scholarly journals Particle Fluxes and Bulk Geochemical Characterization of the Cabo Frio Upwelling System in Southeastern Brazil: Sediment Trap Experiments between Spring 2010 and Summer 2012

2014 ◽  
Vol 86 (2) ◽  
pp. 601-620 ◽  
Author(s):  
ANA LUIZA S. ALBUQUERQUE ◽  
ANDRÉ L. BELÉM ◽  
FRANCISCO J.B. ZULUAGA ◽  
LIVIA G.M. CORDEIRO ◽  
URSULA MENDOZA ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Cold Water ◽  
Ocean Dynamics ◽  
Southeastern Brazil ◽  
Western Boundary ◽  
Shelf Area ◽  
Biogeochemical Processes ◽  
Upwelling System ◽  
Brazil Current ◽  
Cabo Frio

Physical and biogeochemical processes in continental shelves act synergistically in both transporting and transforming suspended material, and ocean dynamics control the dispersion of particles by the coastal zone and their subsequent mixing and dilution within the shelf area constrained by oceanic boundary currents, followed by their gradual settling in a complex sedimentary scenario. One of these regions is the Cabo Frio Upwelling System located in a significantly productive area of Southeastern Brazil, under the control of the nutrient-poor western boundary Brazil Current but also with a wind-driven coastal upwelling zone, inducing cold-water intrusions of South Atlantic Central Water on the shelf. To understand these synergic interactions among physical and biogeochemical processes in the Cabo Frio shelf, a series of four experiments with a total of 98 discrete samples using sediment traps was performed from November 2010 to March 2012, located on the 145 m isobath on the edge of the continental shelf. The results showed that lateral transport might be relevant in some cases, especially in deep layers, although no clear seasonal cycle was detected. Two main physical-geochemical coupling scenarios were identified: singular downwelling events that can enhance particles fluxes and are potentially related to the Brazil Current oscillations; and events of significant fluxes related to the intrusion of the 18°C isotherm in the euphotic zone. The particulate matter settling in the Cabo Frio shelf area seems to belong to multiple marine and terrestrial sources, in which both Paraiba do Sul River and Guanabara Bay could be potential land-sources, although the particulate material might subject intense transformation (diagenesis) during its trajectory to the shelf edge.

scholarly journals Modern sedimentation in the Cabo Frio upwelling system, Southeastern Brazilian shelf

2005 ◽  
Vol 77 (3) ◽  
pp. 535-548 ◽  
Author(s):  
Michel M. de Mahiques ◽  
Marcia C. Bícego ◽  
Ilson C.A. Silveira ◽  
Silvia H.M. Sousa ◽  
Rafael A. Lourenço ◽  
...  
Keyword(s):  
General Trend ◽  
Southeastern Brazil ◽  
Sedimentation Rates ◽  
Wind Regime ◽  
Geographical Variability ◽  
Upwelling System ◽  
Brazil Current ◽  
Upward Transport ◽  
Upwelling Area ◽  
Cabo Frio

The analyses of Uk'37 paleotemperatures and sedimentological parameters in box cores from the Cabo Frio upwelling zone, southeastern Brazil, were used to understand the modern sedimentation as well as to evaluate the role played by the upwelling process in the sedimentary patterns. Three box-cores located closer to the upwelling area show a general trend of cooling waters taking place in the last 700 years. Since the present upwelling is dependent on local and remote wind regime, a phase of dominating NE winds favors a more effective upward transport of the cold thermocline level South Atlantic CentralWater towards the coast. The intensification in the upwelling regime for the last ca. 700 years can be associated with the strengthening of the NE winds off the area and a possible increase of the Brazil Current mesoscale activity. Nevertheless, the lack of significant correlation of the paleotemperatures and most of sedimentological parameters indicate that upwelling is not the only sedimentation mechanism in the area. Also, the comparison of sedimentological parameters reveals that eventual temporal changes are superimposed by the geographical variability. Sedimentation rates vary from 0.26 mm.yr-1 to 0.66 mm.yr-1.

scholarly journals Biophysical interactions in the Cabo Frio upwelling system, southeastern Brazil

