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The water column distribution of carbonate system variables at the ESTOC site from 1995 to 2004
M. González-Dávila, J. M. Santana-Casiano, M. J. Rueda,O. Llinás
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: The accelerated rate of increase in atmospheric carbon dioxide and the substantial fraction of anthropogenic CO2 emissions absorbed by the oceans are affecting the anthropocenic signatures of seawater. Long-term time series are a powerful tool for investigating any change in ocean bio-geochemistry and its effects on the carbon cycle. We have evaluated the ESTOC (European Station for Time series in the Ocean at the Canary islands) observations of measured pH (total scale at 25 °C) and total alkalinity plus computed total dissolved inorganic carbon concentration (CT) from 1995 to 2004 for surface and deep waters, by following all changes in response to increasing atmospheric carbon dioxide. The observed values for the surface partial pressure of CO2 from 1995 to 2008 were also taken into consideration. The data were treated to better understand the fundamental processes controlling vertical distributions in the Eastern North Atlantic Ocean and the accumulation of anthropogenic CO2, CANT. CT at constant salinity, NCT, increased at a rate of 0.85 μmol kg 1 yr 1 in the mixed layer, linked to an fCO2 increase of 1.7±0.7 μatm yr 1 in both the atmosphere and the ocean. Consequently, the mixed layer at ESTOC site has also become more acidic, 0.0017±0.0003 units yr 1, whereas the carbonate ion concentrations and CaCO3 saturation states have also decreased over time. NCT increases at a rate of 0.53, 0.49 and 0.40 μmol kg 1 yr 1 at 300, 600, and 1000 m, respectively. The general processes controlling the vertical variations of alkalinity and the inorganic carbon distribution were computed by considering the pre-formed values, the production/decomposition of organic matter and the formation/dissolution of carbonates. At 3000 m, 30% of the inorganic carbon production is related to the dissolution of calcium carbonate, increasing to 35% at 3685 m. The total column inventory of anthropogenic CO2 for the decade was 66±3 mol m 2. A model fitting indicated that the column inventory of CANT increased from 61.7 mol m 2 in the year 1994 to 70.2 mol m 2 in 2004. The ESTOC site is presented as a reference site to follow CANT changes in the Northeast Atlantic Sub-tropical gyre.
Influence of the Tropical Atlantic Ocean’s Sea Surface Temperature in the Eastern Northeast Brazil Precipitation  [PDF]
Ana Cleide Bezerra Amorim, Rosane Rodrigues Chaves, Cláudio Moisés Santos e Silva
Atmospheric and Climate Sciences (ACS) , 2014, DOI: 10.4236/acs.2014.45077
Abstract: An analysis of the rainfall of the Eastern Northeast Brazil (ENEB) during the period from April to June and the processes of ocean-atmosphere interaction were performed during different episodes of Sea Surface Temperature (SST) inter-hemispheric gradient of Atlantic tropical (GRAD). For this, we used a dataset covering the 1981 to 2010 period, composed by: monthly data of accumulated precipitation of the Global Precipitation Climatology Project (GPCP); surface fluxes obtained from reanalysis of the National Center for Environmental Prediction (NCEP); vertically integrated moisture flux divergence of the global model of European Centre for Medium Range Forecasting (ECMWF) reanalysis; SST data from the NCEP. Seven GRAD_S (southward SST gradient in the intertropical Atlantic) and five GRAD_N (northward SST gradient in the intertropical Atlantic) were selected. When the South Atlantic Ocean is warmer, the oceanic and atmospheric conditions are favorable to higher monthly precipitation near to the ENEB. We also observed a pronounced moisture convergence over parts of the ENEB during both, GRAD_S and GRAD_N episodes. The weather phenomena that operates remotely amplifying or inhibiting the rain also helps the rainy season; however, it appears that the contribution was greater than the spatial distribution of rainfall intensity.
Carbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008
M. González-Dávila, J. M. Santana-Casiano, R. A. Fine, J. Happell, B. Delille,S. Speich
Biogeosciences (BG) & Discussions (BGD) , 2011,
Abstract: Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) from February to March 2008. Eddies detached from the retroflection of the Agulhas Current increased the gradients observed along the fronts. Minima in the fugacity of CO2, fCO2, and maxima in pH on either side of the frontal zone were observed, noting that within the frontal zone fCO2 reached maximum values and pH was at a minimum. Vertical distributions of water masses were described by their carbonate system properties and their relationship to CFC concentrations. Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW) offered pHT,25 values of 7.56 and 7.61, respectively. The UCDW also had higher concentrations of CFC-12 (>0.2 pmol kg 1) as compared to deeper waters, revealing that UCDW was mixed with recently ventilated waters. Calcite and aragonite saturation states (Ω) were also affected by the presence of these two water masses with high carbonate concentrations. The aragonite saturation horizon was observed at 1000 m in the subtropical area and north of the Subantarctic Front. At the position of the Polar Front, and under the influence of UCDW and LCDW, the aragonite saturation horizon deepened from 800 m to 1500 m at 50.37° S, and reached 700 m south of 57.5° S. High latitudes proved to be the most sensitive areas to predicted anthropogenic carbon increase. Buffer coefficients related to changes in [CO2], [H+] and Ω with changes in dissolved inorganic carbon (CT) and total alkalinity (AT) offered minima values in the Antarctic Intermediate Water and UCDW layers. These coefficients suggest that a small increase in CT will sharply decrease the status of pH and carbonate saturation. Here we present data that suggest that south of 55° S, surface water will be under-saturated with respect to aragonite within the next few decades.
Carbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008  [PDF]
M. González-Dávila,J. M. Santana-Casiano,R. A. Fine,J. Happell
Biogeosciences (BG) & Discussions (BGD) , 2011, DOI: 10.5194/bg-8-1401-2011
Abstract: Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) from February to March 2008. Eddies detached from the retroflection of the Agulhas Current increased the gradients observed along the fronts. Minima in the fugacity of CO2, fCO2, and maxima in pH on either side of the frontal zone were observed, noting that within the frontal zone fCO2 reached maximum values and pH was at a minimum. Vertical distributions of water masses were described by their carbonate system properties and their relationship to CFC concentrations. Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW) offered pHT,25 values of 7.56 and 7.61, respectively. The UCDW also had higher concentrations of CFC-12 (>0.2 pmol kg 1) as compared to deeper waters, revealing that UCDW was mixed with recently ventilated waters. Calcite and aragonite saturation states (Ω) were also affected by the presence of these two water masses with high carbonate concentrations. The aragonite saturation horizon was observed at 1000 m in the subtropical area and north of the Subantarctic Front. At the position of the Polar Front, and under the influence of UCDW and LCDW, the aragonite saturation horizon deepened from 800 m to 1500 m at 50.37° S, and reached 700 m south of 57.5° S. High latitudes proved to be the most sensitive areas to predicted anthropogenic carbon increase. Buffer coefficients related to changes in [CO2], [H+] and Ω with changes in dissolved inorganic carbon (CT) and total alkalinity (AT) offered minima values in the Antarctic Intermediate Water and UCDW layers. These coefficients suggest that a small increase in CT will sharply decrease the status of pH and carbonate saturation. Here we present data that suggest that south of 55° S, surface water will be under-saturated with respect to aragonite within the next few decades.
Heavy Rainfall Episodes in the Eastern Northeast Brazil Linked to Large-Scale Ocean-Atmosphere Conditions in the Tropical Atlantic  [PDF]
Yves K. Kouadio,Jacques Servain,Luiz A. T. Machado,Carlos A. D. Lentini
Advances in Meteorology , 2012, DOI: 10.1155/2012/369567
Abstract: Relationships between simultaneous occurrences of distinctive atmospheric easterly wave (EW) signatures that cross the south-equatorial Atlantic, intense mesoscale convective systems (lifespan > 2 hour) that propagate westward over the western south-equatorial Atlantic, and subsequent strong rainfall episodes (anomaly > 10 mm·day−1) that occur in eastern Northeast Brazil (ENEB) are investigated. Using a simple diagnostic analysis, twelve cases with EW lifespan ranging between 3 and 8 days and a mean velocity of 8 m·s−1 were selected and documented during each rainy season of 2004, 2005, and 2006. These cases, which represent 50% of the total number of strong rainfall episodes and 60% of the rainfall amount over the ENEB, were concomitant with an acceleration of the trade winds over the south-equatorial Atlantic, an excess of moisture transported westward from Africa to America, and a strengthening of the convective activity in the oceanic region close to Brazil. Most of these episodes occurred during positive sea surface temperature anomaly patterns over the entire south-equatorial Atlantic and low-frequency warm conditions within the oceanic mixing layer. A real-time monitoring and the simulation of this ocean-atmosphere relationship could help in forecasting such dramatic rainfall events.
