instead the Los Chorros outcrops are relics of the Amazon River system, characterized by extensive wetlands consisting of swamps, shallow lakes, crevasse splays channels and crevasse-delta lakes (e.g. Hoorn et al., 2010). The freshwater ecosystems alternate with some intervals that are rich in marine palynomorphs (such as dinocysts), mangrove pollen, brackish tolerant molluscs and ostracods, which indicate brackish conditions and a marine influence. It is thought that these marine incursion are related to phases of global sea-level rise and rapid subsidence in the Andean foreland (Marshall & Lundberg, 1996). Still, much remains unknown about the Miocene river systems, like the extent and diversity of the wetland system and the nature of the marine incursions. To get a better understanding of the sources of the (in)organic material, geochemical methods were used. Strontium (Sr) and Neodymium (Nd) isotopes were analyzed on bulk sediments, and used for a paleo-provenance study. The Sr and Nd isotopic signature in the older section (Mariñame) is in general more radiogenic compared to the Los Chorros section. The most radiogenic values are comparable to those found nowadays in the the Precambrian Guyana shield. A Guyana sediment source would suggest a distinctly different flow direction of the major rivers during early-middle Miocene. The younger Los Chorros sediments show Sr and Nd values comparable to those nowadays found in the Solimões region, indicating an Andean source existed already during early-middle Miocene times. Lipid biomarkers were identified and quantified and carbon isotopic compositions of organic matter for whole samples were determined to identify the sources of organic matter. Ratio's between typically terrestrial and aquatic GDGTs indicate shifts between more terrestrial settings and more aquatic settings. Intervals which suggest a more aquatic setting often contain marine palynomorphs and thus could result from a marine incursion at the time. Changes in the overall composition of biomarker lipids at each site reflects the diversity and dynamic features of the wetland. Differences in both provenance and biomarker composition between the two sites demonstrate the diversity within the basin. This diversity could either be geographical diversity since the two sites are located about 380 km from each other. Or, considering the differences in age between the two sites of 2-5 Myrs, it could also reflect the fast changing environmental conditions as a result of Andean uplift. Hoorn, C. et al (2010). The Development of the Amazonian Mega-Wetland (Miocene; Brazil, Colombia, Peru, Bolivia). In: C. Hoorn and F. Wesselingh (eds) Amazonia: Landscape and Species Evolution: A look into the past. Wiley-Blackwell Publishing Ltd., pp. 123- 142. Marshall, L.G., Lundberg, J.G. (1996) Miocene deposits in the Amazonian Foreland Basin. Science 273, 123-124.

Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae) in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil).

PubMed

Luiz, Tatiane Ferraz; Velludo, Marcela Roquetti; Peret, Alberto Carvalho; Rodrigues Filho, Jorge Luiz; Peret, André Moldenhauer

2011-06-01

The Blue Peacock Bass (Cichla piquiti), native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50) than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish.

Hydrological Signature From River-Floodplain Interactions

NASA Astrophysics Data System (ADS)

Paiva, R. C. D.; Fleischmann, A. S.; Collischonn, W.; Sorribas, M.; Pontes, P. R.

2015-12-01

Understanding river-floodplain hydraulic processes is fundamental to promote comprehension of related water paths, biogeochemicalcyclesand ecosystems. Large river basins around the globe present enormous developed floodplains, which strongly affect flood waves and water dynamics. Since most of these river-floodplain interactions are not monitored, it is interesting to develop strategies to understand such processes through characteristic hydrological signatures, e.g. hydrographs. We studied observed hydrographs from large South American rivers and found that in several cases rivers with extensive wetlands present a particular hydrograph shape, with slower rising limb in relation to the receding one, due to storage effects and the associated decrease of wave celerity with stage. A negative asymmetry in the hydrograph is generated, which is higher when more water flows through floodplains upstream of the observed point. Finally, we studied the Amazon basin using gauged information and simulation results from the MGB-IPH regional hydrological model. Major rivers with larger wetland areas (e.g. Purus, Madeira and Juruá) were identified with higher negative asymmetry in their hydrographs. The hydrodynamic model was run in scenarios with and without floodplains, and results supported that floodplain storage affects hydrographs in creating a negative asymmetry, besides attenuating peaks, increasing hydrograph smoothness and increasing minimum flows. Finally, different wetland types could be distinguished with hydrograph shape, e.g. differing wetlands fed by local rainfall from wetlands due to overbank flow (floodplains). These metrics and concepts on hydrograph features have great potential to infer about river-floodplain processes from large rivers and wetland systems.

Description of a new catfish genus (Siluriformes, Loricariidae) from the Tocantins River basin in central Brazil, with comments on the historical zoogeography of the new taxon

PubMed Central

Silva, Gabriel S. C.; Roxo, Fábio F.; Ochoa, Luz E.; Oliveira, Claudio

2016-01-01

Abstract This study presents the description of a new genus of the catfish subfamily Neoplecostominae from the Tocantins River basin. It can be distinguished from other neoplecostomine genera by the presence of (1) three hypertrophied bicuspid odontodes on the lateral portion of the body (character apparently present in mature males); (2) a large area without odontodes around the snout; (3) a post-dorsal ridge on the caudal peduncle; (4) a straight tooth series in the dentary and premaxillary rows; (5) the absence of abdominal plates; (6) a conspicuous series of enlarged papillae just posterior to the dentary teeth; and (7) caudal peduncle ellipsoid in cross section. We used maximum likelihood and Bayesian methods to estimate a time-calibrated tree with the published data on 116 loricariid species using one nuclear and three mitochondrial genes, and we used parametric biogeographic analyses (DEC and DECj models) to estimate ancestral geographic ranges and to infer the colonization routes of the new genus and the other neoplecostomines in the Tocantins River and the hydrographic systems of southeastern Brazil. Our phylogenetic results indicate that the new genus and species is a sister taxon of all the other members of the Neoplecostominae, originating during the Eocene at 47.5 Mya (32.7–64.5 Mya 95% HPD). The present distribution of the new genus and other neoplecostomines may be the result of a historical connection between the drainage basins of the Paraguay and Paraná rivers and the Amazon basin, mainly through headwater captures. PMID:27408594

DoD Global Emerging Infections System Annual Report, Fiscal Year 1999

DTIC Science & Technology

1999-01-01

findings provided the impetus to the government of Peru to change national drug policy regarding treatment of malaria in the Peruvian Amazon . As soon as...feasible, a 13 14 Malaria Emerges in the Amazon Basin of Peru (Department of Loreto) 1992-1997 During the last 10-15 years, malaria has emerged as a major...public health problem in the Amazon basin of South America. In Peru the total number of malaria cases reported annually from the Peruvian Amazon

Catalogue of Diptera of Colombia: an introduction.

PubMed

Wolff, Marta; Nihei, Silvio S; Carvalho, Claudio J B De

2016-06-14

Colombia has an imposing natural wealth due to its topography has many unique characteristics as a consequence of having Caribbean and Pacific shores, as well as sharing part of the Amazon basin and northern Andes mountains. Thus, many natural and biological features are due to the convergence of three biogeographical regions: Pacific, Andes and Amazonia. The Andean uplift created a complex mosaic of mountains and isolated valleys, including eleven biogeographical provinces (Morrone 2006). The Andes dominate the Colombian topography and cross the country south to north. There are three mountain ranges (Western, Central, and Eastern) with a maximum elevation of 5,775 m, and an average elevation of 2,000 m. The Magdalena and Cauca River valleys separate these ranges, that along with the Putumayo and Caquetá Rivers, the Catatumbo watershed, the Darién, Pique Hill, the Orinoquia Region (with its savannas), the Amazon region (with tropical rainforests), and some lower mountain ranges (Macarena and Chiribiquete), have generated the conditions for very high levels of endemism. This variety of conditions has resulted in an extremely diverse plant and animal biota, and in which 48% of the nation remains unexplored.

Hafnium and neodymium isotopes and REY distribution in the truly dissolved, nanoparticulate/colloidal and suspended loads of rivers in the Amazon Basin, Brazil

NASA Astrophysics Data System (ADS)

Merschel, Gila; Bau, Michael; Schmidt, Katja; Münker, Carsten; Dantas, Elton L.

2017-09-01

Radiogenic isotopes in river sediments and river waters have been widely used in provenance studies, as these samples naturally integrate the geology/chemistry of the entire catchment. While the Hf and Nd isotope systems are coupled during igneous processes, they are decoupled during supergene processes at the Earth's surface, which is reflected by the isotope composition of riverine sediments. We present the first data for both Hf and Nd isotope compositions of the dissolved (0.2 μm-filtrates rich in nanoparticles and colloids, NPCs) and the truly dissolved (1 kDa-ultrafiltrates) load of rivers. Hafnium and Nd isotope compositions and concentrations of the Rare Earths and Yttrium (REY) and Hf were determined for suspended particles (>0.2 μm) as well as for the dissolved and the truly dissolved load of the Rio Solimões, the Amazon's largest tributary draining the Andes, and of the Rio Negro, an organic NPC- and particle-rich river draining the rainforest of northern Amazonia. We also analyzed the Nd isotope compositions of suspended sediments and 0.2 μm-filtered water samples from the Amazon River and its tributaries Rio Tapajos, Rio Xingu and Rio Jari. Our novel results clearly show that the decoupling of the Hf and Nd isotope systems is related to incongruent weathering processes on the continent, as this decoupling can already be observed in the different Hf and Nd pools, i.e. in the particulate, the NPC-dominated dissolved and the truly dissolved load of rivers. In the Rio Negro and Rio Solimões, a strong particle size-dependent difference in Hf isotope composition is observed. Values of εHf become more radiogenic as filter poresize decreases, which can be related to the density- and size-dependent distribution of Hf-rich minerals, e.g. zircons, and their absence from the truly dissolved pool. In contrast, the Nd isotope composition of Amazonian river waters reflects that of their catchment geology. Tributaries draining the Precambrian Brazilian and Guyana shields show very unradiogenic εNd values of -19 to -25 in their dissolved load, whereas the Rio Solimões draining the Andes yields a more radiogenic εNd signal of only -7. The dissolved Nd isotope composition of the Amazon is dominated by its Andean tributaries and averages at -8. Although Nd isotope compositions are thought to not being fractionated by Earth surface processes, significant differences of 1.3-1.9 ε-units can be observed between the dissolved and suspended loads in the Amazon River and its main tributary, the Rio Solimões. In these rivers, the dissolved load is more radiogenic than the suspended sediment, which is likely due to incongruent weathering and related mineral sorting in the Andean headwaters. In contrast, the organic-rich and mineral-poor shield rivers do not show a difference between the truly dissolved, dissolved and suspended load, as the Nd in all these pools is controlled by surface- and solution-complexation and hence isotopically homogenized by continuous exchange and re-equilibration.

Modelling conservation in the Amazon basin.

PubMed

Soares-Filho, Britaldo Silveira; Nepstad, Daniel Curtis; Curran, Lisa M; Cerqueira, Gustavo Coutinho; Garcia, Ricardo Alexandrino; Ramos, Claudia Azevedo; Voll, Eliane; McDonald, Alice; Lefebvre, Paul; Schlesinger, Peter

2006-03-23

Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we report that protected areas in the Amazon basin--the central feature of prevailing conservation approaches--are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation. By 2050, current trends in agricultural expansion will eliminate a total of 40% of Amazon forests, including at least two-thirds of the forest cover of six major watersheds and 12 ecoregions, releasing 32 +/- 8 Pg of carbon to the atmosphere. One-quarter of the 382 mammalian species examined will lose more than 40% of the forest within their Amazon ranges. Although an expanded and enforced network of protected areas could avoid as much as one-third of this projected forest loss, conservation on private lands is also essential. Expanding market pressures for sound land management and prevention of forest clearing on lands unsuitable for agriculture are critical ingredients of a strategy for comprehensive conservation.

Variation of the isotopic composition of dissolved organic carbon during the runoff cycle in the Amazon River and the floodplains

NASA Astrophysics Data System (ADS)

Albéric, Patrick; Pérez, Marcela A. P.; Moreira-Turcq, Patricia; Benedetti, Marc F.; Bouillon, Steven; Abril, Gwenaël

2018-01-01

Given the relative scarcity of stable isotope data on dissolved organic carbon (DOC) in the Amazon Basin, we hypothesized that the variability in DOC sources may be underestimated in such major river basins. To explore the links between the mainstem and tributaries and the floodplain, particular efforts were made during five distinct cruises at different stages of the hydrograph between October 2008 and January 2011, to document the spatial and temporal variation of DOC concentrations and δ13C-DOC in the central Amazon River system (Brazil). Based on more than 200 data, the spatial and temporal variability of δ13C-DOC values was found to be larger than previously reported in the same area. Although a small range of variation was observed throughout the hydrological cycle in the upper reach of the studied section (-29.2 to -29.5‰ in the Rio Negro and -28.7 to -29.0‰ in the Rio Solimões), a much larger one (-28.0 to -34.6‰) was found in the lower reach of the river, as the proportion of open lakes increased downstream in the floodplains. The low variability in the upper reaches suggests constant and homogeneous DOC sources from upland soils and flooded forest, while lower δ13C-DOC values recorded in the lower reach mainstem at high and falling waters can be attributed to a greater export of plankton-derived 13C-depleted DOC from flooded lakes. Noteworthy are the higher δ13C-DOC values measured in the Rio Madeira and the associated flooded lakes (-26.5 to -28.8‰), which may reflect the imprint from upland headwaters and a weaker density of flooded forest in the watershed. The higher δ13C-DOC values observed in the lower reach during low waters are still not fully understood. Floating meadows principally consisting of C4 macrophytes were found to increase δ13C-DOC values by ∼1.5‰ in their vicinity, but this impact was no longer noticeable at distances of ∼10 m from the plant rafts. This rather modest 13C-enrichment suggests rapid decomposition and/or dilution of this wetland-derived DOC.

Hydraulic characterization of the middle reach of the Congo River

NASA Astrophysics Data System (ADS)

O'Loughlin, F.; Trigg, M. A.; Schumann, G. J.-P.; Bates, P. D.

2013-08-01

The middle reach of the Congo remains one of the most difficult places to access, with ongoing conflicts and a lack of infrastructure. This has resulted in the Congo being perhaps the least understood large river hydraulically, particularly compared to the Amazon, Nile, or Mississippi. Globally the Congo River is important; it is the largest river in Africa and the basin contains some of the largest areas of tropical forests and wetlands in the world, which are important to both the global carbon and methane cycles. This study produced the first detailed hydraulic characterization of the middle reach, utilizing mostly remotely sensed data sets. Using Landsat imagery, a 30 m resolution water-mask was created for the middle reach, from which effective river widths and the number of channels and islands were determined. Water surface slopes were determined using ICESat observations for three different periods during the annual flood pulse, and while the overall slope calculated was similar to previous estimates, greater spatial variability was identified. We find that the water surface slope varies markedly in space but relatively little in time and that this appears to contrast with the Amazon where previous studies indicate that time and spatial variations are of equal magnitude. Five key hydraulic constraints were also identified, which play an important role in the overall dynamics of the Congo. Finally, backwater lengths were approximated for four of these constraints, with the results showing that at high water, over a third of the middle reach is affected by backwater effects.

A field study of the confluence between Negro and Solimões Rivers. Part 2: Bed morphology and stratigraphy

NASA Astrophysics Data System (ADS)

Ianniruberto, Marco; Trevethan, Mark; Pinheiro, Arthur; Andrade, Joao Fernando; Dantas, Elton; Filizola, Naziano; Santos, André; Gualtieri, Carlo

2018-01-01

The confluence of the Negro and Solimões Rivers is an interesting study area under several points of view: it represents the second largest river confluence of the Amazon Basin; the rivers are characterized by very distinct hydrologic behaviour; and it is situated in a peculiar tectonic setting. A field investigation was undertaken to study the characteristics of this confluence, aiming to better understand the bed morphology and stratigraphy resulting from the complex interaction of geological setting, hydrodynamics, and sediment load. Two field campaigns were carried out, during low- and high-flow conditions, using high-resolution seismic, echosounding, and acoustic Doppler current profiling. A third campaign was carried out just in a limited area of the confluence, with a multi-beam echosounder. The results of these surveys provided a more detailed view of the geology, morphology and sediment distribution about the confluence.

Effect of seasonal flooding cycle on litterfall production in alluvial rainforest on the middle Xingu River (Amazon basin, Brazil).

PubMed

Camargo, M; Giarrizzo, T; Jesus, A J S

2015-08-01

The assumption for this study was that litterfall in floodplain environments of the middle Xingu river follows a pattern of seasonal variation. According to this view, litterfall production (total and fractions) was estimated in four alluvial rainforest sites on the middle Xingu River over an annual cycle, and examined the effect of seasonal flooding cycle. The sites included two marginal flooded forests of insular lakes (Ilha Grande and Pimentel) and two flooded forests on the banks of the Xingu itself (Boa Esperança and Arroz Cru). Total litterfall correlated with rainfall and river levels, but whereas the leaf and fruit fractions followed this general pattern, the flower fraction presented an inverse pattern, peaking in the dry season. The litterfall patterns recorded in the present study were consistent with those recorded at other Amazonian sites, and in some other tropical ecosystems.

Provenance of sands from the confluence of the Amazon and Madeira rivers based on detrital heavy minerals and luminescence of quartz and feldspar

NASA Astrophysics Data System (ADS)

do Nascimento, Daniel R.; Sawakuchi, André O.; Guedes, Carlos C. F.; Giannini, Paulo C. F.; Grohmann, Carlos H.; Ferreira, Manuela P.

2015-03-01

Source-to-sink systems are poorly known in tropical rivers. For the Amazonian rivers, the majority of the provenance studies remain focused on the suspended load, implying a poor understanding of the processes governing production and distribution of sands. In this study, we perform heavy mineral and optically stimulated luminescence (OSL) analysis to cover the entire spectrum (heavy and light minerals fraction) of 29 sand samples of the Lower Madeira river region (Amazon and Madeira rivers), of which the main goal was to find provenance indicators specific to these rivers. Despite the tropical humid climate, the sands of the Amazon and Lower Madeira rivers are rich in unstable heavy minerals as augite, hypersthene, green hornblende and andalusite. The Madeira river is highlighted by its higher content of andalusite, with source attributed to the Amazon Craton (medium-to-high grade metamorphic rocks), while the Amazon river, upstream of the Madeira river mouth, has a signature of augite and hypersthene, that suggests an Andean provenance (volcanic rocks). Sands from the Madeira river can be tracked in the Amazon river by the increasing concentration in andalusite. OSL analysis of the light minerals fraction was used as an index of feldspar concentration and sedimentary history of quartz grains. Lower feldspar concentration and quartz grains with longer sedimentary history (higher OSL sensitivity) also point to a major contribution of cratonic sources for the sands in the Madeira river. While the sands from the Lower Madeira would be mainly supplied by cratonic rocks, previous work recognised that suspended sediments (silt and clay) are derived from Andean rocks. Therefore, we interpret a decoupling between the sources of sand and mud (silt and clay) under transport in the Madeira river. Andean sands (rich in augite and hypersthene) would be trapped in the foreland zones of the Beni and Mamoré tributaries. In the Amazon river sands, the low OSL sensitivity of the quartz, higher content of feldspar and unstable heavy mineral assemblage dominated by augite and hypersthene suggest both a fast transport from Andean sources with fine sediment bypass over foreland areas.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-08-19

ISS017-E-013856 (19 Aug. 2008) --- Amazon River, Brazil is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. This image shows the huge sunglint zone, common to oblique views from space, of the setting sun shining off the Amazon River and numerous lakes on its floodplain. About 150 kilometers of the sinuous Amazon course is shown here, as it appears about 1,000 kilometers from the Atlantic Ocean. The Uatuma River enters on the north side of the Amazon (top). A small side channel of the very large Madeira River enters the view from the left. Tupinambarama Island occupies the swampy wetlands between the Amazon and Madeira rivers. Sunglint images reveal great detail in waterbodies -- in this case the marked difference between the smooth outline of the Amazon and the jagged shoreline of the Uatuma River. The jagged shoreline results from valley sides being eroded in relatively hard rocks. The Uatuma River has since been dammed up by the sediment mass of the Amazon floodplain. Because the Amazon flows in its own soft sediment, its huge water discharge smooths the banks. Another dammed valley (known as a ria) is visible beneath the cirrus cloud of a storm (bottom). Although no smoke plumes from forest fires are visible in the view, two kinds of evidence show that there is smoke in the atmosphere. The coppery color of the sunglint is typically produced by smoke particles and other aerosols scattering yellow and red light. Second, a small patch of cloud (top right) casts a distinct shadow. The shadow, say scientists, is visible because so many particles in the surrounding sunlit parts of the atmosphere reflect light to the camera.

On river-floodplain interaction and hydrograph skewness

NASA Astrophysics Data System (ADS)

Fleischmann, Ayan S.; Paiva, Rodrigo C. D.; Collischonn, Walter; Sorribas, Mino V.; Pontes, Paulo R. M.

2016-10-01

Understanding hydrological processes occurring within a basin by looking at its outlet hydrograph can improve and foster comprehension of ungauged regions. In this context, we present an extensive examination of the roles that floodplains play on driving hydrograph shapes. Observations of many river hydrographs with large floodplain influence are carried out and indicate that a negative skewness of the hydrographs is present among many of them. Through a series of numerical experiments and analytical reasoning, we show how the relationship between flood wave celerity and discharge in such systems is responsible for determining the hydrograph shapes. The more water inundates the floodplains upstream of the observed point, the more negatively skewed is the observed hydrograph. A case study is performed in the Amazon River Basin, where major rivers with large floodplain attenuation (e.g., Purus, Madeira, and Juruá) are identified with higher negative skewness in the respective hydrographs. Finally, different wetland types could be distinguished by using this feature, e.g., wetlands maintained by endogenous processes, from wetlands governed by overbank flow (along river floodplains). A metric of hydrograph skewness was developed to quantify this effect, based on the time derivative of discharge. Together with the skewness concept, it may be used in other studies concerning the relevance of floodplain attenuation in large, ungauged rivers, where remote sensing data (e.g., satellite altimetry) can be very useful.

An Investigation on the Spatial Variability of Manning Roughness Coefficients in Continental-scale River Routing Simulations

NASA Astrophysics Data System (ADS)

Luo, X.; Hong, Y.; Lei, X.; Leung, L. R.; Li, H. Y.; Getirana, A.

2017-12-01

As one essential component of the Earth system modeling, the continental-scale river routing computation plays an important role in applications of Earth system models, such as evaluating the impacts of the global change on water resources and flood hazards. The streamflow timing, which depends on the modeled flow velocities, can be an important aspect of the model results. River flow velocities have been estimated by using the Manning's equation where the Manning roughness coefficient is a key and sensitive parameter. In some early continental-scale studies, the Manning coefficient was determined with simplified methods, such as using a constant value for the entire basin. However, large spatial variability is expected in the Manning coefficients for the numerous channels composing the river network in distributed continental-scale hydrologic modeling. In the application of a continental-scale river routing model in the Amazon Basin, we use spatially varying Manning coefficients dependent on channel sizes and attempt to represent the dominant spatial variability of Manning coefficients. Based on the comparisons of simulation results with in situ streamflow records and remotely sensed river stages, we investigate the comparatively optimal Manning coefficients and explicitly demonstrate the advantages of using spatially varying Manning coefficients. The understanding obtained in this study could be helpful in the modeling of surface hydrology at regional to continental scales.

The evolution of organic matter along the lower Amazon River continuum - Óbidos to the ocean

NASA Astrophysics Data System (ADS)

Ward, N. D.; Keil, R. G.; Medeiros, P. M.; Brito, D.; Cunha, A.; Sawakuchi, H. O.; Moura, J. S.; Yager, P. L.; Krusche, A. V.; Richey, J. E.

2013-12-01

The influence of the Amazon River on global hydrologic and biogeochemical cycling is well recognized. The Amazon River provides roughly 16% of the global freshwater supply to the ocean and is a significant source of CO2 to the atmosphere, outgassing 0.5 Pg C y-1 to the atmosphere--a flux roughly equivalent to the amount of carbon 'sequestered' by the Amazon rainforest (Field et al, 1998; Richey et al., 2002; Malhi et al., 2008). However, much of our understanding of the flux of matter from the Amazon River into the Atlantic Ocean (and atmosphere) is limited to measurements made at and upstream of Óbidos, 900 km upstream from the actual river mouth. Further, there are few to no observations documenting the transformation of organic matter in a parcel of water as it travels downstream of Óbidos into the ocean. Here we explore the hydrological and biogeochemical evolution of the lower Amazon River continuum, from Óbidos to the Atlantic Ocean. A suite of dissolved and particulate organic matter (OM) parameters were measured during a series of five river expeditions with stations at Óbidos, the Tapajós tributary, the mouth of the Lago Grande de Curuai floodplain lake, both the north and south channels of the Amazon River mouth near Macapá, and the confluence of the Amazon and Tocantins Rivers near Belém. In addition to bulk carbon isotopic signatures, a suite of biomarkers including dissolved and particulate lignin-derived phenols were measured to trace the sources and degradation history of terrestrial vascular plant derived OM throughout the continuum. Dissolved and particulate lignin phenol concentrations both correlated positively with river discharge in the Amazon River mainstem, with variable export patterns from the tributaries and floodplains. As organic matter travels along the continuum it is degraded by microbial composition, fuelling gross respiration and CO2 outgassing. The flux of organic carbon to the ocean is chemically recalcitrant as a result of the constant biological processing of labile OM throughout the lower river. We estimate that 40% of the vascular plant-derived organic carbon sequestered by the terrestrial biosphere is degraded within soils, 55% is degraded along the river continuum, and less than 5% is delivered to the ocean (Ward et al., 2013) References Cited Field, C., M. Behrenfeld, J. Randerson, and P. Falkowski. 1998. Primary production of the biosphere: Integrating terrestrial and oceanic components. Science 281, 237-240. Malhi, Y., Roberts, J.T., Betts, R.A., Killeen, T.J., Li, W., Nobre, C.A. 2008. Climate change, deforestation, and the fate of the Amazon. Science 319, 169-172. Richey, J. E., Melack, J. M., Aufdenkampe, A. K., Ballester, V. M. & Hess, L. L. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2. Nature 416, 617-620. Ward, N.D.; Keil, R.G.; Medeiros, P.M.; Brito, D.C.; Cunha, A.C.; Dittmar, T.; Yager, P.L.; Krusche, A.V.; Richey, J.E. 2013. Degradation of terrestrially derived macromolecules in the Amazon River. Nature Geoscience. doi: 10.1038/ngeo1817

Amazon Basin climate under global warming: the role of the sea surface temperature.

PubMed

Harris, Phil P; Huntingford, Chris; Cox, Peter M

2008-05-27

The Hadley Centre coupled climate-carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5 degrees C warmer air temperature associated with a global mean SST warming.

Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin

PubMed Central

2018-01-01

Abstract Background Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth’s natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six plots (transects) each, totaling 30 sampling plots. The transects were distributed with 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, the study used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9,165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera and 324 species/morphospecies. The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna. New information Until recently, most studies conducted on hydroelectric plants, located in the Amazon Basin, were carried out after the implementation of dams in order to assess their impacts on the environment and biodiversity (Benchimol and Peres 2015, Latrubesse et al. 2017, Sá-Oliveira et al. 2015). Recent studies on dam impacts have begun to be conducted prior to dam implementation (e.g. Bobrowiec and Tavares 2017, Fraga et al. 2014, Moser et al. 2014), thus providing a better overview of the impact and a better assessment of its magnitude. PMID:29674939

Interannual hydroclimatic variability and the 2009-2011 extreme ENSO phases in Colombia: from Andean glaciers to Caribbean lowlands

NASA Astrophysics Data System (ADS)

Bedoya-Soto, Juan Mauricio; Poveda, Germán; Trenberth, Kevin E.; Vélez-Upegui, Jorge Julián

2018-03-01

During 2009-2011, Colombia experienced extreme hydroclimatic events associated with the extreme phases of El Niño-Southern Oscillation (ENSO). Here, we study the dynamics of diverse land-atmosphere phenomena involved in such anomalous events at continental, regional, and local scales. Standardized anomalies of precipitation, 2-m temperature, total column water (TCW), volumetric soil water (VSW), temperature at 925 hPa, surface sensible heat (SSH), latent heat (SLH), evaporation (EVP), and liquid water equivalent thickness (LWET) are analyzed to assess atmosphere-land controls and relationships over tropical South America (TropSA) during 1986-2013 (long term) and 2009-2011 (ENSO extreme phases). An assessment of the interannual covariability between precipitation and 2-m temperature is performed using singular value decomposition (SVD) to identify the dominant spatiotemporal modes of hydroclimatic variability over the region's largest river basins (Amazon, Orinoco, Tocantins, Magdalena-Cauca, and Essequibo). ENSO, its evolution in time, and strong and consistent spatial structures emerge as the dominant mode of variability. In situ anomalies during both extreme phases of ENSO 2009-2011 over the Magdalena-Cauca River basins are linked at the continental scale. The ENSO-driven hydroclimatic effects extend from the diurnal cycle to interannual timescales, as reflected in temperature data from tropical glaciers and the rain-snow boundary in the highest peaks of the Central Andes of Colombia to river levels along the Caribbean lowlands of the Magdalena-Cauca River basin.

Seroprevalence of Toxoplasma gondii in free-living Amazon river dolphins (Inia geoffrensis) from central Amazon, Brazil

USDA-ARS?s Scientific Manuscript database

Toxoplasma gondii is an important pathogen in aquatic mammals and its presence in these animals may indicate water contamination of aquatic environment by oocysts. Serum samples from 95 dolphins from free-living Amazon River dolphins (Inia geoffrensis) from Sustainable Development Reserve Mamirauá (...

Seroprevalence of Toxoplasma gondii in free-living amazon river dolphins (Inia geoffrensis) from central Amazon, Brazil

USDA-ARS?s Scientific Manuscript database

Toxoplasma gondii is an important pathogen in aquatic mammals and its presence in these animals may indicate water contamination of aquatic environment by oocysts. Serum samples from 95 dolphins from free-living Amazon River dolphins (Inia geoffrensis) from Sustainable Development Reserve Mamirauá (...

Sedimentology and Palynostratigraphy of a Pliocene-Pleistocene (Piacenzian to Gelasian) deposit in the lower Negro River: Implications for the establishment of large rivers in Central Amazonia

NASA Astrophysics Data System (ADS)

Soares, Emílio Alberto Amaral; D'Apolito, Carlos; Jaramillo, Carlos; Harrington, Guy; Caputo, Mario Vicente; Barbosa, Rogério Oliveira; Bonora dos Santos, Eneas; Dino, Rodolfo; Gonçalves, Alexandra Dias

2017-11-01

The Amazonas fluvial system originates in the Andes and runs ca. 6700 km to the Atlantic Ocean, having as the main affluent the Negro River (second largest in water volume). The Amazonas transcontinental system has been dated to the late Miocene, but the timing of origin and evolutionary processes of its tributaries are still poorly understood. Negro River alluvial deposits have been dated to the middle to late Pleistocene. Recently, we studied a number of boreholes drilled for the building of a bridge at the lower course of the Negro River. A thin (centimetric) sedimentary deposit was found, laterally continuous for about 1800 m, unconformably overlaying middle Miocene strata and unconformably overlain by younger Quaternary deposits. This deposit consists predominantly of brownish-gray sandstones cemented by siderite and with subordinate mudstone and conglomerate beds. Palynological, granulometric, textural and mineralogical data suggest that the initial Negro River aggradation took place in the deep incised valley under anoxic conditions and subsequently along the floodplain, with efficient transport of mixed origin particles (Andean and Amazonic). Angiosperm leaves, wood and pollen are indicative of a tropical continental palaeoenvironment. A well preserved palynoflora that includes Alnipollenites verus, Grimsdalea magnaclavata and Paleosantalaceaepites cingulatus suggests a late Pliocene to early Pleistocene (Piacenzian to Gelasian) age for this unit, which was an age yet unrecorded in the Amazon Basin. These results indicate that by the late Pliocene-early Pleistocene, large scale river activity was occurring in Central Amazonia linking this region with the Andean headwaters, and therefore incompatible with Central Amazonia barriers like the Purus arch.

Optical Remote Sensing Algorithm Validation using High-Frequency Underway Biogeochemical Measurements in Three Large Global River Systems

NASA Astrophysics Data System (ADS)

Kuhn, C.; Richey, J. E.; Striegl, R. G.; Ward, N.; Sawakuchi, H. O.; Crawford, J.; Loken, L. C.; Stadler, P.; Dornblaser, M.; Butman, D. E.

2017-12-01

More than 93% of the world's river-water volume occurs in basins impacted by large dams and about 43% of river water discharge is impacted by flow regulation. Human land use also alters nutrient and carbon cycling and the emission of carbon dioxide from inland reservoirs. Increased water residence times and warmer temperatures in reservoirs fundamentally alter the physical settings for biogeochemical processing in large rivers, yet river biogeochemistry for many large systems remains undersampled. Satellite remote sensing holds promise as a methodology for responsive regional and global water resources management. Decades of ocean optics research has laid the foundation for the use of remote sensing reflectance in optical wavelengths (400 - 700 nm) to produce satellite-derived, near-surface estimates of phytoplankton chlorophyll concentration. Significant improvements between successive generations of ocean color sensors have enabled the scientific community to document changes in global ocean productivity (NPP) and estimate ocean biomass with increasing accuracy. Despite large advances in ocean optics, application of optical methods to inland waters has been limited to date due to their optical complexity and small spatial scale. To test this frontier, we present a study evaluating the accuracy and suitability of empirical inversion approaches for estimating chlorophyll-a, turbidity and temperature for the Amazon, Columbia and Mississippi rivers using satellite remote sensing. We demonstrate how riverine biogeochemical measurements collected at high frequencies from underway vessels can be used as in situ matchups to evaluate remotely-sensed, near-surface temperature, turbidity, chlorophyll-a derived from the Landsat 8 (NASA) and Sentinel 2 (ESA) satellites. We investigate the use of remote sensing water reflectance to infer trophic status as well as tributary influences on the optical characteristics of the Amazon, Mississippi and Columbia rivers.

Variability of extreme rainfall over La Plata Basin and Amazon Basin in South America in model simulations of the 20th century and projections under global warming

NASA Astrophysics Data System (ADS)

Cavalcanti, I. F.

2011-12-01

The two largest river basins in South America are Amazon Basin (AMB) in the tropical region and La Plata Basin (LPB) in subtropical and extratropical regions. Extreme droughts have occurred during this decade in Amazonia region which have affected the transportation, fishing activities with impacts in the local population, and also affecting the forest. Droughts or floods over LPB have impacts on agriculture, hydroelectricity power and social life. Therefore, monthly wet and dry extremes in these two regions have a profound effect on the economy and society. Observed rainfall over Amazon Basin (AMB) and La Plata Basin (LPB) is analyzed in monthly timescale using the Standardized Precipitation Index (SPI), from 1979 to 1999. This period is taken to compare GPCP data with HADCM3 simulations (Hadley Centre) of the 20th century and to analyze reanalyses data which have the contribution of satellite information after 1979. HADCM3 projections using SRES A2 scenario is analyzed in two periods: 2000 to 2020 and 2079 to 2099 to study the extremes frequency in a near future and in a longer timescale. Extreme, severe and moderate cases are identified in the northern and southern sectors of LPB and in the western and eastern sectors of AMB. The main objective is to analyze changes in the frequency of cases, considering the global warming and the associated mechanisms. In the observations for the 20th century, the number of extreme rainy cases is higher than the number of dry cases in both sectors of LPB and AMB. The model simulates this variability in the two sectors of LPB and in the west sector of AMB. In the near future 2000 to 2020 the frequency of wet and dry extremes does not change much in LPB and in the western sector of AMB, but the wet cases increase in the eastern AMB. However, in the period of 2079 to 2099 the projections indicate increase of wet cases in LPB and increase of dry cases in AMB. The influence of large scale features related to Sea Surface Temperature Anomalies, Walker and Hadley circulations, teleconnections, as well as the regional features related to humidity flux are discussed. The extreme droughts of 2005 and 2010 in Amazonia are show to be related to these features.

Spatial and temporal variations of evapotranspiration, groundwater and precipitation in Amazonia

NASA Astrophysics Data System (ADS)

Niu, J.; Riley, W. J.; Shen, C.; Melack, J. M.; Qiu, H.

2017-12-01

We used wavelet coherence analysis to investigate the effects of precipitation (P) and groundwater dynamics (total water storage anomaly, TWSA) on evapotranspiration (ET) at kilometer, sub-basin, and whole basin scales in the Amazon basin. The Amazon-scale averaged ET, P, and TWSA have about the same annual periodicity. The phase lag between ET and P (ΦET-P) is 1 to 3 months, and between ET and TWSA (ΦET-TWSA) is 3 to 7 months. The phase patterns have a south-north divide due to significant variation in climatic conditions. The correlation between ΦET-P and ΦET-TWSA is affected by the aridity index (the ratio between potential ET (PET) and P, PET / P), of each sub-basin, as determined using the Budyko framework at the sub-basin level. The spatial structure of ΦET-P is negatively correlated with the spatial structure of annual ET. At Amazon-scale during a drought year (e.g., 2010), both phases decreased, while in the subsequent years, ΦET-TWSA increased, indicating strong groundwater effects on ET immediately following dry years Amazon-wide.

Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin.

PubMed

Camargo, M; Giarrizzo, T; Isaac, V J

2015-08-01

This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.

The Planform Mobility of Large River Channel Confluences

NASA Astrophysics Data System (ADS)

Sambrook Smith, Greg; Dixon, Simon; Nicholas, Andrew; Bull, Jon; Vardy, Mark; Best, James; Goodbred, Steven; Sarker, Maminul

2017-04-01

Large river confluences are widely acknowledged as exerting a controlling influence upon both upstream and downstream morphology and thus channel planform evolution. Despite their importance, little is known concerning their longer-term evolution and planform morphodynamics, with much of the literature focusing on confluences as representing fixed, nodal points in the fluvial network. In contrast, some studies of large sand bed rivers in India and Bangladesh have shown large river confluences can be highly mobile, although the extent to which this is representative of large confluences around the world is unknown. Confluences have also been shown to generate substantial bed scours, and if the confluence location is mobile these scours could 'comb' across wide areas. This paper presents field data of large confluences morphologies in the Ganges-Brahmaputra-Meghna river basin, illustrating the spatial extent of large river bed scours and showing scour depth can extend below base level, enhancing long term preservation potential. Based on a global review of the planform of large river confluences using Landsat imagery from 1972 to 2014 this study demonstrates such scour features can be highly mobile and there is an array of confluence morphodynamic types: from freely migrating confluences, through confluences migrating on decadal timescales to fixed confluences. Based on this analysis, a conceptual model of large river confluence types is proposed, which shows large river confluences can be sites of extensive bank erosion and avulsion, creating substantial management challenges. We quantify the abundance of mobile confluence types by classifying all large confluences in both the Amazon and Ganges-Brahmaputra-Meghna basins, showing these two large rivers have contrasting confluence morphodynamics. We show large river confluences have multiple scales of planform adjustment with important implications for river management, infrastructure and interpretation of the rock record.

A review of green- and blue-water resources and their trade-offs for future agricultural production in the Amazon Basin: what could irrigated agriculture mean for Amazonia?

NASA Astrophysics Data System (ADS)

Lathuillière, Michael J.; Coe, Michael T.; Johnson, Mark S.

2016-06-01

The Amazon Basin is a region of global importance for the carbon and hydrological cycles, a biodiversity hotspot, and a potential centre for future economic development. The region is also a major source of water vapour recycled into continental precipitation through evapotranspiration processes. This review applies an ecohydrological approach to Amazonia's water cycle by looking at contributions of water resources in the context of future agricultural production. At present, agriculture in the region is primarily rain-fed and relies almost exclusively on green-water resources (soil moisture regenerated by precipitation). Future agricultural development, however, will likely follow pathways that include irrigation from blue-water sources (surface water and groundwater) as insurance from variability in precipitation. In this review, we first provide an updated summary of the green-blue ecohydrological framework before describing past trends in Amazonia's water resources within the context of land use and land cover change. We then describe green- and blue-water trade-offs in light of future agricultural production and potential irrigation to assess costs and benefits to terrestrial ecosystems, particularly land and biodiversity protection, and regional precipitation recycling. Management of green water is needed, particularly at the agricultural frontier located in the headwaters of major tributaries to the Amazon River, and home to key downstream blue-water users and ecosystem services, including domestic and industrial users, as well as aquatic ecosystems.

Pando Province, Northern Bolivia, Shaded Relief and Colored Height

NASA Technical Reports Server (NTRS)

2003-01-01

Pando Province, Bolivia, and adjacent parts of Brazil and Peru are seen in this visualization of Shuttle Radar Topography Mission (SRTM) elevation data covering part of the Amazon Basin. Most of this region is covered by tropical rainforest and is still largely unaltered by development, though new roads are providing increased access to the area, leading to changes in the landscape. SRTM data provide the first detailed three-dimensional look at the landforms of this region, and the Amazon Basin in its entirety, and will be particularly helpful in understanding the hydrologic patterns as environmental management becomes increasingly important.

River drainage across this area flows generally east-northeast away from the nearby Andes Mountains. The most prominent river channels seen here are the Purus River in the northwest (upper left) and the Madre de Dios River, which crosses the south central (lower central) part of this view. The Beni and Mamore Rivers combine with the Madre de Dios in the eastern (right central) area to form the Madeira River, which flows northeast to eventually meet the Amazon River near Manaus.

The Trans-Amazon Highway crosses the northern half of the scene, and subtle evidence of rainforest clear cutting, facilitated by this easy access, is apparent just north of the scene center, even at the low resolution of this display (740 m or 2428 feet). As seen here, clear cutting patterns in the rainforest typically show a pattern of parallel lines. SRTM mapped the shape of the Earths solid surface (not exclusively the ground surface), which includes to some degree land covers such as forests. Thus, SRTM data are capable of revealing deforestation patterns.

For a smaller, annotated version of this image, please select Figure 1, below: [figure removed for brevity, see original site] (image size: 184k JPEG)

A combination of visualization methods was used to produce this image, based on shading and color coding. A shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellowish and reddish tans, to white at the highest elevations. A measure of relative local topographic height was added as brightness to enhance the contrast of stream channels to their surrounding terrain.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Imagery and Mapping Agency of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: 536 by 710 kilometers (332 by 440 miles) Location: 10.4 degrees South latitude, 67.25 degrees West longitude Orientation: North toward the top Image Data: Shaded and colored SRTM elevation model Date Acquired: February 2000

Range extension of Myotis midastactus​ (Chiroptera, Vespertilionidae) to Paraguay

PubMed Central

Idárraga, Liu; Wilson, Don Ellis

2015-01-01

Abstract Background Myotis midastactus Moratelli and Wilson, 2014 (Vespertilionidae, Myotinae) was described from the Myotis simus Thomas, 1901 complex based on collections from the Bolivian Savannah. New information Four vouchers previously assigned to M. simus from the Alto Chaco in Paraguay (West of the Paraguay River) are reassigned here to M. midastactus. These specimens extend the geographic distribution of M. midastactus 1200 km southward, and constitute the first evidence of the species in the country. Based on other material from the Brazilian Pantanal and Cerrado, Central Paraguay and north-eastern Argentina, we also discuss the identity of simus-like populations south of the Amazon Basin. The status of these populations is still unclear, but the little evidence we have at hand indicates that these populations may represent another taxon—M. guaycuru Proença, 1943; whereas M. simus seems to be restricted to the Amazon basin. This hypothesis is still very speculative and requires further investigation. With the assignment of material from Alto Chaco to M. midastactus, seven species of Myotis are confirmed for Paraguay: M. albescens, M. lavali, M. levis, M. midastactus, M. nigricans, M. riparius, and M. ruber. PMID:26379462

Study of hydrological extremes - floods and droughts in global river basins using satellite data and model output

NASA Astrophysics Data System (ADS)

Lakshmi, V.; Fayne, J.; Bolten, J. D.