2012 ◽  
Vol 60 (3) ◽  
pp. 353-365 ◽  
Author(s):  
Sergio Augusto Coelho-Souza ◽  
Maria Soledad López ◽  
Jean Remy Davee Guimarães ◽  
Ricardo Coutinho ◽  
Rogério Nader Candella
Keyword(s):  
Cold Water ◽  
Basic Knowledge ◽  
Predatory Fish ◽  
Southeastern Brazil ◽  
Fish Stock ◽  
Phytoplankton Production ◽  
Brazilian Coast ◽  
Upwelled Water ◽  
Biophysical Interactions ◽  
Cabo Frio

The rising of cold water from deeper levels characterizes coastal upwelling systems. This flow makes nutrients available in the euphotic layer, which enhances phytoplankton production and growth. On the Brazilian coast, upwelling is most intense in the Cabo Frio region (RJ). The basic knowledge of this system was reviewed in accordance with concepts of biophysical interactions. The high frequency and amplitude of the prevailing winds are the main factor promoting the rise of South Atlantic Central Water, but meanders and eddies in the Brazil Current as well as local topography and coast line are also important. Upwelling events are common during spring/summer seasons. Primary biomass is exported by virtue of the water circulation and is also controlled by rapid zooplankton predation. Small pelagic fish regulate plankton growth and in their turn are preyed on by predatory fish. Sardine furnishes an important regional fish stock. Shoreline irregularities define the embayment formation of the Marine Extractive Reserve of Arraial do Cabo making it an area with evident different intensities of upwelled water that harbors high species diversity. Consequently, on a small spatial scale there are environments with tropical and subtropical features, a point to be explored as a particularity of this ecosystem.

Bacterial community characterization and biogeochemistry of sediments from a tropical upwelling system (Cabo Frio, Southeastern Brazil)

2016 ◽  
Vol 130 ◽  
pp. 1-13 ◽  
Author(s):  
R. Castelo-Branco ◽  
A. Barreiro ◽  
F.S. Silva ◽  
S.B.V. Carvalhal-Gomes ◽  
L.F. Fontana ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Southeastern Brazil ◽  
Upwelling System ◽  
Cabo Frio

Frontal variability and its impact on chlorophyll in the Arabian Sea

2020 ◽  
Author(s):  
Yuntao Wang ◽  
Wentao Ma ◽  
Feng Zhou ◽  
Chai Fei
Keyword(s):  
Arabian Sea ◽  
Coastal Upwelling ◽  
Cold Water ◽  
Southwest Monsoon ◽  
Ocean Dynamics ◽  
Ekman Transport ◽  
Spatial And Temporal Variability ◽  
Anomalous Field ◽  
The North ◽  
The Impact

<p>Sixteen years satellite observations are used to investigate the frontogenesis, frontal variability and its impact on chlorophyll in the Arabian Sea. Large frontal probability (FP) and high chlorophyll mainly happens near the coast, e.g., near Somalia and Oman, and its value generally decreases with offshore distance. An Empirical Orthogonal Function (EOF) is used to disentangle the spatial and temporal variability of front and chlorophyll. Prominent seasonal cycle of frontal activities is identified, peaking in summer when southwest wind prevails. The seasonality for chlorophyll is same with wind and front near Somalia, which largely impacted by monsoon. During summer, the southwest monsoon drives offshore Ekman transport and induces coastal upwelling. It transports subsurface cold water and nutrients to the surface layer, which generates fronts and enhances chlorophyll, respectively. The frontal activities can be used as an indicator to determine the chlorophyll level that high chlorophyll happens when frontal probability gets higher than 2%. At anomalous field, stronger wind can induce higher frontal activities and chlorophyll. The impact of wind on frontogenesis can extend 1,000km offshore and a simplified linear regression is applied to quantify their relationship. The variability of wind leads chlorophyll by lags increasing with distance, indicating a horizontal offshore transport of coastal water. In winter, the northeast wind is not upwelling favorable, thus the frontal activities and chlorophyll are greatly reduced off Somalia. During this period, large chlorophyll is found in the north off Oman because of mixing, thus its relationship with front is less pronounced. In the upwelling regions, fronts act as an intermedia process that connecting the wind forcing and responses of ecosystem. The frontal activities in Arabian Sea is fundamentally important to improve our understanding of monsoon related ocean dynamics.</p>