Carbonate system buffering in the water masses of the Southwest Atlantic sector of the Southern Ocean during February–March 2008  [PDF]
M. González-Dávila,J. M. Santana-Casiano,R. A. Fine,J. Happell
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-435-2011
Abstract: Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) in February–March 2008. Eddies detach from retroflection of the Agulhas Current located north of the Subantarctic Front (SAF). The eddies increase the gradients observed at the fronts so that minima in fCO2 and maxima in pH in situ on either side of the frontal zone are observed, while within the frontal zone fCO2 reached maximum values and pH in situ was a minimum. Mixing at the frontal zones, in particular where cyclonic rings were located, brought up CO2-rich water (low pH and high nutrient) that spread out the fronts where recent biological production favored by the nutrient input increases the pH in situ and decreases the fCO2 levels. Vertical distributions of water masses were described by their carbonate system properties and their relationship to CFC concentrations. Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW) had pHT,25 values of 7.56 and 7.61, respectively. UCDW also had higher concentrations of CFC-12 (>0.2 pmol kg 1) as compared to deeper waters, revealing the mixing with recently ventilated waters. Calcite and aragonite saturation states (Ω) were also affected by the presence of these two water masses with high carbonate concentration. Ωarag = 1 was observed at 1000 m in the subtropical area and north of the SAF. At the position of the Polar front and under the influence of UCDW and LCDW Ωarag = 1 deepen from 600 m to 1500 m at 50.37° S, and it reaches to 700 m south of 57.5° S. High latitudes are the most sensitive areas under future anthropogenic carbon increase. Buffer coefficients related to changes in [CO2], [H+] and Ω with changes in CT and AT showed the minimum values are found in the Antarctic Intermediate Water (AAIW), and UCDW layers. These coefficients suggest that a small increase in CT will sharply decrease the pH and the carbonate saturation states. Here we present data that are used to suggest that south of 55° S by the year 2045 surface water will be undersaturated in aragonite.
New records of Aphyllophorales (Basidiomycota) in the Atlantic Rain Forest in Northeast Brazil
Gibertoni, Tatiana Baptista;Ryvarden, Leif;Cavalcanti, Maria Auxiliadora de Queiroz;
Acta Botanica Brasilica , 2004, DOI: 10.1590/S0102-33062004000400027
Abstract: non-poroid aphyllophorales (basidiomycota) in areas of the atlantic rain forest in northeast brazil are reported. auriscalpium villipes (lloyd) snell & e.a. dick, climacodon pulcherrimus (berk. & m.a. curtis) nikol., gloeodontia discolor (berk. & m.a. curtis) boidin, irpex lacteus (fr.: fr.) fr. and scytinostroma duriusculum (berk. & broome) donk are new records to northeast brazil.
Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: a biomarker diagnosis
I. J. Alonso-González, J. Arístegui, C. Lee,A. Calafat
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: Sinking particles through the pelagic ocean have been traditionally considered the most important vehicle by which the biological pump sequesters carbon in the ocean interior. Nevertheless, regional scale variability in particle flux is a major outstanding issue in oceanography. Here, we have studied the regional and temporal variability of total particulate organic matter fluxes, as well as chloropigment and total hydrolyzed amino acid (THAA) compositions and fluxes in the Canary Current region, between 20–30° N, during two contrasting periods: August 2006, characterized by warm and stratified waters, but also intense winds which enhanced eddy development south of the Canary Islands, and February 2007, characterized by colder waters, less stratification and higher productivity. We found that the eddy-field generated south of the Canary Islands enhanced by >2 times particulate organic carbon (POC) export with respect to stations (FF; far-field) outside the eddy-field influence. We also observed flux increases of one order of magnitude in chloropigment and 2 times in THAA in the eddy-field relative to FF stations. Principal Components Analysis (PCA) was performed to assess changes in particulate organic matter composition between stations. At eddy-field stations, higher chlorophyll enrichment reflected "fresher" material, while at FF stations a higher proportion of pheophytin indicated greater degradation due to microbes and microzooplankton. PCA also suggests that phytoplankton community structure, particularly the dominance of diatoms versus carbonate-rich plankton, is the major factor influencing the POC export within the eddy field. In February, POC export fluxes were the highest ever reported for this area, reaching values of ~15 mmol C m 2 d 1 at 200 m depth. Compositional changes in pigments and THAA indicate that the source of sinking particles varies zonally and meridionally and suggest that sinking particles were more degraded at near-coastal stations relative to open ocean stations.
Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: a biomarker diagnosis  [PDF]
I. J. Alonso-González,J. Arístegui,C. Lee,A. Calafat
Biogeosciences Discussions , 2009,
Abstract: Sinking particles through the pelagic ocean have been traditionally considered the most important vehicle by which the biological pump sequesters carbon in the ocean interior. Nevertheless, regional scale variability in particle flux is a major outstanding issue in oceanography. Here, we have studied the regional and temporal variability of total particulate organic matter fluxes, as well as chloropigment and total hydrolyzed amino acid (THAA) compositions and fluxes in the Canary Current region, between 20–30° N, during two contrasting periods: August 2006, characterized by warm and stratified waters, but also intense winds which enhanced eddy development south of the Canary Islands, and February 2007, characterized by colder waters, less stratification and higher productivity. We found that the eddy-field generated south of the Canary Islands enhanced by >2 times particulate organic carbon (POC) export with respect to stations (FF; far-field) outside the eddy-field influence. We also observed flux increases of one order of magnitude in chloropigment and 70% in THAA in the eddy-field relative to FF stations. Principal Components Analysis (PCA) was performed to assess changes in particulate organic matter composition between stations. At eddy-field stations, higher chlorophyll enrichment reflected "fresher" material, while at FF stations a higher proportion of pheophytin indicated greater degradation due to microbes and microzooplankton. PCA also suggests that phytoplankton community structure, particularly the dominance of diatoms versus carbonate-rich plankton, is the major factor influencing the POC export within the eddy field. In February, POC export fluxes were the highest ever reported for this area, reaching values of ~15 mmol C m 2 d 1 at 200 m depth. Compositional changes in pigments and THAA indicate that the source of sinking particles varies zonally and meridionally and suggest that sinking particles were more degraded at near-coastal stations relative to open ocean stations.
Comparison of Deep-Water Viromes from the Atlantic Ocean and the Mediterranean Sea  [PDF]
Christian Winter, Juan A. L. Garcia, Markus G. Weinbauer, Michael S. DuBow, Gerhard J. Herndl
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100600
Abstract: The aim of this study was to compare the composition of two deep-sea viral communities obtained from the Romanche Fracture Zone in the Atlantic Ocean (collected at 5200 m depth) and the southwest Mediterranean Sea (from 2400 m depth) using a pyro-sequencing approach. The results are based on 18.7% and 6.9% of the sequences obtained from the Atlantic Ocean and the Mediterranean Sea, respectively, with hits to genomes in the non-redundant viral RefSeq database. The identifiable richness and relative abundance in both viromes were dominated by archaeal and bacterial viruses accounting for 92.3% of the relative abundance in the Atlantic Ocean and for 83.6% in the Mediterranean Sea. Despite characteristic differences in hydrographic features between the sampling sites in the Atlantic Ocean and the Mediterranean Sea, 440 virus genomes were found in both viromes. An additional 431 virus genomes were identified in the Atlantic Ocean and 75 virus genomes were only found in the Mediterranean Sea. The results indicate that the rather contrasting deep-sea environments of the Atlantic Ocean and the Mediterranean Sea share a common core set of virus types constituting the majority of both virus communities in terms of relative abundance (Atlantic Ocean: 81.4%; Mediterranean Sea: 88.7%).
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