2016-12-01

We will use satellite data from TRMM (Tropical Rainfall Measurement Mission), AMSR (Advanced Microwave Scanning Radiometer), GRACE (Gravity Recovery and Climate Experiment) and MODIS (Moderate Resolution Spectroradiometer) and model output from NASA GLDAS (Global Land Data Assimilation System) to understand the linkages between hydrological variables. These hydrological variables include precipitation soil moisture vegetation index surface temperature ET and total water. We will present results for major river basins such as Amazon, Colorado, Mississippi, California, Danube, Nile, Congo, Yangtze Mekong, Murray-Darling and Ganga-Brahmaputra.The major floods and droughts in these watersheds will be mapped in time and space using the satellite data and model outputs mentioned above. We will analyze the various hydrological variables and conduct a synergistic study during times of flood and droughts. In order to compare hydrological variables between river basins with vastly different climate and land use we construct an index that is scaled by the climatology. This allows us to compare across different climate, topography, soils and land use regimes. The analysis shows that the hydrological variables derived from satellite data and NASA models clearly reflect the hydrological extremes. This is especially true when data from different sensors are analyzed together - for example rainfall data from TRMM and total water data from GRACE. Such analyses will help to construct prediction tools for water resources applications.

Virtual mission stage I: Implications of a spaceborne surface water mission

NASA Astrophysics Data System (ADS)

Clark, E. A.; Alsdorf, D. E.; Bates, P.; Wilson, M. D.; Lettenmaier, D. P.

2004-12-01

The interannual and interseasonal variability of the land surface water cycle depend on the distribution of surface water in lakes, wetlands, reservoirs, and river systems; however, measurements of hydrologic variables are sparsely distributed, even in industrialized nations. Moreover, the spatial extent and storage variations of lakes, reservoirs, and wetlands are poorly known. We are developing a virtual mission to demonstrate the feasibility of observing surface water extent and variations from a spaceborne platform. In the first stage of the virtual mission, on which we report here, surface water area and fluxes are emulated using simulation modeling over three continental scale river basins, including the Ohio River, the Amazon River and an Arctic river. The Variable Infiltration Capacity (VIC) macroscale hydrologic model is used to simulate evapotranspiration, soil moisture, snow accumulation and ablation, and runoff and streamflow over each basin at one-eighth degree resolution. The runoff from this model is routed using a linear transfer model to provide input to a much more detailed flow hydraulics model. The flow hydraulics model then routes runoff through various channel and floodplain morphologies at a 250 m spatial and 20 second temporal resolution over a 100 km by 500 km domain. This information is used to evaluate trade-offs between spatial and temporal resolutions of a hypothetical high resolution spaceborne altimeter by synthetically sampling the resultant model-predicted water surface elevations.

Palaeontological evidence for the last temporal occurrence of the ancient western Amazonian river outflow into the Caribbean.

PubMed

Aguilera, Orangel; Lundberg, John; Birindelli, Jose; Sabaj Pérez, Mark; Jaramillo, Carlos; Sánchez-Villagra, Marcelo R

2013-01-01

Fossil catfishes from fluvio-lacustrine facies of late Miocene Urumaco, early Pliocene Castilletes and late Pliocene San Gregorio formations provide evidence of a hydrographic connection in what is today desert regions of northern Colombia and Venezuela. New discoveries and reevaluation of existing materials leads to the recognition of two new records of the pimelodid Brachyplatystoma cf. vaillantii, and of three distinct doradid taxa: Doraops sp., Rhinodoras sp., and an unidentified third form. The presence of fossil goliath long-whiskered catfishes and thorny catfishes are indicative of the persistence of a fluvial drainage system inflow into the South Caribbean during the Pliocene/Pleistocene boundary, complementary to the previous western Amazonian hydrographic system described from the Middle Miocene Villavieja Formation in central Colombia and Late Miocene Urumaco Formation in northwestern Venezuela. The Pliocene Castilletes and San Gregorio formations potentially represent the last lithostratigraphic units related with an ancient western Amazonian fish fauna and that drainage system in the Caribbean. Alternatively, it may preserve faunas from a smaller, peripheral river basin that was cut off earlier from the Amazon-Orinoco, today found in the Maracaibo basin and the Magdalena Rivers.

Palaeontological Evidence for the Last Temporal Occurrence of the Ancient Western Amazonian River Outflow into the Caribbean

PubMed Central

Aguilera, Orangel; Lundberg, John; Birindelli, Jose; Sabaj Pérez, Mark; Jaramillo, Carlos; Sánchez-Villagra, Marcelo R.

2013-01-01

Fossil catfishes from fluvio-lacustrine facies of late Miocene Urumaco, early Pliocene Castilletes and late Pliocene San Gregorio formations provide evidence of a hydrographic connection in what is today desert regions of northern Colombia and Venezuela. New discoveries and reevaluation of existing materials leads to the recognition of two new records of the pimelodid Brachyplatystoma cf. vaillantii, and of three distinct doradid taxa: Doraops sp., Rhinodoras sp., and an unidentified third form. The presence of fossil goliath long-whiskered catfishes and thorny catfishes are indicative of the persistence of a fluvial drainage system inflow into the South Caribbean during the Pliocene/Pleistocene boundary, complementary to the previous western Amazonian hydrographic system described from the Middle Miocene Villavieja Formation in central Colombia and Late Miocene Urumaco Formation in northwestern Venezuela. The Pliocene Castilletes and San Gregorio formations potentially represent the last lithostratigraphic units related with an ancient western Amazonian fish fauna and that drainage system in the Caribbean. Alternatively, it may preserve faunas from a smaller, peripheral river basin that was cut off earlier from the Amazon-Orinoco, today found in the Maracaibo basin and the Magdalena Rivers. PMID:24098778

Manganese and Mercury Levels in Water, Sediments, and Children Living Near Gold-Mining Areas of the Nangaritza River Basin, Ecuadorian Amazon.

PubMed

González-Merizalde, Max V; Menezes-Filho, José A; Cruz-Erazo, Claudia Teresa; Bermeo-Flores, Santos Amable; Sánchez-Castillo, María Obdulia; Hernández-Bonilla, David; Mora, Abrahan

2016-08-01

Artisanal and small-scale gold-mining activities performed in mountain areas of the Southern Ecuadorian Amazon have incorporated several heavy metals into the aquatic systems, thus increasing the risk of exposure in populations living in adjacent zones. Therefore, the objective of this study was to evaluate the contamination levels of mercury (Hg) and manganese (Mn) in several rivers of the Nangaritza River basin and assess the exposure in school-aged children residing near the gold-mining zones. River water and sediment samples were collected from a highly contaminated (HEx) and a moderately contaminated (MEx) zones. Hair Mn (MnH) and urinary Hg (HgU) levels were determined in school-aged children living in both zones. High concentrations of dissolved Mn were found in river waters of the HEx zone (between 2660 and 3990 µg l(-1)); however, Hg levels, in general, were lower than the detection limit (DL; <1.0 µg l(-1)). Similarly, Mn levels in sediments were also increased (3090 to 4086 µg g(-1)). Median values of MnH in children of the HEx and MEx zones were 5.5 and 3.4 µg g(-1), respectively, whereas the median values of HgU concentrations in children living in the HEx and MEx zones were 4.4 and 0.62 µg g-creat(-1), respectively. Statistically significant differences were observed between both biomarkers in children from the HEx and MEx zones. In addition, boys presented significantly greater MnH levels in both zones. The greater MnH values were found in children living in alluvial areas, whereas children living in the high mountain areas, where some ore-processing plants are located close to or inside houses and schools, had the greater HgU concentrations. In summary, the data reported in this paper highlights that artisanal and small-scale gold-mining activities can not only produce mercurial contamination, that can also release other heavy metals (such as Mn) that may pose a risk to human health.

Alluvial plain dynamics and human occupation in SW Amazonia during the Holocene: A paleosol-based reconstruction

NASA Astrophysics Data System (ADS)

Lombardo, Umberto; Rodrigues, Leonor; Veit, Heinz

2018-01-01

The present study reconstructs Holocene fluvial dynamics in the southern Amazonian foreland basin through the analysis of 36 stratigraphic profiles taken along a 300 km long transect across the Llanos de Moxos (LM), in the Bolivian Amazon. Based on 50 radiocarbon ages from paleosols intercalated with fluvial sediments, the most important changes in floodplain dynamics on a millennial scale are reconstructed and the links between pre-Columbian cultural processes and environmental change in the region explored. Results show that the frequency of river avulsions and crevasses, as inferred from the number and age of the cored paleosols, is stable from 8k cal. yrs BP to 4k cal. yrs BP and increases significantly from 4k to 2k cal. yrs BP, following the strengthening of el Niño/la Niña cycle and an increase in average precipitation. Fluvial activity then decreases and reaches its minimum after 2k cal BP. A comparison between the stratigraphic record and the archaeological record shows a match between periods of landscape stability in SW Amazonia (low river activity) and periods of pre-Columbian human occupation. The first Amazonians lived in the LM until 4k yrs. BP, when an abrupt increase in the frequency of river avulsions and crevasses forced the abandonment of the region. After two thousand years of archaeological hiatus, which matches the period of highest river activity in the region, agriculturists reoccupied the Bolivian Amazon.

Holocene palaeoenvironmental history of the Amazonian mangrove belt

NASA Astrophysics Data System (ADS)

Cohen, Marcelo Cancela Lisboa; Pessenda, Luiz Carlos Ruiz; Behling, Hermann; de Fátima Rossetti, Dilce; França, Marlon Carlos; Guimarães, José Tasso Felix; Friaes, Yuri; Smith, Clarisse Beltrão

2012-11-01

Wetland dynamic in the northern Brazilian Amazon region during the Holocene was reviewed using palynological, carbon and nitrogen isotopes records, and C/N ratio previously published. The integration of 72 radiocarbon dates recorded in 34 sediment cores sampled along the marine and fluvial littoral, and mainly influenced by the Amazon River, reveals that marine influence and mangrove vegetation were wider than today on the mouth of Amazon River between >8990-8690 and 2300-2230 cal yr BP, forming a continuous mangrove belt along the northern Brazilian Amazon littoral. The establishment of this mangrove strip is a direct consequence of the marine incursion caused by post-glacial sea-level rise possibly associated with tectonic subsidence during the Early and Middle Holocene. In the Late Holocene, in areas influenced by the Amazon River discharge, the mangroves were replaced by freshwater vegetation, and the coast morphology evolved from an estuarine dominated into a rectilinear coast due to coastal progradation. Nevertheless, the marine-influenced littoral, which is currently dominated by mangroves and salt-marsh vegetation, has persistently had brackish water vegetation over tidal mud flats throughout the entire Holocene. Likely, the fragmentation of this continuous mangrove line during the Late Holocene was caused by the increase of river freshwater discharge associated to the change from dry into wet climates in the Late Holocene. This caused a significant decrease of tidal water salinity in areas near the mouth of Amazon River. These changes in the Amazon discharge are probably associated with dry and wet periods in the northern Amazon region during the Holocene.

Storage and remobilization of suspended sediment in the lower amazon river of Brazil

USGS Publications Warehouse

Meade, R.H.; Dunne, T.; Richey, J.E.; Santos, U.De. M.; Salati, E.

1985-01-01

In the lower Amazon River, suspended sediment is stored during rising stages of the river and resuspended during falling river stages. The storage and resuspension in the reach are related to the mean slope of the flood wave on the river surface; this slope is smaller during rising river stages than during falling stages. The pattern of storage and resuspension damps out the extreme values of high and low sediment discharge and tends to keep them near the mean value between 3.0 ?? 106 and 3.5 ?? 106 metric tons per day. Mean annual discharge of suspended sediment in the lower Amazon is between 1.1 ?? 109 and 1.3 ?? 109 metric tons per year.

The Amazon Basin in transition

Treesearch

Eric A. Davidson; Alessandro C. de Araujo; Paulo Artaxo; Jennifer K. Balch; I. Foster Brown; Mercedes M.C. Bustamente; Michael T. Coe; Ruth S. DeFriess; Michael Keller; Marcos Longo; J. William Munger; Wilfrid Schroeder; Britaldo Soares-Filho; Carlos M. Souza, Jr.; Steven C. Wofsy

2012-01-01

Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional...

An index-based framework for assessing patterns and trends in river fragmentation and flow regulation by global dams at multiple scales

NASA Astrophysics Data System (ADS)

Grill, Günther; Lehner, Bernhard; Lumsdon, Alexander E.; MacDonald, Graham K.; Zarfl, Christiane; Reidy Liermann, Catherine

2015-01-01

The global number of dam constructions has increased dramatically over the past six decades and is forecast to continue to rise, particularly in less industrialized regions. Identifying development pathways that can deliver the benefits of new infrastructure while also maintaining healthy and productive river systems is a great challenge that requires understanding the multifaceted impacts of dams at a range of scales. New approaches and advanced methodologies are needed to improve predictions of how future dam construction will affect biodiversity, ecosystem functioning, and fluvial geomorphology worldwide, helping to frame a global strategy to achieve sustainable dam development. Here, we respond to this need by applying a graph-based river routing model to simultaneously assess flow regulation and fragmentation by dams at multiple scales using data at high spatial resolution. We calculated the cumulative impact of a set of 6374 large existing dams and 3377 planned or proposed dams on river connectivity and river flow at basin and subbasin scales by fusing two novel indicators to create a holistic dam impact matrix for the period 1930-2030. Static network descriptors such as basin area or channel length are of limited use in hierarchically nested and dynamic river systems, so we developed the river fragmentation index and the river regulation index, which are based on river volume. These indicators are less sensitive to the effects of network configuration, offering increased comparability among studies with disparate hydrographies as well as across scales. Our results indicate that, on a global basis, 48% of river volume is moderately to severely impacted by either flow regulation, fragmentation, or both. Assuming completion of all dams planned and under construction in our future scenario, this number would nearly double to 93%, largely due to major dam construction in the Amazon Basin. We provide evidence for the importance of considering small to medium sized dams and for the need to include waterfalls to establish a baseline of natural fragmentation. Our versatile framework can serve as a component of river fragmentation and connectivity assessments; as a standardized, easily replicable monitoring framework at global and basin scales; and as part of regional dam planning and management strategies.

The Fertilizing Role of African Dust in the Amazon Rainforest: A First Multiyear Assessment Based on CALIPSO Lidar Observations

NASA Technical Reports Server (NTRS)

Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Remer, Lorraine A.; Prospero, Joseph M.; Omar, Ali; Winker, David; Yang, Yuekui; Zhang, Yan;

The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations

NASA Astrophysics Data System (ADS)

Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Remer, Lorraine A.; Prospero, Joseph M.; Omar, Ali; Winker, David; Yang, Yuekui; Zhang, Yan; Zhang, Zhibo; Zhao, Chun

2015-03-01

The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three-dimensional (3-D) aerosol measurements over 2007-2013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7 year average of dust deposition into the Amazon Basin is estimated to be 28 (8-48) Tg a-1 or 29 (8-50) kg ha-1 a-1. The dust deposition shows significant interannual variation that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multiyear mean estimate of dust deposition matches better with estimates from in situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3-D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.006-0.037) Tg P of phosphorus per year, equivalent to 23 (7-39) g P ha-1 a-1 to fertilize the Amazon rainforest. This out-of-basin phosphorus input is comparable to the hydrological loss of phosphorus from the basin, suggesting an important role of African dust in preventing phosphorus depletion on timescales of decades to centuries.

Aerial and surface rivers: downwind impacts on water availability from land use changes in Amazonia

NASA Astrophysics Data System (ADS)

Weng, Wei; Luedeke, Matthias K. B.; Zemp, Delphine C.; Lakes, Tobia; Kropp, Juergen P.

2018-02-01

The abundant evapotranspiration provided by the Amazon forests is an important component of the hydrological cycle, both regionally and globally. Since the last century, deforestation and expanding agricultural activities have been changing the ecosystem and its provision of moisture to the atmosphere. However, it remains uncertain how the ongoing land use change will influence rainfall, runoff, and water availability as findings from previous studies differ. Using moisture tracking experiments based on observational data, we provide a spatially detailed analysis recognizing potential teleconnection between source and sink regions of atmospheric moisture. We apply land use scenarios in upwind moisture sources and quantify the corresponding rainfall and runoff changes in downwind moisture sinks. We find spatially varying responses of water regimes to land use changes, which may explain the diverse results from previous studies. Parts of the Peruvian Amazon and western Bolivia are identified as the sink areas most sensitive to land use change in the Amazon and we highlight the current water stress by Amazonian land use change on these areas in terms of the water availability. Furthermore, we also identify the influential source areas where land use change may considerably reduce a given target sink's water reception (from our example of the Ucayali River basin outlet, rainfall by 5-12 % and runoff by 19-50 % according to scenarios). Sensitive sinks and influential sources are therefore suggested as hotspots for achieving sustainable land-water management.

Amazonian and neotropical plant communities on glacial time-scales: The failure of the aridity and refuge hypotheses

NASA Astrophysics Data System (ADS)

Colinvaux, P. A.; De Oliveira, P. E.; Bush, M. B.

2000-01-01

Plants respond to Pleistocene climatic change as species, not as associations or biomes. This has been demonstrated unequivocally by paleobotanical data for temperate latitudes. In the far richer vegetations of the tropics species populations also fluctuated independently in response to climatic forcing, from their longlasting glacial states to the patterns of brief interglacials like the present and back again. We use pollen data to reconstruct the vegetation of the Amazon basin in oxygen isotope stages 3 and 2 of the last glaciation in order to measure how the plant populations of the Amazon responded to the global warming at the onset of the Holocene. We find that plant communities of the neotropics vent copious pollen to lake sediments and that this pollen yields powerful signals for community composition. Three continuous sedimentary records reaching through oxygen isotope stage 2 are available from the Amazon lowlands, those from Carajas, Lake Pata and marine deposits off the mouth of the Amazon River. All three records yield pollen histories of remarkable constancy and stability. By comparing them with deposits of equal antiquity from the cerrado (savanna) of central Brazil, we show that most of the Amazon lowlands remained under forest throughout a glacial cycle. This forest was never fragmented by open vegetation as postulated by the refugia hypothesis. Instead the intact forest of glacial times included significant populations of plants that are now montane, suggesting that the global warming of the early Holocene resulted in the expulsion of heat intolerant plants from the lowland forest. Pollen data from the Amazonian flank of the Andes and from Pacific Panama provide evidence that populations of these heat intolerant plants survive the heat of interglacials in part by maintaining large populations at cooler montane altitudes. Our conclusion that the Amazon lowlands were forested in glacial times specifically refutes the hypothesis of Amazonian glacial aridity. Accordingly we examine the geomorphological evidence for glacial aridity and find it wanting. Of the three paleodune systems reported for tropical South America, that of NE Brazil was active in the Holocene as well as the Pleistocene. Parts of NE Brazil were actually moister than now in late-glacial times. Paleodunes in the Pantanal have never been seen on the ground, and those in the Orinoco Llanos are undated and may be of any age since the Tertiary. Arkosic sands in the Amazon fan deposits came from the Andean foothills or from down cutting by rivers and cannot be evidence of a former arid land surface. White sands of Amazonia formed as podzols, not by aeolian activity. Such Amazonian stone lines as have received critical scrutiny are concretionary pisolites in stratigraphic formations that are more than ten million years old. Although the Amazon was never arid, modeling cooler glacial tropics gives plausibility to a somewhat drier Amazon in glacial times, a concept given substance by pollen data for the movement of ecotones in Rondonia, by stream histories in the Bolivian Andes, and by evidence for lowered lake levels at Carajas and Lake Pata. But this reduced precipitation was never enough to fragment the forest in the Amazon lowlands themselves. Pleistocene mammals of the Napo river valley in Ecuador were able to live along the river system in a forested landscape. Our data suggest that the Amazon forests have been stable since the start of the Pleistocene, a fact that has contributed to the storage of vast diversity. The coming anthropogenic global warming and CO 2 enrichment will add to the global warming already endured by Amazon biota in the Holocene. We think it possible that the expulsion from the lowland forests of heat intolerant species is already complete and that the forest property of maintaining its own microhabitat will allow the high species richness to survive more global warming, provided large enough tracts of forest are preserved.

Color vision impairment with low-level methylmercury exposure of an Amazonian population - Brazil.

PubMed

Feitosa-Santana, Claudia; Souza, Givago da Silva; Sirius, Esaú Ventura Pupo; Rodrigues, Anderson Raiol; Cortes, Maria Izabel Tentes; Silveira, Luiz Carlos de Lima; Ventura, Dora Fix

2018-05-01

Land exploitation that follows deforestation and mining can result in soil erosion and the release of mercury to the waters of rivers in the Amazon Basin. Inorganic mercury is methylated by bacteria that are present in the environment and it serves as a source of human contamination through fish consumption in the form of methylmercury. Long-term exposure to low-level methylmercury in the riverside populations can lead to nervous system alterations, some of which are visual impairments such as loss of luminance contrast sensitivity, restricted visual fields and color vision defects. The present study sought to examine color vision in a group of adults living in the central Brazilian Amazon who were exposed to low-levels of methylmercury. Total Hg concentrations were measured from hair collected at the time of the testing. The D15d and FM100 color vision arrangement tests were applied in a population of 36 (22 males) and 42 (25 males), respectively. Controls were healthy volunteers from the cities of São Paulo for the D15d and Belém for the FM100. There was a statistically significant difference in performance between those who were exposed and controls for both tests (p < 0.01 and p < 0.0001, respectively, Mann-Whitney U test), meaning that adults living in this region of the Amazon made more mistakes on both tests when compared to controls. A linear regression was performed using Hg concentrations and test scores. Hg concentrations accounted for 7% and 2% of color D15d and FM100 arrangement test errors, respectively. Although other studies have previously found color vision impairment in the Amazon, they tested inhabitants on the east side of the Amazon, while this study was conducted in the central Amazon region and it is the first study in a population with no direct contact with the Hg source of contamination. These results suggest that long-term exposure to low-level methylmercury in riverside populations is more widely spread in the Amazon Basin than previously reported. This information is needed to implement public health policies that will ensure a safer environment for the Amazonian population. Copyright © 2018 Elsevier B.V. All rights reserved.

Trace gas and aerosol transports into and out of the Amazon Basin

NASA Technical Reports Server (NTRS)

Garstang, Michael

1992-01-01

Research under Agreement NCC1-106 during the interim period Oct. 1, 1991 to May 31, 1992 has continued to use the data collected during all three ABLE missions. The work reported on in this interim period includes published papers that cover the topic of global interactions between the rain forest of the Amazon Basin and local regional processes interior to the Basin itself.

African Dust Fertilizing the Amazon Rainforest: An Assessment with Seven-year Record of CALIOP Measurements

NASA Astrophysics Data System (ADS)

Yu, H.; Chin, M.; Yuan, T.; Bian, H.; Prospero, J. M.; Omar, A. H.; Remer, L. A.; Winker, D. M.; Yang, Y.; Zhang, Y.; Zhang, Z.

2014-12-01

The productivity of Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of transported African dust in boreal winter and spring is considered an important nutrient input for the Amazon Basin, though its magnitude is not well qunatified. This study provides a remote sensing observation-based estimate of dust deposition in the Amazon Basin using a 7-year (2007-2013) record of three dimensional (3D) distributions of aerosol in both cloud-free and above-cloud conditions from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). It is estimated that the 7-year average of dust deposition into the Amazon Basin amounts to 15.1 ~ 32.1 Tg a-1 (Tg = 1012 g). This imported dust could provide 0.012 ~ 0.025 Tg P a-1 or equivalent to 12 ~ 26 g P ha-1 a-1 to fertilize the Amazon rainforest, which largely compensates the hydrological loss of P. The CLAIOP-based estimate agrees better with estimates from in-situ measurements and model simulations than what has been reported in literature. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The trans-Atlantic transport and deposition of dust shows strong interannual variations that are found to correlate with the North Atlantic Oscillation index in the winter season and anticorrelate with the prior-year Sahel Precipitation Index on an annual basis. Uncertainties associated with the estimate will also be discussed.

Landscape biogeochemistry reflected in shifting distributions of chemical traits in the Amazon forest canopy

NASA Astrophysics Data System (ADS)

Asner, Gregory P.; Anderson, Christopher B.; Martin, Roberta E.; Tupayachi, Raul; Knapp, David E.; Sinca, Felipe

2015-07-01

Tropical forest functional diversity, which is a measure of the diversity of organismal interactions with the environment, is poorly understood despite its importance for linking evolutionary biology to ecosystem biogeochemistry. Functional diversity is reflected in functional traits such as the concentrations of different compounds in leaves or the density of leaf mass, which are related to plant activities such as plant defence, nutrient cycling, or growth. In the Amazonian lowlands, river movement and microtopography control nutrient mobility, which may influence functional trait distributions. Here we use airborne laser-guided imaging spectroscopy to develop maps of 16 forest canopy traits, throughout four large landscapes that harbour three common forest community types on the Madre de Dios and Tambopata rivers in southwestern Amazonia. Our maps, which are based on quantitative chemometric analysis of forest canopies with visible-to-near infrared (400-2,500 nm) spectroscopy, reveal substantial variation in canopy traits and their distributions within and among forested landscapes. Forest canopy trait distributions are arranged in a nested pattern, with location along rivers controlling trait variation between different landscapes, and microtopography controlling trait variation within landscapes. We suggest that processes of nutrient deposition and depletion drive increasing phosphorus limitation, and a corresponding increase in plant defence, in an eastward direction from the base of the Andes into the Amazon Basin.

Campaign datasets for Observations and Modeling of the Green Ocean Amazon (GOAMAZON)

DOE Data Explorer

Martin,Scot; Mei,Fan; Alexander,Lizabeth; Artaxo,Paulo; Barbosa,Henrique; Bartholomew,Mary Jane; Biscaro,Thiago; Buseck,Peter; Chand,Duli; Comstock,Jennifer; Dubey,Manvendra; Godstein,Allen; Guenther,Alex; Hubbe,John; Jardine,Kolby; Jimenez,Jose-Luis; Kim,Saewung; Kuang,Chongai; Laskin,Alexander; Long,Chuck; Paralovo,Sarah; Petaja,Tuukka; Powers,Heath; Schumacher,Courtney; Sedlacek,Arthur; Senum,Gunnar; Smith,James; Shilling,John; Springston,Stephen; Thayer,Mitchell; Tomlinson,Jason; Wang,Jian; Xie,Shaocheng

2016-05-30

The hydrologic cycle of the Amazon Basin is one of the primary heat engines of the Southern Hemisphere. Any accurate climate model must succeed in a good description of the Basin, both in its natural state and in states perturbed by regional and global human activities. At the present time, however, tropical deep convection in a natural state is poorly understood and modeled, with insufficient observational data sets for model constraint. Furthermore, future climate scenarios resulting from human activities globally show the possible drying and the eventual possible conversion of rain forest to savanna in response to global climate change. Based on our current state of knowledge, the governing conditions of this catastrophic change are not defined. Human activities locally, including the economic development activities that are growing the population and the industry within the Basin, also have the potential to shift regional climate, most immediately by an increment in aerosol number and mass concentrations, and the shift is across the range of values to which cloud properties are most sensitive. The ARM Climate Research Facility in the Amazon Basin seeks to understand aerosol and cloud life cycles, particularly the susceptibility to cloud aerosol precipitation interactions, within the Amazon Basin.

The Bi-Modal Pattern of the Summer Circulation Over South America

NASA Technical Reports Server (NTRS)

Herdies, Dirceu Luis; daSilva, Arlindo; SilvaDias, Maria A. F.; Atlas, Robert (Technical Monitor)

2001-01-01

Submonthly variations in warm-season (January-February) precipitation over South America, in special over the Amazon basin, central southwest Brazil, north Argentina, and Paraguay are shown to be strongly linked to variations in the moisture entering the continent from the Atlantic ocean. Two distinct regimes of lower tropospheric winds (westerlies and easterlies) were observed in Rondonia during the Wet Season Atmospheric Mesoscale Campaign (WETAMC) component of the Large Scale Atmosphere-Biosphere Experiment in Amazonia (LBA) and the Tropical Rainfall Measuring Mission (TRMM) field campaign. The westerly (easterly) winds were associated with the strong (weak) convective activity over the South Atlantic Convergence Zone (SACZ). The whole period of this study (January-February) was divided into SACZ and NSACZ (No SACZ) events. The vertically integrated moisture fluxes over the Amazon and Prata basin from the National Aeronautics and Space Administration/Goddard Data Assimilation Office (NASA/DAO) assimilation show that during SACZ (NSACZ) event strong (weak) convergence occurred over the Amazon basin with divergence (convergence) over the Prata basin. Submonthly variations in the SACZ also can be linked to extreme climate anomalies such as droughts or flooding conditions over the Amazon and Prata basin.

Flooding dynamics on the lower Amazon floodplain

NASA Astrophysics Data System (ADS)

Rudorff, C.; Melack, J. M.; Bates, P. D.

2013-05-01

We analyzed flooding dynamics of a large floodplain lake in the lower reach of the Amazon River for the period between 1995 through 2010. Floodplain inundation was simulated using the LISFLOOD-FP model, which combines one-dimensional river routing with two-dimensional overland flow, and a local hydrological model. Accurate representation of floodplain flows and inundation extent depends on the quality of the digital elevation model (DEM). We combined digital topography (derived from the Shuttle Radar Topography Mission) with extensive floodplain echo-sounding data to generate a hydraulically sound DEM. Analysis of daily water balances revealed that the dominant source of inflow alternated seasonally among direct rain and local runoff (October through January), Amazon River (March through August), and seepage (September). As inflows from the Amazon River increase during the rising limb of the hydrograph, regional floodwaters encounter the floodplain partially inundated from local hydrological inputs. At peak flow the floodplain routes, on average, 2.5% of the total discharge for this reach. The falling limb of the hydrograph coincides with the locally dry period, allowing seepage of water stored in sediments to become a dominant source. The average annual inflow from the Amazon River was 58.8 km3 (SD = 33.5), representing more than three thirds (80%) of inputs from all sources, with substantial inter-annual variability. The average annual net export of water from the floodplain to the Amazon River was 7.9 km3 (SD = 2.7).

A geomorphological assessments of the distribution of sediment sinks along the lower Amazon River

NASA Astrophysics Data System (ADS)

Park, E.; Latrubesse, E. M.

2017-12-01

Floodplain sediment storage budget is examined along the 1,000 km reach of the lower Amazon River based on extensive sets of remote sensing data and field measurements. Incorporating the washload discharges at gauge stations at the main channel and major tributaries, we analyzed the roles of vast floodplain on the Amazon River seasonal variability in sediment discharges. Annual washload accumulation rate on floodplain along the reach in between Manacapuru and Obidos of is estimated to be 79 Mt over inter-annual average. Period that the net loss over to the floodplain of washload coincide with discharge rising phase of the Amazon River at Obidos, when the river water level rises to make hydrologic connections to floodplain. Only during the early falling phase (July-August), 3.6 Mt of washload net gain occurred in a year, which was less than 5% of the annual net loss to the floodplain. To assess the spatial distribution of sediment sinks along the lower Amazon, we incorporated various hydro-geomorphic factors regarding floodplain geomorphic styles and morphometric parameters, such floodplain width, levee heights, water-saturated area, suspended sediment distribution over floodplain and distribution of impeded floodplain. Impeded floodplain that contains numerous large rounded lakes is the definition of active sediment sinks along the lower Amazon, which seasonally stores most of the water and traps sediment from the river. The results of these hydro-geomorphic factors collectively indicate that the extent and magnitudes of sediment sinks becomes larger downstream (from Manacapuru to Monte Alegre), which is proportionally related to the development of the water-saturated floodplain. This indicates the nonlinear geomorphic evolution of the Amazon floodplain through its longitudinal profile since the late Holocene that downstream reaches are still to be infilled with sediments (incomplete floodplain) thus acting as sediment sinks.

Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Druffel, E. R. M.; Bauer, J. E.; Griffin, S.

2005-03-01

We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC δ13C signature of the river end-member (-11‰) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (≤10%) of organic matter remineralization in the mesohaline region. The POC Δ14C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.

Emissions from vegetation fires and their influence on atmospheric composition over the Amazon Basin (Invited)

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Artaxo, P.; Bela, M. M.; de Freitas, S. R.; Gerbig, C.; Longo, K. M.; Wiedemann, K. T.; Wofsy, S. C.

2010-12-01

Over the past decades, several campaigns have been conducted in the Amazon Basin, during which the emissions from biomass burning were characterized. Other campaigns, as well as remote sensing studies, have produced clear evidence that the budget of traces gases (including CO2) and aerosols over the Basin are strongly perturbed by vegetation fires. We will briefly review these studies and present some recent measurements made during the the Balanço Atmosférico Regional de Carbono na Amazônia (BARCA) aircraft measurement program, which consisted of two aircraft campaigns during November-December 2008 (BARCA-A) and May-June 2009 (BARCA-B). The measurements covered the altitude range from the surface up to about 4500 m, and spanned across the Amazon Basin. While our results confirm the importance of biomass burning for the atmospheric composition over the Amazon Basin in general, they also highlight some complexities. One is the influence of transatlantic transport: Amazonia is downwind of massive fire regions in Africa, and depending on season and locality, these can make an important contribution to the trace gas and aerosol burden over the Amazon Basin. Another difficulty arises from the fact that representative emission ratios for CO relative to CO2 are difficult to obtain in the field, owing to the influence of biospheric exchange on the distribution of CO2 concentrations. The consequences of these and other uncertainties for a quantitative assessment of the sources of trace gases over Amazonia and for the estimation of carbon exchange with the biosphere will be discussed.

Rivers and Floodplains as Key Components of Global Terrestrial Water Storage Variability

NASA Astrophysics Data System (ADS)

Getirana, Augusto; Kumar, Sujay; Girotto, Manuela; Rodell, Matthew

2017-10-01

This study quantifies the contribution of rivers and floodplains to terrestrial water storage (TWS) variability. We use state-of-the-art models to simulate land surface processes and river dynamics and to separate TWS into its main components. Based on a proposed impact index, we show that surface water storage (SWS) contributes 8% of TWS variability globally, but that contribution differs widely among climate zones. Changes in SWS are a principal component of TWS variability in the tropics, where major rivers flow over arid regions and at high latitudes. SWS accounts for 22-27% of TWS variability in both the Amazon and Nile Basins. Changes in SWS are negligible in the Western U.S., Northern Africa, Middle East, and central Asia. Based on comparisons with Gravity Recovery and Climate Experiment-based TWS, we conclude that accounting for SWS improves simulated TWS in most of South America, Africa, and Southern Asia, confirming that SWS is a key component of TWS variability.

Deforestation effects on Amazon forest resilience

NASA Astrophysics Data System (ADS)

Zemp, D. C.; Schleussner, C.-F.; Barbosa, H. M. J.; Rammig, A.

2017-06-01

Through vegetation-atmosphere feedbacks, rainfall reductions as a result of Amazon deforestation could reduce the resilience on the remaining forest to perturbations and potentially lead to large-scale Amazon forest loss. We track observation-based water fluxes from sources (evapotranspiration) to sinks (rainfall) to assess the effect of deforestation on continental rainfall. By studying 21st century deforestation scenarios, we show that deforestation can reduce dry season rainfall by up to 20% far from the deforested area, namely, over the western Amazon basin and the La Plata basin. As a consequence, forest resilience is systematically eroded in the southwestern region covering a quarter of the current Amazon forest. Our findings suggest that the climatological effects of deforestation can lead to permanent forest loss in this region. We identify hot spot regions where forest loss should be avoided to maintain the ecological integrity of the Amazon forest.

Mouth of the Amazon

NASA Image and Video Library

2001-02-07

Flowing over 6450 kilometers eastward across Brazil, the Amazon River originates in the Peruvian Andes as tiny mountain streams that eventually combine to form one of the world mightiest rivers as shown in this image from NASA Terra satellite.

On the role of flood wave celerity-discharge relationship and its applications on hydrological studies

NASA Astrophysics Data System (ADS)

Fleischmann, Ayan; Collischonn, Walter; Jardim, Pedro; Meyer, Aline; Paiva, Rodrigo

2017-04-01

The non-linear relationship between flood wave celerity (C) and discharge (Q) plays an important role on defining how flood waves are routed through the river network. The behavior of this curve is driven by cross section geometry, which leads to increasing celerity with discharge in rivers without floodplains. In reaches with floodplain storage, C may decrease after bankfull Q. Thus, in a set of studies we investigate the effects of C x Q relationships on the basin hydrological response. (i) We studied these curves for several Brazilian river reaches, and analyzed to which extent they are related to river channel geometry and other characteristics (e.g., slope, width, drainage area and sinuosity). (ii) It is shown through empirical, analytical and numerical experiments how C x Q relation affects hydrograph skewness, and how the decreasing relationship existent in rivers with important floodplain storage leads to negatively skewed hydrographs, such as in the Amazon and Pantanal regions, which could be used to infer important floodplain processes (e.g., presence of overbank flow wetlands, which feature negatively skewed hydrographs or interfluvial wetlands not directly connected to rivers). (iii) Finally, we found that it is possible to use these concepts to calibrate the effective bathymetry of a hydrodynamic model by fitting the C x Q relationship using SCE-UA optimization method. Our results show how important it is to investigate the non-linear hydraulic processes occurring throughout river basins to understand the overall hydrological response, and propose new frameworks to assist such studies, including the evaluation of hydrograph skewness and estimation of hydraulic geometry.

Andes hantavirus variant in rodents, southern Amazon Basin, Peru.

PubMed

Razuri, Hugo; Tokarz, Rafal; Ghersi, Bruno M; Salmon-Mulanovich, Gabriela; Guezala, M Claudia; Albujar, Christian; Mendoza, A Patricia; Tinoco, Yeny O; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T; Hirschberg, David L; Lipkin, W Ian; Bausch, Daniel G; Montgomery, Joel M

2014-02-01

We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted.

Effects of Land Use Changes on the Water and Energy Balance Over South America

NASA Astrophysics Data System (ADS)

Nascimento, M.; Herdies, D. L.; Angelis, C.

2013-05-01

With the objective of analyzing the effects of land use changes in the Amazon and its consequences on the main components of the water and energy balance over South America, with emphasis on the Amazon and La Plata Basin, two experiments were carried for 10-year period (1999-2008), in which the land use conditions were modified, representing conditions for the 90s (CONTROL Experiment) and current conditions over land use in the Amazon region (Experiment 1). Changes in land use were observed mainly in the Amazon region and southern Brazil. The numerical model used to perform the simulations was the ETA in its climate version, using as an initial and boundary condition the CFSR/NCEP reanalysis datasets. The results show for the analyzed period that there was a reduction of 3.3 mm/month in average rainfall rates in the La Plata Basin and 4.2 mm/month in the Amazon region, with some places where this reduction was more pronounced. Seasonally was observed that during the summer there is an average reduction of 3.9 mm/month in the Amazon region. Already on the La Plata Basin was observed an average increase of 11.7 mm/month in the La Plata Basin during the summer and an reduction in winter season. Through the overall result was also possible to conclude that the changes in land use for more realistic conditions, there were significant reductions in evapotranspiration and latent heat fluxes, as well as an increase in sensible heat fluxes, especially over the regions where the changes were more pronounced. Through the analyzes it can be observed that in general the La Plata Basin is sensitive to changes in land use over the Amazon and adjacent regions, allowing to conclude that such changes can influence the amount of rainfall, the intensity of the major meteorological systems, as well as temperature trends on the regions analyzed.

ORCHILEAK (revision 3875): a new model branch to simulate carbon transfers along the terrestrial-aquatic continuum of the Amazon basin

NASA Astrophysics Data System (ADS)

Lauerwald, Ronny; Regnier, Pierre; Camino-Serrano, Marta; Guenet, Bertrand; Guimberteau, Matthieu; Ducharne, Agnès; Polcher, Jan; Ciais, Philippe

2017-10-01

Lateral transfer of carbon (C) from terrestrial ecosystems into the inland water network is an important component of the global C cycle, which sustains a large aquatic CO2 evasion flux fuelled by the decomposition of allochthonous C inputs. Globally, estimates of the total C exports through the terrestrial-aquatic interface range from 1.5 to 2.7 Pg C yr-1 (Cole et al., 2007; Battin et al., 2009; Tranvik et al., 2009), i.e. of the order of 2-5 % of the terrestrial NPP. Earth system models (ESMs) of the climate system ignore these lateral transfers of C, and thus likely overestimate the terrestrial C sink. In this study, we present the implementation of fluvial transport of dissolved organic carbon (DOC) and CO2 into ORCHIDEE (Organising Carbon and Hydrology in Dynamic Ecosystems), the land surface scheme of the Institut Pierre-Simon Laplace ESM. This new model branch, called ORCHILEAK, represents DOC production from canopy and soils, DOC and CO2 leaching from soils to streams, DOC decomposition, and CO2 evasion to the atmosphere during its lateral transport in rivers, as well as exchange with the soil carbon and litter stocks on floodplains and in swamps. We parameterized and validated ORCHILEAK for the Amazon basin, the world's largest river system with regard to discharge and one of the most productive ecosystems in the world. With ORCHILEAK, we are able to reproduce observed terrestrial and aquatic fluxes of DOC and CO2 in the Amazon basin, both in terms of mean values and seasonality. In addition, we are able to resolve the spatio-temporal variability in C fluxes along the canopy-soil-water continuum at high resolution (1°, daily) and to quantify the different terrestrial contributions to the aquatic C fluxes. We simulate that more than two-thirds of the Amazon's fluvial DOC export are contributed by the decomposition of submerged litter. Throughfall DOC fluxes from canopy to ground are about as high as the total DOC inputs to inland waters. The latter, however, are mainly sustained by litter decomposition. Decomposition of DOC and submerged plant litter contributes slightly more than half of the CO2 evasion from the water surface, while the remainder is contributed by soil respiration. Total CO2 evasion from the water surface equals about 5 % of the terrestrial NPP. Our results highlight that ORCHILEAK is well suited to simulate carbon transfers along the terrestrial-aquatic continuum of tropical forests. It also opens the perspective that provided parameterization, calibration and validation is performed for other biomes, the new model branch could improve the quantification of the global terrestrial C sink and help better constrain carbon cycle-climate feedbacks in future projections.

Mouths of the Amazon River, Brazil, South America

NASA Image and Video Library

1992-08-08

STS046-80-009 (31 July-8 Aug. 1992) --- A view of the mouth of the Amazon River and the Amazon Delta shows a large sediment plume expanding outward into the Atlantic Ocean. The sediment plume can be seen hugging the coast north of the Delta. This is caused by the west-northwest flowing Guyana Current. The large island of Marajo is partially visible through the clouds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Hongbin; Chin, Mian; Yuan, Tianle

The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three dimensional (3D) aerosol measurements over 2007-2013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7-year average of dust deposition into the Amazon Basin is estimated to be 28 (8~48) Tg a -1 or 29 (8~50) kg ha -1 a -1. The dust deposition shows significant interannual variationmore » that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multi-year mean estimate of dust deposition matches better with estimates from in-situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.006~0.037) Tg P of phosphorus per year, equivalent to 23 (7~39) g P ha -1 a -1 to fertilize the Amazon rainforest. This out-of-Basin P input is comparable to the hydrological loss of P from the Basin, suggesting an important role of African dust in preventing phosphorus depletion on time scales of decades to centuries.« less

Characterizing Temporal and Spatial Changes in Land Surface Temperature across the Amazon Basin using Thermal and Infrared Satellite Data

NASA Astrophysics Data System (ADS)

Cak, A. D.

2017-12-01

The Amazon Basin has faced innumerable pressures in recent years, including logging, mining and resource extraction, agricultural expansion, road building, and urbanization. These changes have drastically altered the landscape, transforming a predominantly forested environment into a mosaic of different types of land cover. The resulting fragmentation has caused dramatic and negative impacts on its structure and function, including on biodiversity and the transfer of water and energy to and from soil, vegetation, and the atmosphere (e.g., evapotranspiration). Because evapotranspiration from forested areas, which is affected by factors including temperature and water availability, plays a significant role in water dynamics in the Amazon Basin, measuring land surface temperature (LST) across the region can provide a dynamic assessment of hydrological, vegetation, and land use and land cover changes. It can also help to identify widespread urban development, which often has a higher LST signal relative to surrounding vegetation. Here, we discuss results from work to measure and identify drivers of change in LST across the entire Amazon Basin through analysis of past and current thermal and infrared satellite imagery. We leverage cloud computing resources in new ways to allow for more efficient analysis of imagery over the Amazon Basin across multiple years and multiple sensors. We also assess potential drivers of change in LST using spatial and multivariate statistical analyses with additional data sources of land cover, urban development, and demographics.