Holocene oscillations of Southwest Atlantic shelf circulation based on planktonic foraminifera from an upwelling system (off Cabo Frio, Southeastern Brazil)

The Holocene ◽  
2016 ◽  
Vol 26 (8) ◽  
pp. 1175-1187 ◽  
Author(s):  
Douglas VO Lessa ◽  
Igor M Venancio ◽  
Thiago P dos Santos ◽  
André L Belem ◽  
Bruno J Turcq ◽  
...  
Keyword(s):  
Planktonic Foraminifera ◽  
Southeastern Brazil ◽  
Southwest Atlantic ◽  
Shelf Circulation ◽  
Upwelling System ◽  
Cabo Frio

scholarly journals Factors controlling plankton community production, export flux, and particulate matter stoichiometry in the coastal upwelling system off Peru

2020 ◽  
Vol 17 (19) ◽  
pp. 4831-4852
Author(s):  
Lennart Thomas Bach ◽  
Allanah Joy Paul ◽  
Tim Boxhammer ◽  
Elisabeth von der Esch ◽  
Michelle Graco ◽  
...  
Keyword(s):  
Organic Matter ◽  
Coastal Upwelling ◽  
Inorganic Nitrogen ◽  
Abiotic Factors ◽  
Plankton Community ◽  
Light Limitation ◽  
Biogeochemical Processes ◽  
Upwelling System ◽  
Phytoplankton Communities ◽  
Surface Production

Abstract. Eastern boundary upwelling systems (EBUS) are among the most productive marine ecosystems on Earth. The production of organic material is fueled by upwelling of nutrient-rich deep waters and high incident light at the sea surface. However, biotic and abiotic factors can modify surface production and related biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predictions of their future functioning requires understanding of the mechanisms driving the biogeochemical cycles therein. In this field experiment, we used in situ mesocosms as tools to improve our mechanistic understanding of processes controlling organic matter cycling in the coastal Peruvian upwelling system. Eight mesocosms, each with a volume of ∼55 m3, were deployed for 50 d ∼6 km off Callao (12∘ S) during austral summer 2017, coinciding with a coastal El Niño phase. After mesocosm deployment, we collected subsurface waters at two different locations in the regional oxygen minimum zone (OMZ) and injected these into four mesocosms (mixing ratio ≈1.5 : 1 mesocosm: OMZ water). The focus of this paper is on temporal developments of organic matter production, export, and stoichiometry in the individual mesocosms. The mesocosm phytoplankton communities were initially dominated by diatoms but shifted towards a pronounced dominance of the mixotrophic dinoflagellate (Akashiwo sanguinea) when inorganic nitrogen was exhausted in surface layers. The community shift coincided with a short-term increase in production during the A. sanguinea bloom, which left a pronounced imprint on organic matter C : N : P stoichiometry. However, C, N, and P export fluxes did not increase because A. sanguinea persisted in the water column and did not sink out during the experiment. Accordingly, export fluxes during the study were decoupled from surface production and sustained by the remaining plankton community. Overall, biogeochemical pools and fluxes were surprisingly constant for most of the experiment. We explain this constancy by light limitation through self-shading by phytoplankton and by inorganic nitrogen limitation which constrained phytoplankton growth. Thus, gain and loss processes remained balanced and there were few opportunities for blooms, which represents an event where the system becomes unbalanced. Overall, our mesocosm study revealed some key links between ecological and biogeochemical processes for one of the most economically important regions in the oceans.

Early diagenesis of sulfur in a tropical upwelling system, Cabo Frio, southeastern Brazil

Geology ◽  
2012 ◽  
Vol 40 (10) ◽  
pp. 879-882 ◽  
Author(s):  
Rut Diaz ◽  
Manuel Moreira ◽  
Ursula Mendoza ◽  
Wilson Machado ◽  
Michael E. Böttcher ◽  
...  
Keyword(s):  
Early Diagenesis ◽  
Southeastern Brazil ◽  
Upwelling System ◽  
Cabo Frio
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