Hydrology and climate in the southwestern Amazon basin (Bolivia)

NASA Astrophysics Data System (ADS)

Ronchail, J.; Bourrel, L.; Maurice-Bourgoin, L.; Vauchel, P.; Cochonneau, G.; Guyot, J. L.; Phillips, L.; Castro, A.

2003-04-01

The variability of the runoff of the Bolivian tributaries of the Madeira River, the greatest southern affluent of the Amazon R., is of major importance for the riparian people safety and for the economic development of the region. We investigated whether the discharge of these rivers is predictable or not, using the Sea Surface Temperatures Anomalies (SSTAs) in the Equatorial Pacific and in the Tropical Atlantic oceans. The hydrological variability is studied using daily river discharge data of 3 tributaries: the Rio Beni in Rurrenabaque, the Rio Ichilo in Puerto Villaroel and the Mamoré River in Puerto Varador, respectively representative of the Andes, the Andean Piedmont and the lowlands. This information has been collected and criticized in the mark of successive Bolivian - French conventions. The hydrological response of the Andean river is out of phase with that of the piedmont and plain rivers. The Rio Beni in Rurrenabaque experiments high runoff during La Niña events and during cool (warm) events in the northern (southern) tropical Atlantic. On the contrary, the Ichilo and Mamoré Rivers and inundation data show that high runoff are more frequent during El Niño events and when the southern tropical Atlantic Ocean is cooler than normally. 30% of the Beni R. discharge variability is explained by the ENSO events and 25% by the SSTAs in the tropical Atlantic. In the Andean piedmont and in the lowlands, the ENSO explains 45% of the discharges, but differences in series lengths may also contribute to this better result. On the contrary, the relationship with the southern tropical Atlantic is only a tendency and is not statistically significant. To conclude, the SSTAs in the tropical oceans do not allow a prediction of the discharge variability of the Bolivian tributaries of the Madeira River but they contribute to their comprehension. The present results, different for Andean and Piedmont or lowlands tributaries, are consistent with those relative to the ENSO and tropical Atlantic related rainfall anomalies in both regions of Bolivia.

Comparing Amazon Basin CO2 fluxes from an atmospheric inversion with TRENDY biosphere models

NASA Astrophysics Data System (ADS)

Diffenbaugh, N. S.; Alden, C. B.; Harper, A. B.; Ahlström, A.; Touma, D. E.; Miller, J. B.; Gatti, L. V.; Gloor, M.

2015-12-01

Net exchange of carbon dioxide (CO2) between the atmosphere and the terrestrial biosphere is sensitive to environmental conditions, including extreme heat and drought. Of particular importance for local and global carbon balance and climate are the expansive tracts of tropical rainforest located in the Amazon Basin. Because of the Basin's size and ecological heterogeneity, net biosphere CO2 exchange with the atmosphere remains largely un-constrained. In particular, the response of net CO2 exchange to changes in environmental conditions such as temperature and precipitation are not yet well known. However, proper representation of these relationships in biosphere models is a necessary constraint for accurately modeling future climate and climate-carbon cycle feedbacks. In an effort to compare biosphere response to climate across different biosphere models, the TRENDY model intercomparison project coordinated the simulation of CO2 fluxes between the biosphere and atmosphere, in response to historical climate forcing, by 9 different Dynamic Global Vegetation Models. We examine the TRENDY model results in the Amazon Basin, and compare this "bottom-up" method with fluxes derived from a "top-down" approach to estimating net CO2 fluxes, obtained through atmospheric inverse modeling using CO2 measurements sampled by aircraft above the basin. We compare the "bottom-up" and "top-down" fluxes in 5 sub-regions of the Amazon basin on a monthly basis for 2010-2012. Our results show important periods of agreement between some models in the TRENDY suite and atmospheric inverse model results, notably the simulation of increased biosphere CO2 loss during wet season heat in the Central Amazon. During the dry season, however, model ability to simulate observed response of net CO2 exchange to drought was varied, with few models able to reproduce the "top-down" inversion flux signals. Our results highlight the value of atmospheric trace gas observations for helping to narrow the possibilities of future carbon-climate interactions, especially in historically under-observed regions like the Amazon.

The Role of Competition in Structuring Primate Communities under Different Productivity Regimes in the Amazon

PubMed Central

Rocha, Juliana Monteiro de Almeida; Pinto, Míriam Plaza; Boubli, Jean Philippe; Grelle, Carlos Eduardo Viveiros

2015-01-01

The factors responsible for the formation of Amazonian primate communities are not well understood. Here we investigated the influence of interspecific competition in the assembly of these communities, specifically whether they follow an assembly rule known as "favored states". According to this rule, interspecific competition influences final species composition, resulting in functional groups that are equally represented in the community. We compiled presence-absence data for primate species at 39 Amazonian sites in Brazil, contrasting two regions with distinct productivity regimes: the eutrophic Juruá River basin and the oligotrophic Negro River basin. We tested two hypotheses: that interspecific competition is a mechanism that influences the structure of Amazonian primate communities, and that competition has had a greater influence on the structure of primate communities in regions with low productivity, where resources are more limited. We used null models to test the statistical significance of the results, and found a non-random pattern compatible with the favored states rule in the two regions. Our findings suggest that interspecific competition is an important force driving primate community assembly regardless of productivity regimes. PMID:26696089

Hypotheses regarding the mechanisms of ayahuasca in the treatment of addictions.

PubMed

Liester, Mitchell B; Prickett, James I

2012-01-01

Ayahuasca is a medicinal plant mixture utilized by indigenous peoples throughout the Amazon River basin for healing purposes. The "vine of the soul" or "vine of death," as it is known in South America, contains a combination of monoamine oxidase inhibitors and N,N-dimethyltryptamine (DMT). When ingested together, these medicines produce profound alterations in consciousness. Increasingly, ayahuasca is being utilized to treat addictions. However, the mechanism of action by which ayahuasca treats addictions remains unclear. We offer four hypotheses to explain possible biochemical, physiological, psychological, and transcendent mechanisms by which ayahuasca may exert its anti-addiction effects.

Properties and reactivity of aquatic organic matter from an Amazonian floodplain system

NASA Astrophysics Data System (ADS)

Perez, M. A. P.; Benedetti, M. F.; Moreira-Turcq, P.

2009-04-01

The aim of this study was to characterize the nature of the bulk dissolved organic matter (DOM) in different types of environments in the Amazon River-floodplain system and determine the importance of two different fractions of dissolved organic matter onto adsorption processes that occurs through the transport of organic matter in the Amazon Basin. Seven samples were collected in the Amazon River - "Lago Grande de Curuai" floodplain system, in rising water levels cruise (March 2006). The samples were taken in the Amazon main stem, in white and black floodplain waters, and in the middle of a phytoplaktonic bloom. The bulk, dissolved (i.e. < 0.22 micrometer), hydrophobic (HPO) and transphilic (TPH) fractions extracted by XAD-8 and XAD-4 columns chromatography respectively were isolated. Organic carbon (OC) and total nitrogen (TN) concentrations, Specific UV absorbance (SUVA), Size-Exclusion Chromatography (SEC), d13C and d15N isotopes, and reactivity (acid-base titration) were characterized for these fractions. Adsorption experiments onto mineral phase from de surface sediment of the Curuai floodplain lake (rich in smectite and kaolinite) were realized with HPO and TPH fractions. The OC concentrations in the natural organic matter (Bulk and < 0.22 micrometer fractions) varied between 3.7-5.7 mg/L. The OC and TN concentrations varied between 510 - 528 mg C/g in the HPO fraction, and 408 - 462 mg C/g in the TPH compounds and between 14.3 - 17.6 mg N/g (HPO), and 22.1 - 30.0 mg N/g (TPH). The molecular weight of both fractions (HPO and TPH) didn't present significant variation. Both fractions presented high aromaticity and they were rich in carboxylic groups, although smaller values are systematically reported for the HPO fractions. The OM of the main stem was the most adsorbed, followed by the white water lake, the phytoplanktonic bloom, and black water lake sample. These results helped us to strengthen the hypothesis that the organic matter carried from the river and sediment in the floodplain is closely associated with mineral phase.

Extravagance in the commons: Resource exploitation and the frontiers of ecosystem service depletion in the Amazon estuary.

PubMed

de Araujo Barbosa, Caio C; Atkinson, Peter M; Dearing, John A

2016-04-15

Estuaries hold major economic potential due their strategic location, close to seas and inland waterways, thereby supporting intense economic activity. The increasing pace of human development in coastal deltas over the past five decades has also strained local resources and produced extensive changes across both social and ecological systems. The Amazon estuary is located in the Amazon Basin, North Brazil, the largest river basin on Earth and also one of the least understood. A considerable segment of the population living in the estuary is directly dependent on the local extraction of natural resources for their livelihood. Areas sparsely inhabited may be exploited with few negative consequences for the environment. However, recent and increasing pressure on ecosystem services is maximised by a combination of factors such as governance, currency exchange rates, exports of beef and forest products. Here we present a cross methodological approach in identifying the political frontiers of forest cover change in the estuary with consequences for ecosystem services loss. We used a combination of data from earth observation satellites, ecosystem service literature, and official government statistics to produce spatially-explicit relationships linking the Green Vegetation Cover to the availability of ecosystems provided by forests in the estuary. Our results show that the continuous changes in land use/cover and in the economic state have contributed significantly to changes in key ecosystem services, such as carbon sequestration, climate regulation, and the availability of timber over the last thirty years. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating the sources and sinks of water of Congo's wetlands

NASA Astrophysics Data System (ADS)

Paiva, R. C. D.; O'Loughlin, F.; Alsdorf, D. E.; Durand, M. T.; Beighley, E., II; Calmant, S.; Lee, H.; Santos Da Silva, J.

2014-12-01

The Congo is the second largest river basin in the world and indeed there is still a lot to be investigated about the hydrology of this system. This region presents extensive wetlands that may play an important role on the hydrology, carbon and ecological dynamics of the Congo. However, previous studies indicate that these wetlands behave differently from the Amazon, other major rainforest basin, and how water enters and leaves the Cuvette Centrale wetland is still to be quantified. We investigate the sources and sinks of water to the Congo's wetlands. Our analyses range from simple examinations of precipitation and evaporation historical data to remote sensing datasets and 2 D hydrodynamic modelling of Congo wetlands. Early results show that water levels at wetlands are usually higher than adjacent Congo River water levels and amplitude of variation is considerably smaller. Also, floodplain channels are not observed in this region indicating that surface flows are diffusive. Mean annual precipitation range from 1600 to 2000 mm/year, evapotranspiration estimates are approximately 1100 mm/year while some estimates of groundwater recharge indicate values larger than 300 mm/year. These assessments suggest that volumes coming from local water balance could flood the wetlands to depths of only a few centimeters. Preliminary 2D hydrodynamic simulations show that water coming from main rivers produces at upstream areas can flood only a small part of wetland, mainly alongside these rivers.

A morphological and molecular study of two species of Raphidascaroides Yamaguti, 1941 (Nematoda: Anisakidae), parasites of doradid catfish (Siluriformes) in South America, with a description of R. moraveci n. sp.

PubMed

Pereira, Felipe B; Tavares, Luiz E R; Scholz, Tomáš; Luque, José L

2015-05-01

Nematodes of the genus Raphidascaroides Yamaguti, 1941 parasitising doradid catfishes (Siluriformes: Doradidae) in Brazil were studied based on morphological and molecular evaluation of newly collected material. A new species, Raphidascaroides moraveci n. sp., is described from the intestine of Platydoras armatulus (Valenciennes) from River Miranda, River Paraguay basin, Pantanal, Mato Grosso do Sul. The new species differs from all of the congeners in having short spicules (163-217 μm in length) representing less than 1% of the total body length and in the posterior region of cloacal opening covered by small rudimentary spines. In addition, it differs from the other congeneric species in the number and arrangement of the caudal papillae and the structure of lips and tail. Raphidascaroides moraveci n. sp. is the third species described from freshwater fishes and the second one in the Neotropical Region. New morphological data on R. brasiliensis Moravec & Thatcher, 1997 from Megalodoras uranoscopus (Eigenmann & Eigenmann) and Platydoras costatus (Linnaeus) (both new host records) from River Xingu, River Amazon basin, Pará, are provided including scanning electron micrographs of taxonomically important structures. The differentiation of the new species is supported by molecular data (partial sequences of the small and large subunits of the rRNA gene).

The Wavelet ToolKat: A set of tools for the analysis of series through wavelet transforms. Application to the channel curvature and the slope control of three free meandering rivers in the Amazon basin.

NASA Astrophysics Data System (ADS)

Vaudor, Lise; Piegay, Herve; Wawrzyniak, Vincent; Spitoni, Marie

2016-04-01

The form and functioning of a geomorphic system result from processes operating at various spatial and temporal scales. Longitudinal channel characteristics thus exhibit complex patterns which vary according to the scale of study, might be periodic or segmented, and are generally blurred by noise. Describing the intricate, multiscale structure of such signals, and identifying at which scales the patterns are dominant and over which sub-reach, could help determine at which scales they should be investigated, and provide insights into the main controlling factors. Wavelet transforms aim at describing data at multiple scales (either in time or space), and are now exploited in geophysics for the analysis of nonstationary series of data. They provide a consistent, non-arbitrary, and multiscale description of a signal's variations and help explore potential causalities. Nevertheless, their use in fluvial geomorphology, notably to study longitudinal patterns, is hindered by a lack of user-friendly tools to help understand, implement, and interpret them. We have developed a free application, The Wavelet ToolKat, designed to facilitate the use of wavelet transforms on temporal or spatial series. We illustrate its usefulness describing longitudinal channel curvature and slope of three freely meandering rivers in the Amazon basin (the Purus, Juruá and Madre de Dios rivers), using topographic data generated from NASA's Shuttle Radar Topography Mission (SRTM) in 2000. Three types of wavelet transforms are used, with different purposes. Continuous Wavelet Transforms are used to identify in a non-arbitrary way the dominant scales and locations at which channel curvature and slope vary. Cross-wavelet transforms, and wavelet coherence and phase are used to identify scales and locations exhibiting significant channel curvature and slope co-variations. Maximal Overlap Discrete Wavelet Transforms decompose data into their variations at a series of scales and are used to provide smoothed descriptions of the series at the scales deemed relevant.

Regional simulation of interannual variability over South America

NASA Astrophysics Data System (ADS)

Misra, V.; Dirmeyer, P. A.; Kirtman, B. P.; Juang, H.-M. Henry; Kanamitsu, M.

2002-08-01

Three regional climate simulations covering the austral summer season during three contrasting phases of the El Niño-Southern Oscillation cycle were conducted with the Regional Spectral Model (RSM) developed at the National Centers for Environmental Prediction (NCEP). The simulated interannual variability of precipitation over the Amazon River Basin, the Intertropical Convergence Zone, the Pacific and Atlantic Ocean basins, and extratropical South America compare reasonably well with observations. The RSM optimally filters the peturbations about a time-varying base field, thereby enhancing the information content of the global NCEP reanalysis. The model is better than the reanalysis in reproducing the observed interannual variability of outgoing longwave radiation at both high frequencies (3-30 days) and intraseasonal (30-60 days) scales. The low-level jet shows a peak in its speed in 1998 and a minimum in the 1999 simulations. The lag correlation of the jet index with convection over various areas in continental South America indicates that the jet induces precipitation over the Pampas region downstream. A detailed moisture budget was conducted over various subregions. This budget reveals that moisture flux convergence determines most of the interannual variability of precipitation over the Amazon Basin, the Atlantic Intertropical Convergence Zone, and the Nordeste region of Brazil. However, both surface evaporation and surface moisture flux convergence were found to be critical in determining the interannual variability of precipitation over the southern Pampas, Gran Chaco area, and the South Atlantic Convergence Zone.

Paleovalley fills: Trunk vs. tributary

USGS Publications Warehouse

Kvale, E.P.; Archer, A.W.

2007-01-01

A late Mississippian-early Pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the Illinois Basin in the eastern United States. This drainage system was filled during the early part of the Pennsylvanian. Distinct differences can be recognized between the trunk and tributary paleovalley fills. Fills preserved within the trunk systems tend to be fluvially dominated and consist of bed-load deposits of coarse- to medium-grained sandstone and conglomerate. Conversely, the incised valleys of tributary systems tend to be filled with dark mudstone, thinly interbedded sandstones, and mudstones and siltstones. These finer grained facies exhibit marine influences manifested by tidal rhythmites, certain traces fossils, and macro- and microfauna. Examples of tributary and trunk systems, separated by no more than 7 km (4.3 mi) along strike, exhibit these styles of highly contrasting fills. Useful analogs for understanding this Pennsylvanian system include the Quaternary glacial sluiceways present in the lower Ohio, White, and Wabash river valleys of Indiana (United States) and the modern Amazon River (Brazil). Both the Amazon River and the Quaternary rivers of Indiana have (or had) trunk rivers that are (were) dominated by large quantities of bed load relative to their tributaries. The trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys, which evolved into lakes because depositional rates along the trunk are (were) so high that the mouths of the tributaries have been dammed by bed-load deposits. These Holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

Increasing incidence of malaria in the Negro River basin, Brazilian Amazon.

PubMed

Cabral, A C; Fé, N F; Suárez-Mutis, M C; Bóia, M N; Carvalho-Costa, F A

2010-08-01

Malaria in Brazil is virtually restricted to the Amazon Region, where it has a heterogeneous geographic distribution. We reviewed secondary data in order to describe the regional and temporal distribution of 8018 malaria cases seen between 2003 and 2007 in Santa Isabel do Rio Negro, a municipality in the northwest Brazilian Amazon. A significant rise in malaria incidence, mainly in the Yanomami Indian reservation, was observed during this time. Anopheline breeding sites were also mapped and entomological data were obtained through the capture of larval and adult mosquitoes. Thirty-three potential breeding sites were identified in the urban and periurban areas, 28 of which were positive for anopheline larvae. Anopheles darlingi specimens were captured in both intra- and peridomicile locations in the urban areas. Demographic data were also assessed via a sectional survey, revealing that the majority of dwellings were vulnerable to mosquitoes. This study suggests that urban and periurban areas of this municipality are highly susceptible to epidemic malaria, which is endemic in the Yanomami Indian reservation near the city. In addition, transmission can be perpetuated autochthonously in the urban area, drawing attention to the continuous need for preventative measures such as controlling adult and aquatic stages of mosquitoes and improving housing.

Evaluation of Primary Production in the Lower Amazon River Based on a Dissolved Oxygen Stable Isotopic Mass Balance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gagne-Maynard, William C.; Ward, Nicholas D.; Keil, Richard G.

The Amazon River outgasses nearly an equivalent amount of CO 2 as the rainforest sequesters on an annual basis due to microbial decomposition of terrigenous and aquatic organic matter. Most research performed in the Amazon has been focused on unraveling the mechanisms driving CO 2 production since the recognition of a persistent state of CO 2 supersaturation. However, although the river system is clearly net heterotrophic, the interplay between primary production and respiration is an essential aspect to understanding the overall metabolism of the ecosystem and potential transfer of energy up trophic levels. For example, an efficient ecosystem is capablemore » of both decomposing high amounts of organic matter at lower trophic levels, driving CO 2 emissions, and accumulating energy/biomass in higher trophic levels, stimulating fisheries production. Early studies found minimal evidence for primary production in the Amazon River mainstem and it has since been assumed that photosynthesis is strongly limited by low light penetration attributed to the high sediment load. Here, we test this assumption by measuring the stable isotopic composition of O 2 (δ 18O-O 2) and O 2 saturation levels in the lower Amazon River from Óbidos to the river mouth and its major tributaries, the Xingu and Tapajós rivers, during high and low water periods. An oxygen mass balance model was developed to estimate the input of photosynthetic oxygen in the discrete reach from Óbidos to Almeirim, midway to the river mouth. Based on the oxygen mass balance we estimate that primary production occurred at a rate of 0.39 ± 0.24 g O m 3 d -1 at high water and 1.02 ± 0.55 g O m 3 d -1 at low water. This translates to 41 ± 24% of the rate of O 2 drawdown via respiration during high water and 67 ± 33% during low water. These primary production rates are 2-7 times higher than past estimates for the Amazon River mainstem. In conclusion, it is possible that at high water much of this productivity signal is the result of legacy advection from floodplains, whereas limited floodplain connectivity during low water implies that most of this signal is the result of in situ primary production in the Amazon River mainstem.« less

Andes Hantavirus Variant in Rodents, Southern Amazon Basin, Peru

PubMed Central

Tokarz, Rafal; Ghersi, Bruno M.; Salmon-Mulanovich, Gabriela; Guezala, M. Claudia; Albujar, Christian; Mendoza, A. Patricia; Tinoco, Yeny O.; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T.; Hirschberg, David L.; Lipkin, W. Ian; Bausch, Daniel G.; Montgomery, Joel M.

2014-01-01

We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted. PMID:24447689

Wood anatomy of the neotropical Sapotaceae : XIV. Elaeoluma

Treesearch

Bohumil Francis Kukachka

1980-01-01

The genus Elaeoluma consists of three species distributed in the Amazon Basin, Surinam, Guyana, and Venezuela. The description presented here is based on E. glabrescens of the Amazon Basin. The wood is easily differentiated from all other neotropical Sapotaceae by its pale brown color, reticulate parenchyma, which is hardly discernable with a hand lens, and a low...

Methane airborne measurements and comparison to global models during BARCA

NASA Astrophysics Data System (ADS)

Beck, Veronika; Chen, Huilin; Gerbig, Christoph; Bergamaschi, Peter; Bruhwiler, Lori; Houweling, Sander; Röckmann, Thomas; Kolle, Olaf; Steinbach, Julia; Koch, Thomas; Sapart, Célia J.; van der Veen, Carina; Frankenberg, Christian; Andreae, Meinrat O.; Artaxo, Paulo; Longo, Karla M.; Wofsy, Steven C.

2012-08-01

Tropical regions, especially the Amazon region, account for large emissions of methane (CH4). Here, we present CH4 observations from two airborne campaigns conducted within the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) project in the Amazon basin in November 2008 (end of the dry season) and May 2009 (end of the wet season). We performed continuous measurements of CH4 onboard an aircraft for the first time in the Amazon region, covering the whole Amazon basin with over 150 vertical profiles between altitudes of 500 m and 4000 m. The observations support the finding of previous ground-based, airborne, and satellite measurements that the Amazon basin is a large source of atmospheric CH4. Isotope analysis verified that the majority of emissions can be attributed to CH4 emissions from wetlands, while urban CH4 emissions could be also traced back to biogenic origin. A comparison of five TM5 based global CH4 inversions with the observations clearly indicates that the inversions using SCIAMACHY observations represent the BARCA observations best. The calculated CH4 flux estimate obtained from the mismatch between observations and TM5-modeled CH4 fields ranges from 36 to 43 mg m-2 d-1 for the Amazon lowland region.

Lead exposure in indigenous communities of the Amazon basin, Peru.

PubMed

Anticona, Cynthia; Bergdahl, Ingvar A; Lundh, Thomas; Alegre, Yuri; Sebastian, Miguel San

2011-12-01

Since 2006, three studies have reported elevated levels of lead (Pb) among the indigenous population of the Corrientes river, in the Amazon basin of Peru. Due to the large evidence of environmental pollution related to oil exploitation in the area, this activity has been suggested as the source of exposure. This study aimed to evaluate Pb levels in the population and environment of two communities exposed and one community non-exposed to the oil exploitation activity. Blood lead levels (BLL) were determined by the instrument Leadcare. A comparison with the graphite furnace atomic absorption technique was performed in order to validate the Leadcare results. Environmental samples were analyzed by inductively coupled plasma atomic emission spectroscopy. Among 361 capillary samples, the mean BLL was 9.4 μg/dl. Mean BLL of the communities exposed (n=171, x¯=9.5 μg/dl) and non-exposed (n=190, x¯=9.2 μg/dl) to the oil activity were not significantly different. Pb levels in environmental samples were below the maximum permissible levels. The sources of exposure could not be identified. Elevated levels of Pb in the oil-non-exposed community pointed out at other sources not yet clarified. Copyright © 2011 Elsevier GmbH. All rights reserved.

Velocity-amplified microbial respiration rates in the lower Amazon River: Amazon River respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Nicholas D.; Sawakuchi, Henrique O.; Neu, Vania

Most measurements of respiration rates in large tropical rivers do not account for the influence of river flow conditions on microbial activity. We developed a ship-board spinning incubation system for measuring O2 drawdown under different rotation velocities and deployed the system along the lower Amazon River during four hydrologic periods. Average respiration rates in incubation chambers rotated at 0.22 and 0.66 m s-1 were 1.4 and 2.4 times higher than stationary chambers, respectively. On average, depth-integrated respiration rates in chambers spun at 0.22 and 0.66 m s-1 accounted for 64 ± 22% and 104 ± 36% of CO2 outgassing rates,more » respectively, in mainstem sites. Continuous measurements of in situ pCO2 were also made along with cross-channel profiles of river velocity. A positive correlation between river velocity and pCO2 was observed along the lower river (r2=0.67-0.96) and throughout a tidal cycle.« less

Progress in Remote Sensing of Photosynthetic Activity over the Amazon Basin

NASA Technical Reports Server (NTRS)

Resende de Sousa, Celio Helder; Hilker, Thomas; Waring, Richard; Mendes De Moura, Yhasmin; Lyapustin, Alexei

2017-01-01

Although quantifying the massive exchange of carbon that takes place over the Amazon Basin remains a challenge, progress is being made as the remote sensing community moves from using traditional, reflectance-based vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), to the more functional Photochemical Reflectance Index (PRI). This new index, together with satellite-derived estimates of canopy light interception and Sun-Induced Fluorescence (SIF), provide improved estimates of Gross Primary Production (GPP). This paper traces the development of these new approaches, compares the results of their analyses from multiple years of data acquired across the Amazon Basin and suggests further improvements in instrument design, data acquisition and processing. We demonstrated that our estimates of PRI are in generally good agreement with eddy-flux tower measurements of photosynthetic light use efficiency (epsilon) at four sites in the Amazon Basin: r(exp 2) values ranged from 0.37 to 0.51 for northern flux sites and to 0.78for southern flux sites. This is a significant advance over previous approaches seeking to establish a link between global-scale photosynthetic activity and remotely-sensed data. When combined with measurements of Sun-Induced Fluorescence (SIF), PRI provides realistic estimates of seasonal variation in photosynthesis over the Amazon that relate well to the wet and dry seasons. We anticipate that our findings will steer the development of improved approaches to estimate photosynthetic activity over the tropics.

Progress in Remote Sensing of Photosynthetic Activity over the Amazon Basin

PubMed Central

de Sousa, Celio Helder Resende; Hilker, Thomas; Waring, Richard; de Moura, Yhasmin Mendes; Lyapustin, Alexei

2017-01-01

Although quantifying the massive exchange of carbon that takes place over the Amazon Basin remains a challenge, progress is being made as the remote sensing community moves from using traditional, reflectance-based vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), to the more functional Photochemical Reflectance Index (PRI). This new index, together with satellite-derived estimates of canopy light interception and Sun-Induced Fluorescence (SIF), provide improved estimates of Gross Primary Production (GPP). This paper traces the development of these new approaches, compares the results of their analyses from multiple years of data acquired across the Amazon Basin and suggests further improvements in instrument design, data acquisition and processing. We demonstrated that our estimates of PRI are in generally good agreement with eddy-flux tower measurements of photosynthetic light use efficiency (ε) at four sites in the Amazon Basin: r2 values ranged from 0.37 to 0.51 for northern flux sites and to 0.78 for southern flux sites. This is a significant advance over previous approaches seeking to establish a link between global-scale photosynthetic activity and remotely-sensed data. When combined with measurements of Sun-Induced Fluorescence (SIF), PRI provides realistic estimates of seasonal variation in photosynthesis over the Amazon that relate well to the wet and dry seasons. We anticipate that our findings will steer the development of improved approaches to estimate photosynthetic activity over the tropics. PMID:29375895

Progress in Remote Sensing of Photosynthetic Activity over the Amazon Basin.

PubMed

de Sousa, Celio Helder Resende; Hilker, Thomas; Waring, Richard; de Moura, Yhasmin Mendes; Lyapustin, Alexei

2017-01-01

Although quantifying the massive exchange of carbon that takes place over the Amazon Basin remains a challenge, progress is being made as the remote sensing community moves from using traditional, reflectance-based vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), to the more functional Photochemical Reflectance Index (PRI). This new index, together with satellite-derived estimates of canopy light interception and Sun-Induced Fluorescence (SIF), provide improved estimates of Gross Primary Production (GPP). This paper traces the development of these new approaches, compares the results of their analyses from multiple years of data acquired across the Amazon Basin and suggests further improvements in instrument design, data acquisition and processing. We demonstrated that our estimates of PRI are in generally good agreement with eddy-flux tower measurements of photosynthetic light use efficiency (ε) at four sites in the Amazon Basin: r 2 values ranged from 0.37 to 0.51 for northern flux sites and to 0.78 for southern flux sites. This is a significant advance over previous approaches seeking to establish a link between global-scale photosynthetic activity and remotely-sensed data. When combined with measurements of Sun-Induced Fluorescence (SIF), PRI provides realistic estimates of seasonal variation in photosynthesis over the Amazon that relate well to the wet and dry seasons. We anticipate that our findings will steer the development of improved approaches to estimate photosynthetic activity over the tropics.

IAI Global Change Agenda and Support of Higher Education in the Andean Amazon Countries.

NASA Astrophysics Data System (ADS)

Galarraga, R.; McClain, M.; Fierro, V.

2007-05-01

The Andean Amazon River Analysis and Management project, an IAI Collaborative Research Network operating during 1999-2004, examined the impacts of climate and land-use changes on the hydrobiogeochemistry of rivers draining the Amazon Andes of Ecuador, Peru, Colombia and Bolivia. The project also provided a means to strengthen scientific collaboration among these Andean countries and the USA. Research in these countries was carried out under the guidance of investigators with backgrounds in the relevant environmental fields, but the bulk of the research activities were carried out by undergraduate and graduate students who studied within these countries and overseas. Twenty graduate students and 15 undergraduates completed studies within the project, in topics related to monitoring hydrometeorological variables both in time and space. Student research and capacity building were focused in areas central to global environmental change, including modeling of precipitation and precipitation-runoff processes, basin-scale water quality characterization and biogeochemical cycling, and socioeconomic controls on the use and management of riverine resources. The analysis of human dimension aspects of climate change research was also featured, especially those aspects that linked the consequences of water quality degradation on human health. Most of undergraduate and graduate students that collaborated in the AARAM project have joined national environmental institutions and some have continued for higher scientific degrees in fields closely related to the IAI scientific agenda. Through this IAI initiative, the number of trained global change scientists in the Andean countries has grown and there is enhanced awareness of key global change science issues among the scientific community.

Megascours: the morphodynamics of large river confluences

NASA Astrophysics Data System (ADS)

Dixon, Simon; Sambrook Smith, Greg; Nicholas, Andrew; Best, Jim; Bull, Jon; Vardy, Mark; Goodbred, Steve; Haque Sarker, Maminul

2015-04-01

River confluences are wildly acknowledged as crucial controlling influences upon upstream and downstream morphology and thus landscape evolution. Despite their importance very little is known about their evolution and morphodynamics, and there is a consensus in the literature that confluences represent fixed, nodal points in the fluvial network. Confluences have been shown to generate substantial bed scours around five times greater than mean depth. Previous research on the Ganges-Jamuna junction has shown large river confluences can be highly mobile, potentially 'combing' bed scours across a large area, although the extent to which this is representative of large confluences in general is unknown. Understanding the migration of confluences and associated scours is important for multiple applications including: designing civil engineering infrastructure (e.g. bridges, laying cable, pipelines, etc.), sequence stratigraphic interpretation for reconstruction of past environmental and sea level change, and in the hydrocarbon industry where it is crucial to discriminate autocyclic confluence scours from widespread allocyclic surfaces. Here we present a wide-ranging global review of large river confluence planforms based on analysis of Landsat imagery from 1972 through to 2014. This demonstrates there is an array of confluence morphodynamic types: from freely migrating confluences such as the Ganges-Jamuna, through confluences migrating on decadal timescales and fixed confluences. Along with data from recent geophysical field studies in the Ganges-Brahmaputra-Meghna basin we propose a conceptual model of large river confluence types and hypothesise how these influence morphodynamics and preservation of 'megascours' in the rock record. This conceptual model has implications for sequence stratigraphic models and the correct identification of surfaces related to past sea level change. We quantify the abundance of mobile confluence types by classifying all large confluences in the Amazon and Ganges-Brahmaputra-Meghna basins, showing these two basins have contrasting confluence morphodynamics. For the first time we show large river confluences have multiple scales of planform adjustment with important implications for infrastructure and interpretation of the rock record.

The impact of rise of the Andes and Amazon landscape evolution on diversification of lowland terra-firme forest birds

NASA Astrophysics Data System (ADS)

Aleixo, A.; Wilkinson, M. J.

2011-12-01

Since the 19th Century, the unmatched biological diversity of Amazonia has stimulated a diverse set of hypotheses accounting for patterns of species diversity and distribution in mega-diverse tropical environments. Unfortunately, the evidence supporting particular hypotheses to date is at best described as ambiguous, and no generalizations have emerged yet, mostly due to the lack of comprehensive comparative phylogeographic studies with thorough trans-Amazonian sampling of lineages. Here we report on spatial and temporal patterns of diversification estimated from mitochondrial gene trees for 31 lineages of birds associated with upland terra-firme forest, the dominant habitat in modern lowland Amazonia. The results confirm the pervasive role of Amazonian rivers as primary barriers separating sister lineages of birds, and a protracted spatio-temporal pattern of diversification, with a gradual reduction of earlier (1st and 2nd) and older (> 2 mya) splits associated with each lineage in an eastward direction (the easternmost tributaries of the Amazon, the Xingu and Tocantins Rivers, are not associated with any splits older than > 2 mya). This "younging-eastward" pattern may have an abiotic explanation related to landscape evolution. Triggered by a new pulse of Andean uplift, it has been proposed that modern Amazon basin landscapes may have evolved successively eastward, away from the mountain chain, starting ~10 mya. This process was likely based on the deposition of vast fluvial sediment masses, known as megafans, which apparently extended in series progressively eastward from Andean sources. The effects on drainage patterns are apparent from the location of axial rivers such as the Negro / Orinoco and Madeira which lie at the distal ends of major megafan ramparts at cratonic margins furthest from the Andes. Megafan extension plausibly explains the progressive extinction of the original Pebas wetland of west-central Amazonia by the present fluvial landsurfaces where upland terra-firme forest develop. The youngest landsurfaces thus appear to lie furthest from the mountains. In this scenario major drainages were also reoriented in wholesale fashion from a northward (Caribbean) outlet to a generally eastward, Atlantic Ocean outlet. More importantly, other major river courses in western-central Amazonia will have been established at progressively younger dates with distance eastward. The bird DNA data appears to confirm the role of Amazonian rivers as primary diversification barriers, and thus probably as promoters of bird speciation. We show for the first time that a general spatio-temporal pattern of diversification for terra-firme lineages in the Amazon is associated with rivers of apparently different ages ("younging-eastward"), and furthermore parallels a specific scenario of regional drainage evolution.

Extreme seasonal droughts and floods in Amazonia: causes, trends and impacts

NASA Astrophysics Data System (ADS)

Marengo, J. A.

2015-12-01

J. A. Marengo * and J. C. Espinoza** * Centro Nacional de Monitoramento e Alerta de Desastres Naturais, Ministério da Ciência, Tecnologia e Inovação, Sao Paulo, Brazil ** Subdirección de Ciencias de la Atmósfera e Hidrósfera (SCAH), Instituto Geofísico del Perú, Lima, Peru This paper reviews recent progress in the study and understanding of extreme seasonal events in the Amazon region, focusing on drought and floods. The review includes a history of droughts and floods in the past, in the present and some discussions on future extremes in the context of climate change and its impacts on the Amazon region. Several extreme hydrological events, some of them characterized as 'once in a century', have been reported in the Amazon region during the last decade. While abundant rainfall in various sectors of the basin has determined extreme floods along the river's main stem in 1953, 1989, 1999, 2009, 2012-2015, deficient rainfall in 1912, 1926, 1963, 1980, 1983, 1995, 1997, 1998, 2005 and 2010 has caused anomalously low river levels, and an increase in the risk and number of fires in the region, with consequences for humans. This is consistent with changes in the variability of the hydrometeorology of the basin and suggests that extreme hydrological events have been more frequent in the last two decades. Some of these intense/reduced rainfalls and subsequent floods/droughts were associated (but not exclusively) with La Niña/El Niño events. In addition, moisture transport anomalies from the tropical Atlantic into Amazonia, and from northern to southern Amazonia alter the water cycle in the region year-to-year. We also assess the impacts of such extremes on natural and human systems in the region, considering ecological, economic and societal impacts in urban and rural areas, particularly during the recent decades. In the context of the future climate change, studies show a large range of uncertainty, but suggest that drought might intensify through the 21st century.

Methane and carbon dioxide production in soils flooded by the Belo Monte hydropower reservoir in the Amazon Basin, Brazil

NASA Astrophysics Data System (ADS)

Sawakuchi, H. O.; Bertassoli, D. J., Jr.; Silveira, A. M.; Bozi, B. S.; de Jesus, J. S.; Sawakuchi, A. O.; Ward, N. D.; Bastviken, D.; Krusche, A. V.; Richey, J. E.

2016-12-01

The Xingu River, one of the major tributary of the Amazon River, was recently impounded by the Belo Monte dam, a massive and controversial hydropower plant that will become the third biggest power station in generating capacity of the world. Given the limited data associated with greenhouse gas emissions from reservoirs in the Amazon basin, the impacts of hydroelectric expansion in this region to the global carbon budget remains unclear. Here, we used a bottom-up assessment to quantify a fraction of the possible emissions associated with the Belo Monte reservoir. Eighteen soil samples were collected before the impoundment from seven different locations and depths in areas that were going to be permanently flooded by the reservoir (forests and pasturelands). Soil samples were split in triplicates and incubated in anoxic conditions during two phases totaling 160 days of anoxic incubation in order to quantify the potential methane and carbon dioxide production through time. Our results showed that pasturelands soil presented higher potential production of both gases in relation to the soils from forested areas, reaching up to 0.072 mg CH4 g-¹d-1 and 0.078 mg CO2 g-¹d-1 during the first period of 65 days in the first phase of incubations. Significant differences in production were also noted through soil depth and time. In several areas, the first 15 cm of soil generated 99% of the methane volume that was being produced in the 60 cm sampled profile. The first 65 days of the second phase of incubations showed production that was 35% (CH4) and 44% (CO2) lower than the same period in the first stage. Extrapolations towards the total flooded area demonstrates that 27.3-43.3 ton CH4 d-1 may be generated from flooded soils in the Belo Monte reservoir during only the first several months of flooding, maintaining significant production rates during upcoming months as long as favorable conditions are maintained.

Amazon river basin evapotranspiration and its influence on the rainfall in southern Brazil

NASA Astrophysics Data System (ADS)

Folegatti, M. V.; Wolff, W.

2017-12-01

Amazon river basin (ARB) presents a positive water balance, i.e. the precipitation is higher than evapotranspiration. Regarding the regional circulation, ARB evapotranspiration represents an important source of humidity for the South of Brazil. Thus, the aim of this work is to answer the question: how much is the correlation between ARB evapotranspiration and rainfall in South of Brazil? The shapefiles data of ARB and countries/states boundary were obtained through the Oak Ridge National Laboratory (ORNL) and Instituto Brasileiro de Geografia e Estatística (IBGE), respectively. According to rasters data, the precipitation was obtained from study of Numerical Terradynamic Simulation Group (NTSG) for images of Moderate Resolution Imaging Spectroradiometer (MODIS), under code MOD16A2, whereas rasters data for evapotranspiration were obtained from National Aeronautics and Space Administration (NASA) by Tropical Rainfall Measuring Mission Multi-Satellite Precipitation Analysis (TMPA), under code 3B43_V7. The products MOD16A2 and 3B43_V7 have a respective spatial resolution of 0.5º and 0.25º, and a monthly temporal resolution from January/2000 to December/2014. For ARB and South region of Brazil was calculated the mean evapotranspiration and mean precipitation through the pixels within of the respective polygons. To answer the question of this work was performed the cross-correlation analysis between these time series. We observed the highest value for the lag that corresponds the begin of spring (October), being 0.3 approximately. As a result, the mean precipitation on South region of Brazil during spring and summer was in the order of 15% to 30 %, explained by ARB evapotranspiration. For this reason, the maintenance of ARB is extremely important for water resource grant in South of Brazil.

Land Use Change Impacts to Flows and Hydropower at the Southern Fringe of the Brazilian Amazon: A Regional, Empirical Study of Land-Water-Energy Nexus Dynamics

NASA Astrophysics Data System (ADS)

Levy, M. C.; Thompson, S. E.; Cohn, A.

2014-12-01

Land use/cover change (LUCC) has occurred extensively in the Brazilian Amazon rainforest-savanna transition. Agricultural development-driven LUCC at regional scales can alter surface energy budgets, evapotranspiration (ET) and rainfall; these hydroclimatic changes impact streamflows, and thus hydropower. To date, there is only limited empirical understanding of these complex land-water-energy nexus dynamics, yet understanding is important to developing countries where both agriculture and hydropower are expanding and intensifying. To observe these changes and their interconnections, we synthesize a novel combination of ground network, remotely sensed, and empirically modeled data for LUCC, rainfall, flows, and hydropower potential. We connect the extensive temporal and spatial trends in LUCC occurring from 2000-2012 (and thus observable in the satellite record) to long-term historical flow records and run-of-river hydropower generation potential estimates. Changes in hydrologic condition are observed in terms of dry and wet season moments, extremes, and flow duration curves. Run-of-river hydropower generation potential is modeled at basin gauge points using equation models parameterized with literature-based low-head turbine efficiencies, and simple algorithms establishing optimal head and capacity from elevation and flows, respectively. Regression analyses are used to demonstrate a preliminary causal analysis of LUCC impacts to flow and energy, and discuss extension of the analysis to ungauged basins. The results are transferable to tropical and transitional forest regions worldwide where simultaneous agricultural and hydropower development potentially compete for coupled components of regional water cycles, and where policy makers and planners require an understanding of LUCC impacts to hydroclimate-dependent industries and ecosystems.

Biomass burning CCN enhance the dynamics of a mesoscale convective system over the La Plata Basin: a numerical approach

NASA Astrophysics Data System (ADS)

Camponogara, Gláuber; Assunção Faus da Silva Dias, Maria; Carrió, Gustavo G.

2018-02-01

High aerosol loadings are discharged into the atmosphere every year by biomass burning in the Amazon and central Brazil during the dry season (July-December). These particles, suspended in the atmosphere, can be carried via a low-level jet toward the La Plata Basin, one of the largest hydrographic basins in the world. Once they reach this region, the aerosols can affect mesoscale convective systems (MCSs), whose frequency is higher during the spring and summer over the basin. The present study is one of the first that seeks to understand the microphysical effects of biomass burning aerosols from the Amazon Basin on mesoscale convective systems over the La Plata Basin. We performed numerical simulations initialized with idealized cloud condensation nuclei (CCN) profiles for an MCS case observed over the La Plata Basin on 21 September 2010. The experiments reveal an important link between CCN number concentration and MCS dynamics, where stronger downdrafts were observed under higher amounts of aerosols, generating more updraft cells in response. Moreover, the simulations show higher amounts of precipitation as the CCN concentration increases. Despite the model's uncertainties and limitations, these results represent an important step toward the understanding of possible impacts on the Amazon biomass burning aerosols over neighboring regions such as the La Plata Basin.

Sources and routing of the Amazon River Flood Wave

NASA Astrophysics Data System (ADS)

Richey, Jeffrey E.; Mertes, Leal A. K.; Dunne, Thomas; Victoria, Reynaldo L.; Forsberg, Bruce R.; Tancredi, AntôNio C. N. S.; Oliveira, Eurides

1989-09-01

We describe the sources and routing of the Amazon River flood wave through a 2000-km reach of the main channel, between São Paulo de Olivença and Obidos, Brazil. The damped hydrograph of the main stem reflects the large drainage basin area, the 3-month phase lag in peak flows between the north and south draining tributaries due to seasonal differences in precipitation, and the large volume of water stored on the floodplain. We examined several aspects of the valley floor hydrology that are important for biogeochemistry. These include volumes of water storage in the channel and the floodplain and the rates of transfer between these two storage elements at various seasons and in each segment of the valley. We estimate that up to 30% of the water in the main stem is derived from water that has passed through the floodplain. To predict the discharge at any cross section within the study reach, we used the Muskingum formula to predict the hydrograph at downriver cross sections from a known hydrograph at upstream cross-sections and inputs and outputs along each reach. The model was calibrated using three years of data and was successfully tested against an additional six years of data. With this model it is possible to interpolate discharges for unsampled times and sites.

The size distribution of organic carbon in headwater streams in the Amazon basin.

PubMed

de Paula, Joana D'Arc; Luizão, Flávio Jesus; Piedade, Maria Teresa Fernandez

2016-06-01

Despite the strong representativeness of streams in the Amazon basin, their role in the accumulation of coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), and dissolved organic carbon (DOC) in transport, an important energy source in these environments, is poorly known. It is known that the arboreal vegetation in the Amazon basin is influenced by soil fertility and rainfall gradients, but would these gradients promote local differences in organic matter in headwater streams? To answer this question, 14 low-order streams were selected within these gradients along the Amazon basin, with extensions that varied between 4 and 8 km. The efficiency of the transformation of particulate into dissolved carbon fractions was assessed for each stream. The mean monthly benthic organic matter storage ranged between 1.58 and 9.40 t ha(-1) month(-1). In all locations, CPOC was the most abundant fraction in biomass, followed by FPOC and DOC. Rainfall and soil fertility influenced the distribution of the C fraction (p = 0.01), showing differentiated particulate organic carbon (POC) storage and DOC transportation along the basin. Furthermore, the results revealed that carbon quantification at the basin level could be underestimated, ultimately influencing the global carbon calculations for the region. This is especially due to the fact that the majority of studies consider only fine particulate organic matter and dissolved organic matter, which represent less than 50 % of the stored and transported carbon in streambeds.

Physical basis for river segmentation from water surface observables

NASA Astrophysics Data System (ADS)

Samine Montazem, A.; Garambois, P. A.; Calmant, S.; Moreira, D. M.; Monnier, J.; Biancamaria, S.

2017-12-01

With the advent of satellite missions such as SWOT we will have access to high resolution estimates of the elevation, slope and width of the free surface. A segmentation strategy is required in order to sub-sample the data set into reach master points for further hydraulic analyzes and inverse modelling. The question that arises is : what will be the best node repartition strategy that preserves hydraulic properties of river flow? The concept of hydraulic visibility introduced by Garambois et al. (2016) is investigated in order to highlight and characterize the spatio-temporal variations of water surface slope and curvature for different flow regimes and reach geometries. We show that free surface curvature is a powerful proxy for characterizing the hydraulic behavior of a reach since concavity of water surface is driven by variations in channel geometry that impacts the hydraulic properties of the flow. We evaluated the performance of three segmentation strategies by means of a well documented case, that of the Garonne river in France. We conclude that local extrema of free surface curvature appear as the best candidate for locating the segment boundaries for an optimal hydraulic representation of the segmented river. We show that for a given river different segmentation scales are possible: a fine-scale segmentation which is driven by fine-scale hydraulic to large-scale segmentation driven by large-scale geomorphology. The segmentation technique is then applied to high resolution GPS profiles of free surface elevation collected on the Negro river basin, a major contributor of the Amazon river. We propose two segmentations: a low-resolution one that can be used for basin hydrology and a higher resolution one better suited for local hydrodynamic studies.

Mouths of the Amazon River, Brazil, South America

NASA Technical Reports Server (NTRS)

1991-01-01

Huge sediment loads from the interior of the country flow through the Mouths of the Amazon River, Brazil (0.5S, 50.0W). The river current carries hundreds of tons of sediment through the multiple outlets of the great river over 100 miles from shore before it is carried northward by oceanic currents. The characteristic 'fair weather cumulus' pattern of low clouds over the land but not over water may be observed in this scene.

Mouths of the Amazon River, Brazil, South America

NASA Image and Video Library

1991-08-11

Huge sediment loads from the interior of the country flow through the Mouths of the Amazon River, Brazil (0.5S, 50.0W). The river current carries hundreds of tons of sediment through the multiple outlets of the great river over 100 miles from shore before it is carried northward by oceanic currents. The characteristic "fair weather cumulus" pattern of low clouds over the land but not over water may be observed in this scene.

Hydraulic characterization of the middle reach of the Congo River

NASA Astrophysics Data System (ADS)

O'Loughlin, F.; Trigg, M.; Schumann, G.; Bates, P. D.

2012-12-01

Little is known about the hydraulics of the Congo River compared to other large rivers, such as the Amazon, Nile and Mississippi, despite it draining an area greater than 3.7 million square kilometers and being the seconded largest river in terms of discharge. While there has been some study of the Congo Basin, most of these concentrate on ecology or the human aspects, but few look at the either the hydrology or hydraulic characteristics of the river. Of the published hydrology/hydraulic research, most concentrates on the hydrology of the Congo Basin aiming to alleviate some of the issues relating to a sparse river gauging network that currently exists. Even fewer studies have looked at hydraulics of the Congo, and usually over a relatively small area of the basin. To undertake a larger study area requires more details on the characteristics of the Congo River. The Congo River can be divided into three distinct reaches; the upper, middle and lower reaches. We concentrate on the middle reach which starts upstream at Boyoma falls, just south of Kisangani, and ends downstream at Livingstone Falls, at Kinshasa (DRC), Brazzaville (Congo) and the Pool Malebo. From Kisangani to Kinshasa, the middle Congo crosses the equator twice and is join by two large tributaries (Ubangi, Kasai) and is highly braided. The middle reach of the Congo is especially important as its still largely undisturbed wetlands are the seconded largest tropical wetlands globally. It is also the main transportation link between Kisangani and Kinshasa, the two largest cities in the DRC. By utilizing remotely sensed Landsat and Icesat datasets, we present the first detailed study on the hydraulic characterization of the middle reach of the Congo River. With these datasets we identify the main control points of flow in the middle reach, investigate how the water surface slope, channel width, islands and braids vary between high and low flows and spatially along the reach. We compare the middle reach of the Congo to other large braided rivers to highlight how the Congo is unique. This detailed analysis will yield key hydraulic characteristics for large reaches of the main channel and tributaries that will be essential for correct hydraulic modeling of the river in due course, and will also provide new insights into the behavior and hydrodynamics of this mysterious river.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupre, B.; Rousseau, D.; Gaillardet, J.

The Congo river Basin is the second largest drainage basin in the world, after the Amazon. The materials carried by its main rivers provide the opportunity to study the products of denudation of a large fraction of the upper continental crust of the African continent. This paper presents the chemical composition of the different phases carried in the Congo rivers and is followed by a companion paper, devoted to the modelling of major and trace elements. The Congo river between Bangui and Brazzaville as well as its main tributaries, including a few organic-rich rivers, also called Black Rivers, were sampledmore » during the 1989 high water stage. The three main phases (suspended load, dissolved load, and bedload) were analysed for twenty-five major and trace elements. Concentrations normalized to the upper continental crust show that in each river, suspended sediments and dissolved load are chemical complements for the most soluble elements (Ca, Na, Sr, K, Ba, Rb, and U). While these elements are enriched in the dissolved loads, they are considerably depleted in the corresponding suspended sediments. This is consistent with their high mobility during weathering. Another type of complementarity is observed for Zr and Hf between suspended sediments and bedload, related to the differential velocity of suspended sediments and zircons which are concentrated in bedloads. Compared to other rivers, absolute dissolved concentrations of Ca, Na, Sr, K, Ba, Rb, and U are remarkably low. Surprisingly, high dissolved concentrations are found in the Congo waters for other trace elements (e.g., REEs), especially in the Black rivers. On a world scale, these concentrations are among the highest measured in rivers and are shown to be pH dependent for a number of dissolved trace elements. The dissolved loads are systematically normalized to the suspended loads for each river, in order to remove the variations of the element abundances owing to source rock variations.« less

Environmental variables associated with anopheline larvae distribution and abundance in Yanomami villages within unaltered areas of the Brazilian Amazon.

PubMed

Sánchez-Ribas, Jordi; Oliveira-Ferreira, Joseli; Gimnig, John E; Pereira-Ribeiro, Cleomar; Santos-Neves, Maycon Sebastião Alberto; Silva-do-Nascimento, Teresa Fernandes

2017-11-16

Many indigenous villages in the Amazon basin still suffer from a high malaria burden. Despite this health situation, there are few studies on the bionomics of anopheline larvae in such areas. This publication aims to identify the main larval habitats of the most abundant anopheline species and to assess their associations with some environmental factors. We conducted a 19-month longitudinal study from January 2013 to July 2014, sampling anopheline larvae in two indigenous Yanomami communities, comprised of four villages each. All natural larval habitats were surveyed every two months with a 350 ml manual dipper, following a standardized larval sampling methodology. In a third study area, we conducted two field expeditions in 2013 followed by four systematic collections during the long dry season of 2014-2015. We identified 177 larval habitats in the three study areas, from which 9122 larvae belonging to 13 species were collected. Although species abundance differed between villages, An. oswaldoi (s.l.) was overall the most abundant species. Anopheles darlingi, An. oswaldoi (s.l.), An. triannulatus (s.s.) and An. mattogrossensis were primarily found in larval habitats that were partially or mostly sun-exposed. In contrast, An. costai-like and An. guarao-like mosquitoes were found in more shaded aquatic habitats. Anopheles darlingi was significantly associated with proximity to human habitations and larval habitats associated with river flood pulses and clear water. This study of anopheline larvae in the Brazilian Yanomami area detected high heterogeneities at micro-scale levels regarding species occurrence and densities. Sun exposure was a major modulator of anopheline occurrence, particularly for An. darlingi. Lakes associated with the rivers, and particularly oxbow lakes, were the main larval habitats for An. darlingi and other secondary malaria vectors. The results of this study will serve as a basis to plan larval source management activities in remote indigenous communities of the Amazon, particularly for those located within low-order river-floodplain systems.

Deforestation in Amazonia impacts riverine carbon dynamics

NASA Astrophysics Data System (ADS)

Langerwisch, F.; Walz, A.; Rammig, A.; Tietjen, B.; Thonicke, K.; Cramer, W.

2015-10-01

Fluxes of organic and inorganic carbon within the Amazon basin are considerably controlled by annual flooding, which triggers the export of terrigenous organic material to the river and ultimately to the Atlantic Ocean. The amount of carbon imported to the river and the further conversion, transport and export of it, depend on terrestrial productivity and discharge, as well as temperature and atmospheric CO2. Both terrestrial productivity and discharge are influenced by climate and land use change. To assess the impact of these changes on the riverine carbon dynamics, the coupled model system of LPJmL and RivCM (Langerwisch et al., 2015) has been used. Vegetation dynamics (in LPJmL) as well as export and conversion of terrigenous carbon to and within the river (RivCM) are included. The model system has been applied for the years 1901 to 2099 under two deforestation scenarios and with climate forcing of three SRES emission scenarios, each for five climate models. The results suggest that, following deforestation, riverine particulate and dissolved organic carbon will strongly decrease by up to 90 % until the end of the current century. In parallel, discharge increases, leading to roughly unchanged net carbon transport during the first decades of the century, as long as a sufficient area is still forested. During the following decades the amount of transported carbon will decrease drastically. In contrast to the riverine organic carbon, the amount of riverine inorganic carbon is only determined by climate change forcing, namely increased temperature and atmospheric CO2 concentration. Mainly due to the higher atmospheric CO2 it leads to an increase in riverine inorganic carbon by up to 20 % (SRES A2). The changes in riverine carbon fluxes have direct effects on the export of carbon, either to the atmosphere via outgassing, or to the Atlantic Ocean via discharge. Basin-wide the outgassed carbon will increase slightly, but can be regionally reduced by up to 60 % due to deforestation. The discharge of organic carbon to the ocean will be reduced by about 40 % under the most severe deforestation and climate change scenario. The changes would have local and regional consequences on the carbon balance and habitat characteristics in the Amazon basin itself but also in the adjacent Atlantic Ocean.

Climate Change-Induced Shifts in the Hydrological Regime of the Upper Amazon Basin and Its Impacts on Local Eco-Hydrology

NASA Astrophysics Data System (ADS)

Zulkafli, Z. D.; Buytaert, W.; Veliz, C.

2014-12-01

The potential impact of a changing climate on Andean-Amazonian hydrology is an important question for scientists and policymakers alike, because of its implications for local ecosystem services such as water resources availability, river flow regulation, and eco-hydrology. This study presents new projections of climate change impacts on the hydrological regime of the upper Amazon river in Peru, and the consequent effect on two vulnerable species of freshwater turtle populations Podocnemis expansa (Amazon turtle) and Podocnemis unilis (yellow-spotted side neck turtle), which nest on its banks. To do this, the global climate model outputs of radiation, temperature, precipitation, wind, and humidity data from the Coupled Model Inter-comparison Project Phase 5 (CMIP5) are propagated through a hydrological model to simulate changes in river flow. The model consists of a land surface scheme called the Joint-UK Land Environment Simulator (JULES) that is coupled to a distributed river flow routing routine, which also accounts for floodplain attenuation of flood peaks. It is parameterized using a combination of remote sensing (TRMM, MODIS, an Landsat) and ground observational data to reproduce reliably the historical floodplain regime. The climate-induced shifts are inferred from a comparison between the RCP 4.5 and 8.5 projections against the historical scenario. Changes in the 10th and 95th percentile of flows, as well as the distributions in the length of the dry and wet seasons are analysed. These parameters are then used to construct probability models of biologically significant events (BSEs - extreme dry year, extreme wet year and repiquete), which are negative drivers of the turtle-egg ovipositioning, nesting and hatching. The results indicate that the projected increase in wet-season precipitation overcome the increase in evapotranspirative demand from an increase in temperature, resulting in more frequent and longer term flooding that causes a net loss of total turtle-egg counts. Additionally, changes in air and water temperature may alter the male / female ratio of the turtles.

Rivers in the sea - Can we quantify pigments in the Amazon and the Orinoco River plumes from space?

NASA Technical Reports Server (NTRS)

Muller-Karger, Frank E.; Walsh, John J.; Carder, Kendall L.; Zika, Rod G.

1989-01-01

Coastal Zone Color Scanner (CZCS) images of the western tropical Atlantic (1979-1982) were combined into monthly mean surface pigment fields. These suggest that Amazon River water flows along northeastern South America directly toward the Caribbean sea early in the year. After June, however, the North Brazil Current is shunted eastward, carrying a large fraction of Amazon water into the North Equatorial Countercurrent (NECC). This eastward flow causes diminished flow through the Caribbean, which permits northwestward dispersal of Orinoco River water due to local Ekman forcing. The Orinoco plume crosses the Caribbean, leading to seasonal variation in surface salinity near Puerto Rico. At least 50 percent of the pigment concentration estimated in these plumes seems due to viable phytoplankton.

Nest placement of the giant Amazon river turtle, Podocnemis expansa, in the Araguaia River, Goiás State, Brazil.

PubMed

Ferreira, Paulo Dias Júnior; Castro, Paulo de Tarso Amorim

2005-05-01

The giant Amazon river turtle (Podocnemis expansa) nests on extensive sand bars on the margins and interior of the channel during the dry season. The high concentration of nests in specific points of certain beaches indicates that the selection of nest placement is not random but is related to some geological aspects, such as bar margin inclination and presence of a high, sandy platform. The presence of access channels to high platform points or ramp morphology are decisive factors in the choice of nesting areas. The eroded and escarped margins of the beaches hinder the Amazon river turtle arriving at the most suitable places for nesting. Through the years, changes in beach morphology can alter nest distribution.

Cumulative Total South America Freshwater Losses as Seen by NASA GRACE, 2002-15

NASA Image and Video Library

2015-12-08

Cumulative total freshwater losses in South America from 2002 to 2015 (in inches) observed by NASA's Gravity Recovery and Climate Experiment (GRACE) mission. Total water refers to all of the snow, surface water, soil water and groundwater combined. Much of the Amazon River basin experienced increasing total water storage during this time period, though the persistent Brazilian drought is apparent to the east. Groundwater depletion strongly impacted total water losses in the Guarani aquifer of Argentina and neighboring countries. Significant water losses due to the melting ice fields of Patagonia are also observed. http://photojournal.jpl.nasa.gov/catalog/PIA20205

Protecting the Amazon with protected areas

PubMed Central

Walker, Robert; Moore, Nathan J.; Arima, Eugenio; Perz, Stephen; Simmons, Cynthia; Caldas, Marcellus; Vergara, Dante; Bohrer, Claudio

2009-01-01

This article addresses climate-tipping points in the Amazon Basin resulting from deforestation. It applies a regional climate model to assess whether the system of protected areas in Brazil is able to avoid such tipping points, with massive conversion to semiarid vegetation, particularly along the south and southeastern margins of the basin. The regional climate model produces spatially distributed annual rainfall under a variety of external forcing conditions, assuming that all land outside protected areas is deforested. It translates these results into dry season impacts on resident ecosystems and shows that Amazonian dry ecosystems in the southern and southeastern basin do not desiccate appreciably and that extensive areas experience an increase in precipitation. Nor do the moist forests dry out to an excessive amount. Evidently, Brazilian environmental policy has created a sustainable core of protected areas in the Amazon that buffers against potential climate-tipping points and protects the drier ecosystems of the basin. Thus, all efforts should be made to manage them effectively. PMID:19549819

Protecting the Amazon with protected areas.

PubMed

Walker, Robert; Moore, Nathan J; Arima, Eugenio; Perz, Stephen; Simmons, Cynthia; Caldas, Marcellus; Vergara, Dante; Bohrer, Claudio

2009-06-30

This article addresses climate-tipping points in the Amazon Basin resulting from deforestation. It applies a regional climate model to assess whether the system of protected areas in Brazil is able to avoid such tipping points, with massive conversion to semiarid vegetation, particularly along the south and southeastern margins of the basin. The regional climate model produces spatially distributed annual rainfall under a variety of external forcing conditions, assuming that all land outside protected areas is deforested. It translates these results into dry season impacts on resident ecosystems and shows that Amazonian dry ecosystems in the southern and southeastern basin do not desiccate appreciably and that extensive areas experience an increase in precipitation. Nor do the moist forests dry out to an excessive amount. Evidently, Brazilian environmental policy has created a sustainable core of protected areas in the Amazon that buffers against potential climate-tipping points and protects the drier ecosystems of the basin. Thus, all efforts should be made to manage them effectively.

Tree ring reconstructed rainfall over the southern Amazon Basin

NASA Astrophysics Data System (ADS)

Lopez, Lidio; Stahle, David; Villalba, Ricardo; Torbenson, Max; Feng, Song; Cook, Edward

2017-07-01

Moisture sensitive tree ring chronologies of Centrolobium microchaete have been developed from seasonally dry forests in the southern Amazon Basin and used to reconstruct wet season rainfall totals from 1799 to 2012, adding over 150 years of rainfall estimates to the short instrumental record for the region. The reconstruction is correlated with the same atmospheric variables that influence the instrumental measurements of wet season rainfall. Anticyclonic circulation over midlatitude South America promotes equatorward surges of cold and relatively dry extratropical air that converge with warm moist air to form deep convection and heavy rainfall over this sector of the southern Amazon Basin. Interesting droughts and pluvials are reconstructed during the preinstrumental nineteenth and early twentieth centuries, but the tree ring reconstruction suggests that the strong multidecadal variability in instrumental and reconstructed wet season rainfall after 1950 may have been unmatched since 1799.

Spacebased Observations of Oceanic Influence on the Annual Variation of South American Water Balance

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Xie, Xiaosu; Tang, Wenqing; Zlotnicki, Victor

2006-01-01

The mass change of South America (SA) continent measured by the Gravity Recovery and Climate Experiment (GRACE) imposes a constraint on the uncertainties in estimating the annual variation of rainfall measured by Tropical Rain Measuring Mission (TRMM) and ocean moisture influx derived from QuikSCAT data. The approximate balance of the mass change rate with the moisture influx less climatological river discharge, in agreement with the conservation principle, bolsters not only the credibility of the spacebased measurements, but supports the characterization of ocean's influence on the annual variation of continental water balance. The annual variation of rainfall is found to be in phase with the mass change rate in the Amazon and the La Plata basins, and the moisture advection across relevant segments of the Pacific and Atlantic coasts agrees with the annual cycle of rainfall in the two basins and the Andes mountains.

Size distribution of Amazon River bed sediment

USGS Publications Warehouse

Nordin, C.F.; Meade, R.H.; Curtis, W.F.; Bosio, N.J.; Landim, P.M.B.

1980-01-01

The first recorded observations of bed material of the Amazon River were made in 1843 by Lt William Lewis Herndon of the US Navy, when he travelled the river from its headwaters to its mouth, sounding its depths, and noting the nature of particles caught in a heavy grease smeared to the bottom of his sounding weight1. He reported the bed material of the river to be mostly sand and fine gravel. Oltman and Ames took samples at a few locations in 1963 and 1964, and reported the bed material at O??bidos, Brazil, to be fine sands, with median diameters ranging from 0.15 to 0.25 mm (ref. 2). We present here a summary of particle-size analyses of samples of streambed material collected from the Amazon River and its major tributaries along a reach of the river from Iquitos in Peru, ???3,500 km above Macapa?? Brazil, to a point 220 km above Macapa??3. ?? 1980 Nature Publishing Group.

Estimating Sediment Delivery to The Rio Maranon, Peru Prior to Large-Scale Hydropower Developments Using High Resolution Imagery from Google Earth and a DJI Phantom 3 Drone

NASA Astrophysics Data System (ADS)

Goode, J. R.; Candelaria, T.; Kramer, N. R.; Hill, A. F.

2016-12-01

As global energy demands increase, generating hydroelectric power by constructing dams and reservoirs on large river systems is increasingly seen as a renewable alternative to fossil fuels, especially in emerging economies. Many large-scale hydropower projects are located in steep mountainous terrain, where environmental factors have the potential to conspire against the sustainability and success of such projects. As reservoir storage capacity decreases when sediment builds up behind dams, high sediment yields can limit project life expectancy and overall hydropower viability. In addition, episodically delivered sediment from landslides can make quantifying sediment loads difficult. These factors, combined with remote access, limit the critical data needed to effectively evaluate development decisions. In the summer of 2015, we conducted a basic survey to characterize the geomorphology, hydrology and ecology of 620 km of the Rio Maranon, Peru - a major tributary to the Amazon River, which flows north from the semi-arid Peruvian Andes - prior to its dissection by several large hydropower dams. Here we present one component of this larger study: a first order analysis of potential sediment inputs to the Rio Maranon, Peru. To evaluate sediment delivery and storage in this system, we used high resolution Google Earth imagery to delineate landslides, combined with high resolution imagery from a DJI Phantom 3 Drone, flown at alluvial fan inputs to the river in the field. Because hillslope-derived sediment inputs from headwater tributaries are important to overall ecosystem health in large river systems, our study has the potential to contribute to the understanding the impacts of large Andean dams on sediment connectivity to the Amazon basin.

Using LandSat and SRTM datasets to develop relationships for estimating bankfull channel widths in the Amazon Basin

NASA Astrophysics Data System (ADS)

Gummadi, V.; He, Y.; Beighley, E. R.

2007-12-01

Modeling fine scale spatial and temporal processes of the hydrologic cycle over continental to global extents is vital for assessing the potential impacts of climate and land use change on global water resources and related systems. Significant advancement in understanding and predicting the magnitude, trend, timing and partitioning of terrestrial water stores and fluxes requires the development of methodologies and knowledge for extracting representative hydraulic geometries from remote sensing data products and field data, suitable for estimating inundation characteristics and water storage changes which are limited for much of the globe. In this research, relationships between channel and floodplain widths and spatial drainage characteristics are developed for the Amazon Basin. Channel and floodplain widths were measured using SRTM data and LandSat TM/ETM imagery at 510 sites. The study sites were selected based on the Pfafstetter decomposition methodology which provides an irregular model grid based on repeatedly subdividing landscape units into nine subunits consisting of basins and interbasins. The selected sites encompass all possible combinations of Pfafstetter modeling units (ex., basins of interbasins, interbasins of basins, etc.). The 510 study sites are within the Amazon Basin with drainage areas ranging 10 to 5.4 million sq km and mean watershed ground slopes ranging from 0.4 and 30 percent. Preliminary results indicate that channel widths can be predicted using drainage area and mean watershed slope (R2 = 0.85). Floodplain widths can be predicted using channel width and the local slope (R2 = 0.70). Using the Purus watershed, a sub-basin to the Amazon (350,000 sq km), effects of channel and floodplain widths on simulated hydrographs are presented.

Distribution of Aboveground Live Biomass in the Amazon Basin

NASA Technical Reports Server (NTRS)

Saatchi, S. S.; Houghton, R. A.; DosSantos Alvala, R. C.; Soares, J. V.; Yu, Y.

2007-01-01

The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB for seven distinct biomass classes of lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types, such as the woody and herbaceous savanna and secondary forests, was directly estimated with a regression based on satellite data. Results show that AGLB is highest in Central Amazonia and in regions to the east and north, including the Guyanas. Biomass is generally above 300Mgha(sup 1) here except in areas of intense logging or open floodplains. In Western Amazonia, from the lowlands of Peru, Ecuador, and Colombia to the Andean mountains, biomass ranges from 150 to 300Mgha(sup 1). Most transitional and seasonal forests at the southern and northwestern edges of the basin have biomass ranging from 100 to 200Mgha(sup 1). The AGLB distribution has a significant correlation with the length of the dry season. We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and below ground biomass, is 86 PgC with +/- 20% uncertainty.

Description of Lutzomyia (Trichophoromyia) nautaensis n. sp. (Diptera: Psychodidae) from the Peruvian Amazon Basin

PubMed Central

Fernandez, Roberto; Lopez, Victor; Cardenas, Roldan; Requena, Edwin

2015-01-01

A new species of sand fly, which we describe as Lutzomyia (Trichophoromyia) nautaensis n. sp., was collected in the northern Peruvian Amazon Basin. In this region of Peru, cutaneous leishmaniasis is transmitted primarily by anthropophilic sand flies; however, zoophilic sand flies of the subgenus Trichophoromyia may also be incriminated in disease transmission. Detection of Leishmania spp. in Lutzomyia auraensis Mangabeira captured in the southern Peruvian Amazon indicates the potential of this and other zoophilic sand flies for human disease transmission, particularly in areas undergoing urban development. Herein, we describe Lutzomyia (Trichophoromyia) nautaensis n. sp., and report new records of sand flies in Peru. PMID:26335468

Hydroclimate changes across the Amazon lowlands over the past 45,000 years.

PubMed

Wang, Xianfeng; Edwards, R Lawrence; Auler, Augusto S; Cheng, Hai; Kong, Xinggong; Wang, Yongjin; Cruz, Francisco W; Dorale, Jeffrey A; Chiang, Hong-Wei

2017-01-11

Reconstructing the history of tropical hydroclimates has been difficult, particularly for the Amazon basin-one of Earth's major centres of deep atmospheric convection. For example, whether the Amazon basin was substantially drier or remained wet during glacial times has been controversial, largely because most study sites have been located on the periphery of the basin, and because interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting. Here we show that rainfall in the basin responds closely to changes in glacial boundary conditions in terms of temperature and atmospheric concentrations of carbon dioxide. Our results are based on a decadally resolved, uranium/thorium-dated, oxygen isotopic record for much of the past 45,000 years, obtained using speleothems from Paraíso Cave in eastern Amazonia; we interpret the record as being broadly related to precipitation. Relative to modern levels, precipitation in the region was about 58% during the Last Glacial Maximum (around 21,000 years ago) and 142% during the mid-Holocene epoch (about 6,000 years ago). We find that, as compared with cave records from the western edge of the lowlands, the Amazon was widely drier during the last glacial period, with much less recycling of water and probably reduced plant transpiration, although the rainforest persisted throughout this time.

Geochemistry of the Amazon Estuary

USGS Publications Warehouse

Smoak, Joseph M.; Krest, James M.; Swarzenski, Peter W

2006-01-01

The Amazon River supplies more freshwater to the ocean than any other river in the world. This enormous volume of freshwater forces the estuarine mixing out of the river channel and onto the continental shelf. On the continental shelf, the estuarine mixing occurs in a very dynamic environment unlike that of a typical estuary. The tides, the wind, and the boundary current that sweeps the continental shelf have a pronounced influence on the chemical and biological processes occurring within the estuary. The dynamic environment, along with the enormous supply of water, solutes and particles makes the Amazon estuary unique. This chapter describes the unique features of the Amazon estuary and how these features influence the processes occurring within the estuary. Examined are the supply and cycling of major and minor elements, and the use of naturally occurring radionuclides to trace processes including water movement, scavenging, sediment-water interaction, and sediment accumulation rates. The biogeochemical cycling of carbon, nitrogen, and phosphorus, and the significances of the Amazon estuary in the global mass balance of these elements are examined.

Empty forest or empty rivers? A century of commercial hunting in Amazonia.

PubMed

Antunes, André P; Fewster, Rachel M; Venticinque, Eduardo M; Peres, Carlos A; Levi, Taal; Rohe, Fabio; Shepard, Glenn H

2016-10-01

The Amazon basin is the largest and most species-rich tropical forest and river system in the world, playing a pivotal role in global climate regulation and harboring hundreds of traditional and indigenous cultures. It is a matter of intense debate whether the ecosystem is threatened by hunting practices, whereby an "empty forest" loses critical ecological functions. Strikingly, no previous study has examined Amazonian ecosystem resilience through the perspective of the massive 20th century international trade in furs and skins. We present the first historical account of the scale and impacts of this trade and show that whereas aquatic species suffered basin-wide population collapse, terrestrial species did not. We link this differential resilience to the persistence of adequate spatial refuges for terrestrial species, enabling populations to be sustained through source-sink dynamics, contrasting with unremitting hunting pressure on more accessible aquatic habitats. Our findings attest the high vulnerability of aquatic fauna to unregulated hunting, particularly during years of severe drought. We propose that the relative resilience of terrestrial species suggests a marked opportunity for managing, rather than criminalizing, contemporary traditional subsistence hunting in Amazonia, through both the engagement of local people in community-based comanagement programs and science-led conservation governance.

Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

NASA Technical Reports Server (NTRS)

Devol, Allan H.; Richey, Jeffrey E.; Forsberg, Bruce R.; Martinelli, Luiz A.

1990-01-01

Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emission from eight lakes located in the central Amazon basis showed similar results. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg/yr, which indicates the importance of the area in global atmospheric chemistry.

Selenium Levels in the Whole Blood of Children and Teenagers from Two Riparian Communities at the Madeira River Basin in the Western Brazilian Amazon.

PubMed

Vega, Claudia M; Godoy, José M; Barrocas, Paulo R G; Gonçalves, Rodrigo A; De Oliveira, Beatriz F A; Jacobson, Ludmilla V; Mourão, Dennys S; Hacon, Sandra S

2017-01-01

Selenium (Se) is an essential micronutrient that exerts multiple functions in the organism, and both its deficiency and excess can cause health impairments. Thus, it is important to monitor its levels in the population, especially in vulnerable groups, such as children from the Brazilian Amazon region, where there is a lack of information in this regard. The aim of this research was to study Se levels in the whole blood of children and teenagers (5-16 years old) from two riparian communities at the Madeira River (Cuniã RESEX and Belmont). Se level variations related to the communities' location, seasonality, diet, and body mass index (BMI) were assessed. Blood samples were collected in both communities for Se determinations, using ICP-MS and hemogram analyses, during May and September of 2011. Food frequency questionnaires were applied to assess consumption rates of specific food items. Non-parametric tests and linear multiple regressions were applied in the data analyses. Median Se levels were significantly higher during May (Cuniã RESEX 149 μg L -1 ; Belmont 85 μg L -1 ) compared to September (Cuniã RESEX 79 μg L -1 ; Belmont 53 μg L -1 ). No significant differences were found between the communities regarding BMI measurements and anemia prevalence. However, Se blood levels were significantly higher at the Cuniã RESEX compared to Belmont. In addition, the former showed higher fish and Brazil nut intakes, which may be the main Se sources for this community. These results contribute to a better understanding of Se reference levels for children and teenagers of Western Amazon riparian communities.

Interannual Variation in Offshore Advection of Amazon-Orinoco Plume Waters: Observations, Forcing Mechanisms, and Impacts

NASA Astrophysics Data System (ADS)

Fournier, S.; Vandemark, D.; Gaultier, L.; Lee, T.; Jonsson, B.; Gierach, M. M.

2017-11-01

This study investigates sea surface salinity (SSS) and sea surface temperature (SST) variations in the tropical Atlantic east of the Lesser Antilles, a region where freshwater advection from the Amazon and Orinoco Rivers, may potentially impact air-sea interaction. Observations are used to document later-summer variability and evaluate offshore riverine transport from 2010 to 2014. During this period, the largest difference in plume-affected areas, defined as the extent covered by SSS lower than 35.5 pss, is found between 2011 and 2014. Plume waters covered 92% of the study region in 2011 and 60% in 2014, with the average SSS in the study region being 2 pss lower in 2011. Lagrangian particle tracking based on satellite-derived ocean currents is used to diagnose the impact of the river plumes on SSS and SST from 2010 to 2014. Northward freshwater flux in summer 2014 was significantly weaker than fluxes in 2010-2013. This difference is not due to interannual discharge variability, but to significant changes in eddy-driven transport and cross-shore winds. In particular, the stronger cross-shore wind in May 2014 restricted offshore freshwater flow and lead to a smaller plume-affected area. Persistent SST gradients are often found near the plume edge, which may have implications for ocean-atmosphere coupling associated with atmospheric convection. SST in the study region was 1°C higher in 2010 compared to other years, and is related to basin-scale ocean-atmosphere processes. Interannual variation in Amazon advective pathways and the associated SSS changes are also influenced by changes in the ITCZ position between 2011 and 2014.

Interannual Variation in Offshore Advection of Amazon-Orinoco Plume Waters: Observations, Forcing Mechanisms, and Impacts

NASA Astrophysics Data System (ADS)

Fournier, S.; Vandemark, D. C.; Gaultier, L.; Lee, T.; Jonsson, B. F.; Gierach, M. M.

2017-12-01

Sea surface salinity (SSS) and sea surface temperature (SST) variations in the tropical Atlantic east of the Lesser Antilles, a region impacted by freshwater advection from the Amazon and Orinoco Rivers have potential implications to late-summer tropical cyclones (TCs). This study examines these variations during late summer and their forcing mechanisms using observations. During the period 2010-2014, the largest difference in plume-affected area, defined as the extent covered by SSS lower than 35.5 pss, is found between 2011 and 2014. Plume waters covered 92% (60%) of the study region in 2011 (2014) with the averaged SSS in the study region being 2-pss lower in 2011. Lagrangian particle tracking based on satellite-derived ocean currents is used to diagnose the impacts of the river plumes on SSS and SST during 2010-2014. Northward freshwater flux in the summer of 2014 is significantly weaker than those in 2010-2013. This is not due to interannual discharge variability, but significant changes in eddy-driven transport and cross-shore winds. In particular, the stronger cross-shore wind in May 2014 restricted offshore freshwater flow, leading to a smaller extent of the plume-affected area. Persistent SST gradients are often found near the plume edge, which may have implication to ocean-atmosphere coupling associated with TC-related convection. SST in the study region is 1°C higher in 2010 than in other years, and is related to basin-scale ocean-atmosphere processes. Interannual variation in Amazon advective pathways and the associated SSS changes are also influenced by changes in the ITCZ position between 2011 and 2014.

Global Terrestrial Water Storage Changes and Connections to ENSO Events

NASA Astrophysics Data System (ADS)

Ni, Shengnan; Chen, Jianli; Wilson, Clark R.; Li, Jin; Hu, Xiaogong; Fu, Rong

2018-01-01

Improved data quality of extended record of the Gravity Recovery and Climate Experiment (GRACE) satellite gravity solutions enables better understanding of terrestrial water storage (TWS) variations. Connections of TWS and climate change are critical to investigate regional and global water cycles. In this study, we provide a comprehensive analysis of global connections between interannual TWS changes and El Niño Southern Oscillation (ENSO) events, using multiple sources of data, including GRACE measurements, land surface model (LSM) predictions and precipitation observations. We use cross-correlation and coherence spectrum analysis to examine global connections between interannual TWS changes and the Niño 3.4 index, and select four river basins (Amazon, Orinoco, Colorado, and Lena) for more detailed analysis. The results indicate that interannual TWS changes are strongly correlated with ENSO over much of the globe, with maximum cross-correlation coefficients up to 0.70, well above the 95% significance level ( 0.29) derived by the Monte Carlo experiments. The strongest correlations are found in tropical and subtropical regions, especially in the Amazon, Orinoco, and La Plata basins. While both GRACE and LSM TWS estimates show reasonably good correlations with ENSO and generally consistent spatial correlation patterns, notably higher correlations are found between GRACE TWS and ENSO. The existence of significant correlations in middle-high latitudes shows the large-scale impact of ENSO on the global water cycle.

Phylogenetic relationships among Synallaxini spinetails (Aves: Furnariidae) reveal a new biogeographic pattern across the Amazon and Paraná river basins.

PubMed

Claramunt, Santiago

2014-09-01

Relationships among genera in the tribe Synallaxini have proved difficult to resolve. In this study, I investigate relationships among Synallaxis, Certhiaxis and Schoeniophylax using DNA sequences from the mitochondrion and three nuclear regions. I implemented novel primers and protocols for amplifying and sequencing autosomal and sex-linked introns in Furnariidae that resolved basal relationships in the Synallaxini with strong support. Synallaxis propinqua is sister to Schoeniophylax phryganophilus, and together they form a clade with Certhiaxis. The results are robust to analytical approaches when all genomic regions are analyzed jointly (parsimony, maximum likelihood, and species-tree analysis) and the same basal relationships are recovered by most genomic regions when analyzed separately. A sister relationship between S. propinqua, an Amazonian river island specialist, and S. phryganophilus, from the Paraná River basin region, reveals a new biogeographic pattern shared by at least other four pairs of taxa with similar distributions and ecologies. Estimates of divergence times for these five pairs span from the late Miocene to the Pleistocene. Identification of the historical events that produced this pattern is difficult and further advances will require additional studies of the taxa involved and a better understanding of the recent environmental history of South America. A new classification is proposed for the Synallaxini, including the description of a new genus for S. propinqua. Copyright © 2014 Elsevier Inc. All rights reserved.

Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate

NASA Astrophysics Data System (ADS)

Quesada, C. A.; Phillips, O. L.; Schwarz, M.; Czimczik, C. I.; Baker, T. R.; Patiño, S.; Fyllas, N. M.; Hodnett, M. G.; Herrera, R.; Almeida, S.; Alvarez Dávila, E.; Arneth, A.; Arroyo, L.; Chao, K. J.; Dezzeo, N.; Erwin, T.; di Fiore, A.; Higuchi, N.; Honorio Coronado, E.; Jimenez, E. M.; Killeen, T.; Lezama, A. T.; Lloyd, G.; López-González, G.; Luizão, F. J.; Malhi, Y.; Monteagudo, A.; Neill, D. A.; Núñez Vargas, P.; Paiva, R.; Peacock, J.; Peñuela, M. C.; Peña Cruz, A.; Pitman, N.; Priante Filho, N.; Prieto, A.; Ramírez, H.; Rudas, A.; Salomão, R.; Santos, A. J. B.; Schmerler, J.; Silva, N.; Silveira, M.; Vásquez, R.; Vieira, I.; Terborgh, J.; Lloyd, J.

2012-06-01

Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the interacting effects of soil physical and chemical properties with climate. A hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining endogenous disturbance levels, species composition, and forest productivity across the Amazon Basin.

Using an Expedition Storyline, Baseline Data, Multiple Partnerships and a Varied Outreach Strategy to Engage Diverse Audiences in Geoscience Discourse: A Case Study on the Rio Maranon, Peru

NASA Astrophysics Data System (ADS)

Hill, A. F.; Goode, J. R.; Kramer, N. R.

2016-12-01

Growing energy demands in mountain regions motivate hydropower development on remote rivers previously not pursued due to difficult access and challenging terrain. These same physical factors have in part resulted in a dearth of data needed to understand these important water resources and the river systems as a whole. Resource management decisions not founded on data-driven science can not evaluate river system sustainability; decisions regarding the fate of globally important environmental resources without public awareness and discourse are missed opportunities to leverage international perspectives and lessons learned on the process. In the summer of 2015, we launched a 620 km, 30-day river expedition on the headwater stem of the Amazon River, Peru's Rio Maranon, to collect a baseline dataset as a start to filling this data gap on this river under threat from major hydropower development. We conducted a longitudinal characterization from Rio Maranon's Peruvian Andes headwaters to its lower lying Amazon jungle basin including continuous data collection on water quality, source water isotopes and invertebrate samples. A central focus of this project included outreach to broad audiences for public awareness and conservation advocacy of this critical river corridor at risk of imminent disconnection across ecosystems from dams. Outreach strategies were multi-pronged to encompass different audiences, including: a short-format documentary film, publicly available online data, oral presentations, magazine articles, blog posts and a science-education childrens' book highlighting both the adventure of the expedition and the female-dominated science team. Initiating non-traditional partnerships has been a key component of the project success given the minimal budget, including continuing partnerships with National Geographic, the Natural History Museum of Peru, Adventurers for Science and Conservation, Sierra Rios recreational river outfitter, Maranon Waterkeeper and the Centro de Capacitación en Conservación y Desarrollo Sostenible (CDS). Our diverse outreach approach illustrates the potential for using basic datasets to ignite - and partnerships to facilitate - geoscience communication and environmental education, especially in the context of multi-faceted natural resource issues.

Scanning proton microprobe applied to analysis of individual aerosol particles from Amazon Basin

NASA Astrophysics Data System (ADS)

Gerab, Fábio; Artaxo, Paulo; Swietlicki, Erik; Pallon, Jan

1998-03-01

The development of the Scanning Proton Microprobe (SPM) offers a new possibility for individual aerosol particle studies. The SPM joins Particle Induced X-ray Emission (PIXE) elemental analysis qualities with micrometric spatial resolution. In this work the Lund University SPM facility was used for elemental characterization of individual aerosol particles emitted to the atmosphere in the Brazilian Amazon Basin, during gold mining activities by the so-called "gold shops".

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin

PubMed Central

Palermo, Pedro M.; Aguilar, Patricia V.; Sanchez, Juan F.; Zorrilla, Víctor; Flores-Mendoza, Carmen; Huayanay, Anibal; Guevara, Carolina; Lescano, Andrés G.; Halsey, Eric S.

2016-01-01

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrome b gene. Psorophora (Janthinosoma) albigenu, Psorophora (Grabhamia) cingulata, Mansonia humeralis, Anopheles oswaldoi s.l., and Anopheles benarrochi s.l. had mainly anthropophilic feeding preferences; Aedes (Ochlerotatus) serratus, and Aedes (Ochlerotatus) fulvus had feeding preferences for peridomestic animals; and Culex (Melanoconion) spp. fed on a variety of vertebrates, mainly rodents (spiny rats), birds, and amphibians. On the basis of these feeding preferences, many mosquitoes could be considered as potential enzootic and bridge arbovirus vectors in the Amazon Basin of Peru. PMID:27621304

Interannual rainfall variability in the Amazon basin and sea-surface temperatures in the equatorial Pacific and the tropical Atlantic Oceans

NASA Astrophysics Data System (ADS)

Ronchail, Josyane; Cochonneau, Gérard; Molinier, Michel; Guyot, Jean-Loup; Chaves, Adriana Goretti De Miranda; Guimarães, Valdemar; de Oliveira, Eurides

2002-11-01

Rainfall variability in the Amazon basin is studied in relation to sea-surface temperatures (SSTs) in the equatorial Pacific and the northern and southern tropical Atlantic during the 1977-99 period, using the HiBAm original rainfall data set and complementary cluster and composite analyses.The northeastern part of the basin, north of 5 °S and east of 60 °W, is significantly related with tropical SSTs: a rainier wet season is observed when the equatorial Pacific and the northern (southern) tropical Atlantic are anomalously cold (warm). A shorter and drier wet season is observed during El Niño events and negative rainfall anomalies are also significantly associated with a warm northern Atlantic in the austral autumn and a cold southern Atlantic in the spring. The northeastern Amazon rainfall anomalies are closely related with El Niño-southern oscillation during the whole year, whereas the relationships with the tropical Atlantic SST anomalies are mainly observed during the autumn. A time-space continuity is observed between El Niño-related rainfall anomalies in the northeastern Amazon, those in the northern Amazon and south-eastern Amazon, and those in northern South America and in the Nordeste of Brazil.A reinforcement of certain rainfall anomalies is observed when specific oceanic events combine. For instance, when El Niño and cold SSTs in the southern Atlantic are associated, very strong negative anomalies are observed in the whole northern Amazon basin. Nonetheless, the comparison of the cluster and the composite analyses results shows that the rainfall anomalies in the northeastern Amazon are not always associated with tropical SST anomalies.In the southern and western Amazon, significant tropical SST-related rainfall anomalies are very few and spatially variable. The precipitation origins differ from those of the northeastern Amazon: land temperature variability, extratropical perturbations and moisture advection are important rainfall factors, as well as SSTs. This could partially explain why: (a) the above-mentioned signals weaken or disappear, with the exception of the relative dryness that is observed at the peak of an El Niño event and during the dry season when northern Atlantic SSTs are warmer than usual; (b) rainfall anomalies tend to resemble those of southeastern South America, noticeably at the beginning and the end of El Niño and La Niña events; (c) some strong excesses of rain are not associated with any SST anomalies and merit further investigation.

The Impact of Rise of the Andes and Amazon Landscape Evolution on Diversification of Lowland terra-firme Forest Birds

NASA Technical Reports Server (NTRS)

Aleixo, Alexandre; Wilkinson, M. Justin

2011-01-01

Since the 19th Century, the unmatched biological diversity of Amazonia has stimulated a diverse set of hypotheses accounting for patterns of species diversity and distribution in mega-diverse tropical environments. Unfortunately, the evidence supporting particular hypotheses to date is at best described as ambiguous, and no generalizations have emerged yet, mostly due to the lack of comprehensive comparative phylogeographic studies with thorough trans-Amazonian sampling of lineages. Here we report on spatial and temporal patterns of diversification estimated from mitochondrial gene trees for 31 lineages of birds associated with upland terra-firme forest, the dominant habitat in modern lowland Amazonia. The results confirm the pervasive role of Amazonian rivers as primary barriers separating sister lineages of birds, and a protracted spatio-temporal pattern of diversification, with a gradual reduction of earlier (1st and 2nd) and older (> 2 mya) splits associated with each lineage in an eastward direction. (The easternmost tributaries of the Amazon, the Xingu and Tocantins Rivers, are not associated with any splits older than > 2 mya). For the suboscine passerines, maximum-likelihood estimates of rates of diversification point to an overall constant rate over the past 5 my (up to a significant downturn at 300,000 y ago). This "younging-eastward" pattern may have an abiotic explanation related to landscape evolution. Triggered by a new pulse of Andean uplift, it has been proposed that modern Amazon basin landscapes may have evolved successively eastward, away from the mountain chain, starting approximately 10 mya. This process was likely based on the deposition of vast fluvial sediment masses, known as megafans, that may have extended progressively and in series eastward from Andean sources. This process plausibly explains the progressive extinction of original Pebas wetland of western-central Amazonia by the present fluvial landsurfaces of a more terra-firme type. The youngest landsurfaces thus lie furthest from the mountains. In this scenario major drainages were also reoriented in wholesale fashion away from a northerly orientation generally towards the east and an Atlantic Ocean outlet. The advance of megafans is best seen by the location of axial rivers such as the Orinoco and Mamore which lie against the cratonic margins furthest from the Andes, at the distal ends of major megafan ramparts. More importantly, other major river courses in western-central Amazonia will have been established at progressively younger dates with distance eastward. If this landscape-sequence scenario is accurate, it parallels the progressive younging of the passerine lineages. The bird DNA data appears to confirm strongly the pervasive role of Amazonian rivers--as primary barriers separating sister lineages of birds, and thus probably as facilitaters of bird speciation. We show for the first time that a general spatio-temporal pattern of diversification for terra-firme lineages in the Amazon is associated with rivers ("younging-eastward"), and furthermore parallels a specific scenario of regional drainage evolution.

Mercury in fish of the Madeira river (temporal and spatial assessment), Brazilian Amazon.

PubMed

Bastos, Wanderley R; Dórea, José G; Bernardi, José Vicente E; Lauthartte, Leidiane C; Mussy, Marilia H; Lacerda, Luiz D; Malm, Olaf

2015-07-01

The Madeira River is the largest tributary of the Amazon River Basin and one of the most impacted by artisanal gold-mining activities, deforestation for agricultural projects, and recent hydroelectric reservoirs. Total Hg (and methylmercury-MeHg) concentrations was determined in 3182 fish samples of 84 species from different trophic levels as a function of standard size. Species at the top of the trophic level (Piscivorous, Carnivorous) showed the highest mean total Hg concentrations (51-1242 µg/kg), Planctivorous and Omnivorous species showed intermediate total Hg concentrations (26-494 µg/kg), while Detritivorous and Herbivorous species showed the lowest range of mean total Hg concentrations (9-275 µg/kg). Significant correlations between fish size (standard length) and total Hg concentrations were seen for Planctivorous (r=0.474, p=0.0001), Piscivorous (r=0.459, p=0.0001), Detritivorous (r=0.227, p=0.0001), Carnivorous (r=0.212, p=0.0001), and Herbivorous (r=0.156, p=0.01), but not for the Omnivorous species (r=-0.064, p=0.0685). Moreover, fish trophic levels influenced the ratio of MeHg to total Hg (ranged from 70% to 92%). When adjusted for standard body length, significant increases in Hg concentrations in the last 10 years were species specific. Spatial differences, albeit significant for some species, were not consistent with time trends for environmental contamination from past alluvial gold mining activities. Fish-Hg bioaccumulation is species specific but fish feeding strategies are the predominant influence in the fish-Hg bioaccumulation pattern. Copyright © 2015 Elsevier Inc. All rights reserved.

The impact of channel capture on estuarine hydro-morphodynamics and water quality in the Amazon delta.

PubMed

Silva Dos Santos, Eldo; Pinheiro Lopes, Paula Patrícia; da Silva Pereira, Hyrla Herondina; de Oliveira Nascimento, Otávio; Rennie, Colin David; da Silveira Lobo O'Reilly Sternberg, Leonel; Cavalcanti da Cunha, Alan

2018-05-15

Due to progressive erosion of the new Urucurituba Channel, the Amazon River has recently captured almost all discharge from the lower Araguari River (Amapá-AP, Brazil), which previously flowed directly to the Atlantic Ocean. These recent geomorphological changes have caused strong impacts on the landscape and hydrodynamic patterns near the Araguari River mouth, especially the alteration of the riverine drainage system and its water quality. Landsat images were used to assess the estuarine landscape morphodynamic, particularly the expansion of the Urucurituba Channel, 80km from the Araguari River mouth, chronicling its connection to the Amazon River. The results suggest that the Urucurituba developed by headward migration across the Amazon delta; this is perhaps the first observation of estuarine distributary network development by headward channel erosion. The rate of Urucurituba Channel width increase has been ≈5m/month since 2011, increasing drainage capacity of the channel. We also collected in situ hydrodynamic measurements and analyzed 17 water quality parameters. Having 2011 as baseline, the flowrate of Araguari River has been diverted by up to 98% through Urucurituba Channel, with substantial changes in net discharge recorded at 3 monitoring stations. Statistically significant differences in water quality (p<0.05) were observed between 2011 and 2015, associated with the change in the flow pattern. Estuarine salinity and solids concentrations have increased. Overall, we demonstrate changes in landscape, hydrodynamics and water quality of the lower Araguari River. Copyright © 2017 Elsevier B.V. All rights reserved.

On the offshore dispersal of the Amazon's Plume in the North Atlantic: Comments on the paper by A. Longhurst, ``Seasonal cooling and blooming in tropical oceans''

NASA Astrophysics Data System (ADS)

Muller-Karger, F. E.; Richardson, P. L.; Mcgillicuddy, D.

1995-11-01

Coastal Zone Color Scanner (CZCS) satellite images show extensive plumes of discolored water extending from South America into the western tropical Atlantic. The most conspicuous plumes originate at the mouths of the Amazon and Orinoco Rivers, and plumes originating at smaller rivers can also be seen from space. In a recent paper by Longhurst (1993), the plume associated with the Amazon River was attributed to phytoplankton blooms stimulated by nutrients supplied via eddy upwelling. We revisit the argument that this plume is of riverine origin, and offer evidence that material present near continental margins can be advected offshore and trace circulation patterns in the adjacent ocean.

DoD Global Emerging Infections System Annual Report, Fiscal Year 2000

DTIC Science & Technology

2000-01-01

partners in Peru , Bolivia, and Suriname and was conducted largely under the supervision of a CDC officer assigned to NMRCD. Surveillance in the Amazon ...pyrimethamine on the north coast of Peru . In the Amazon basin, resistance to both chloroquine and sulfadoxine-pyrimethamine is noted in the central Amazon ...the north coast and in the Amazon region, respectively.As a result of this work, Peru now has better and more up-to-date information on antimalarial

DNA Metabarcoding of Amazonian Ichthyoplankton Swarms.

PubMed

Maggia, M E; Vigouroux, Y; Renno, J F; Duponchelle, F; Desmarais, E; Nunez, J; García-Dávila, C; Carvajal-Vallejos, F M; Paradis, E; Martin, J F; Mariac, C

2017-01-01

Tropical rainforests harbor extraordinary biodiversity. The Amazon basin is thought to hold 30% of all river fish species in the world. Information about the ecology, reproduction, and recruitment of most species is still lacking, thus hampering fisheries management and successful conservation strategies. One of the key understudied issues in the study of population dynamics is recruitment. Fish larval ecology in tropical biomes is still in its infancy owing to identification difficulties. Molecular techniques are very promising tools for the identification of larvae at the species level. However, one of their limits is obtaining individual sequences with large samples of larvae. To facilitate this task, we developed a new method based on the massive parallel sequencing capability of next generation sequencing (NGS) coupled with hybridization capture. We focused on the mitochondrial marker cytochrome oxidase I (COI). The results obtained using the new method were compared with individual larval sequencing. We validated the ability of the method to identify Amazonian catfish larvae at the species level and to estimate the relative abundance of species in batches of larvae. Finally, we applied the method and provided evidence for strong temporal variation in reproductive activity of catfish species in the Ucayalí River in the Peruvian Amazon. This new time and cost effective method enables the acquisition of large datasets, paving the way for a finer understanding of reproductive dynamics and recruitment patterns of tropical fish species, with major implications for fisheries management and conservation.

Floodplain ecosystem processes

NASA Astrophysics Data System (ADS)

Melack, John M.; Novo, Evlyn M. L. M.; Forsberg, Bruce R.; Piedade, Maria T. F.; Maurice, Laurence

Floodplains represent a major component of the central Amazon Basin and influence the hydrology, ecology, and biogeochemistry. Hess et al. (2003) used a classification of synthetic aperture radar data with 100 m resolution for a 1.77 million km2 quadrat in central Amazonia and identified 17% as wetland most of which was inundated a portion of each year. Total net production attributed to flooded forests (excluding wood increments), aquatic macrophytes, phytoplankton, and periphyton for the 1.77 million km2 quadrat was estimated to be about 300 Tg C a-1. Flooded forests accounted for 62% of the total, aquatic macrophytes accounted for 34%, and the remaining 4% was associated with periphyton and phytoplankton. Approximately 10% of the total is the amount of organic carbon exported annually by the Amazon River according to Richey et al. (1990), methane emission is about 2.5% according to Melack et al. (2004), and a similar percent is estimated to be buried in sediments. The remaining portion is close to being sufficient to fuel the respiration that results in the degassing of 210 ± 60 Tg C a-1 as carbon dioxide from the rivers and floodplains according to Richey et al. (2002). Variations in the distribution and inundation of floodplain habitats play a key role in the ecology and production of many commercially important freshwater fish. A significant relationship exists between maximum inundated area lagged by 5 years and annual yield of omnivores.

Co-variability of smoke and fire in the Amazon basin

NASA Astrophysics Data System (ADS)

Mishra, Amit Kumar; Lehahn, Yoav; Rudich, Yinon; Koren, Ilan

2015-05-01

The Amazon basin is a hot spot of anthropogenically-driven biomass burning, accounting for approximately 15% of total global fire emissions. It is essential to accurately measure these fires for robust regional and global modeling of key environmental processes. Here we have explored the link between spatio-temporal variability patterns in the Amazon basin's fires and the resulting smoke loading using 11 years (2002-2012) of data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET) observations. Focusing on the peak burning season (July-October), our analysis shows strong inter-annual correlation between aerosol optical depth (AOD) and two MODIS fire products: fire radiative power (FRP) and fire pixel counts (FC). Among these two fire products, the FC better indicates the amount of smoke in the basin, as represented in remotely sensed AOD data. This fire product is significantly correlated both with regional AOD retrievals from MODIS and with point AOD measurements from the AERONET stations, pointing to spatial homogenization of the smoke over the basin on a seasonal time scale. However, MODIS AODs are found better than AERONET AODs observation for linking between smoke and fire. Furthermore, MODIS AOD measurements are strongly correlated with number of fires ∼10-20 to the east, most likely due to westward advection of smoke by the wind. These results can be rationalized by the regional topography and the wind regimes. Our analysis can improve data assimilation of satellite and ground-based observations into regional and global model studies, thus improving the assessment of the environmental and climatic impacts of frequency and distribution variability of the Amazon basin's fires. We also provide the optimal spatial and temporal scales for ground-based observations, which could be used for such applications.

Mercury and selenium in fishes from the Tapajós River in the Brazilian Amazon: An evaluation of human exposure.

PubMed

Lino, A S; Kasper, D; Guida, Y S; Thomaz, J R; Malm, O

2018-07-01

This work aimed to evaluate associated risks of fish consumption to human health, concerning mercury (Hg) and selenium (Se) concentrations in fish species largely consumed in the Tapajós River basin in the Brazilian Amazon. Total mercury (THg), methylmercury (MeHg) and Se concentrations were measured in 129 fish specimens from four sites of the Tapajós River basin. Estimated daily intake (EDI) of Hg and Se were reported regarding fish consumption. EDI were compared with the reference value of provisional tolerable daily intake proposed by the World Health Organization (WHO). Se:Hg ratios and selenium health benefit values (Se HBVs) seem to offer a more comprehensive fish safety model. THg concentrations in fishes ranged from 0.03 to 1.51 μg g -1 of wet weight (w.w.) and MeHg concentrations ranged from 0.02 to 1.44 μg g -1 (w.w.). 80% of the samples were below the value of Hg recommended by the WHO for human consumption (0.5 μg g -1 w.w.). However, Hg EDI exceeded the dose suggested by the United States Environmental Protection Agency (0.1 μg kg -1  day -1 ), due to the large level of fish consumption in that area. Se concentrations in fishes ranged from 0.02 to 0.44 μg g -1 w.w. An inverse pattern was observed between Hg and Se concentrations in the trophic chain (highest levels of Se in the lowest trophic levels). The molar ratio Se:Hg and Se HBVs were higher in iliophagous and herbivorous fishes, which is noteworthy to reduce toxic effects of Hg contamination. For planktivores, the content of Se and Hg was almost equimolar. Carnivorous fishes - with the exception of Hemisorubim platyrhynchos and Pseudoplatystoma fasciatum -, showed Se:Hg ratios <1. Thus, they do not act as a favorable source of Se in the diet. Therefore, reduced intake of carnivorous fishes with preferential consumption of iliophages, herbivores and, to some extent, even planktivores should be promoted as part of a healthier diet. Copyright © 2018 Elsevier GmbH. All rights reserved.

The Amazon Boundary Layer Experiment (ABLE 2A) - Dry season 1985

NASA Technical Reports Server (NTRS)

Harriss, R. C.; Browell, E. V.; Hoell, J. M., Jr.; Bendura, R. J.; Beck, S. M.; Wofsy, S. C.; Mcneal, R. J.; Navarro, R. L.; Riley, J. T.; Snell, R. L.

1988-01-01

The Amazon Boundary Layer Experiment (ABLE 2A) used data from aircraft, ground-based, and satellite platforms to characterize the chemistry and dynamics of the lower atmosphere over the Amazon Basin during the early-to-middle dry season, July and August 1985. This paper reports the conceptual framework and experimental approach used in ABLE 2A and serves as an introduction to the detailed papers which follow in this issue. The results of ABLE 2A demonstrate that isoprene, methane, carbon dioxide, nitric oxide, dimethylsulfide, and organic aerosol emissions from soils and vegetation play a major role in determining the chemical composition of the atmospheric mixed layer over undisturbed forest and wetland environments. As the dry season progresses, emissions from both local and distant biomass burning become an important source of carbon monoxide, nitric oxide and ozone in the atmosphere over the central Amazon Basin.

Global Overview On Delivery Of Sediment To The Coast From Tropical River Basins

NASA Astrophysics Data System (ADS)

Syvitski, J. P.; Kettner, A. J.; Brakenridge, G. R.

2011-12-01

Depending on definition, the tropics occupy between 16% and 19% of the earth's land surface, and discharge ~18.5% of the earth's fluvial water runoff. These flow regimes are driven by three types of sub-regional climate: rainforest, monsoon, and savannah. Even though the tropics include extreme precipitation events, particularly for the SE Asian islands, the general rainfall pattern alternates between wet and dry seasons as the ITCZ follows the sun and where annual monsoonal rain occurs. ITCZ convective rainfall is the dominant style of precipitation but this can be influenced by rare intra-tropical cyclone events, and by atmospheric river events set up by strong monsoonal conditions. Though a rainy season is normal (for example, portions of India discharge in summer may reach 50 times that of winter), the actual rainfall events are in the form of short bursts of precipitation (hours to days) separated by periods of dry (hours to weeks). Some areas of the tropics receive more than 100 thunderstorms per year. Rivers respond to this punctuated weather by seasonal flooding. For the smaller island nations and locales (e.g. Indonesia, Philippines, Borneo, Hainan, PNG, Madagascar, Hawaii, Taiwan) flash floods are common. Larger tropical river systems (Niger, Ganges, Brahmaputra, Congo, Amazon, Orinoco, Magdalena) show typical seasonally modulated discharges. The sediment flux from tropical rivers is approximately 17% to 19% of the global total - however individual river basins offer a wide range in sediment yields reflecting highly variable differences in their hinterland lithology, tectonic activity and volcanism, land-sliding, and relief. Human influences also greatly influence the range for tropical river sediment yield. Some SE Asian Rivers continue to be greatly affected by deforestation, road construction, and monoculture plantations. Sediment flux is more than twice the pre-Anthropocene flux in many of these SE Asian countries, especially where dams and reservoir emplacements do not impact sediment delivery, as is the case in most temperate regions.

The silicon isotopic composition of fine-grained river sediments and its relation to climate and lithology

NASA Astrophysics Data System (ADS)

Bayon, G.; Delvigne, C.; Ponzevera, E.; Borges, A. V.; Darchambeau, F.; De Deckker, P.; Lambert, T.; Monin, L.; Toucanne, S.; André, L.

2018-05-01

The δ30Si stable isotopic composition of silicon in soils and fine-grained sediments can provide insights into weathering processes on continents, with important implications on the Si budget of modern and past oceans. To further constrain the factors controlling the distribution of Si isotopes in sediments, we have analysed a large number (n = 50) of separate size-fractions of sediments and suspended particulate materials collected near the mouth of rivers worldwide. This includes some of the world's largest rivers (e.g. Amazon, Congo, Mackenzie, Mississippi, Murray-Darling, Nile, Yangtze) and rivers from the case study areas of the Congo River Basin and Northern Ireland. Silt-size fractions exhibit a mean Si isotopic composition (δ30Si = -0.21 ± 0.19‰; 2 s.d.) similar to that previously inferred for the upper continental crust. In contrast, clay-size fractions display a much larger range of δ30Si values from -0.11‰ to -2.16‰, which yield a global δ30Siclay of -0.57 ± 0.60‰ (2 s.d.) representative of the mean composition of the average weathered continental crust. Overall, these new data show that the Si isotopic signature transported by river clays is controlled by the degree of chemical weathering, as inferred from strong relationships with Al/Si ratios. At a global scale, the clay-bound Si isotopic composition of the world's largest river systems demonstrates a link with climate, defining a general correlation with mean annual temperature (MAT) in corresponding drainage basins. While the distribution of Si isotopes in river sediments also appears to be influenced by the tectonic setting, lithological effects and sediment recycling from former sedimentary cycles, our results pave the way for their use as paleo-weathering and paleo-climate proxies in the sedimentary record.

Satellite-based Analysis of CO Variability over the Amazon Basin

NASA Astrophysics Data System (ADS)

Deeter, M. N.; Emmons, L. K.; Martinez-Alonso, S.; Tilmes, S.; Wiedinmyer, C.

2017-12-01

Pyrogenic emissions from the Amazon Basin exert significant influence on both climate and air quality but are highly variable from year to year. The ability of models to simulate the impact of biomass burning emissions on downstream atmospheric concentrations depends on (1) the quality of surface flux estimates (i.e., emissions inventories), (2) model dynamics (e.g., horizontal winds, large-scale convection and mixing) and (3) the representation of atmospheric chemical processes. With an atmospheric lifetime of a few months, carbon monoxide (CO) is a commonly used diagnostic for biomass burning. CO products are available from several satellite instruments and allow analyses of CO variability over extended regions such as the Amazon Basin with useful spatial and temporal sampling characteristics. The MOPITT ('Measurements of Pollution in the Troposphere') instrument was launched on the NASA Terra platform near the end of 1999 and is still operational. MOPITT is uniquely capable of measuring tropospheric CO concentrations using both thermal-infrared and near-infrared observations, resulting in the ability to independently retrieve lower- and upper-troposphere CO concentrations. We exploit the 18-year MOPITT record and related datasets to analyze the variability of CO over the Amazon Basin and evaluate simulations performed with the CAM-chem chemical transport model. We demonstrate that observed differences between MOPITT observations and model simulations provide important clues regarding emissions inventories, convective mixing and long-range transport.

Hepatitis B infection control in Colombian Amazon after 15 years of hepatitis B vaccination. Effectiveness of birth dose and current prevalence.

PubMed

Garcia, Diego; Porras, Alexandra; Rico Mendoza, Alejadro; Alvis, Nelson; Navas, Maria Cristina; De La Hoz, Fernando; De Neira, Marlen; Osorio, Elkin; Valderrama, José Fernando

2018-05-03

Hepatitis B virus (HBV) infection is highly endemic in the Colombian Amazon basin. In Colombia, the universal hepatitis B vaccination in that area has been active since 1993. The program targets children aged under five years. Newborns receive at least three doses, and in 2001, HBV vaccine birth dose was included. This study aimed to evaluate the advances on HBV control in the Colombian Amazon. A population-based cross-sectional study was conducted in children less than 11 years old in rural areas of the Colombian Amazon, in order to assess the current levels of HBV prevalence and evaluate the effectiveness of HBV vaccination. Participants were selected from villages scattered along the Amazon, Putumayo and Loretoyaco Rivers. Blood samples were taken from children. All the samples were examined for surface antigen (HBsAg) and IgG antibodies against core antigen (AntiHBc) of HBV. Data on HBV vaccination status and other risk factors were also collected. Blood samples from 1275 children were included in the study. The positivity for IgG AntiHBC and HBsAg was 3.8% and 0.5%, respectively. It was observed that receiving a dose of HBV vaccine within 48 h after birth decreased the risk of HBV infection and carriage by 95%. Being born to an AntiHBc positive mother increased 8 times the risk of HBV infection (OR = 7.8 CI 95% 3.3-10.2) and 7 times the risk of HBsAg carriage (OR = 6.6 CI 95% 2.1-10.1). The prevalence of HBV infection and HBsAg carriage continues to decrease among children living in the Colombian Amazon. The high protective effectiveness of an HBV birth does suggest that perinatal transmission is important in endemic areas of Latin America, an aspect that has not been fully studied in the region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aquatic Biodiversity in the Amazon: Habitat Specialization and Geographic Isolation Promote Species Richness

PubMed Central

Albert, James S.; Carvalho, Tiago P.; Petry, Paulo; Holder, Meghan A.; Maxime, Emmanuel L.; Espino, Jessica; Corahua, Isabel; Quispe, Roberto; Rengifo, Blanca; Ortega, Hernan; Reis, Roberto E.

2011-01-01

Simple Summary The immense rainforest ecosystems of tropical America represent some of the greatest concentrations of biodiversity on the planet. Prominent among these are evolutionary radiations of freshwater fishes, including electric eels, piranhas, stingrays, and a myriad of small-bodied and colorful tetras, cichlids, and armored catfishes. In all, the many thousands of these forms account for nearly 10% of all the vertebrate species on Earth. This article explores the complimentary roles that ecological and geographic filters play in limiting dispersal in aquatic species, and how these factors contribute to the accumulation of species richness over broad geographic and evolutionary time scales. Abstract The Neotropical freshwater ichthyofauna has among the highest species richness and density of any vertebrate fauna on Earth, with more than 5,600 species compressed into less than 12% of the world's land surface area, and less than 0.002% of the world's total liquid water supply. How have so many species come to co-exist in such a small amount of total habitat space? Here we report results of an aquatic faunal survey of the Fitzcarrald region in southeastern Peru, an area of low-elevation upland (200–500 m above sea level) rainforest in the Western Amazon, that straddles the headwaters of four large Amazonian tributaries; the Juruá (Yurúa), Ucayali, Purús, and Madre de Dios rivers. All measures of fish species diversity in this region are high; there is high alpha diversity with many species coexisting in the same locality, high beta diversity with high turnover between habitats, and high gamma diversity with high turnover between adjacent tributary basins. Current data show little species endemism, and no known examples of sympatric sister species, within the Fitzcarrald region, suggesting a lack of localized or recent adaptive divergences. These results support the hypothesis that the fish species of the Fitzcarrald region are relatively ancient, predating the Late Miocene-Pliocene (c. 4 Ma) uplift that isolated its several headwater basins. The results also suggest that habitat specialization (phylogenetic niche conservatism) and geographic isolation (dispersal limitation) have contributed to the maintenance of high species richness in this region of the Amazon Basin. PMID:26486313

Strategies for detection of floodplain inundation with multi-frequency polarimetric SAR

NASA Technical Reports Server (NTRS)

Hess, Laura L.; Melack, John M.

1992-01-01

Mapping of floodplain inundation patterns is a key element in developing hydrological and biogeochemical models for large tropical river basins such as the Amazon. Knowledge of the time sequence of inundation is necessary to determine both water routing and biogenic gas fluxes. Synthetic Aperture Radar (SAR) is uniquely suited for this application because of its ability to penetrate cloud cover and, in many cases, to detect flooding beneath a forest or herbaceous canopy. A procedure for discriminating flooded forest, flooded herbaceous vegetation, and open water from other cover types for a coastal wetland site on the lower Altamaha floodplain, Georgia, emphasizing robust classifiers that are not site-specific is currently being developed.

Lobomycosis in Colombian Amer Indian patients.

PubMed

Rodríguez-Toro, G; Tellez, N

1992-10-01

Several foci of lobomycosis among Colombian Amer Indians population were described in the Casanare region of Colombia, near the Orinoco river on the Colombian-Venezuelan border. This paper reports 16 new patients. The prevalence of Lobo's disease was 8.5% in the Amoruas tribe. Nodular lesions were located on the elbow, scapular and lumbar regions, knees, feet and legs. Leg lesions were especially numerous, were confluent and tended to ulcerate. All cases were confirmed histologically. Two Negro patients were also described. The cases bring the total number of confirmed patients with lobomycosis in Colombia to 41. Twenty-five of these were Amer Indian patients from tribes living in the Orinoco and Amazon basins of the country.

Bacterial Biogeography across the Amazon River-Ocean Continuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ~675 km of the lower Amazon River mainstem, in the Tapajos River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitionalmore » assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity nearshore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.« less

Bacterial Biogeography across the Amazon River-Ocean Continuum.

PubMed

Doherty, Mary; Yager, Patricia L; Moran, Mary Ann; Coles, Victoria J; Fortunato, Caroline S; Krusche, Alex V; Medeiros, Patricia M; Payet, Jérôme P; Richey, Jeffrey E; Satinsky, Brandon M; Sawakuchi, Henrique O; Ward, Nicholas D; Crump, Byron C

2017-01-01

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.

Bacterial Biogeography across the Amazon River-Ocean Continuum

DOE PAGES

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann; ...

2017-05-23

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ~675 km of the lower Amazon River mainstem, in the Tapajos River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitionalmore » assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity nearshore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.« less

Bacterial Biogeography across the Amazon River-Ocean Continuum

PubMed Central

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann; Coles, Victoria J.; Fortunato, Caroline S.; Krusche, Alex V.; Medeiros, Patricia M.; Payet, Jérôme P.; Richey, Jeffrey E.; Satinsky, Brandon M.; Sawakuchi, Henrique O.; Ward, Nicholas D.; Crump, Byron C.

2017-01-01

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2–2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum. PMID:28588561

River logjams cause frequent large-scale forest die-off events in southwestern Amazonia

NASA Astrophysics Data System (ADS)

Lombardo, Umberto

2017-07-01

This paper investigates the dynamics of logjam-induced floods and alluvial deposition in the Bolivian Amazon and the effects these have on forest disturbance and recovery cycles. It expands on previous work by Gullison et al. (1996) who reported a case of catastrophic floods triggered by logjams in the Chimane Forest in the Bolivian Amazon. No further studies have followed up on this observation and no research has been published on the effects of large wood in tropical lowland rivers. The study is based on the analysis of a time series of Landsat imagery (1984-2016) and field evidence. Results show that logjam-induced floods are a major driver of forest disturbance along the Andean piedmont in the Bolivian Amazon. New logjams form on an almost yearly basis, always further upriver, until an avulsion takes place. Logjam-induced floods are characterized here by the sudden deposition of a thick sand layer and the death of forest in a V-shaped area. The Bolivian Amazon offers a unique opportunity for further research on how large wood affects river behavior in lowland tropical settings and how large and frequent forest disturbance events resulting from river logjams affect forest biodiversity and community successions.

Suspended sediments of the modern Amazon and Orinoco rivers

USGS Publications Warehouse

Meade, R.H.

1994-01-01

The Amazon and Orinoco Rivers are massive transcontinental conveyance systems for suspended sediment. They derive about 90% of their sediment from the Andes that support their western headwaters, transport it for thousands of kilometers across the breadth of the continent and deposit it in the coastal zones of the Atlantic. At their points of maximum suspended-sediment discharge, the Amazon transports an average of 1100-1300 ?? 106 tons per year and the Orinoco transports about 150 ?? 106 tons per year. Relations of sediment discharge to water discharge are complicated by unusual patterns of seasonal storage and remobilization, increased storage and reduced transport of sediment in the middle Orinoco during periods of peak water discharge, and storage of suspended sediment in the lower Amazon during rising discharge and resuspension during falling discharge. Spatial distributions of suspended sediment in cross-sections of both rivers are typically heterogeneous, not only in the vertical sense but also in the lateral. The cross-channel mixing of tributary inputs into the mainstem waters is a slow process that requires several hundred kilometers of downriver transport to complete. Considerable fine-grained sediment is exchanged between rivers and floodplains by the combination of overbank deposition and bank erosion. ?? 1994.

Virioplankton Assemblage Structure in the Lower River and Ocean Continuum of the Amazon.

PubMed

Silva, Bruno S de O; Coutinho, Felipe H; Gregoracci, Gustavo B; Leomil, Luciana; de Oliveira, Louisi S; Fróes, Adriana; Tschoeke, Diogo; Soares, Ana Carolina; Cabral, Anderson S; Ward, Nicholas D; Richey, Jeffrey E; Krusche, Alex V; Yager, Patricia L; de Rezende, Carlos Eduardo; Thompson, Cristiane C; Thompson, Fabiano L

2017-01-01

The Amazon River watershed and its associated plume comprise a vast continental and oceanic area. The microbial activities along this continuum contribute substantially to global carbon and nutrient cycling, and yet there is a dearth of information on the diversity, abundance, and possible roles of viruses in this globally important river. The aim of this study was to elucidate the diversity and structure of virus assemblages of the Amazon River-ocean continuum. Environmental viral DNA sequences were obtained for 12 locations along the river's lower reach ( n = 5) and plume ( n = 7). Sequence assembly yielded 29,358 scaffolds, encoding 82,546 viral proteins, with 15 new complete viral genomes. Despite the spatial connectivity mediated by the river, virome analyses and physical-chemical water parameters clearly distinguished river and plume ecosystems. Bacteriophages were ubiquitous in the continuum and were more abundant in the transition region. Eukaryotic viruses occurred mostly in the river, while the plume had more viruses of autotrophic organisms ( Prochlorococcus , Synechococcus ) and heterotrophic bacteria ( Pelagibacter ). The viral families Microviridae and Myoviridae were the most abundant and occurred throughout the continuum. The major functions of the genes in the continuum involved viral structures and life cycles, and viruses from plume locations and Tapajós River showed the highest levels of functional diversity. The distribution patterns of the viral assemblages were defined not only by the occurrence of possible hosts but also by water physical and chemical parameters, especially salinity. The findings presented here help to improve understanding of the possible roles of viruses in the organic matter cycle along the river-ocean continuum. IMPORTANCE The Amazon River forms a vast plume in the Atlantic Ocean that can extend for more than 1,000 km. Microbial communities promote a globally relevant carbon sink system in the plume. Despite the importance of viruses for the global carbon cycle, the diversity and the possible roles of viruses in the Amazon are poorly understood. The present work assesses, for the first time, the abundance and diversity of viruses simultaneously in the river and ocean in order to elucidate their possible roles. DNA sequence assembly yielded 29,358 scaffolds, encoding 82,546 viral proteins, with 15 new complete viral genomes from the 12 river and ocean locations. Viral diversity was clearly distinguished by river and ocean. Bacteriophages were the most abundant and occurred throughout the continuum. Viruses that infect eukaryotes were more abundant in the river, whereas phages appeared to have strong control over the host prokaryotic populations in the plume.

Trocara virus: a newly recognized Alphavirus (Togaviridae) isolated from mosquitoes in the Amazon Basin.

PubMed

Travassos da Rosa, A P; Turell, M J; Watts, D M; Powers, A M; Vasconcelos, P F; Jones, J W; Klein, T A; Dohm, D J; Shope, R E; Degallier, N; Popov, V L; Russell, K L; Weaver, S C; Guzman, H; Calampa, C; Brault, A C; Lemon, A P; Tesh, R B

2001-01-01

This report describes Trocara virus, a newly recognized member of the genus Alphavirus, that has been isolated from Aedes serratus mosquitoes collected at two widely separated sites in the Amazon Basin. Biological, antigenic and genetic characteristics of the new virus are given. Results of these studies indicate that Trocara virus is the first member of a newly discovered antigenic complex within the family Togaviridae genus Alphavirus. The public health and veterinary importance of Trocara virus is still unknown.

A River Model Intercomparison Project in Preparation for SWOT

NASA Astrophysics Data System (ADS)

David, C. H.; Andreadis, K.; Famiglietti, J. S.; Beighley, E.; Boone, A. A.; Yamazaki, D.; Paiva, R. C. D.; Fleischmann, A. S.; Collischonn, W.; Fisher, C. K.; Kim, H.; Biancamaria, S.

2017-12-01

The Surface Water and Ocean Topography (SWOT) mission is currently scheduled to launch at the beginning of next decade. SWOT is expected to retrieve unprecedented measurements of water extent, elevation, and slope in the largest terrestrial water bodies. Such potential transformative information motivates the investigation of our ability to ingest the associated data into continental-scale models of terrestrial hydrology. In preparation for the expected SWOT observations, an inter-comparison of continental-scale river models is being performed. This comparison experiment focuses on four of the world's largest river basins: the Amazon, the Mississippi, the Niger, and the Saint-Lawrence. This ongoing project focuses on two main research questions: 1) How can we best prepare for the expected SWOT continental to global measurements before SWOT even flies?, and 2) What is the added value of including SWOT terrestrial measurements into global hydro models for enhancing our understanding of the terrestrial water cycle and the climate system? We present here the results of the second year of this project which now includes simulations from six numerical models of rivers over the Mississippi and sheds light on the implications of various modeling choices on simulation quality as well as on the potential impact of SWOT observations.

Amazon river flow regime and flood recessional agriculture: Flood stage reversals and risk of annual crop loss

NASA Astrophysics Data System (ADS)

Coomes, Oliver T.; Lapointe, Michel; Templeton, Michael; List, Geneva

2016-08-01

The annual flood cycle is an important driver of ecosystem structure and function in large tropical rivers such as the Amazon. Riparian peasant communities rely on river fishing and annual floodplain agriculture, closely adapted to the recession phase of the flood pulse. This article reports on a poorly documented but important challenge facing farmers practicing flood recessional agriculture along the Amazon river: frequent, unpredictable stage reversals (repiquetes) which threaten to ruin crops growing on channel bars. We assess the severity of stage reversals for rice production on exposed river mud bars (barreales) near Iquitos, Peru. Crop loss risk is estimated based on a quantitative analysis of 45 years of daily Amazon stage data and field data from floodplain communities nearby in the Muyuy archipelago, upstream of Iquitos. Rice varieties selected, elevations of silt rich bars where rice is sown, as well as planting and harvest dates are analyzed in the light of the timing, frequencies and amplitudes of observed stage reversals that have the potential to destroy growing rice. We find that unpredictable stage reversals can produce substantial crop losses and shorten significantly the length of average growing seasons on lower elevation river bars. The data reveal that local famers extend planting down to lower bar elevations where the mean probabilities of re-submergence before rice maturity (due to reversals) approach 50%, below which they implicitly consider that the risk of crop loss outweighs the potential reward of planting.

Virioplankton Assemblage Structure in the Lower River and Ocean Continuum of the Amazon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, Bruno S. de O.; Coutinho, Felipe H.; Gregoracci, Gustavo B.

ABSTRACT The Amazon River watershed and its associated plume comprise a vast continental and oceanic area. The microbial activities along this continuum contribute substantially to global carbon and nutrient cycling, and yet there is a dearth of information on the diversity, abundance, and possible roles of viruses in this globally important river. The aim of this study was to elucidate the diversity and structure of virus assemblages of the Amazon River-ocean continuum. Environmental viral DNA sequences were obtained for 12 locations along the river’s lower reach (n= 5) and plume (n= 7). Sequence assembly yielded 29,358 scaffolds, encoding 82,546 viralmore » proteins, with 15 new complete viral genomes. Despite the spatial connectivity mediated by the river, virome analyses and physical-chemical water parameters clearly distinguished river and plume ecosystems. Bacteriophages were ubiquitous in the continuum and were more abundant in the transition region. Eukaryotic viruses occurred mostly in the river, while the plume had more viruses of autotrophic organisms (Prochlorococcus,Synechococcus) and heterotrophic bacteria (Pelagibacter). The viral familiesMicroviridaeandMyoviridaewere the most abundant and occurred throughout the continuum. The major functions of the genes in the continuum involved viral structures and life cycles, and viruses from plume locations and Tapajós River showed the highest levels of functional diversity. The distribution patterns of the viral assemblages were defined not only by the occurrence of possible hosts but also by water physical and chemical parameters, especially salinity. The findings presented here help to improve understanding of the possible roles of viruses in the organic matter cycle along the river-ocean continuum. IMPORTANCEThe Amazon River forms a vast plume in the Atlantic Ocean that can extend for more than 1,000 km. Microbial communities promote a globally relevant carbon sink system in the plume. Despite the importance of viruses for the global carbon cycle, the diversity and the possible roles of viruses in the Amazon are poorly understood. The present work assesses, for the first time, the abundance and diversity of viruses simultaneously in the river and ocean in order to elucidate their possible roles. DNA sequence assembly yielded 29,358 scaffolds, encoding 82,546 viral proteins, with 15 new complete viral genomes from the 12 river and ocean locations. Viral diversity was clearly distinguished by river and ocean. Bacteriophages were the most abundant and occurred throughout the continuum. Viruses that infect eukaryotes were more abundant in the river, whereas phages appeared to have strong control over the host prokaryotic populations in the plume.« less

Virioplankton Assemblage Structure in the Lower River and Ocean Continuum of the Amazon

PubMed Central

Silva, Bruno S. de O.; Coutinho, Felipe H.; Gregoracci, Gustavo B.; Leomil, Luciana; de Oliveira, Louisi S.; Fróes, Adriana; Tschoeke, Diogo; Soares, Ana Carolina; Cabral, Anderson S.; Ward, Nicholas D.; Richey, Jeffrey E.; Krusche, Alex V.; Yager, Patricia L.; de Rezende, Carlos Eduardo; Thompson, Cristiane C.

2017-01-01

ABSTRACT The Amazon River watershed and its associated plume comprise a vast continental and oceanic area. The microbial activities along this continuum contribute substantially to global carbon and nutrient cycling, and yet there is a dearth of information on the diversity, abundance, and possible roles of viruses in this globally important river. The aim of this study was to elucidate the diversity and structure of virus assemblages of the Amazon River-ocean continuum. Environmental viral DNA sequences were obtained for 12 locations along the river’s lower reach (n = 5) and plume (n = 7). Sequence assembly yielded 29,358 scaffolds, encoding 82,546 viral proteins, with 15 new complete viral genomes. Despite the spatial connectivity mediated by the river, virome analyses and physical-chemical water parameters clearly distinguished river and plume ecosystems. Bacteriophages were ubiquitous in the continuum and were more abundant in the transition region. Eukaryotic viruses occurred mostly in the river, while the plume had more viruses of autotrophic organisms (Prochlorococcus, Synechococcus) and heterotrophic bacteria (Pelagibacter). The viral families Microviridae and Myoviridae were the most abundant and occurred throughout the continuum. The major functions of the genes in the continuum involved viral structures and life cycles, and viruses from plume locations and Tapajós River showed the highest levels of functional diversity. The distribution patterns of the viral assemblages were defined not only by the occurrence of possible hosts but also by water physical and chemical parameters, especially salinity. The findings presented here help to improve understanding of the possible roles of viruses in the organic matter cycle along the river-ocean continuum. IMPORTANCE The Amazon River forms a vast plume in the Atlantic Ocean that can extend for more than 1,000 km. Microbial communities promote a globally relevant carbon sink system in the plume. Despite the importance of viruses for the global carbon cycle, the diversity and the possible roles of viruses in the Amazon are poorly understood. The present work assesses, for the first time, the abundance and diversity of viruses simultaneously in the river and ocean in order to elucidate their possible roles. DNA sequence assembly yielded 29,358 scaffolds, encoding 82,546 viral proteins, with 15 new complete viral genomes from the 12 river and ocean locations. Viral diversity was clearly distinguished by river and ocean. Bacteriophages were the most abundant and occurred throughout the continuum. Viruses that infect eukaryotes were more abundant in the river, whereas phages appeared to have strong control over the host prokaryotic populations in the plume. PMID:28989970

The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers

USGS Publications Warehouse

Swarzenski, P.; Campbell, P.; Porcelli, D.; McKee, B.

2004-01-01

Natural concentrations of 238U and ??234U values were determined in estuarine surface waters and pore waters of the Amazon and Fly (Papua New Guinea) Rivers to investigate U transport phenomena across river-dominated land-sea margins. Discharge from large, tropical rivers is a major source of dissolved and solid materials transported to the oceans, and are important in defining not only oceanic mass budgets, but also terrestrial weathering rates. On the Amazon shelf, salinity-property plots of dissolved organic carbon, pH and total suspended matter revealed two vastly contrasting water masses that were energetically mixed. In this mixing zone, the distribution of uranium was highly non-conservative and exhibited extensive removal from the water column. Uranium removal was most pronounced within a salinity range of 0-16.6, and likely the result of scavenging and flocculation reactions with inorganic (i.e., Fe/Mn oxides) and organic colloids/particles. Removal of uranium may also be closely coupled to exchange and resuspension processes at the sediment/water interface. An inner-shelf pore water profile indicated the following diagenetic processes: extensive (???1 m) zones of Fe(III) - and, to a lesser degree, Mn(IV) - reduction in the absence of significant S(II) concentrations appeared to facilitate the formation of various authigenic minerals (e.g., siderite, rhodocrosite and uraninite). The pore water dissolved 238U profile co-varied closely with Mn(II). Isotopic variations as evidenced in ??234U pore waters values from this site revealed information on the origin and history of particulate uranium. Only after a depth of about 1 m did the ??234U value approach unity (secular equilibrium), denoting a residual lattice bound uranium complex that is likely an upper-drainage basin weathering product. This suggests that the enriched ??234U values represent a riverine surface complexation product that is actively involved in Mn-Fe diagenetic cycles and surface complexation reactions. In the Fly River estuary, 238U appears to exhibit a reasonably conservative distribution as a function of salinity. The absence of observed U removal does not necessarily imply non-reactivity, but instead may record an integration of concurrent U removal and release processes. There is not a linear correlation between ??234U vs. 1/ 238U that would imply simple two component mixing. It is likely that resuspension of bottom sediments, prolonged residence times in the lower reaches of the Fly River, and energetic particle-colloid interactions contribute to the observed estuarine U distribution. The supply of uranium discharged from humid, tropical river systems to the sea appears to be foremost influenced by particle/water interactions that are ultimately governed by the particular physiographic and hydrologic characteristics of an estuary. ?? 2004 Elsevier Ltd. All rights reserved.

Interaction of the Global Energy and Water Cycle Experiment (GEWEX) Water Resources Applications Project (WRAP) and Coordinated Enhanced Observing Project (CEOP) in Support of Water Resource Management and Planning

NASA Astrophysics Data System (ADS)

Martz, L.

2004-05-01

The Water Resources Applications Project (WRAP) has been developed within the Global Energy and Water Cycle Experiment (GEWEX) to facilitate the testing of GEWEX products and their transfer to operational water managers. The WRAP activity builds upon projects within the GEWEX Continental Scale Experiments (CSEs), and facilitates dialogue between these CSEs and their local water management communities regarding their information needs and opportunities for GEWEX products to meet those needs. Participating Continental Scale Experiments are located in the United States, the Mackenzie River Basin in Canada, the Amazon River Basin in Brazil, the Baltic Sea drainage area, eastern Asia and the Murray-Darling Basin in Australia. In addition, the development of WRAP is facilitating the transfer of techniques and demonstration projects to other areas through collaboration with IAHS, UNESCO/WMO HELP, WMO Hydrology and WWAP. The initiation of CEOP presents a significant new opportunity for collaborations to support the application of global hydro-climatological scientific data and techniques to water resource management. Some important scientific and operational issues identified by water resource management professionals in earlier workshops will be reviewed, some scientific initiatives needed to address these issues will be presented, and some case study examples of the application of GEWEX knowledge to water resource problems will be presented. Against this background, the unique opportunities that CEOP provides to improve our use and management of water resources globally will be discussed.

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin.

PubMed

Palermo, Pedro M; Aguilar, Patricia V; Sanchez, Juan F; Zorrilla, Víctor; Flores-Mendoza, Carmen; Huayanay, Anibal; Guevara, Carolina; Lescano, Andrés G; Halsey, Eric S

2016-11-02

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrome b gene. Psorophora (Janthinosoma) albigenu, Psorophora (Grabhamia) cingulata, Mansonia humeralis, Anopheles oswaldoi s.l., and Anopheles benarrochi s.l. had mainly anthropophilic feeding preferences; Aedes (Ochlerotatus) serratus, and Aedes (Ochlerotatus) fulvus had feeding preferences for peridomestic animals; and Culex (Melanoconion) spp. fed on a variety of vertebrates, mainly rodents (spiny rats), birds, and amphibians. On the basis of these feeding preferences, many mosquitoes could be considered as potential enzootic and bridge arbovirus vectors in the Amazon Basin of Peru. © The American Society of Tropical Medicine and Hygiene.

Multifactorial genetic divergence processes drive the onset of speciation in an Amazonian fish

PubMed Central

Torrente-Vilara, Gislene; Quilodran, Claudio; Rodrigues da Costa Doria, Carolina; Montoya-Burgos, Juan I.

2017-01-01

Understanding the processes that drive population genetic divergence in the Amazon is challenging because of the vast scale, the environmental richness and the outstanding biodiversity of the region. We addressed this issue by determining the genetic structure of the widespread Amazonian common sardine fish Triportheus albus (Characidae). We then examined the influence, on this species, of all previously proposed population-structuring factors, including isolation-by-distance, isolation-by-barrier (the Teotônio Falls) and isolation-by-environment using variables that describe floodplain and water characteristics. The population genetics analyses revealed an unusually strong structure with three geographical groups: Negro/Tapajós rivers, Lower Madeira/Central Amazon, and Upper Madeira. Distance-based redundancy analyses showed that the optimal model for explaining the extreme genetic structure contains all proposed structuring factors and accounts for up to 70% of the genetic structure. We further quantified the contribution of each factor via a variance-partitioning analysis. Our results demonstrate that multiple factors, often proposed as individual drivers of population divergence, have acted in conjunction to divide T. albus into three genetic lineages. Because the conjunction of multiple long-standing population-structuring processes may lead to population reproductive isolation, that is, the onset of speciation, we suggest that the multifactorial population-structuring processes highlighted in this study could account for the high speciation rate characterising the Amazon Basin. PMID:29261722

Understanding moisture recycling for atmospheric river management in Amazonian communities

NASA Astrophysics Data System (ADS)

Weng, Wei; Luedeke, Matthias; Zemp, Delphine-Clara; Lakes, Tobia; Pradhan, Prajal; Kropp, Juergen

2017-04-01

The invisible atmospheric transports of moisture have recently attracted more research efforts into understanding their structures, processes involved and their function as an ecosystem service. Current attention has been focused on larger scale analysis such as studying global or continental level moisture recycling. Here we applied a water balance model to backtrack the flying river that sustains two local communities in the Colombian and Peruvian Amazon where vulnerable communities rely highly on the rainfall for agricultural practices. By utilising global precipitation (TRMM Multisatillite Precipitation Analysis; TMPA) and evapotranspiration products (Moderate Resolution Imaging Spectroradiometer MODIS, MOD16ET) as input data in the present modelling experiments to compensate the sparse ground observation data in these regions, the moisture recycling process targeting the two amazonian communities which has not yet been explored quantitatively has been shown. The TMPA was selected because of its proved comparativeness with observation data in its precipitation estimations over Amazon regions while the MOD16ET data was chosen for being validated by previous studies in the Amazon basin and for reported good performance. In average, 45.5 % of the precipitation occurring to Caquetá region in Colombia is of terrestrial origin from the South American continent while 48.2% of the total rainfall received by Peruvian Yurimaguas is also from the South American land sources. The spatial distribution of the precipitationsheds (defined previously as the upwind contribution of evapotranspiration to a specific location's precipitation) shows transboundary and transnational shares in the moisture contributors of the precipitation for both regions. An interesting reversed upstream-downstream roles can be observed when the upstream regions in traditional watershed thinking become downstream areas considering precipitationsheds and flying rivers. Strong seasonal variations are also detected by our results. Since undergoing rapid land cultivation expansion in the precipitationsheds of these study areas can potentially alter the moisture recycling process which sustains ecosystem and communities, the tele-connection linking the contributors and recipients presented in this study has highlighted that region-wise collaboration and communication will be essential for an adaptive Amazonia facing environmental change, especially in regards to its vulnerable communities.

Evaluation of last extreme drought events in Amazon basin using remotely sensing data

NASA Astrophysics Data System (ADS)

Panisset, Jéssica S.; Gouveia, Célia M.; Libonati, Renata; Peres, Leonardo; Machado-Silva, Fausto; França, Daniela A.; França, José R. A.

2017-04-01

Amazon basin has experienced several intense droughts among which were highlighted last recent ones in 2005 and 2010. Climate models suggest these events will be even more frequent due to higher concentration of greenhouse gases that are also driven forward by alteration in forest dynamics. Environmental and social impacts demand to identify these intense droughts and the behavior of climate parameters that affect vegetation. This present study also identifies a recent intense drought in Amazon basin during 2015. Meteorological parameters and vegetation indices suggest this event was the most severe already registered in the region. We have used land surface temperature (LST), vegetation indices, rainfall and shortwave radiation from 2000 to 2015 to analyze and compare droughts of 2005, 2010 and 2015. Our results show singularities among the three climate extreme events. The austral winter was the most affected season in 2005 and 2010, but not in 2015 when austral summer presented extreme conditions. Precipitation indicates epicenter of 2005 in west Amazon corroborating with previous studies. In 2010, the west region was strongly affected again together with the northwest and the southeast areas. However, 2015 epicenters were concentrated in the east of the basin. In 2015, shortwave radiation has exceeded the maximum values of 2005 and temperature the maximum value of 2010. Vegetation indices have shown positive and negative anomalies. Despite of heterogenous response of Amazon forest to drought, hybrid vegetation indices using NDVI (Normalized Difference Vegetation Index) and LST highlights the exceptionality of 2015 drought episode that exhibits higher vegetation water stress than the cases of 2010 and 2005. Finally, this work has shown how meteorological parameters influence droughts and the effects on vegetation in Amazon basin. Complexity of climate, ecosystem heterogeneity and high diversity of Amazon forest are response by idiosyncrasies of each drought. All these information improve the predictability of future climate scenarios and their effects in the environment. Research performed was supported by FAPESP/FCT Project Brazilian Fire-Land-Atmosphere System (BrFLAS) (1389/2014 and 2015/01389-4), by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) through a Master grant from PPGM/IGEO/UFRJ (first author), and by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) through grants E-26/201.521/2014; E-26/101.423/2014; E-26/201.221/2015; and E-26/203.174/2016.

SE Asian freshwater fish population and networks: the impacts of climatic and environmental change on a vital resource

NASA Astrophysics Data System (ADS)

Santos, Rita; Parsons, Daniel; Cowx, Ian

2016-04-01

The Mekong River is the 10th largest freshwater river in the world, with the second highest biodiversity wealth, behind the much larger Amazon basin. The fisheries activity in the Lower Mekong countries counts for 2.7 million tons of fish per year, with an estimated value worth up to US 7 billion. For the 60 million people living in the basin, fish represent their primary source of economic income and protein intake, with an average per capita consumption estimated at 45.4 Kg. The proposed hydropower development in the basin is threatening its sustainability and resilience. Such developments affect fish migration patterns, hydrograph flood duration and magnitudes and sediment flux. Climate change is also likely to impact the basin, exacerbating the issues created by development. As a monsoonal system, the Mekong River's pronounced annual flood pulse cycle is important in creating variable habitat for fish productivity. Moreover, the annual flood also triggers fish migration and provides vital nutrients carried by the sediment flux. This paper examines the interactions between both dam development and climate change scenarios on fish habitat and habitat connectivity, with the aim of predicting how these will affect fish species composition and fisheries catch. The project will also employ Environmental DNA (eDNA) to quantify and understand the species composition of this complex and large freshwater system. By applying molecular analysis, it is possible to trace species abundance and migration patterns of fish and evaluate the ecological networks establish between an inland system. The aim of this work is to estimate, using process-informed models, the impacts of the proposed dam development and climate change scenarios on the hydrological and hydraulic conditions of habitat availability for fish. Furthermore, it will evaluate the connectivity along the Mekong and its tributaries, and the importance of maintaining these migration pathways, used by a great diversity of fish species. It will also present the preliminary findings on eDNA analysis for species composition and the ecological networks established along the river and particularly on the fish hotspot place for biodiversity, the Tonle Sap system in Cambodia. Keywords: Mekong River, climate change, fish production, dams, eDNA analysis, numerical modelling.

Empty forest or empty rivers? A century of commercial hunting in Amazonia

PubMed Central

Antunes, André P.; Fewster, Rachel M.; Venticinque, Eduardo M.; Peres, Carlos A.; Levi, Taal; Rohe, Fabio; Shepard, Glenn H.

2016-01-01

The Amazon basin is the largest and most species-rich tropical forest and river system in the world, playing a pivotal role in global climate regulation and harboring hundreds of traditional and indigenous cultures. It is a matter of intense debate whether the ecosystem is threatened by hunting practices, whereby an “empty forest” loses critical ecological functions. Strikingly, no previous study has examined Amazonian ecosystem resilience through the perspective of the massive 20th century international trade in furs and skins. We present the first historical account of the scale and impacts of this trade and show that whereas aquatic species suffered basin-wide population collapse, terrestrial species did not. We link this differential resilience to the persistence of adequate spatial refuges for terrestrial species, enabling populations to be sustained through source-sink dynamics, contrasting with unremitting hunting pressure on more accessible aquatic habitats. Our findings attest the high vulnerability of aquatic fauna to unregulated hunting, particularly during years of severe drought. We propose that the relative resilience of terrestrial species suggests a marked opportunity for managing, rather than criminalizing, contemporary traditional subsistence hunting in Amazonia, through both the engagement of local people in community-based comanagement programs and science-led conservation governance. PMID:27757421

A TRMM-Calibrated Infrared Technique for Convective and Stratiform Rainfall: Analysis and Validation

NASA Technical Reports Server (NTRS)

Negri, Andrew; Starr, David OC. (Technical Monitor)

2001-01-01

A satellite infrared technique with passive microwave calibration has been developed for estimating convective and stratiform rainfall. The Convective-Stratiform Technique, calibrated by coincident, physically retrieved rain rates from the TRMM Microwave Imager (TMI), has been applied to 30 min interval GOES infrared data and aggregated over seasonal and yearly periods over northern South America. The diurnal cycle of rainfall, as well as the division between convective and stratiform rainfall is presented. For the period Jan-April 1999, analysis revealed significant effects of local circulations (river breeze, land/sea breeze, mountain/valley) on both the total rainfall and it's diurnal cycle. Results compared well (a one-hour lag) with the diurnal cycle derived from TOGA radar-estimated rainfall in Rondonia. The satellite estimates revealed that the convective rain constituted 24% of the rain area while accounting for 67% of the rain volume. Estimates of the diurnal cycle (both total rainfall and convective/stratiform) for an area encompassing the Amazon Basin (3 x 10(exp 6) sq km) were in phase with those from the TRMM Precipitation Radar, despite the latter's limited sampling. Results will be presented comparing the yearly (2000) diurnal cycle for large regions (including the Amazon Basin), and an intercomparison of January-March estimates for three years, (1999-2001). We hope to demonstrate the utility of using the TRMM PR observations as verification for infrared estimates of the diurnal cycle, and as verification of the apportionment of rainfall into convective and stratiform components.

A TRMM-Calibrated Infrared Technique for Convective and Stratiform Rainfall: Analysis and Validation

NASA Technical Reports Server (NTRS)

Negri, Andrew; Starr, David OC. (Technical Monitor)

2001-01-01

A satellite infrared technique with passive microwave calibration has been developed for estimating convective and stratiform. rainfall. The Convective-Stratiform Technique, calibrated by coincident, physically retrieved rain rates from the TRMM Microwave Imager (TMI), has been applied to 30 min interval GOES infrared data and aggregated over seasonal and yearly periods over northern South America. The diurnal cycle of rainfall, as well as the division between convective and stratiform rainfall is presented. For the period Jan-April 1999, analysis revealed significant effects of local circulations (river breeze, land/sea breeze, mountain/valley) on both the total rainfall and it's diurnal cycle. Results compared well (a one-hour lag) with the diurnal cycle derived from TOGA radar-estimated rainfall in Rondonia. The satellite estimates revealed that the convective rain constituted 24% of the rain area while accounting for 67% of the rain volume. Estimates of the diurnal cycle (both total rainfall and convective/stratiform) for an area encompassing the Amazon Basin (3 x 10(exp 6) square km) were in phase with those from the TRMM Precipitation Radar, despite the latter's limited sampling. Results will be presented comparing the yearly (2000) diurnal cycle for large regions (including the Amazon Basin), and an intercomparison of January-March estimates for three years, 1999-2001. We hope to demonstrate the utility of using the TRMM PR observations as verification for infrared estimates of the diurnal cycle, and as verification of the apportionment of rainfall into convective and stratiform components.

Peru: Current Conditions and U.S. Relations

DTIC Science & Technology

2009-07-21

to development and poverty reduction. Of Peru’s 173 million acres of rainforest in the Amazon basin, about 70% has been granted or offered as...investment that will benefit the country as a whole. Indigenous peoples of the Amazon rainforest counter that the government is ignoring and/or...sent police to break up blockades set up by thousands of indigenous protesters in the Amazon . The deadly clash between the indigenous protesters and

Spectrometry of Pasture Condition and Biogeochemistry in the Central Amazon

NASA Technical Reports Server (NTRS)

Asner, Gregory P.; Townsend, Alan R.; Bustamante, Mercedes M. C.

1999-01-01

Regional analyses of Amazon cattle pasture biogeochemistry are difficult due to the complexity of human, edaphic, biotic and climatic factors and persistent cloud cover in satellite observations. We developed a method to estimate key biophysical properties of Amazon pastures using hyperspectral reflectance data and photon transport inverse modeling. Remote estimates of live and senescent biomass were strongly correlated with plant-available forms of soil phosphorus and calcium. These results provide a basis for monitoring pasture condition and biogeochemistry in the Amazon Basin using spaceborne hyperspectral sensors.

Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010.

PubMed

Song, Xiao-Peng; Huang, Chengquan; Saatchi, Sassan S; Hansen, Matthew C; Townshend, John R

2015-01-01

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates-critical inputs for setting reference emission levels for REDD+-are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr(-1) and 0.18 ± 0.07 Pg C•yr(-1) respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha(-1), ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha(-1)). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha(-1)•yr(-1) from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts.

Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010

PubMed Central

Song, Xiao-Peng; Huang, Chengquan; Saatchi, Sassan S.; Hansen, Matthew C.; Townshend, John R.

2015-01-01

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates―critical inputs for setting reference emission levels for REDD+―are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr−1 and 0.18 ± 0.07 Pg C•yr−1 respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha−1, ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha−1). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha−1•yr−1 from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts. PMID:25951328

Basin-Wide Amazon Forest Tree Mortality From a Large 2005 Storm

NASA Astrophysics Data System (ADS)

Negron Juarez, R. I.; Chambers, J. Q.; Guimaraes, G.; Zeng, H.; Raupp, C.; Marra, D. M.; Ribeiro, G.; Saatchi, S. S.; Higuchi, N.

2010-12-01

Blowdowns are a recurrent characteristic of Amazon forests and are produced, among others, by squall lines. Squall lines are aligned clusters (typical length of 1000 km, width of 200 km) of deep convective cells that produce heavy rainfall during the dry season and significant rainfall during the wet season. These squall lines (accompanied by intense downbursts from convective cells) have been associated with large blowdowns characterized by uprooted, snapped trees, and trees being dragged down by other falling trees. Most squall lines in Amazonia form along the northeastern coast of South America as sea breeze-induced instability lines and propagate inside the continent. They occur frequently (~4 times per month), and can reach the central and even extreme western parts of Amazonia. Squall lines can also be generated inside the Amazon and propagate toward the equator. In January 2005 a squall line propagated from south to north across the entire Amazon basin producing widespread forest tree mortality and contributed to the elevated mortality observed that year. Over the Manaus region (3.4 x104 km2), disturbed forest patches generated by the squall produced a mortality of 0.3-0.5 million trees, equivalent to 30% of the observed annual deforestation reported in 2005 over the same area. The elevated mortality observed in the Central Amazon in 2005 is unlikely to be related to the 2005 Amazon drought since drought did not affect Central or Eastern Amazonia. Assuming a similar rate of forest mortality across the basin, the squall line could have potentially produced tree mortality estimated at 542 ± 121 million trees, equivalent to 23% of the mean annual biomass accumulation estimated for these forests. Our results highlight the vulnerability of Amazon trees to wind-driven mortality associated with convective storms. This vulnerability is likely to increase in a warming climate with models projecting an increase in storm intensity.

Hydroclimate changes across the Amazon lowlands over the past 45,000 years

NASA Astrophysics Data System (ADS)

Wang, Xianfeng; Edwards, R. Lawrence; Auler, Augusto S.; Cheng, Hai; Kong, Xinggong; Wang, Yongjin; Cruz, Francisco W.; Dorale, Jeffrey A.; Chiang, Hong-Wei

2017-01-01

Reconstructing the history of tropical hydroclimates has been difficult, particularly for the Amazon basin—one of Earth’s major centres of deep atmospheric convection. For example, whether the Amazon basin was substantially drier or remained wet during glacial times has been controversial, largely because most study sites have been located on the periphery of the basin, and because interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting. Here we show that rainfall in the basin responds closely to changes in glacial boundary conditions in terms of temperature and atmospheric concentrations of carbon dioxide. Our results are based on a decadally resolved, uranium/thorium-dated, oxygen isotopic record for much of the past 45,000 years, obtained using speleothems from Paraíso Cave in eastern Amazonia; we interpret the record as being broadly related to precipitation. Relative to modern levels, precipitation in the region was about 58% during the Last Glacial Maximum (around 21,000 years ago) and 142% during the mid-Holocene epoch (about 6,000 years ago). We find that, as compared with cave records from the western edge of the lowlands, the Amazon was widely drier during the last glacial period, with much less recycling of water and probably reduced plant transpiration, although the rainforest persisted throughout this time.

High genetic diversity and connectivity in Colossoma macropomum in the Amazon basin revealed by microsatellite markers.

PubMed

Fazzi-Gomes, Paola; Guerreiro, Sávio; Palheta, Glauber David Almeida; Melo, Nuno Filipe Alves Correa de; Santos, Sidney; Hamoy, Igor

2017-01-01

Colossoma macropomum is the second largest scaled fish of the Amazon. It is economically important for commercial fisheries and for aquaculture, but few studies have examined the diversity and genetic structure of natural populations of this species. The aim of this study was to investigate the levels of genetic variability and connectivity that exist between three natural populations of C. macropomum from the Amazon basin. In total, 247 samples were collected from the municipalities of Tefé, Manaus, and Santarém. The populations were genotyped using a panel of 12 multiplex microsatellite markers. The genetic diversity found in these populations was high and similar to other populations described in the literature. These populations showed a pattern of high gene flow associated with the lack of a genetic structure pattern, indicating that the number of migrants per generation and recent migration rates are high. The values of the FST, RST, and exact test of differentiation were not significant for pairwise comparisons between populations. The Bayesian population clustering analysis indicated a single population. Thus, the data provide evidence for high genetic diversity and high gene flow among C. macropomum populations in the investigated region of the Amazon basin. This information is important for programs aiming at the conservation of natural populations.

High genetic diversity and connectivity in Colossoma macropomum in the Amazon basin revealed by microsatellite markers

PubMed Central

Fazzi-Gomes, Paola; Guerreiro, Sávio; Palheta, Glauber David Almeida; de Melo, Nuno Filipe Alves Correa; Santos, Sidney; Hamoy, Igor

2017-01-01

Abstract Colossoma macropomum is the second largest scaled fish of the Amazon. It is economically important for commercial fisheries and for aquaculture, but few studies have examined the diversity and genetic structure of natural populations of this species. The aim of this study was to investigate the levels of genetic variability and connectivity that exist between three natural populations of C. macropomum from the Amazon basin. In total, 247 samples were collected from the municipalities of Tefé, Manaus, and Santarém. The populations were genotyped using a panel of 12 multiplex microsatellite markers. The genetic diversity found in these populations was high and similar to other populations described in the literature. These populations showed a pattern of high gene flow associated with the lack of a genetic structure pattern, indicating that the number of migrants per generation and recent migration rates are high. The values of the FST, RST, and exact test of differentiation were not significant for pairwise comparisons between populations. The Bayesian population clustering analysis indicated a single population. Thus, the data provide evidence for high genetic diversity and high gene flow among C. macropomum populations in the investigated region of the Amazon basin. This information is important for programs aiming at the conservation of natural populations. PMID:28170026

Can Transport of Saharan Dust Explain Extensive Clay Deposits in the Amazon Basin? A Test Using Radiogenic Isotopes

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Abouchami, W.; Näthe, K.; Kumar, A.; Galer, S. J.; Jochum, K. P.; Williams, E.; Horbe, A. M.; Rosa, J. W.; Adams, D. K.; Balsam, W. R.

2012-12-01

The Bodélé Depression, located in the Southern Sahara, is a huge source of atmospheric dust and thus an important element in biogeochemical cycles and the radiative budget of Earth's atmosphere. Previous studies have shown that Saharan dust transport across the Atlantic acts as an important source of mineral nutrients to the Amazon rainforest. The Belterra Clay, which outcrops extensively across the Amazon Basin in Brazil, has been proposed to result from dry deposition of African dusts. We have investigated this hypothesis by measuring the radiogenic isotopic composition (Sr, Nd and Pb) of a suite of samples from the Belterra Clay, the Bodélé Depression, dusts deposits collected at various locations along the airmass transport trajectory, as well as loess from the Cape Verde Islands. Radiogenic isotope systems are powerful tracers of provenance and can be used to fingerprint dust sources and atmospheric transport patterns. Our results identify distinct isotopic signatures in the Belterra Clay samples and the African sources. The Belterra Clay display radiogenic Sr and Pb isotope ratios associated with non-radiogenic Nd isotope signatures. In contrast, Bodélé samples and dusts deposits show lower Pb isotope ratios, variable 87Sr/86Sr, and relatively homogeneous Nd isotopic compositions, albeit more radiogenic than those of the Belterra Clay. Our data show unambiguously that the Belterra Clay is not derived from African dust deposition, nor from the Andean chain, as originally suggested by W. Sombroek. Rather, isotopic compositions and Nd model ages are consistent with simple mixing of Archean and younger Proterozoic terranes within the Amazon Basin as a result of weathering and erosion under humid tropical conditions. Whether Saharan dusts contribute to the fertilization in the Amazon Basin cannot be ruled out, however, since the African dust isotopic signature is expected to be entirely overprinted by local sources. Radiogenic isotope data obtained on aerosol filters collected in the US Virgin Islands and Tobago are similar to those of aerosols from Mali, demonstrating that the African dust isotope signal is detectable and transported as far as Central and South America. Thus, while it appears undeniable that Saharan dust reaches the Amazon Basin, its importance for overall soil fertility requires a careful assessment of the dust budget versus bedrock weathering rates for key nutrient elements.

Forecasting Excessive Rainfall and Low-Cloud Bases East of the Northern Andes and Mesoscale Convective Complex Movement in Central South America

DTIC Science & Technology

2003-03-01

wonderful companion and girlfriend . After all these years, you are the only one who truly stands by me unconditionally. Words can’t express my...than 300 ft, although rare, do occur mainly in the more moisture rich West Amazon Basin. Occurrences with bases less than 300 ft are about 3-5% in the...heating may not be a primary factor for time of convection probably due to smaller diurnal temperature differences in the moisture rich Amazon Basin

Trophic Structure and Mercury Biomagnification in Tropical Fish Assemblages, Iténez River, Bolivia

PubMed Central

Pouilly, Marc; Rejas, Danny; Pérez, Tamara; Duprey, Jean-Louis; Molina, Carlos I.; Hubas, Cédric; Guimarães, Jean-Remy D.

2013-01-01

We examined mercury concentrations in three fish assemblages to estimate biomagnification rates in the Iténez main river, affected by anthropogenic activities, and two unperturbed rivers from the Iténez basin, Bolivian Amazon. Rivers presented low to moderate water mercury concentrations (from 1.25 ng L−1 to 2.96 ng L−1) and natural differences in terms of sediment load. Mercury biomagnification rates were confronted to trophic structure depicted by carbon and nitrogen stable isotopes composition (δ15N; δ13C) of primary trophic sources, invertebrates and fishes. Results showed a slight fish contamination in the Iténez River compared to the unperturbed rivers, with higher mercury concentrations in piscivore species (0.15 µg g−1 vs. 0.11 µg g−1 in the unperturbed rivers) and a higher biomagnification rate. Trophic structure analysis showed that the higher biomagnification rate in the Iténez River could not be attributed to a longer food chain. Nevertheless, it revealed for the Iténez River a higher contribution of periphyton to the diet of the primary consumers fish species; and more negative δ13C values for primary trophic sources, invertebrates and fishes that could indicate a higher contribution of methanotrophic bacteria. These two factors may enhance methylation and methyl mercury transfer in the food web and thus, alternatively or complementarily to the impact of the anthropogenic activities, may explain mercury differences observed in fishes from the Iténez River in comparison to the two other rivers. PMID:23741452

Dissolved rainfall inputs and streamwater outputs in an undisturbed watershed on highly weathered soils in the Brazilian cerrado

NASA Astrophysics Data System (ADS)

Markewitz, Daniel; Resende, Julio C. F.; Parron, Lucilia; Bustamante, Mercedes; Klink, Carlos A.; Figueiredo, Ricardo De O.; Davidson, Eric A.

2006-08-01

The cerrados of Brazil cover 2 million km2. Despite the extent of these seasonally dry ecosystems, little watershed research has been focused in this region, particularly relative to the watersheds of the Amazon Basin. The cerrado shares pedogenic characteristics with the Amazon Basin in draining portions of the Brazilian shield and in possessing Oxisols over much of the landscape. The objective of this research was to quantify the stream water geochemical relationships of an undisturbed 1200 ha cerrado watershed for comparison to river geochemistry in the Amazon. Furthermore, this undisturbed watershed was used to evaluate stream discharge versus dissolved ion concentration relationships. This research was conducted in the Córrego Roncador watershed of the Reserva Ecológica do Roncador (RECOR) of the Instituto Brasileiro Geografia e Estatística (IBGE) near Brasilia, Brazil. Bulk precipitation and stream water chemistry were analysed between May 1998 and May 2000. The upland soils of this watershed are nutrient poor possessing total stocks of exchangeable elements in the upper 1 m of 81 +/- 13, 77 +/- 4, 25 +/- 3, and 1 +/- 1 kg ha-1 of K, Ca, Mg, and P, respectively. Bulk precipitation inputs of dissolved nutrients for this watershed are low and consistent with previous estimates. The nutrient-poor soils of this watershed, however, increase the relative importance of precipitation for nutrient replenishment to vegetation during episodes of ecosystem disturbance. Stream water dissolved loads were extremely dilute with conductivities ranging from 4 to 10 μS cm-1 during periods of high- and low-flow, respectively. Despite the low concentrations in this stream, geochemical relationships were similar to other Amazonian streams draining shield geologies. Discharge-concentration relationships for Ca and Mg in these highly weathered soils developed from igneous rocks of the Brazilian shield demonstrated a significant negative relationship indicating a continued predominance of groundwater baseflow contributions these cationic elements.

DNA Metabarcoding of Amazonian Ichthyoplankton Swarms

PubMed Central

Maggia, M. E.; Vigouroux, Y.; Renno, J. F.; Duponchelle, F.; Desmarais, E.; Nunez, J.; García-Dávila, C.; Carvajal-Vallejos, F. M.; Paradis, E.; Martin, J. F.; Mariac, C.

2017-01-01

Tropical rainforests harbor extraordinary biodiversity. The Amazon basin is thought to hold 30% of all river fish species in the world. Information about the ecology, reproduction, and recruitment of most species is still lacking, thus hampering fisheries management and successful conservation strategies. One of the key understudied issues in the study of population dynamics is recruitment. Fish larval ecology in tropical biomes is still in its infancy owing to identification difficulties. Molecular techniques are very promising tools for the identification of larvae at the species level. However, one of their limits is obtaining individual sequences with large samples of larvae. To facilitate this task, we developed a new method based on the massive parallel sequencing capability of next generation sequencing (NGS) coupled with hybridization capture. We focused on the mitochondrial marker cytochrome oxidase I (COI). The results obtained using the new method were compared with individual larval sequencing. We validated the ability of the method to identify Amazonian catfish larvae at the species level and to estimate the relative abundance of species in batches of larvae. Finally, we applied the method and provided evidence for strong temporal variation in reproductive activity of catfish species in the Ucayalí River in the Peruvian Amazon. This new time and cost effective method enables the acquisition of large datasets, paving the way for a finer understanding of reproductive dynamics and recruitment patterns of tropical fish species, with major implications for fisheries management and conservation. PMID:28095487

Low Genetic Diversity and Structuring of the Arapaima (Osteoglossiformes, Arapaimidae) Population of the Araguaia-Tocantins Basin.

PubMed

Vitorino, Carla A; Nogueira, Fabrícia; Souza, Issakar L; Araripe, Juliana; Venere, Paulo C

2017-01-01

The arapaima, Arapaima gigas , is a fish whose populations are threatened by both overfishing and the ongoing destruction of its natural habitats. In the Amazon basin, varying levels of population structure have been found in A. gigas , although no data are available on the genetic diversity or structure of the populations found in the Araguaia-Tocantins basin, which has a topographic profile, hydrological regime, and history of fishing quite distinct from those of the Amazon. In this context, microsatellite markers were used to assess the genetic diversity and connectivity of five wild A. gigas populations in the Araguaia-Tocantins basin. The results of the analysis indicated low levels of genetic diversity in comparison with other A. gigas populations, studied in the Amazon basin. The AMOVA revealed that the Arapaima populations of the Araguaia-Tocantins basin are structured significantly. No correlation was found between pairwise F ST values and the geographical distance among populations. The low level of genetic variability and the evidence of restricted gene flow may both be accounted for by overfishing, as well as the other human impacts that these populations have been exposed to over the years. The genetic fragility of these populations demands attention, given that future environmental changes (natural or otherwise) may further reduce these indices and eventually endanger these populations. The results of this study emphasize the need to take the genetic differences among the study populations into account when planning management measures and conservation strategies for the arapaima stocks of the Araguaia-Tocantins basin.

Low Genetic Diversity and Structuring of the Arapaima (Osteoglossiformes, Arapaimidae) Population of the Araguaia-Tocantins Basin

PubMed Central

Vitorino, Carla A.; Nogueira, Fabrícia; Souza, Issakar L.; Araripe, Juliana; Venere, Paulo C.

2017-01-01

The arapaima, Arapaima gigas, is a fish whose populations are threatened by both overfishing and the ongoing destruction of its natural habitats. In the Amazon basin, varying levels of population structure have been found in A. gigas, although no data are available on the genetic diversity or structure of the populations found in the Araguaia-Tocantins basin, which has a topographic profile, hydrological regime, and history of fishing quite distinct from those of the Amazon. In this context, microsatellite markers were used to assess the genetic diversity and connectivity of five wild A. gigas populations in the Araguaia-Tocantins basin. The results of the analysis indicated low levels of genetic diversity in comparison with other A. gigas populations, studied in the Amazon basin. The AMOVA revealed that the Arapaima populations of the Araguaia-Tocantins basin are structured significantly. No correlation was found between pairwise FST values and the geographical distance among populations. The low level of genetic variability and the evidence of restricted gene flow may both be accounted for by overfishing, as well as the other human impacts that these populations have been exposed to over the years. The genetic fragility of these populations demands attention, given that future environmental changes (natural or otherwise) may further reduce these indices and eventually endanger these populations. The results of this study emphasize the need to take the genetic differences among the study populations into account when planning management measures and conservation strategies for the arapaima stocks of the Araguaia-Tocantins basin. PMID:29114261

Rivers of the Andes and the Amazon Basin: Deciphering global change from the hydroclimatic variability in the critical zone

NASA Astrophysics Data System (ADS)

Moreira-Turcq, Patricia; Carlo Espinoza, Jhan; Filizola, Naziano; Martinez, Jean-Michel

2018-01-01

The Critical Zone has been defined as the thin layer of the continental surfaces extending from fresh bedrock and the bottom of groundwater up to vegetation canopy, where soil, rock, water, air, and living organisms interact (Banwart et al., 2012; Lin et al., 2011). Despite the Critical Zone's importance to terrestrial life, it remains poorly understood. In this context, understanding the complex interactions between physical, chemical, and biological processes of the Critical Zone requires long-term observations (Anderson et al., 2012; Brantley et al., 2017), not only because different mechanisms have varying time frames, but also because it is necessary to monitor its natural and anthropogenic evolution in response to global climate and environmental changes.

Following Saharan Dust Outbreak Toward The Amazon Basin

NASA Astrophysics Data System (ADS)

Ben Ami, Y.; Koren, I.; Rudich, Y.; Flores, M.

2008-12-01

The role of the Amazon rainforest on earth climatic system is well recognized. To keep forest wellbeing and the fragile balance between the rainforest and the atmosphere, the Amazon must contain a satisfactory amount of nutrients to support the plants. The extensive rain and floods wash most of the soluble nutrients from the rainforest soil, leaving behind acidic kaolinite clay or sandy soil, with limited minerals for plant growth. It was suggested that lack of mineral in the soil may be replenished by deposition of Saharan mineral dust. Using remote sensing data (from the A-train satellites constellation) following with in-situ measurements (as part of the AMazonian Aerosol CharacteriZation Experiment (AMZE) campaign), ground-based data (from AErosol RObotic NETwork (AERONET)) and back trajectory calculations, we analyzed Saharan dust transport toward the Amazon basin during the AMZE period (Feb 7 to Mar 14, 2008). Dust mass, sink, vertical distribution and surface wind speeds were analyzed over the Bodele depression (located in Chad), where most of the dust is emitted, along the Atlantic Ocean and near the Brazilian coastline. Using an integrated data analysis approach we followed dust packages from their emission in the Sahara to their sink in the Amazon forest.

Miocene oceanographic changes of the western equatorial Atlantic (Ceara Rise) based on calcareous dinoflagellate cysts

NASA Astrophysics Data System (ADS)

Heinrich, S.; Zonneveld, K. A. F.; Willems, H.

2010-09-01

The middle- and upper Miocene represent a time-interval of major changes in palaeoceanography that favoured the cooling of the climate and culminated in the Northern Hemisphere Glaciation (NHG). The basis for the development of the modern deepwater circulation pattern, e.g. thermohaline circulation, was hereby established. Tectonic events played a key role in the progressing Miocene oceanography, such as the narrowing of the Panama gateway (e.g. Duque-Caro 1990) and the possible linked changes in North Atlantic Deep Water formation (Lear et al. 2003). However, the complex interaction between the closing of the Panama Gateway, the development of NADW, and thus the oceanographic progression towards our present day circulation is far from being fully understood. We want to improve the understanding of these processes by establishing a detailed palaeoceanographic reconstruction of the western equatorial Atlantic Ocean on the basis of calcareous dinoflagellate cyst (dinocyst) associations. Within this study, we investigated sediment samples from ODP Site 926A by defining the calcareous dinocyst assemblage. Site 926A is located at the southwestern flank of the Ceara Rise, an area of highest sensitivity to global deep water circulation changes. At about 12 Ma, when NADW production increased (e.g. Wright et al. 1992), we see a distinct increase in the absolute abundances of the calcareous dinocysts. This might be related to enhanced productivity or to better carbonate preservation. At 11.3 Ma, Leonella granifera, a species known to be strongly related to terrestrial input occurs. This could be a signal for the initiation of the Amazon River as a transcontinental river with the development of the Amazon fan (11.8 - 11.3 Ma; Figueiredo et al. 2009) in relation to Andean tectonism. References: Duque-Caro, H. (1990): Neogene stratigraphy, paleoceanography and palebiology in Northwest South America and the evolution of the Panama Seaway. Palaeogeography, Palaeoclimatology, Palaeoecology 77, 203-234. Figueiredo, J., Hoorn, C., van der Veen, P., Soares, E. (2009): Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Foz do Amazonas Basin. Geology; v. 37, no. 7; p. 619-622. Lear, C.H., Rosenthal, Y., Wright, J.D. (2003): The closing of a seaway: ocean water masses and global climate change. Earth and Planetary Science Letters 210, 425-436. Wright, J.D., Miller, K.G., Fairbanks, R.G. (1992): Early and middle Miocene stable isotopes: implications for deepwater circulation and climate. Paloceanography 7(3): 357-398.

Using "Journeys in Film" to Bring Authentic STEM Activities to the K-12 Classroom.

NASA Astrophysics Data System (ADS)

Rock, B. N.

2017-12-01

The "Journeys in Film" project brings important films and documentaries ("The Martian," "Hidden Figures," "River of Gold" and others) and curriculum-based, educational support activities to the classroom. Faculty from the University of New Hampshire, in partnership with selected local middle and high school teachers, developed a STEM Lesson Plan for Journeys in Film" focused on the soon-to-released documentary "River of Gold" which highlights tropical deforestation and illegal gold mining activities in the Peruvian jungles of the Amazon Basin. Using film clips (the Trailer) from the movie and the Lesson Plan, this approach allows pre-college students to learn how to use "Google Earth" to monitor chang-over-time and to quantify the areas of deforestation and mining using multi-date NOAA/USGS Landsat Thematic Mapper and ESA Copernicus satellite data. This approach will allow students to dconduct authentic hands-on science and mathematics to address a wide range of social and environmental issues associated with tropical deforestation in Peru.

A new distinctively banded-species of Panaqolus (Siluriformes: Loricariidae) from the western Amazon Basin in Peru.

PubMed

Lujan, Nathan K; Steele, Sarah; Velasquez, Miquel

2013-01-01

Panaqolus albivermis is described as a new species based on four specimens from the San Alejandro River, a tributary of the upper Ucayali River in central Peru. Panaqolus albivermis is diagnosed from all other Panaqolus except P. maccus by having head, body, and fins with widely separated small white to yellow spots, vermiculations, and/or thin oblique bands on a black base (vs. exclusively small white to yellow spots on a black base in P. alboinaculatus, generally broad oblique bands of alternating light to dark brown in P. changae, P. gnomus, P purusiensis, and a uniformly dark gray to black body color in P. dentex, P. koko, and P. nocturnus); P. albivernis can be diagnosed from P. maccus by having a black base color (vs. brown), by having parallel dentary tooth cups (vs. acute intermandibular tooth cup angle), and by having a larger known adult body size (95.8 mm SL vs. 84.8).

Amazonian freshwater habitats experiencing environmental and socioeconomic threats affecting subsistence fisheries.

PubMed

Alho, Cleber J R; Reis, Roberto E; Aquino, Pedro P U

2015-09-01

Matching the trend seen among the major large rivers of the globe, the Amazon River and its tributaries are facing aquatic ecosystem disruption that is affecting freshwater habitats and their associated biodiversity, including trends for decline in fishery resources. The Amazon's aquatic ecosystems, linked natural resources, and human communities that depend on them are increasingly at risk from a number of identified threats, including expansion of agriculture; cattle pastures; infrastructure such as hydroelectric dams, logging, mining; and overfishing. The forest, which regulates the hydrological pulse, guaranteeing the distribution of rainfall and stabilizing seasonal flooding, has been affected by deforestation. Flooding dynamics of the Amazon Rivers are a major factor in regulating the intensity and timing of aquatic organisms. This study's objective was to identify threats to the integrity of freshwater ecosystems, and to seek instruments for conservation and sustainable use, taking principally fish diversity and fisheries as factors for analysis.

PAH Baselines for Amazonic Surficial Sediments: A Case of Study in Guajará Bay and Guamá River (Northern Brazil).

PubMed

Rodrigues, Camila Carneiro Dos Santos; Santos, Ewerton; Ramos, Brunalisa Silva; Damasceno, Flaviana Cardoso; Correa, José Augusto Martins

2018-06-01

The 16 priority PAH were determined in sediment samples from the insular zone of Guajará Bay and Guamá River (Southern Amazon River mouth). Low hydrocarbon levels were observed and naphthalene was the most representative PAH. The low molecular weight PAH represented 51% of the total PAH. Statistical analysis showed that the sampling sites are not significantly different. Source analysis by PAH ratios and principal component analysis revealed that PAH are primary from a few rate of fossil fuel combustion, mainly related to the local small community activity. All samples presented no biological stress or damage potencial according to the sediment quality guidelines. This study discuss baselines for PAH in surface sediments from Amazonic aquatic systems based on source determination by PAH ratios and principal component analysis, sediment quality guidelines and through comparison with previous studies data.

Seasonal and inter-annual dynamics of suspended sediment at the mouth of the Amazon river: The role of continental and oceanic forcing, and implications for coastal geomorphology and mud bank formation

NASA Astrophysics Data System (ADS)

Gensac, Erwan; Martinez, Jean-Michel; Vantrepotte, Vincent; Anthony, Edward J.

2016-04-01

Fine-grained sediments supplied to the Ocean by the Amazon River and their transport under the influence of continental and oceanic forcing drives the geomorphic change along the 1500 km-long coast northward to the Orinoco River delta. The aim of this study is to give an encompassing view of the sediment dynamics in the shallow coastal waters from the Amazon River mouth to the Capes region (northern part of the Amapa region of Brazil and eastern part of French Guiana), where large mud banks are formed. Mud banks are the overarching features in the dynamics of the Amazon-Orinoco coast. They start migrating northward in the Capes region. Suspended Particulate Matter (SPM) concentrations were calculated from satellite products (MODIS Aqua and Terra) acquired over the period 2000-2013. The Census-X11 decomposition method used to discriminate short-term, seasonal and long-term time components of the SPM variability has rendered possible a robust analysis of the impact of continental and oceanic forcing. Continental forcing agents considered are the Amazon River water discharge, SPM concentration and sediment discharge. Oceanic forcing comprises modelled data of wind speed and direction, wave height and direction, and currents. A 150 km-long area of accretion is detected at Cabo Norte that may be linked with a reported increase in the river's sediment discharge concurrent with the satellite data study period. We also assess the rate of mud bank migration north of Cabo Norte, and highlight its variability. Although we confirm a 2 km y-1 migration rate, in agreement with other authors, we show that this velocity may be up to 5 km y-1 along the Cabo Orange region, and we highlight the effect of water discharge by major rivers debouching on this coastal mud belt in modulating such rates. Finally, we propose a refined sediment transport pattern map of the region based on our results and of previous studies in the area such as the AMASSEDS programme, and discuss the relationship between sediment transport and accumulation patterns and the coastal geomorphology of this region.

Seasonal uranium distributions in the coastal waters off the Amazon and Mississippi Rivers

USGS Publications Warehouse

Swarzenski, P.W.; McKee, B.A.

1998-01-01

The chemical reactivity of uranium was investigated across estuarine gradients from two of the world's largest river systems: the Amazon and Mississippi. Concentrations of dissolved (<0.45 ??m) uranium (U) were measured in surface waters of the Amazon shelf during rising (March 1990), flood (June 1990) and low (November 1991) discharge regimes. The dissolved U content was also examined in surface waters collected across estuarine gradients of the Mississippi outflow region during April 1992, August 1993, and November (1993). All water samples were analyzed for U by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS). In Amazon shelf surface waters uranium increased nonconservatively from about 0.01 ??g l-1 at the river's mouth to over 3 ??g l-1 at the distal site, irrespective of river discharge stage. Observed large-scale U removal at salinities generally less than 15 implies a) that riverine dissolved U was extensively adsorbed by freshly-precipitated hydrous metal oxides (e.g., FeOOH, MnO2) as a result of flocculation and aggregation, and b) that energetic resuspension and reworking of shelf sediments and fluid muds on the Amazon shelf released a chemically reactive particle/colloid to the water column which can further scavenge dissolved U across much of the estuarine gradient. In contrast, the estuarine chemistry of U is inconclusive within surface waters of the Mississippi shelf-break region. U behavior is most likely controlled less by traditional sorption and/or desorption reactions involving metal oxides or colloids than by the river's variable discharge regime (e.g., water parcel residence time during estuarine mixing, nature of particulates, sediment storage and resuspension in the confined lower river), and plume dispersal. Mixing of the thin freshwater lens into ambient seawater is largely defined by wind-driven rather than physical processes. As a consequence, in the Mississippi outflow region uranium predominantly displays ConserVative behavior; removal is evident only during anomalous river discharge regimes. 'Products-approach' mixing experiments conducted during the Flood of 1993 suggest the importance of small particles and/or colloids in defining a depleted U versus salinity distribution.

Contribution of rivers and floodplains to the global terrestrial water storage variability

NASA Astrophysics Data System (ADS)

Getirana, A.; Kumar, S.; Girotto, M.; Rodell, M.

2017-12-01

Since the launch of the GRACE mission in 2002, the scientific community has gained significant insight into terrestrial water storage (TWS) variations around the world. Still, understanding of the relationship between TWS variations and changes in its individual components (groundwater, soil moisture, surface waters, snow, and vegetation water storage) has not advanced beyond small-scale studies based on in situ data. Although a few studies have demonstrated the impact that surface water storage (SWS) has on TWS in tropical basins, the vast majority of investigations on TWS decomposition systematically neglect SWS by assuming that its contribution to TWS is trivial. Even though that assumption might be a close representation of the truth in specific locations, the actual impact of SWS on the global TWS change and its spatial variability is unknown. This study aims to quantify the contribution of rivers and floodplains on the global terrestrial water storage (TWS) variability. We use state-of-the-art models to simulate land surface processes and river dynamics in order to separate TWS into its main components. Based on a proposed impact index, we show that surface water storage (SWS) contributes to 7% of TWS globally, but that contribution highly varies spatially. The primary contribution of SWS to TWS is in the tropics, and in major rivers flowing over arid regions or at high latitudes. About 20-23% of both Amazon and Nile basins' TWS changes are due to SWS. SWS has low impact in Western U.S., Northern Africa, Middle-East and central Asia. Based on comparisons against GRACE-based estimates, we conclude that using SWS significantly improves TWS simulations in most South America, Africa and Northern India, confirming the need for SWS as a key component of TWS change.

Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basins

USGS Publications Warehouse

Winemiller, K.O.; Lopez-Fernandez, H.; Taphorn, D.C.; Nico, L.G.; Duque, A.B.

2008-01-01

Aim: The aim of this study was to determine whether the Casiquiare River functions as a free dispersal corridor or as a partial barrier (i.e. filter) for the interchange of fish species of the Orinoco and Negro/Amazon basins using species assemblage patterns according to geographical location and environmental features. Location: The Casiquiare, Upper Orinoco and Upper Negro rivers in southern Venezuela, South America. Methods: Our study was based on an analysis of species presence/absence data and environmental information (11 habitat characteristics) collected by the authors and colleagues between the years 1984 and 1999. The data set consisted of 269 sampled sites and 452 fish species (> 50,000 specimens). A wide range of habitat types was included in the samples, and the collection sites were located at various points along the entire length of the Casiquiare main channel, at multiple sites on its tributary streams, as well as at various nearby sites outside the Casiquiare drainage, within the Upper Orinoco and Upper Rio Negro river systems. Most specimens and field data used in this analysis are archived in the Museo de Ciencias Naturales in Guanare, Venezuela. We performed canonical correspondence analysis (CCA) based on species presence/absence using two versions of the data set: one that eliminated sites having < 5 species and species occurring at < 5 sites; and another that eliminated sites having < 10 species and species occurring at < 10 sites. Cluster analysis was performed on sites based on species assemblage similarity, and a separate analysis was performed on species based on CCA loadings. Results: The CCA results for the two versions of the data set were qualitatively the same. The dominant environmental axis contrasted assemblages and sites associated with blackwater vs. clearwater conditions. Longitudinal position on the Casiquiare River was correlated (r2 = 0.33) with CCA axis-1 scores, reflecting clearwater conditions nearer to its origin (bifurcation of the Orinoco) and blackwater conditions nearer to its mouth (junction with the Rio Negro). The second CCA axis was most strongly associated with habitat size and structural complexity. Species associations derived from the unweighted pair-group average clustering method and pair-wise squared Euclidean distances calculated from species loadings on CCA axes 1 and 2 showed seven ecological groupings. Cluster analysis of species assemblages according to watershed revealed a stronger influence of local environmental conditions than of geographical proximity. Main conclusions: Fish assemblage composition is more consistently associated with local environmental conditions than with geographical position within the river drainages. Nonetheless, the results support the hypothesis that the mainstem Casiquiare represents a hydrochemical gradient between clearwaters at its origin and blackwaters at its mouth, and as such appears to function as a semi-permeable barrier (environmental filter) to dispersal and faunal exchanges between the partially vicariant fish faunas of the Upper Orinoco and Upper Negro rivers. ?? 2008 The Authors.

Questioning the Influence of Sunspots on Amazon Hydrology: Even a Broken Clock Tells the Right Time Twice a Day

NASA Astrophysics Data System (ADS)

Baker, J. C. A.; Gloor, M.; Boom, A.; Neill, D. A.; Cintra, B. B. L.; Clerici, S. J.; Brienen, R. J. W.

2018-02-01

It was suggested in a recent article that sunspots drive decadal variation in Amazon River flow. This conclusion was based on a novel time series decomposition method used to extract a decadal signal from the Amazon River record. We have extended this analysis back in time, using a new hydrological proxy record of tree ring oxygen isotopes (δ18OTR). Consistent with the findings of Antico and Torres, we find a positive correlation between sunspots and the decadal δ18OTR cycle from 1903 to 2012 (r = 0.60, p < 0.001). However, the relationship does not persist into the preceding century and even becomes weakly negative (r = -0.30, p = 0.11, 1799-1902). This result casts considerable doubt over the mechanism by which sunspots are purported to influence Amazon hydrology.

The phylogeography of Amazonia revisited: new evidence from riodinid butterflies.

PubMed

Hall, Jason P W; Harvey, Donald J

2002-07-01

A fully resolved cladogram for 19 species in the Charis cleonus group of riodinid butterflies, which have closely parapatric ranges throughout the Amazon basin, is used to derive an area cladogram for the region. This represents the first comprehensive species-level analysis using insects and results in a hypothesis of Amazonian area relationships that is the most detailed to date. The Charis area cladogram is interpreted as supporting an historical vicariant split between the Guianas and the remainder of the Amazon and then between the upper and lower Amazon. The latter two clades can be further divided into the six most widely recognized areas of endemism and even smaller endemic centers within these, some of which, especially along the Madeira and lower Amazon Rivers, have never been previously hypothesized for butterflies. The overall pattern of historical interrelationships indicated is Guiana + ((Rondĵnia + (Pará + Belém)) + (Imeri + (Napo + Inambari))). The area relationships for riodinid butterflies show substantial congruence with those presented from the literature for amphibians, reptiles, birds, primates, rodents, and marsupials, suggesting a common vicariant history for these organisms. A summary area cladogram generated by combining area cladograms for all the aforementioned groups of organisms indicated the pattern of historical interrelationships to be (Guiana + (Rondĵnia + (Pará + Belém))) + (Imeri + (Napo + Inambari)). Charis cleonus group species distributions are noticeably larger around the upland periphery of Amazonia and smaller in the central and lower regions. A significant positive correlation between the proportion of range area above 100 m and total range size for each species is used to suggest that past sea-level rises may explain smaller range sizes in low-lying regions and that riverine barriers have been important in shaping the current distribution of C. cleonus group species.

Ethnography of a parasite: A quantitative ethnographic observation of forest malaria in the Amazon basin.

PubMed

Feged-Rivadeneira, Alejandro; Evans, Sian

2018-05-01

Malaria in the Amazon basin is persistently more prevalent among low density populations (1-4 people/[Formula: see text]). Describing malaria transmission in small populations, such as ethnic minorities in the Amazon basin, living in reserves in groups that amount to 110-450 individuals, is fundamental for the implementation of adequate interventions. Here, we examine malaria transmission in a context of high prevalence in a small population of Nükak ethnicity (ethnic group [Formula: see text] individuals, study group, [Formula: see text] individuals) living in the peri-urban area of a city with [Formula: see text] inhabitants in the Amazon basin. Using methods from behavioral ecology, we conducted a quantitative ethnography and collected data to inform of individual behavioral profiles. Individual malarial infection reports were available from the local public health offices, so each behavioral profile was associated with an epidemic profile for the past 5 years. Our research shows that, in-line with current opinion, malaria among the Nükak is not associated with an occupational hazard risk and follows a holoendemic pattern, where children are most susceptible to the parasite. Parasite loads of malarial infection among the Nükak persist at much higher rates than in any other neighboring ethnicity, which indicates an association between high incidence rates and endemicity. We hypothesize that malarial infection in the forest follows a pattern where the parasite persists in pockets of holoendemicity, and occupational hazard risk for individuals outside those pockets is associated with behaviors that take place in the proximity of the pockets of endemicity.

Earth observation taken by the Expedition 20 crew

NASA Image and Video Library

2009-08-25

ISS020-E-034693 (25 Aug. 2009) --- Lake Erepecu and Rio Trombetas in Brazil are featured in this sun glint image photographed by an Expedition 20 crew member on the International Space Station. The 38 kilometers long Lake Erepecu runs parallel to the lower Rio (river) Trombetas which snakes along the lower half of this photograph. Waterbodies in the Amazon rainforest are often so dark they can be difficult to distinguish. In this image, however, the lake and river stand out from the uniform green of the forest in great detail as a result of sun glint on the water surface. Sun glint is light reflected off of a surface directly back towards the viewer, in this case a crew member onboard the space station. Soil color beneath the forest is red, as shown by airfield clearings near Porto Trombetas (upper left), a river port on the south side of the Trombetas River. The Trombetas flows into the Amazon River from the north about 800 kilometers from the Amazon mouth. Despite being so far from the sea, seagoing ore ships export most of Brazil?s bauxite from Porto Trombetas. Bauxite is the raw material formed in these tropical soils for the production of aluminum (the Trombetas bauxite mine is outside the upper margin of the image). Central Amazonia has many lakes like Erepecu?relatively straight, large waterbodies located just off the main axis of the large rivers. These lakes, as distinct from smaller floodplain lakes next to the large rivers, were created as rivers cut down during the repeated low global sea levels of the recent geological past (according to scientists, related to the ice ages of the last 1.7 million years). River water filled the valleys to form lakes during intervening periods of high sea level. Many larger rivers like the Trombetas and Amazon carried enough sediment to fill their immediate valleys?rivers flowing in unconsolidated sediment produce sinuous courses like those along the upper part of the image?but not enough to fill tributary valleys further from the axis of flow, so that lakes like Erepecu are formed.

Description of Lutzomyia (Trichophoromyia) nautaensis n. sp. (Diptera: Psychodidae) from the Peruvian Amazon Basin.

PubMed

Fernandez, Roberto; Lopez, Victor; Cardenas, Roldan; Requena, Edwin

2015-07-01

A new species of sand fly, which we describe as Lutzomyia (Trichophoromyia) nautaensis n. sp., was collected in the northern Peruvian Amazon Basin. In this region of Peru, cutaneous leishmaniasis is transmitted primarily by anthropophilic sand flies; however, zoophilic sand flies of the subgenus Trichophoromyia may also be incriminated in disease transmission. Detection of Leishmania spp. in Lutzomyia auraensis Mangabeira captured in the southern Peruvian Amazon indicates the potential of this and other zoophilic sand flies for human disease transmission, particularly in areas undergoing urban development. Herein, we describe Lutzomyia (Trichophoromyia) nautaensis n. sp., and report new records of sand flies in Peru. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

Multi-decadal Hydrological Retrospective: Case study of Amazon floods and droughts

NASA Astrophysics Data System (ADS)

Wongchuig Correa, Sly; Paiva, Rodrigo Cauduro Dias de; Espinoza, Jhan Carlo; Collischonn, Walter

2017-06-01

Recently developed methodologies such as climate reanalysis make it possible to create a historical record of climate systems. This paper proposes a methodology called Hydrological Retrospective (HR), which essentially simulates large rainfall datasets, using this as input into hydrological models to develop a record of past hydrology, making it possible to analyze past floods and droughts. We developed a methodology for the Amazon basin, where studies have shown an increase in the intensity and frequency of hydrological extreme events in recent decades. We used eight large precipitation datasets (more than 30 years) as input for a large scale hydrological and hydrodynamic model (MGB-IPH). HR products were then validated against several in situ discharge gauges controlling the main Amazon sub-basins, focusing on maximum and minimum events. For the most accurate HR, based on performance metrics, we performed a forecast skill of HR to detect floods and droughts, comparing the results with in-situ observations. A statistical temporal series trend was performed for intensity of seasonal floods and droughts in the entire Amazon basin. Results indicate that HR could represent most past extreme events well, compared with in-situ observed data, and was consistent with many events reported in literature. Because of their flow duration, some minor regional events were not reported in literature but were captured by HR. To represent past regional hydrology and seasonal hydrological extreme events, we believe it is feasible to use some large precipitation datasets such as i) climate reanalysis, which is mainly based on a land surface component, and ii) datasets based on merged products. A significant upward trend in intensity was seen in maximum annual discharge (related to floods) in western and northwestern regions and for minimum annual discharge (related to droughts) in south and central-south regions of the Amazon basin. Because of the global coverage of rainfall datasets, this methodology can be transferred to other regions for better estimation of future hydrological behavior and its impact on society.

Precipitation recycling in the Amazon basin

NASA Technical Reports Server (NTRS)

Eltahir, E. A. B.; Bras, R. L.

1994-01-01

Precipitation recycling is the contribution of evaporation within a region to precipitation in that same region. The recycling rate is a diagnostic measure of the potential for interactions between land surface hydrology and regional climate. In this paper we present a model for describing the seasonal and spatial variability of the recycling process. The precipitation recycling ratio, rho, is the basic variable in describing the recycling process. Rho is the fraction of precipitation at a certain location and time which is contributed by evaporation within the region under study. The recycling model is applied in studyiing the hydrologic cycle in the Amazon basin. It is estimated that about 25% of all the rain that falls in the Amazon basin is contributed by evaporation within the basin. This estimate is based on analysis of a data set supplied by the European Centre for Medium-range Weather Forecasts (ECMWF). The same analysis is repeated using a different data set from the Geophysical Fluid Dynamics Laboratory (GFDL). Based on this data set, the recycling ratio is estimated to be 35%. The seasonal variability of the recycling ratio is small compared with the yearly average. The new estimates of the recycling ratio are compared with results of previous studies, and the differences are explained.

Land Use Change Increases Streamflow Across the Arc of Deforestation in Brazil

NASA Astrophysics Data System (ADS)

Levy, M. C.; Lopes, A. V.; Cohn, A.; Larsen, L. G.; Thompson, S. E.

2018-04-01

Nearly half of recent decades' global forest loss occurred in the Amazon and Cerrado (tropical savanna) biomes of Brazil, known as the arc of deforestation. Despite prior analysis in individual river basins, a generalizable empirical understanding of the effect of deforestation on streamflow across this region is lacking. We frame land use change in Brazil as a natural experiment and draw on in situ and remote sensing evidence in 324 river basins covering more than 3 × 106 km2 to estimate streamflow changes caused by deforestation and agricultural development between 1950 and 2013. Deforestation increased dry season low flow by between 4 and 10 percentage points (relative to the forested condition), corresponding to a regional- and time-averaged rate of increase in specific streamflow of 1.29 mm/year2, equivalent to a 4.08 km3/year2 increase, assuming a stationary climate. In conjunction with rainfall and temperature variations, the net (observed) average increase in streamflow over the same period was 0.76 mm/year2, or 2.41 km3/year2. Thus, net increases in regional streamflow in the past half century are 58% of those that would have been experienced with deforestation given a stationary climate. This study uses a causal empirical analysis approach novel to the water sciences to verify the regional applicability of prior basin-scale studies, provides a proof of concept for the use of observational causal identification methods in the water sciences, and demonstrates that deforestation masks the streamflow-reducing effects of climate change in this region.

A new species of Pseudocrepidobothrium (Cestoda: Proteocephalidea) from Pseudoplatystoma reticulatum (Pisces: Siluriformes) in the Paraná River basin (Argentina).

PubMed

Arredondo, Nathalia J; De Pertierra, Alicia A Gil; De Chambrier, Alain

2014-10-01

This study describes the proteocephalidean tapeworm Pseudocrepidobothrium chanaorum sp. n. (Proteocephalidae: Proteocephalinae), which was found in the intestine of Pseudoplatystoma reticulatum (Eigenmann et Eigenmann) from the Colastiné River, a tributary of the Paraná River. The new species differs from the two other species of the genus, P. eirasi (Rego et de Chambrier, 1995) and P. ludovici Ruedi et de Chambrier, 2012, parasites of Phractocephalus hemioliopterus (Bloch et Schneider) from the Amazon River in Brazil, in having fewer proglottides (4-8 without ventral appendages vs 7-12 with ventral appendages and 20-36 without ventral appendages, respectively), a smaller scolex (350-450 μm wide vs 495-990 μm and 515-1020 μm wide, respectively), in the total number of testes (21-25 vs 21-51 and 37-79, respectively), a cirrus-sac usually directed anteriorly if the vagina is posterior to the cirrus-sac vs transversely situated in the known species. The study of the tegumental surface of Pseudocrepidobothrium spp. revealed the presence of four types of microtriches: papilliform, acicular and capilliform filitriches, and gladiate spinitriches. The three species have a similar microthrix pattern, with minor differences on the immature proglottis surface. Pseudocrepidobothrium chanaorum sp. n. is the ninth proteocephalid reported from P. reticulatum.

A direct estimate of evapotranspiration over the Amazon basin and implications for our understanding of carbon and water cycling

NASA Astrophysics Data System (ADS)

Swann, A. L. S.; Koven, C.; Lombardozzi, D.; Bonan, G. B.

2017-12-01

Evapotranspiration (ET) is a critical term in the surface energy budget as well as the water cycle. There are few direct measurements of ET, and thus the magnitude and variability is poorly constrained at large spatial scales. Estimates of the annual cycle of ET over the Amazon are critical because they influence predictions of the seasonal cycle of carbon fluxes, as well as atmospheric dynamics and circulation. We estimate ET for the Amazon basin using a water budget approach, by differencing rainfall, discharge, and time-varying storage from the Gravity Recovery and Climate Experiment. We find that the climatological annual cycle of ET over the Amazon basin upstream of Óbidos shows suppression of ET during the wet season, and higher ET during the dry season, consistent with flux tower based observations in seasonally dry forests. We also find a statistically significant decrease in ET over the time period 2002-2015 of -1.46 mm/yr. Our direct estimate of the seasonal cycle of ET is largely consistent with previous indirect estimates, including energy budget based approaches, an up-scaled station based estimate, and land surface model estimates, but suggests that suppression of ET during the wet season is underestimated by existing products. We further quantify possible contributors to the phasing of the seasonal cycle and downward time trend using land surface models.

Introduction: Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5)

NASA Astrophysics Data System (ADS)

Martin, S. T.; Artaxo, P.; Machado, L. A. T.; Manzi, A. O.; Souza, R. A. F.; Schumacher, C.; Wang, J.; Andreae, M. O.; Barbosa, H. M. J.; Fan, J.; Fisch, G.; Goldstein, A. H.; Guenther, A.; Jimenez, J. L.; Pöschl, U.; Silva Dias, M. A.; Smith, J. N.; Wendisch, M.

2016-04-01

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin for 2 years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, the pollution plume from the Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as the introduction to the special issue of GoAmazon2014/5, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G-1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the 2-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. The G-1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year-round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This introduction also organizes information relevant to many papers in the special issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorologies relevant to the two IOPs are presented. Regional and long-range transport of emissions during the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5 as presented in this introduction, research articles including thematic overview articles are anticipated in this special issue to describe the detailed results and findings of the GoAmazon2014/5 Experiment.

Relationship of tooth wear to chronological age among indigenous Amazon populations.

PubMed

Vieira, Elma Pinto; Barbosa, Mayara Silva; Quintão, Cátia Cardoso Abdo; Normando, David

2015-01-01

In indigenous populations, age can be estimated based on family structure and physical examination. However, the accuracy of such methods is questionable. The aim of this cross-sectional study was to evaluate occlusal tooth wear related to estimated age in the remote indigenous populations of the Xingu River, Amazon. Two hundred and twenty three semi-isolated indigenous subjects with permanent dentition from the Arara (n = 117), Xicrin-Kayapó (n = 60) and Assurini (n = 46) villages were examined. The control group consisted of 40 non-indigenous individuals living in an urban area in the Amazon basin (Belem). A modified tooth wear index was applied and then associated with chronological age by linear regression analysis. A strong association was found between tooth wear and chronological age in the indigenous populations (p <0.001). Tooth wear measurements were able to explain 86% of the variation in the ages of the Arara sample, 70% of the Xicrin-Kaiapó sample and 65% of the Assurini sample. In the urban control sample, only 12% of ages could be determined by tooth wear. These findings suggest that tooth wear is a poor estimator of chronological age in the urban population; however, it has a strong association with age for the more remote indigenous populations. Consequently, these findings suggest that a simple tooth wear evaluation method, as described and applied in this study, can be used to provide a straightforward and efficient means to assist in age determination of newly contacted indigenous groups.

Relationship of Tooth Wear to Chronological Age among Indigenous Amazon Populations

PubMed Central

Vieira, Elma Pinto; Barbosa, Mayara Silva; Quintão, Cátia Cardoso Abdo; Normando, David

2015-01-01

In indigenous populations, age can be estimated based on family structure and physical examination. However, the accuracy of such methods is questionable. The aim of this cross-sectional study was to evaluate occlusal tooth wear related to estimated age in the remote indigenous populations of the Xingu River, Amazon. Two hundred and twenty three semi-isolated indigenous subjects with permanent dentition from the Arara (n = 117), Xicrin-Kayapó (n = 60) and Assurini (n = 46) villages were examined. The control group consisted of 40 non-indigenous individuals living in an urban area in the Amazon basin (Belem). A modified tooth wear index was applied and then associated with chronological age by linear regression analysis. A strong association was found between tooth wear and chronological age in the indigenous populations (p <0.001). Tooth wear measurements were able to explain 86% of the variation in the ages of the Arara sample, 70% of the Xicrin-Kaiapó sample and 65% of the Assurini sample. In the urban control sample, only 12% of ages could be determined by tooth wear. These findings suggest that tooth wear is a poor estimator of chronological age in the urban population; however, it has a strong association with age for the more remote indigenous populations. Consequently, these findings suggest that a simple tooth wear evaluation method, as described and applied in this study, can be used to provide a straightforward and efficient means to assist in age determination of newly contacted indigenous groups. PMID:25602501

Patterns of Geographic Expansion of Aedes aegypti in the Peruvian Amazon

PubMed Central

Guagliardo, Sarah Anne; Barboza, José Luis; Morrison, Amy C.; Astete, Helvio; Vazquez-Prokopec, Gonzalo; Kitron, Uriel

2014-01-01

Background and Objectives In the Peruvian Amazon, the dengue vector Aedes aegypti is abundant in large urban centers such as Iquitos. In recent years, it has also been found in a number of neighboring rural communities with similar climatic and socioeconomic conditions. To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities. Methods We conducted pupal-demographic surveys and deployed ovitraps in 34 communities surrounding the city of Iquitos. Communities surveyed were located along two transects: the Amazon River and a 95km highway. We calculated entomological indices, mapped Ae. aegypti presence, and developed univariable and multivariable logistic regression models to predict Ae. aegypti presence at the community, household, or container level. Results Large communities closer to Iquitos were more likely to be infested with Ae. aegypti. Within infested communities, houses with Ae. aegypti had more passively-filled containers and were more often infested with other mosquito genera than houses without Ae. aegypti. For containers, large water tanks/drums and containers with solar exposure were more likely to be infested with Ae. aegypti. Maps of Ae. aegypti presence revealed a linear pattern of infestation along the highway, and a scattered pattern along the Amazon River. We also identified the geographical limit of Ae. aegypti expansion along the highway at 19.3 km south of Iquitos. Conclusion In the Peruvian Amazon, Ae. aegypti geographic spread is driven by human transportation networks along rivers and highways. Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads. Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats. PMID:25101786

Patterns of geographic expansion of Aedes aegypti in the Peruvian Amazon.

PubMed

Guagliardo, Sarah Anne; Barboza, José Luis; Morrison, Amy C; Astete, Helvio; Vazquez-Prokopec, Gonzalo; Kitron, Uriel

2014-08-01

In the Peruvian Amazon, the dengue vector Aedes aegypti is abundant in large urban centers such as Iquitos. In recent years, it has also been found in a number of neighboring rural communities with similar climatic and socioeconomic conditions. To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities. We conducted pupal-demographic surveys and deployed ovitraps in 34 communities surrounding the city of Iquitos. Communities surveyed were located along two transects: the Amazon River and a 95 km highway. We calculated entomological indices, mapped Ae. aegypti presence, and developed univariable and multivariable logistic regression models to predict Ae. aegypti presence at the community, household, or container level. Large communities closer to Iquitos were more likely to be infested with Ae. aegypti. Within infested communities, houses with Ae. aegypti had more passively-filled containers and were more often infested with other mosquito genera than houses without Ae. aegypti. For containers, large water tanks/drums and containers with solar exposure were more likely to be infested with Ae. aegypti. Maps of Ae. aegypti presence revealed a linear pattern of infestation along the highway, and a scattered pattern along the Amazon River. We also identified the geographical limit of Ae. aegypti expansion along the highway at 19.3 km south of Iquitos. In the Peruvian Amazon, Ae. aegypti geographic spread is driven by human transportation networks along rivers and highways. Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads. Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats.

Proceedings of the Department of Defense (DoD) Symposium. DoD Entomology: Global, Diverse, and Improving Public Health

DTIC Science & Technology

2010-12-14

Parasitology in the Amazon city of Iquitos, Peru , where NAMRU-6 has 90 permanent field and laboratory staff. Over 10 years of research have focused on...laboratory in Iquitos, Peru , a city of approximately 380,000 people (INEI 2008) in the Amazon Basin (Figures 3 and 4). The mission of NAMRU-6 is... Amazon Malaria Initiative and a military-to-military training program in Peru , Ecuador, and Colombia (Figure 5). NAMRU-6 Entomology has been

Effects of Point Mutations in Plasmodium falciparum Dihydrofolate Reductase and Dihydropterate Synthase Genes on Clinical Outcomes and In Vitro Susceptibility to Sulfadoxine and Pyrimethamine

DTIC Science & Technology

2009-08-01

therapeutic efficacy of SP in two locations in the Amazon rainforest region of Peru, and to correlate the presence of molecular markers associated with...pyrimethamine at two locations in the Peruvian Amazon enrolling 99 patients of which, 86 patients completed the protocol specified 28 day follow up. Our...the Amazon basin, it may be possible to predict treatment failure with sulfadoxine- pyrimethamine equally well by determination of either of the

Tree rings and rainfall in the equatorial Amazon

NASA Astrophysics Data System (ADS)

Granato-Souza, Daniela; Stahle, David W.; Barbosa, Ana Carolina; Feng, Song; Torbenson, Max C. A.; de Assis Pereira, Gabriel; Schöngart, Jochen; Barbosa, Joao Paulo; Griffin, Daniel

2018-05-01

The Amazon basin is a global center of hydroclimatic variability and biodiversity, but there are only eight instrumental rainfall stations with continuous records longer than 80 years in the entire basin, an area nearly the size of the coterminous US. The first long moisture-sensitive tree-ring chronology has been developed in the eastern equatorial Amazon of Brazil based on dendrochronological analysis of Cedrela cross sections cut during sustainable logging operations near the Rio Paru. The Rio Paru chronology dates from 1786 to 2016 and is significantly correlated with instrumental precipitation observations from 1939 to 2016. The strength and spatial scale of the precipitation signal vary during the instrumental period, but the Rio Paru chronology has been used to develop a preliminary reconstruction of February to November rainfall totals from 1786 to 2016. The reconstruction is related to SSTs in the Atlantic and especially the tropical Pacific, similar to the stronger pattern of association computed for the instrumental rainfall data from the eastern Amazon. The tree-ring data estimate extended drought and wet episodes in the mid- to late-nineteenth century, providing a valuable, long-term perspective on the moisture changes expected to emerge over the Amazon in the coming century due to deforestation and anthropogenic climate change.

Particle size of sediments collected from the bed of the Amazon River and its tributaries in May and June 1977

USGS Publications Warehouse

Nordin, Carl F.; Meade, R.H.; Curtis, W.F.; Bosio, N.J.; Delaney, B.M.

1979-01-01

One-hundred-eight samples of bed material were collected from the Amazon River and its major tributaries between Belem, Brazil , and Iquitos, Peru. Samples were taken with a standard BM-54 sampler or with pipe dredges from May 18 to June 5, 1977. Most of the samples have median diameters in the size range of fine to medium sand and contain small percentages of fine gravel. Complete size distributions are tabulated. (Woodard-USGS)

Particle size of sediments collected from the bed of the Amazon River and its tributaries in June and July 1976

USGS Publications Warehouse

Nordin, Carl F.; Meade, R.H.; Mahoney, H.A.; Delany, B.M.

1977-01-01

Sixty-five samples of bed material were collected from the Amazon River and its major tributaries between Belem, Brazil, and Iquitos, Peru. Samples were taken with a standard BM-54 sampler, a pipe dredge, or a Helley-Smith bedload sampler. Most of the samples have median diameters in the size range of fine to medium sand and contain small percentages of fine gravel. Complete size distributions are tabulated.

Modified Streamflows 1990 Level of Irrigation : Missouri, Colorado, Peace and Slave River Basin, 1928-1989.

DOE Office of Scientific and Technical Information (OSTI.GOV)

A.G. Crook Company; United States. Bonneville Power Administration

1993-07-01

This report presents data for monthly mean streamflows adjusted for storage change, evaporation, and irrigation, for the years 1928-1990, for the Colorado River Basin, the Missouri River Basin, the Peace River Basin, and the Slave River Basin.

Regional aerosol chemistry of the Amazon Basin during the dry season

NASA Technical Reports Server (NTRS)

Talbot, R. W.; Harriss, R. C.; Andreae, M. O.; Andreae, T. W.

1988-01-01

The distribution and chemical composition of the atmospheric aerosol over the Amazon Basin forest were determined during the 1985 July-August dry season, using data on the aerosol chemical constituent concentration collected during the NASA Global Tropospheric Experiment Amazon Boundary Layer Experiment 2A mission. The results of the analyses suggest that there is a remarkable compositional and spatial homogeneity of the atmospheric aerosol on an extensive regional scale. Particulate organic carbon is the dominant component of the atmospheric aerosol, exhibiting an average concentration of about 740 nmol/cu m in the mixed layer and about 220 nmol/cu m in free tropospheric air. Oxalate and SO4(2-) exhibited the greatest enrichment in the mixed layer, while Cl(-) showed essentially no enrichment. The aerosol in the Amazonian atmosphere is essentially acid-base neutral, primarily as a result of incorporation of NH(+), which is presumably derived from NH3 released by the forest ecosystem.

Dispersal assembly of rain forest tree communities across the Amazon basin

PubMed Central

Lavin, Mathew; Torke, Benjamin M.; Twyford, Alex D.; Kursar, Thomas A.; Coley, Phyllis D.; Drake, Camila; Hollands, Ruth; Pennington, R. Toby

2017-01-01

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga. We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, Swartzia, Protieae, and Guatteria. Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin. PMID:28213498

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pedlowski, M.A.; Dale, V.H.

Road development and colonization projects have brought about wide-scale deforestation in the Brazilian Amazon. The state of Rondonia, located in the western Amazon Basin, best exemplifies the problems related to land-use changes because it has the highest rates of deforestation in the Amazon Basin. In order to identify the main land-use practices in Rondonia, interviews with local farmers were carried out in the central part of Rondonia, in the PIC (Integrated Colonization Project) Ouro Preto do Oeste. This is the oldest colonization project in the state. The governmental colonization programs attracted migrants to the area through the construction of roadsmore » and infrastructure necessary for the colonists to occupy the land for agricultural practices. The interviews were done on lots of the PIC Ouro Preto and in PAD Urupa to define the background of the colonists, their land-use practices, their economic situation, and their relationships with governmental institutions.« less

Land Use and Land Cover Change in Forest Frontiers: The Role of Household Life Cycles

NASA Technical Reports Server (NTRS)

Walker, Robert

2002-01-01

Tropical deforestation remains a critical issue given its present rate and a widespread consensus regarding its implications for the global carbon cycle and biodiversity. Nowhere is the problem more pronounced than in the Amazon basin, home to the world's largest intact, tropical forest. This article addresses land cover change processes at household level in the Amazon basin, and to this end adapts a concept of domestic life cycle to the current institutional environment of tropical frontiers. In particular, it poses a risk minimization model that integrates demography with market-based factors such as transportation costs and accessibility. In essence, the article merges the theory of Chayanov with the household economy framework, in which markets exist for inputs (including labor), outputs, and capital. The risk model is specified and estimated, using survey data for 261 small producers along the Transamazon Highway in the eastern sector of the Brazilian Amazon.

Dispersal assembly of rain forest tree communities across the Amazon basin.

PubMed

Dexter, Kyle G; Lavin, Mathew; Torke, Benjamin M; Twyford, Alex D; Kursar, Thomas A; Coley, Phyllis D; Drake, Camila; Hollands, Ruth; Pennington, R Toby

2017-03-07

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, Swartzia , Protieae, and Guatteria Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin.

Evapotranspiration estimation using a parameter-parsimonious energy partition model over Amazon basin

NASA Astrophysics Data System (ADS)

Xu, D.; Agee, E.; Wang, J.; Ivanov, V. Y.

2017-12-01

The increased frequency and severity of droughts in the Amazon region have emphasized the potential vulnerability of the rainforests to heat and drought-induced stresses, highlighting the need to reduce the uncertainty in estimates of regional evapotranspiration (ET) and quantify resilience of the forest. Ground-based observations for estimating ET are resource intensive, making methods based on remotely sensed observations an attractive alternative. Several methodologies have been developed to estimate ET from satellite data, but challenges remained in model parameterization and satellite limited coverage reducing their utility for monitoring biodiverse regions. In this work, we apply a novel surface energy partition method (Maximum Entropy Production; MEP) based on Bayesian probability theory and nonequilibrium thermodynamics to derive ET time series using satellite data for Amazon basin. For a large, sparsely monitored region such as the Amazon, this approach has the advantage methods of only using single level measurements of net radiation, temperature, and specific humidity data. Furthermore, it is not sensitive to the uncertainty of the input data and model parameters. In this first application of MEP theory for a tropical forest biome, we assess its performance at various spatiotemporal scales against a diverse field data sets. Specifically, the objective of this work is to test this method using eddy flux data for several locations across the Amazonia at sub-daily, monthly, and annual scales and compare the new estimates with those using traditional methods. Analyses of the derived ET time series will contribute to reducing the current knowledge gap surrounding the much debated response of the Amazon Basin region to droughts and offer a template for monitoring the long-term changes in global hydrologic cycle due to anthropogenic and natural causes.

Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

NASA Astrophysics Data System (ADS)

Gatti, L. V.; Gloor, M.; Miller, J. B.; Doughty, C. E.; Malhi, Y.; Domingues, L. G.; Basso, L. S.; Martinewski, A.; Correia, C. S. C.; Borges, V. F.; Freitas, S.; Braz, R.; Anderson, L. O.; Rocha, H.; Grace, J.; Phillips, O. L.; Lloyd, J.

2014-02-01

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48+/-0.18 petagrams of carbon per year (PgCyr-1) during the dry year but was carbon neutral (0.06+/-0.1PgCyr-1) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25+/-0.14PgCyr-1, which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39+/-0.10PgCyr-1 previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

Modern Environmental Changes on Amapa Coastal Plain under Amazon River Influence

NASA Astrophysics Data System (ADS)

Santos, V. F.; Figueiredo, A. G.; Silveira, O. M.; Polidori, L.

2007-05-01

The Amazonian coastal environment is very dynamic compared to other coasts. It is situated at the edge of the Earth's largest forest, and is segmented by fluvial systems, with the biggest being the Amazon River. The rivers are particularly influenced by the Intertropical Convergence Zone (ITCZ), which controls the water and particle discharge, and the flooding regime. Moderate and strong El Nino conditions correlate with low-precipitation periods, and La Nina events cause precipitation to increase. These variables and others related to the Amazon dispersal system create an interesting area for the study of global and regional environmental changes. The Araguari River floodplain on the Amapa coast is influenced by natural processes of global scale such as ENSO events and ITCZ, and by local processes such as Amazon River discharge, tides and tidal bore (pororoca). Anthropogenic processes such as extensive water-buffalo farming also promote environmental changes. Time- series analyses of remote sensing images and suspended sediment have shown that the maximum turbidity zone inside Araguari River is related to the pororoca phenomenon. The pororoca remobilizes sediment from the river bottom and margins, developing sediment suspension >15 g/l as it passes - creating fluid muds. The pororoca also introduces Amazon- and shelf-derived sediment into the Araguari estuary. Measurements during eight spring-tide cycles indicate erosion of 3 cm of consolidated mud and deposition of 1 cm. The pororoca also influences the remobilization and cycling of nutrients and consequently affects the distribution of benthic organisms, including benthonic foraminifera and thecamoebians. For more than a century, the coastal plain has had water-buffalo farming (>42,000 animals today), which modifies the drainage system and affects sedimentary processes. Areas with more buffalo trails have higher suspended-sediment concentration (SSC) during the dry season and lower SSC during the rainy season. This relationship is reversed in drainages without the influence of the herd. The development of small channels, one meter deep by one meter wide, induced by the buffalos can evolve into a large drainage network in a short period of time. The Santana Creek started as a buffalo trail and in three decades it evolved into a network with a main channel 200 m wide and 6 km long. Despite the Amazon River having the largest influence in the region, the Araguari River also has a considerable water discharge of 2.4x103 m3/s and particulate discharge of 7x105 tons/y, and is able to impose changes to the Amapa coastal environments and inner shelf. The natural closure of the Araguari north arm during middle of the 19th century has induced the development of a wide coastal plain in the Cape Norte region, and decreased fresh water to the Carapaporis channel. On the other hand, deforestation for farm development and buffalo farming has influenced the hydrologic regime, sediment and nutrient balance.

Neotropical Monogenoidea. 56. New species of Anacanthorus (Dactylogyridae) from the gills of matrinchã, Brycon orthotaenia (Characiformes: Characidae), in the Rio São Francisco, Brazil.

PubMed

Monteiro, Cassandra M; Kritsky, Delane C; Brasil-Sato, Marilia C

2010-09-01

Anacanthorus franciscanus sp. n. and Anacanthorus brevicirrus sp. n. (Dactylogyridae) are described from the gills of the matrinchã, Brycon orthotaenia Günther (Characidae), from the Rio São Francisco in Brazil. Anacanthorusfranciscanus most closely resembles Anacanthorus e[egans and A. kruidenieri from the matrinchõ, Brycon melanopterus, of the Amazon River Basin. It differs from these species in part by having the bulbous proximal end of the hook shank with two translucent regions. Anacanthorus brevicirrus resembles A. franciscanus, A. kruidenieri and A. elegans but is differentiated from these species by its short straight male copulatory organ and by having one translucent region in the bulbous base of the hook shank.

Characterization of Particle Backscattering of Global Highly Turbid Waters From VIIRS Ocean Color Observations

NASA Astrophysics Data System (ADS)

Shi, Wei; Wang, Menghua

2017-11-01

Normalized water-leaving radiance spectra nLw(λ) at the near-infrared (NIR) from five years of observations (2012-2016) with the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) are used to derive the particle backscattering coefficients bbp(λ) for global highly turbid coastal and inland waters. Based on the fact that the absorption coefficient of sea water aw(λ) is generally much larger than those of the other constituents aiop(λ) at the NIR wavelengths in coastal and inland waters, an NIR-based bbp(λ) algorithm for turbid coastal and inland waters has been developed and used in this study. This algorithm can be safely used for highly turbid waters with nLw(745) and nLw(862) < ˜6 and ˜4 mW cm-2 μm-1 sr-1, respectively. Seasonal and interannual variations of bbp(λ) in China's east coastal region, the Amazon River Estuary, the La Plata River Estuary, the Meghna River Estuary, the Atchafalaya River Estuary, and Lake Taihu are characterized and quantified. The coefficient bbp(λ) can reach over ˜3-4 m-1 in the Amazon River Estuary and China's east coastal region. The Amazon River Estuary is identified as the most turbid region in the global ocean in terms of bbp(λ) magnitude. bbp(λ) spectra in these five highly turbid regions are also seasonal-dependent and regional-dependent. In the highly turbid waters of China's east coastal region and the Amazon River Estuary, bbp(λ) generally increases in wavelength from 410 to 862 nm, while it decreases in the La Plata River Estuary and Atchafalaya River Estuary. This is attributed to the different particle size distributions in these waters. The geophysical implication of the bbp(λ) spectral curvatures for different waters is discussed. To improve global bbp(λ) for both open oceans and coastal turbid waters, a new combined NIR-based and Quasi-Analytical Algorithm (QAA)-based bbp(λ) algorithm is proposed and demonstrated.

Methane emissions from floodplains in the Amazon Basin: challenges in developing a process-based model for global applications

NASA Astrophysics Data System (ADS)

Ringeval, B.; Houweling, S.; van Bodegom, P. M.; Spahni, R.; van Beek, R.; Joos, F.; Röckmann, T.

2014-03-01

Tropical wetlands are estimated to represent about 50% of the natural wetland methane (CH4) emissions and explain a large fraction of the observed CH4 variability on timescales ranging from glacial-interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This publication documents a first step in the development of a process-based model of CH4 emissions from tropical floodplains for global applications. For this purpose, the LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was slightly modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially explicit hydrology model PCR-GLOBWB. We introduced new plant functional types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote-sensing data sets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX reproduces the average magnitude of observed net CH4 flux densities for the Amazon Basin. However, the model does not reproduce the variability between sites or between years within a site. Unfortunately, site information is too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. Sensitivity analyses gave insights into the main drivers of floodplain CH4 emission and their associated uncertainties. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr-1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin, modulated emissions by about 20%. Correcting the LPX-simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the full dynamics in CH4 emissions but we proposed solutions to this issue. The interannual variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is accounted for, but still remains lower than in most of the WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results helped identify and prioritize directions towards more accurate estimates of tropical CH4 emissions, and they stress the need for more research to constrain floodplain CH4 emissions and their temporal variability, even before including other fundamental mechanisms such as floating macrophytes or lateral water fluxes.

Energy at the Junction of the Rivers Negro and Solimões, Contributors of the Amazon River, in the Brazilian Amazon

PubMed Central

de Souza, Paulo Kroeff

2014-01-01

The Negro and Solimoes rivers join in front of the Brazilian city of Manaus to form the Amazon River. This “meeting of the waters” is a natural phenomenon of great aesthetic beauty that has been the focus of attention of researchers all over the world in various scientific fields. The waters of the Negro are darker and warmer, while the waters of the Solimoes are lighter and cooler. These waters have very different characteristics and remain without mixing, flowing side by side for several miles. Some reports indicate a temperature gradient between the waters of the order of 6°C, which can be used in conjunction with very high flow rates delivered by the two rivers, with a heat engine operating on a thermodynamic cycle to provide electricity. This review paper identifies this energy resource and presents a preliminary assessment of the potential for power generation. A realistic assessment of the potential points to an available power of about 1 GW. It is clear that further studies are needed to accurately assess the available thermal gradient and its variation over time, to move forward in the design of the power converter, and to establish an appropriate location for a power plant. PMID:27437451

Using CDOM optical properties for estimating DOC concentrations and pCO 2 in the Lower Amazon River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valerio, Aline de Matos; Kampel, Milton; Vantrepotte, Vincent

Colored dissolved organic matter (CDOM) is largely responsible for the optical properties of freshwaters and coastal areas and can be used as a proxy to assess the non-optical carbon content as the dissolved organic carbon (DOC) and the partial pressure of carbon dioxide (pCO 2). Nevertheless, riverine studies that explores the former relationship are more challenging due to the spectral mixture caused by the high content of inorganic materials in the suspended sediment. Here we evaluate the spatial-temporal variability of CDOM, DOC and pCO 2, as well as the potential of CDOM absorption coefficient (aCDOM(412)) for estimating DOC concentration andmore » pCO 2 along the lower Amazon River. Our results revealed differences in the dissolved organic matter (DOM) quality between clear water (CW) tributaries and the Amazon River mainstem. A linear relationship between DOC and CDOM was observed when tributaries and mainstem are evaluated separately (Amazon waters: N=42, R2=0.74; CW: N= 13, R2 = 0.57). However, this linear relationship was not observed during periods of higher rainfall and river discharge, requiring a model specific to these time periods to be developed (N = 25, R2 = 0.58). A strong linear positive relation was found between aCDOM(412) and pCO 2( N=69, R2=0.65) along the lower river. pCO 2 was less affected by the optical difference between tributaries and mainstem water or by the presence of higher hygrometric conditions when compared to CDOM to DOC relationships. Including the river water temperature in the model improves our ability to estimate pCO 2 (N=69; R2 = 0.80). Our results also illustrate the complexity of DOM temporal dynamics in the lower Amazon River where the occurrence of extreme high and low discharge due to factors such as El Niño, can significantly alter the expected seasonal oscillation, as was the case during this study period. The ability to remotely assess both DOC and pCO 2 from CDOM optical properties highlight the importance of using remote sensing data for monitoring carbon dynamics in large running water systems worldwide.« less

Velocity-amplified microbial respiration rates in the lower Amazon River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Nicholas D.; Sawakuchi, Henrique O.; Neu, Va

2018-01-31

Most measurements of respiration rates in large tropical rivers do not account for the influence of river flow conditions on microbial activity. We developed a ship-board spinning incubation system for measuring O2 drawdown under different rotation velocities and deployed the system along the lower Amazon River during four hydrologic periods. Average respiration rates in incubation chambers rotated at 0.22 and 0.66 m s-1 were 1.4 and 2.4 times higher than stationary chambers, respectively. On average, depth-integrated respiration rates in chambers spun at 0.22 and 0.66 m s-1 accounted for 64 ± 22% and 104 ± 36% of CO2 outgassing rates,more » respectively, in mainstem sites. Continuous measurements of in situ pCO2 were also made along with cross-channel profiles of river velocity. A positive correlation between river velocity and pCO2 was observed along the lower river (r2=0.67-0.96) and throughout a tidal cycle.« less

Crew Earth Observations (CEO) taken during Expedition 9 over Brazil

NASA Image and Video Library

2004-07-20

ISS009-E-15488 (7 July 2004) --- Solimoes-Negro River confluence at Manaus, Amazonia is featured in this image photographed by an Expedition 9 crewmember on the International Space Station (ISS). The largest river on the planet, the Amazon, forms from the confluence of the Solimoes (the upper Amazon River) and the Negro at the Brazilian city of Manaus in central Amazonas. At the river conjunction, the muddy, tan colored waters of the Solimoes meet the “black” water of the Negro River. The unique mixing zone where the waters meet extends downstream through the rainforest for hundreds of kilometers, and is a famous attraction for tourists all over the world. It is the vast quantity of sediment eroded from the Andes Mountains that gives the Solimoes its tan color. By comparison, water in the Negro derives from the low jungles where reduced physical erosion of rock precludes mud entering the river. In place of sediment, organic matter from the forest floor stains the river the color of black tea.

Act No. 24994 of 19 January 1989. Basic Law on the Rural Development of the Peruvian Amazon Region.

PubMed

1989-01-01

This Act sets forth the government's policy on rural development of the Peruvian Amazon region. Major objectives of the Act include the promotion of new rural settlements in the Amazon region, the promotion of migration from the Andes to the Amazon region, and the stimulation of agriculture, livestock, and forestry activities in the Amazon region. The following are the means that the government will use, among others, to attain these goals: 1) the development of Population Displacement Programmes, which will give individual persons and families economic and logistic support in moving; 2) the establishment of Civic Colonizing Services, temporary mobile units, which will offer settlers health services, education services, technical assistance with respect to agriculture and livestock, and promotional credits; 3) the creation of the Council for Amazon River Transport to coordinate and recommend activities to improve river transport; 4) the granting to settlers of land, free education for their children, medical care, technical training and assistance with respect to agriculture, and a supply of seeds; 5) the exemption of certain investors from payment of income taxes; and 6) the granting of a wide range of incentives for agricultural production. The Act also creates a Council for Planning and Development in the Amazon Region to draw up and approve a Plan for the Development of the Amazon Region. It calls for the rational use of the natural resources of the Amazon Region in the framework of preserving the ecosystem and preventing its ruin and delegates to the regional governments the authority to enter into contracts on the use of forest materials and to undertake reforestation programs. Finally, the Act provides various guarantees for the native population, including guarantees with respect to land and preservation of ethnic and social identity.

An extensive reef system at the Amazon River mouth

PubMed Central

Moura, Rodrigo L.; Amado-Filho, Gilberto M.; Moraes, Fernando C.; Brasileiro, Poliana S.; Salomon, Paulo S.; Mahiques, Michel M.; Bastos, Alex C.; Almeida, Marcelo G.; Silva, Jomar M.; Araujo, Beatriz F.; Brito, Frederico P.; Rangel, Thiago P.; Oliveira, Braulio C. V.; Bahia, Ricardo G.; Paranhos, Rodolfo P.; Dias, Rodolfo J. S.; Siegle, Eduardo; Figueiredo, Alberto G.; Pereira, Renato C.; Leal, Camille V.; Hajdu, Eduardo; Asp, Nils E.; Gregoracci, Gustavo B.; Neumann-Leitão, Sigrid; Yager, Patricia L.; Francini-Filho, Ronaldo B.; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S.; Moreira, Ana P. B.; Oliveira, Louisi; Soares, Ana C.; Araujo, Lais; Oliveira, Nara L.; Teixeira, João B.; Valle, Rogerio A. B.; Thompson, Cristiane C.; Rezende, Carlos E.; Thompson, Fabiano L.

2016-01-01

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 106–km2 plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume’s eastward retroflection, conditions the existence of this extensive (~9500 km2) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth–ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes. PMID:27152336

An extensive reef system at the Amazon River mouth.

PubMed

Moura, Rodrigo L; Amado-Filho, Gilberto M; Moraes, Fernando C; Brasileiro, Poliana S; Salomon, Paulo S; Mahiques, Michel M; Bastos, Alex C; Almeida, Marcelo G; Silva, Jomar M; Araujo, Beatriz F; Brito, Frederico P; Rangel, Thiago P; Oliveira, Braulio C V; Bahia, Ricardo G; Paranhos, Rodolfo P; Dias, Rodolfo J S; Siegle, Eduardo; Figueiredo, Alberto G; Pereira, Renato C; Leal, Camille V; Hajdu, Eduardo; Asp, Nils E; Gregoracci, Gustavo B; Neumann-Leitão, Sigrid; Yager, Patricia L; Francini-Filho, Ronaldo B; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S; Moreira, Ana P B; Oliveira, Louisi; Soares, Ana C; Araujo, Lais; Oliveira, Nara L; Teixeira, João B; Valle, Rogerio A B; Thompson, Cristiane C; Rezende, Carlos E; Thompson, Fabiano L

2016-04-01

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (~9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.

Major shifts in Amazon wildlife populations from recent intensification of floods and drought.

PubMed

Bodmer, Richard; Mayor, Pedro; Antunez, Miguel; Chota, Kimberlyn; Fang, Tula; Puertas, Pablo; Pittet, Marlini; Kirkland, Maire; Walkey, Mike; Rios, Claudia; Perez-Peña, Pedro; Henderson, Peter; Bodmer, William; Bicerra, Andy; Zegarra, Joseph; Docherty, Emma

2018-04-01

In the western Amazon Basin, recent intensification of river-level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high-water seasons, and a drought occurred during the 2010 low-water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km 2 ) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish. © 2017 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

Reduced precipitation over large water bodies in the Brazilian Amazon shown from TRMM data

NASA Astrophysics Data System (ADS)

Paiva, Rodrigo Cauduro Dias; Buarque, Diogo Costa; Clarke, Robin T.; Collischonn, Walter; Allasia, Daniel Gustavo

2011-02-01

Tropical Rainfall Measurement Mission (TRMM) data show lower rainfall over large water bodies in the Brazilian Amazon. Mean annual rainfall (P), number of wet days (rainfall > 2 mm) (W) and annual rainfall accumulated over 3-hour time intervals (P3hr) were computed from TRMM 3B42 data for 1998-2009. Reduced rainfall was marked over the Rio Solimões/Amazon, along most Amazon tributaries and over the Balbina reservoir. In a smaller test area, a heuristic argument showed that P and W were reduced by 5% and 6.5% respectively. Allowing for TRMM 3B42 spatial resolution, the reduction may be locally greater. Analyses of diurnal rainfall patterns showed that rainfall is lowest over large rivers during the afternoon, when most rainfall is convective, but at night and early morning the opposite occurs, with increased rainfall over rivers, although this pattern is less marked. Rainfall patterns reported from studies of smaller Amazonian regions therefore exist more widely.

Exploring the Geomorphology of the Amazon's Planalto with Imaging Radar: Understanding the Origins of the Modern Amazon Basin

NASA Astrophysics Data System (ADS)

McDonald, K. C.; Campbell, K.; Islam, R.; Azarderakhsh, M.; Cracraft, J.

2013-12-01

Amazonia is Earth's most iconic center of biological diversity and endemism and, owing to its contributions to global systems ecology, is arguably Earth's most important terrestrial biome . Amazonia includes a vast landscape of mostly lowland rainforest found in Brazil, Peru, Colombia, Ecuador, Bolivia, and Venezuela. It harbors the world's highest species diversity, the largest fresh-water ecosystem in the world, and contributes substantially to shaping the Earth's atmospheric gasses and oceans and consequently its climate. Despite this global importance, we still have an incomplete understanding of how this biodiversity-rich biome developed over time. Knowing its history is crucially important for understanding how the short and long-term effects of biodiversity loss and climate change will impact the region, and the globe, in the future. Hence, we seek to understand the evolutionary and environmental-ecological history of Amazonia over the past 10 million years through a comparative approach that integrates across the disciplines of systematic biology, population biology, ecosystem structure and function, geology, Earth systems modeling and remote sensing, and paleoenvironmental history. During springtime 2013, the NASA/JPL airborne imaging radar, UAVSAR, conducted airborne studies over many regions of South America including portions of the western Amazon basin. We utilize UAVSAR imagery acquired over the Madre de Dios region of southeastern Peru in an assessment of the underlying geomorphology of the Amazon's planalto, its relationship to the current distribution of vegetation, and its relationship to geologic processes through deep time. In the late Neogene, the Amazonian lowlands comprised either a series of independent basins or a single sedimentary basin. The Amazonian planalto is variously described as either an erosional surface or a surface of deposition. We employ UAVSAR data collections to assess (1) the utility of these high quality imaging radar data for use in identifying associated geomorphologic features, and (2) UAVSAR's utility in aiding interpretation of ALOS PALSAR and SRTM datasets to support a basin-wide characterization. The results of the analysis will have a major impact on interpreting the evolutionary history of the Amazon Basin. We are grateful to Bruce Chapman, Naira Pinto, and the JPL UAVSAR team for supporting the planning and acquisition of the UAVSAR data, and to the NASA Biodiversity Program for providing funding to support the UAVSAR acquisitions. This work was carried out under a grant from the NASA Biodiversity Program and the NSF DIMENSIONS of Biodiversity Program.

Terrain Analysis Procedural Guide for Climate,

DTIC Science & Technology

1980-09-01

such as the Amazon Tropical Rain Forest Basin and the Congo Basin, the air is IN Singapore F always hot and damp, there are fre-30...to protect certain mele-annual evaporation rate. These lands are orological instruments from exposure tocharacterized by rainforest , jungle, and

Cloud characteristics, thermodynamic controls and radiative impacts during the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giangrande, Scott E.; Feng, Zhe; Jensen, Michael P.

Routine cloud, precipitation and thermodynamic observations collected by the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) and Aerial Facility (AAF) during the 2-year US Department of Energy (DOE) ARM Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign are summarized. These observations quantify the diurnal to large-scale thermodynamic regime controls on the clouds and precipitation over the undersampled, climatically important Amazon basin region. The extended ground deployment of cloud-profiling instrumentation enabled a unique look at multiple cloud regimes at high temporal and vertical resolution. This longer-term ground deployment, coupled with two short-term aircraft intensive observing periods, allowed new opportunitiesmore » to better characterize cloud and thermodynamic observational constraints as well as cloud radiative impacts for modeling efforts within typical Amazon wet and dry seasons.« less

Cloud characteristics, thermodynamic controls and radiative impacts during the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment

DOE PAGES

Giangrande, Scott E.; Feng, Zhe; Jensen, Michael P.; ...

2017-12-06

Routine cloud, precipitation and thermodynamic observations collected by the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) and Aerial Facility (AAF) during the 2-year US Department of Energy (DOE) ARM Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign are summarized. These observations quantify the diurnal to large-scale thermodynamic regime controls on the clouds and precipitation over the undersampled, climatically important Amazon basin region. The extended ground deployment of cloud-profiling instrumentation enabled a unique look at multiple cloud regimes at high temporal and vertical resolution. This longer-term ground deployment, coupled with two short-term aircraft intensive observing periods, allowed new opportunitiesmore » to better characterize cloud and thermodynamic observational constraints as well as cloud radiative impacts for modeling efforts within typical Amazon wet and dry seasons.« less

Efficiently approximating the Pareto frontier: Hydropower dam placement in the Amazon basin

USGS Publications Warehouse

Wu, Xiaojian; Gomes-Selman, Jonathan; Shi, Qinru; Xue, Yexiang; Garcia-Villacorta, Roosevelt; Anderson, Elizabeth; Sethi, Suresh; Steinschneider, Scott; Flecker, Alexander; Gomes, Carla P.

2018-01-01

Real–world problems are often not fully characterized by a single optimal solution, as they frequently involve multiple competing objectives; it is therefore important to identify the so-called Pareto frontier, which captures solution trade-offs. We propose a fully polynomial-time approximation scheme based on Dynamic Programming (DP) for computing a polynomially succinct curve that approximates the Pareto frontier to within an arbitrarily small > 0 on treestructured networks. Given a set of objectives, our approximation scheme runs in time polynomial in the size of the instance and 1/. We also propose a Mixed Integer Programming (MIP) scheme to approximate the Pareto frontier. The DP and MIP Pareto frontier approaches have complementary strengths and are surprisingly effective. We provide empirical results showing that our methods outperform other approaches in efficiency and accuracy. Our work is motivated by a problem in computational sustainability concerning the proliferation of hydropower dams throughout the Amazon basin. Our goal is to support decision-makers in evaluating impacted ecosystem services on the full scale of the Amazon basin. Our work is general and can be applied to approximate the Pareto frontier of a variety of multiobjective problems on tree-structured networks.

CCN numerical simulations for the GoAmazon with the OLAM model

NASA Astrophysics Data System (ADS)

Ramos-da-Silva, R.; Haas, R.; Barbosa, H. M.; Machado, L.

2015-12-01

Manaus is a large city in the center of the Amazon rainforest. The GoAmazon field project is exploring the region through various data collection and modeling to investigate in impacts of the urban polluted plume on the surrounding pristine areas. In this study a numerical model was applied to simulate the atmospheric dynamics and the Cloud Condensation Nucleai (CCN) concentrations evolution. Simulations with and without the urban plume was performed to identify its dynamics and local impacts. The results show that the land surface characteristics has important hole on the CCN distribution and rainfall over the region. At the south of Manaus the atmospheric dynamics is dominated by the cloud streets that are aligned with the trade winds and the Amazon River. At the north of Manaus, the Negro River produces the advection of a more stable atmosphere causing a higher CCN concentration on the boundary layer. Assuming a local high CCN concentration at the Manaus boundary layer region, the simulations show that the land-atmosphere interaction sets important dynamics on the plume. The model shows that the CCN plume moves along with the flow towards southwest of Manaus following the cloud streets and the river direction having the highest concentrations over the most stable water surface regions.

Beyond harm’s reach? Submersion of river turtle nesting areas and implications for restoration actions after Amazon hydropower development

PubMed Central

Michalski, Fernanda; Gibbs, James P.

2018-01-01

The global expansion of energy demands combined with abundant rainfall, large water volumes and high flow in tropical rivers have led to an unprecedented expansion of dam constructions in the Amazon. This expansion generates an urgent need for refined approaches to river management; specifically a move away from decision-making governed by overly generalized guidelines. For the first time we quantify direct impacts of hydropower reservoir establishment on an Amazon fresh water turtle. We conducted surveys along 150 km of rivers upstream of a new dam construction during the low water months that correspond to the nesting season of Podocnemis unifilis in the study area. Comparison of nest-areas before (2011, 2015) and after (2016) reservoir filling show that reservoir impacts extend 13% beyond legally defined limits. The submerged nesting areas accounted for a total of 3.8 ha of nesting habitat that was inundated as a direct result of the reservoir filling in 2016. Our findings highlight limitations in the development and implementation of existing Brazilian environmental impact assessment process. We also propose potential ways to mitigate the negative impacts of dams on freshwater turtles and the Amazonian freshwater ecosystems they inhabit. PMID:29333347

Beyond harm's reach? Submersion of river turtle nesting areas and implications for restoration actions after Amazon hydropower development.

PubMed

Norris, Darren; Michalski, Fernanda; Gibbs, James P

2018-01-01

The global expansion of energy demands combined with abundant rainfall, large water volumes and high flow in tropical rivers have led to an unprecedented expansion of dam constructions in the Amazon. This expansion generates an urgent need for refined approaches to river management; specifically a move away from decision-making governed by overly generalized guidelines. For the first time we quantify direct impacts of hydropower reservoir establishment on an Amazon fresh water turtle. We conducted surveys along 150 km of rivers upstream of a new dam construction during the low water months that correspond to the nesting season of Podocnemis unifilis in the study area. Comparison of nest-areas before (2011, 2015) and after (2016) reservoir filling show that reservoir impacts extend 13% beyond legally defined limits. The submerged nesting areas accounted for a total of 3.8 ha of nesting habitat that was inundated as a direct result of the reservoir filling in 2016. Our findings highlight limitations in the development and implementation of existing Brazilian environmental impact assessment process. We also propose potential ways to mitigate the negative impacts of dams on freshwater turtles and the Amazonian freshwater ecosystems they inhabit.

Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks.

PubMed

Zemp, Delphine Clara; Schleussner, Carl-Friedrich; Barbosa, Henrique M J; Hirota, Marina; Montade, Vincent; Sampaio, Gilvan; Staal, Arie; Wang-Erlandsson, Lan; Rammig, Anja

2017-03-13

Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation-atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. We apply a novel complex-network approach, in which Amazon forest patches are linked by observation-based atmospheric water fluxes. Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. Under dry-season Amazonian rainfall reductions, comparable to Last Glacial Maximum conditions, additional forest loss due to self-amplified effects occurs in 10-13% of the Amazon basin. Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest.

Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

NASA Astrophysics Data System (ADS)

Zemp, Delphine Clara; Schleussner, Carl-Friedrich; Barbosa, Henrique M. J.; Hirota, Marina; Montade, Vincent; Sampaio, Gilvan; Staal, Arie; Wang-Erlandsson, Lan; Rammig, Anja

2017-03-01

Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation-atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. We apply a novel complex-network approach, in which Amazon forest patches are linked by observation-based atmospheric water fluxes. Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. Under dry-season Amazonian rainfall reductions, comparable to Last Glacial Maximum conditions, additional forest loss due to self-amplified effects occurs in 10-13% of the Amazon basin. Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest.

Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

PubMed Central

Zemp, Delphine Clara; Schleussner, Carl-Friedrich; Barbosa, Henrique M. J.; Hirota, Marina; Montade, Vincent; Sampaio, Gilvan; Staal, Arie; Wang-Erlandsson, Lan; Rammig, Anja

2017-01-01

Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation–atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. We apply a novel complex-network approach, in which Amazon forest patches are linked by observation-based atmospheric water fluxes. Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. Under dry-season Amazonian rainfall reductions, comparable to Last Glacial Maximum conditions, additional forest loss due to self-amplified effects occurs in 10–13% of the Amazon basin. Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest. PMID:28287104

Impact of urban contamination of the La Paz River basin on thermotolerant coliform density and occurrence of multiple antibiotic resistant enteric pathogens in river water, irrigated soil and fresh vegetables.

PubMed

Poma, Violeta; Mamani, Nataniel; Iñiguez, Volga

2016-01-01

La Paz River in Andean highlands is heavily polluted with urban run-off and further contaminates agricultural lowlands and downstream waters at the Amazon watershed. Agricultural produce at this region is the main source of vegetables for the major Andean cities of La Paz and El Alto. We conducted a 1 year study, to evaluate microbial quality parameters and occurrence of multiple enteropathogenic bacteria (Enterohemorrhagic E. coli-EHEC, Enteroinvasive E. coli or Shigella-EIEC/Shigella, Enteroaggregative E. coli-EAEC, Enteropathogenic E. coli-EPEC Enterotoxigenic E. coli-ETEC and Salmonella) and its resistance to 11 antibiotics. Four sampling locations were selected: a fresh mountain water reservoir (un-impacted, site 1) and downstream sites receiving wastewater discharges (impacted, sites 2-4). River water (sites 1-4, N = 48), and soil and vegetable samples (site 3, N = 24) were collected during dry (April-September) and rainy seasons (October-March). Throughout the study, thermotolerant coliform density values at impacted sites greatly exceeded the guidelines for recreational and agricultural water uses. Seasonal differences were found for thermotolerant coliform density during dry season in water samples nearby a populated and hospital compound area. In contrast to the un-impacted site, where none of the tested enteropathogens were found, 100 % of surface water, 83 % of soil and 67 % of vegetable samples at impacted sites, were contaminated with at least one enteropathogen, being ETEC and Salmonella the most frequently found. ETEC isolates displayed different patterns of toxin genes among sites. The occurrence of enteropathogens was associated with the thermotolerant coliform density. At impacted sites, multiple enteropathogens were frequently found during rainy season. Among isolated enteropathogens, 50 % were resistant to at least two antibiotics, with resistance to ampicillin, nalidixic acid, trimethoprim-sulfamethoxazole and tetracycline commonly present. Moreover, some Salmonella isolates were distinguished by their multi-resistance to ≥8 antibiotics, within soil and vegetable samples. Overall, this study demonstrates that La Paz River-an affluent of the Amazon macrobasin-is heavily polluted along the year with a high density of thermotolerant coliforms and is a reservoir of multiple antibiotic resistant enteropathogens, present in river water, soil and vegetables. These data highlight health risk associated with food and waterborne diseases at the region.

Introduction: Observations and modeling of the Green Ocean Amazon (GoAmazon2014/5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, S. T.; Artaxo, P.; Machado, L. A. T.

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin for 2 years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, the pollution plume from themore » Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as the introduction to the special issue of GoAmazon2014/5, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G-1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the 2-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. In addition, the G-1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year-round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This introduction also organizes information relevant to many papers in the special issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorologies relevant to the two IOPs are presented. Regional and long-range transport of emissions during the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5 as presented in this introduction, research articles including thematic overview articles are anticipated in this special issue to describe the detailed results and findings of the GoAmazon2014/5 Experiment.« less

Introduction: Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5)

NASA Astrophysics Data System (ADS)

Martin, S. T.; Artaxo, P.; Machado, L. A. T.; Manzi, A. O.; Souza, R. A. F.; Schumacher, C.; Wang, J.; Andreae, M. O.; Barbosa, H. M. J.; Fan, J.; Fisch, G.; Goldstein, A. H.; Guenther, A.; Jimenez, J. L.; Pöschl, U.; Silva Dias, M. A.; Smith, J. N.; Wendisch, M.

2015-11-01

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin during two years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, the pollution plume from the Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as the Introduction to the GoAmazon2014/5 Special Issue, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the two-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. The G1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This Introduction also organizes information relevant to many papers in the Special Issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorologies relevant to the two IOPs are presented. Regional and long-range transport of emissions during the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5, as presented herein in this Introduction, research articles published in this Special Issue are anticipated in the near future to describe the detailed results and findings of the GoAmazon2014/5 Experiment.

Introduction: Observations and modeling of the Green Ocean Amazon (GoAmazon2014/5)

DOE PAGES

Martin, S. T.; Artaxo, P.; Machado, L. A. T.; ...

2016-04-19

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin for 2 years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, the pollution plume from themore » Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as the introduction to the special issue of GoAmazon2014/5, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G-1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the 2-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. In addition, the G-1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year-round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This introduction also organizes information relevant to many papers in the special issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorologies relevant to the two IOPs are presented. Regional and long-range transport of emissions during the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5 as presented in this introduction, research articles including thematic overview articles are anticipated in this special issue to describe the detailed results and findings of the GoAmazon2014/5 Experiment.« less

A comparison of drainage basin nutrient inputs with instream nutrient loads for seven rivers in Georgia and Florida, 1986-90

USGS Publications Warehouse

Asbury, C.E.; Oaksford, E.T.

1997-01-01

Instream nutrient loads of the Altamaha, Suwannee, St. Johns, Satilla, Ogeechee, Withlacoochee, and Ochlockonee River Basins were computed and compared with nutrient inputs for each basin for the period 1986-90. Nutrient constituents that were considered included nitrate, ammonia, organic nitrogen, and total phosphorus. Sources of nutrients considered for this analysis included atmospheric deposition, fertilizer, animal waste, wastewater-treatment plant discharge, and septic discharge. The mean nitrogen input ranged from 2,400 kilograms per year per square kilometer (kg/yr)km2 in the Withlacoochee River Basin to 5,470 (kg/yr)km2 in the Altamaha River Basin. The Satilla and Ochlockonee River Basins also had large amounts of nitrogen input per unit area, totaling 5,430 and 4,920 (kg/yr)km2, respectively.Fertilizer or animal waste, as sources of nitrogen, predominated in all basins. Atmospheric deposition contributed less than one-fourth of the mean total nitrogen input to all basins and was consistently the third largest input in all but the Ogeechee River Basin, where it was the second largest.The mean total phosphorus input ranged from 331 (kg/yr)km2 in the Withlacoochee River Basin to 1,380 (kg/yr)km2 in both the Altamaha and Satilla River Basins. The Ochlockonee River Basin had a phosphorus input of 1,140 (kg/yr)km2.Per unit area, the Suwannee River discharged the highest instream mean total nitrogen and phosphorus loads and also discharged higher instream nitrate loads per unit area than the other six rivers. Phosphorus loads in stream discharge were highest in the Suwannee and Ochlockonee Rivers.The ratio of nutrient outputs to inputs for the seven studied rivers ranged from 4.2 to 14.9 percent, with the St. Johns (14.9 percent) and Suwannee (12.1 percent) Rivers having significantly higher percentages than those from the other basins. The output/input percentages for mean total phosphorus ranged from 1.0 to 7.0 percent, with the St. Johns (6.2 percent) and Suwannee (7.0 percent) Rivers exporting the highest percentage of phosphorus.Although instream nutrient loads constitute only one of the various pathways nutrients may take in leaving a river basin, only a relatively small part of nutrient input to the basin leaves the basin in stream discharge for the major coastal rivers examined in this study. The actual amount of nutrient transported in a river basin depends on the ways in which nutrients are physically handled, geographically distributed, and chemically assimilated within a river basin.

Effects of seasonality and land-use change on carbon and water fluxes across the Amazon basin: synthesizing results from satellite-based remote sensing, towers, and models

NASA Astrophysics Data System (ADS)

Saleska, S.; Goncalves, L. G.; Baker, I.; Costa, M.; Poulter, B.; Christoffersen, B.; Da Rocha, H. R.; Didan, K.; Huete, A.; Imbuziero, H.; Kruijt, B.; Manzi, A.; von Randow, C.; Restrepo-Coupe, N.; Silva, R.; Tota, J.; Denning, S.; Gulden, L.; Rosero, E.; Zeng, X.

2008-12-01

Amazon forests play an important and complex role in the global carbon cycle, and important advances have been made in understanding Amazon processes in recent years. However, reconciling modeled mechanisms of carbon cycling with observations across scales remains a challenge. To better address this challenge, we initiated a Model intercomparison Project for the 'Large-Scale Biosphere Atmosphere Experiment in Amazonia' (LBA-MIP) to integrate modeling and observational studies for improved understanding of Amazon basin carbon cycling. Here, we report on the initial results of this project, which used the network of meteorological and climate data (sunlight, radiation, precipitation) from Amazon tower sites in forest and converted lands to drive a suite of 20 ecosystem models that simulate energy, water and CO2 fluxes. We compared model mechanisms to each other and to the relevant flux observations from those towers, as well as from satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Remote sensing and flux tower observations tend to show higher primary forest photosynthetic activity in the dry season than in the wet season in central Amazon, a broad pattern that is now captured in many models, but for different reasons. A reversal from the primary forest pattern was observed in areas converted to pasture, agriculture, or secondary forests, likely a consequence of the elimination of deep root access to deep soil waters which often persist through the dry season. Testing the models with observed fluxes under different land use patterns, and across different spatial scales with remote sensing, is enabling us to distinguish correct vs. incorrect model mechanisms and improve understanding of Amazon processes.

A century of Amazon burning driven by Atlantic climate

NASA Astrophysics Data System (ADS)

Makou, M.; Thompson, L. G.; Davis, M. E.; Eglinton, T. I.

2011-12-01

Very little is known about annual burning trends in the Amazon Basin prior to remote sensing of fires beginning in the late 1970's. Fires reduce Amazon forest biomass and species richness, release pollutant aerosols, and impact the carbon cycle, compelling further investigation of fire-climate dynamics. We measured organic compounds derived from vegetation burning in ice core samples from the Quelccaya Ice Cap in Peru at better than annual resolution to reconstruct wet and dry season burning throughout the Twentieth Century. Variations in the abundance of methyl hexadecanoate, which is produced by thermal alteration of vascular plant alkanoic acids, were used as a proxy for past fire activity. Concentrations of this compound in Quelccaya ice varied strongly on seasonal, interannual, and decadal time scales over the last 100 years, with high-amplitude dry season variability and muted, decadal-scale changes in wet season fire activity. Decade-long periods of repeatedly enhanced burning occurred during the 1930's and 1960's when dry season precipitation was perpetually reduced, as evidenced by low stages of the Rio Negro. These decadal trends suggest that changes in dry season precipitation drive fire activity in the western Amazon and highlight the potential of Amazon forests to undergo repeated strong burning. Fires occurred during years when sea surface temperatures (SSTs) in the north tropical Atlantic were elevated and the north-south tropical Atlantic SST gradient was enhanced; this SST pattern likely displaced the intertropical convergence zone northward, driving subsidence and drought in the western and southern Amazon basin. Thus, our novel ice core record suggests that Amazon forest fire activity during the Twentieth Century was driven primarily by Atlantic climate processes, and future forest health will depend heavily on the evolution of tropical climate.

75 FR 25877 - Colorado River Basin Salinity Control Advisory Council

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-10

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Colorado River Basin Salinity Control Advisory... River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control [[Page 25878

Chemistry of uranium, thorium, and radium isotopes in the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal

NASA Astrophysics Data System (ADS)

Sarin, M. M.; Krishnaswami, S.; somayajulu, B. L. K.; Moore, W. S.

1990-05-01

The most comprehensive data set on uranium, thorium, and radium isotopes in the Ganga-Brahmaputra, one of the major river systems of the world, is reported here. The dissolved 238U concentration in these river waters ranges between 0.44 and 8.32 μ/1, and it exhibits a positive correlation with major cations (Na + K + Mg + Ca). The 238U /∑Cations ratio in waters is very similar to that measured in the suspended sediments, indicating congruent weathering of uranium and major cations. The regional variations observed in the [ 234U /238U ] activity ratio are consistent with the lithology of the drainage basins. The lowland tributaries (Chambal, Betwa, Ken, and Son), draining through the igneous and metamorphic rocks of the Deccan Traps and the Vindhyan-Bundelkhand Plateau, have [ 234U /238U ] ratio in the range 1.16 to 1.84. This range is significantly higher than the near equilibrium ratio (~1.05) observed in the highland rivers which drain through sedimentary terrains. The dissolved 226Ra concentration ranges between 0.03 and 0.22 dpm/1. The striking feature of the radium isotopes data is the distinct difference in the 228Ra and 226Ra abundances between the highland and lowland rivers. The lowland waters are enriched in 228Ra while the highland waters contain more 226Ra. This difference mainly results from the differences in their weathering regimes. The discharge-weighted mean concentration of dissolved 238U in the Ganga (at Patna) and in the Brahmaputra (at Goalpara) are 1.81 and 0.63 μ/1, respectively. The Ganga-Brahmaputra river system constitutes the major source of dissolved uranium to the Bay of Bengal. These rivers transport annually about 1000 tons of uranium to their estuaries, about 10% of the estimated global supply of dissolved uranium to the oceans via rivers. The transport of uranium by these rivers far exceeds that of the Amazon, although their water discharge is only about 20% of that of the Amazon. The high intensity of weathering of uranium in the Ganga-Brahmapura River system can also be deduced from the [ 232Th /238U ] and [ 230Th /238U ] activity ratios measured in the suspended sediments. 230Th is enriched by about 19% in the suspended sediments relative to its parent 238U. The flux of excess 230Th supplied to the Bay of Bengal via these river sediments is 980 × 10 12 dpm/a, about six times more than its in situ production from seawater in the entire Bay of Bengal.

Ecological restoration of Xingu Basin headwaters: motivations, engagement, challenges and perspectives

PubMed Central

Durigan, Giselda; Guerin, Natalia; da Costa, José Nicola Martorano Neves

2013-01-01

Over the past two decades, the headwaters of the Xingu Basin in the Amazon have been subjected to one of the highest deforestation rates in Brazil, with negative effects on both terrestrial and aquatic systems. The environmental consequences of forest land conversion have concerned the indigenous people living downstream, and this was the first motivation for the Y Ikatu Xingu campaign—‘save the good water of the Xingu’. Among the objectives of the initiative was to restore riparian forests on private land across the basin. For a region where the rivers, rainstorms, forest remnants, distances and farms are huge, the challenges were equally large: crossing the biotic and abiotic thresholds of degradation, as well as addressing the lack of technology, know-how, seeds, forest nurseries, trained personnel and roads, and the lack of motivation for restoration. After 6 years, despite the remarkable advances in terms of technical innovation coupled with a broad and effective social involvement, the restored areas represent only a small portion of those aimed for. The still high costs of restoration, the uncertainties of legislation and also the global economy have been strong forces constraining the expansion of restored forests. Additional efforts and strategies are necessary to overcome these barriers. PMID:23610171

Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought

Treesearch

Steve Frolking; Stephen Hagen; Bobby Braswell; Tom Milliman; Christina Herrick; Seth Peterson; Dar Roberts; Michael Keller; Michael Palace; Krishna Prasad Vadrevu

2017-01-01

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave...

Upland agricultural and forestry development in the Amazon: sustainability, criticality and resilience

Treesearch

Emmanuel Adilson S. Serrao; Daniel Nepstad; Robert Walker

1996-01-01

This paper provides an overview of agricultural and forestry development in the Amazon basin, and presents and discusses the main land use systems in evidence today in that region. These are logging, shifting-cultivation and ranching. The issue of sustainability is addressed, and current Amazonian land use is interpreted in light of ecological impacts and long-run...

Modelling multiple threats to water security in the Peruvian Amazon using the WaterWorld Policy Support System

NASA Astrophysics Data System (ADS)

van Soesbergen, A. J. J.; Mulligan, M.

2013-06-01

This paper explores a multitude of threats to water security in the Peruvian Amazon using the WaterWorld policy support system. WaterWorld is a spatially explicit, physically-based globally-applicable model for baseline and scenario water balance that is particularly well suited to heterogeneous environments with little locally available data (e.g. ungauged basins) and which is delivered through a simple web interface, requiring little local capacity for use. The model is capable of producing a hydrological baseline representing the mean water balance for 1950-2000 and allows for examining impacts of population, climate and land use change as well as land and water management interventions on hydrology. This paper describes the application of WaterWorld to the Peruvian Amazon, an area that is increasingly under pressure from deforestation and water pollution as a result of population growth, rural to urban migration and oil and gas extraction, potentially impacting both water quantity and water quality. By applying single and combined scenarios of: climate change, deforestation around existing and planned roads, population growth and rural-urban migration, mining and oil and gas exploitation, we explore the potential combined impacts of these multiple changes on water resources in the Peruvian Amazon and discuss the likely pathways for adaptation to and mitigation against their worst effects. See Mulligan et al. (2013) for a similar analysis for the entire Amazon Basin.

Evaluation of Water Resources in Bolivia, South America

DTIC Science & Technology

1991-01-01

sub-basins: Madre de Dios 31,000 square kilometers Beni 183,000 square kilometers Mamore 216,000 square kilometers Itenez/Cuapore 294,000 square...infrastructure; cumbersome institutional bureaucracies and a viable and growing black market production and retail sector ( de Soto 1989); and the human and...See Figure 3 oi, page 34): The Amazon Basin 724,000 square kilometers The De La Plata Basin 229,500 square kilometers The Altiplano Basin 145,081

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Scot T.

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin during two years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, themore » pollution plume from the Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as Introduction to the GoAmazon2014/5 Special Issue, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the two-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. The G1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This Introduction also organizes information relevant to many papers in the Special Issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorology relevant to the two IOPs is presented. Regional and long-range transport of emissions for the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5, as presented herein in this Introduction, research articles published in this Special Issue are anticipated in the near future to describe the detailed results and findings of GoAmazon2014/5.« less

Biomarkers in Transit Reveal the Nature of Fluvial Integration

NASA Astrophysics Data System (ADS)

Ponton, C.; West, A.; Feakins, S. J.; Galy, V.

2013-12-01

The carbon and hydrogen isotopic composition of vascular plant leaf waxes are common proxies for hydrologic and vegetation change. Sedimentary archives off major river systems are prime targets for continental paleoclimate studies under the assumption that rivers integrate changes in terrestrial organic carbon (OC) composition over their drainage basin. However, the proportional contribution of sources within the basin (e.g. head waters vs. floodplain) and the transit times of OC through the fluvial system remain largely unknown. This lack of quantifiable information about the proportions and timescales of integration within large catchments poses a challenge for paleoclimate reconstructions. To examine the sources of terrestrial OC eroded and supplied to a river system and the spatial distribution of these sources, we use compound specific isotope analysis (i.e. δ13C, Δ14C, and δD) on plant-derived leaf waxes, filtered from large volumes of river water (20-200L) along a major river system. We selected the Kosñipata River that drains the western flank of the Andes in Peru, joins the Madre de Dios River across the Amazonian floodplain, and ultimately contributes to the Amazon River. Our study encompassed an elevation gradient of >4 km, in an almost entirely forested catchment. Precipitation δD values vary by >50‰ due to the isotopic effect of elevation, a feature we exploit to identify the sources of plant wax n-alkanoic acids transported by the river. We used the δD plant wax values from tributary rivers as source constrains and the main stem values as the integrated signal. In addition, compound specific radiocarbon on individual chain length n-alkanoic acids provide unprecedented detail on the integrated age of these compounds. Preliminary results have established that 1) most of the OC transport occurs in the wet season; 2) total carbon transport in the Madre de Dios is dominated by lowland sources because of the large floodplain area, but initial data suggest that OC from high elevations may be proportionally overrepresented relative to areal extent, with possibly important implications for biomarker isotope composition; 3) timescales of different biomarkers vary considerably; 4) the composition of OC varies downstream and with depth stratification within large rivers. We filtered >1000L of river water in this remote location during the wet season, and are presently replicating that study during the dry season, providing a seasonal comparison of OC transport in this major river system.