Carbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008

[EN]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 ( ) were also affected by the presence of these two water masses with high carbonate concentrations. The aragonite saturation horizon was observed at 1000m 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 800m to 1500m at 50.37_ S, and reached 700m 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 with changes in dissolved inorganic carbon (CT)and total alkalinity (AT) offered minima values in the Antarctic IntermediateWater and UCDWlayers. 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.

El cubo de proyecciones

[ES] Video tutorial que explica el mecanismo de los Sistemas de Representación para representar la realidad tridimensional en una superficie bidimensional.

Soporte para cable

[ES] Video tutorial en el que se explica la solución del conjunto Soporte para cale

Mordaza para cable

[ES] Vídeo tutorial en el que se explica la solución del conjunto Mordaza para cable

Soporte oscilante

[ES] Víedo tutorial en el que se explica la solución del conjunto Mordaza para cable

Escala

[ES] Vídeo tutorial en el que se explica la aplicación del concepto de Escala para cambiar el tamaño de los dibujos técnicos

Válvula de bola

[ES] Vídeo tutorial en el que se explica la solución del conjunto Válvula de bola

Gancho de sujeción

[ES] vídeo tutorial en el que se explica la solución del conjunto Gancho de sujeción

Soporte para cable. Alternativas

[ES] Video tutorial en el que se explican diversas alternativas de solucionar la pieza "base" del conjunto Soporte para cable

Foro técnico: La pesca en Gran Canaria

[ES] foro organizado por la Universidad de Las Palmas de Gran Canaria y la Comisión de Pesca de la Unión Europea celebrado en la Facultad de Ciencias del Mar de la Universidad de Las Palmas de Gran Canaria, el 25 de enero de 2013. Presenta el acto el Rector de la Universidad de Las Palmas de Gran Canaria, don José Regidor García, el Decano de la Facultad de Ciencias del Mar, don Melchor González Dávila, el Presidente de la Comisión de Pesca del Parlamento Europeo, don Gabriel Mato Adrover, el Secretario General de Pesca del Ministerio de Agricultura, Alimentación y Medio Ambiente, don Carlos Domínguez, finalmente el Consejero de Agricultura, Ganadería, Pesca y Aguas del Gobierno Canario, Juan Ramón Hernández. Asimismo, se desarrollaron tres ponencias que recogieron algunos de los aspectos más relevantes en estos momentos, como son la pesca artesanal, en la que José Pascual Fernández, del Instituto Universitario de Ciencias Políticas y Sociales de la Universidad de La Laguna, puso el acento en las experiencias existentes en cogestión y gobernanza. La economía de la pesca en Canarias fue otro de los puntos tratados, a través de la ponencia desarrollada por Javier Macías, representante de la consultoría de pesca, CANAEST, así como la opinión de la Consejería de Agricultura, Ganadería y Pesca del Cabildo de Gran Canaria, a través de la exposición que realizarán Alejandro Báez y María Marrero. La nueva propuesta de gestión pesquera para Gran Canaria, a cargo del Centro de Investigación en Biodiversidad y Gestión Ambiental del Departamento de Biología de la Universidad de Las Palmas de Gran Canaria (Bioges), en la figura de José Juan Castro, fue otro de los puntos abordados.

Effect of organic exudates of Phaeodactylum tricornutum on the Fe(II) oxidation rate constant

[EN] Fe(II) oxidation kinetics were studied in seawater and in seawater enriched with exudates excreted by Phaeodactylum tricornutum as an organic ligand model. The exudates produced after 2, 4, and 8 days of culture at 6.21 .. 107, 2.29 .. 108, and 4.98 .. 108 cell L?1 were selected. The effects of pH (7.2?8.2), temperature (5?35 ºC), and salinity (10?36.72) on the Fe(II) oxidation rate were studied. All the data were compared with the results for seawater without exudates (control). The Fe(II) rate constant decreased as a function of culture time and cell concentration in the culture at different pH, temperature, and salinity. All the experimental data obtained in this study were fitted to a polynomial function in order to quantify the fractional contribution of the organic exudates from the diatoms to the Fe(II) oxidation rate in natural seawater. Experimental results showed that the organic exudates excreted by P. tricornutum affect Fe(II) oxidation, increasing the lifetime of Fe(II) in seawater. A kinetic model approach was carried out to account for the speciation of each Fe(II) type together with its contribution to the overall rate.

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

[EN] We used 5-yr concomitant data of tracer distribution from the BATS (Bermuda Time-series Study) and ESTOC (European Station for Time-Series in the Ocean, Canary Islands) sites to build a 1-D tracer model conservation including horizontal advection, and then compute net production and shallow remineralization rates for both sites. Our main goal was to verify if differences in these rates are consistent with the lower export rates of particulate organic carbon observed at ESTOC. Net production rates computed below the mixed layer to 110m from April to December for oxygen, dissolved inorganic carbon and nitrate at BATS (1.34±0.79 molO2 m?2, ?1.73±0.52 molCm?2 and ?125±36 mmolNm?2) were slightly higher for oxygen and carbon compared to ESTOC (1.03±0.62 molO2 m?2, ?1.42±0.30 molCm?2 and ?213±56 mmolNm?2), although the differences were not statistically significant. Shallow remineralization rates between 110 and 250m computed at ESTOC (?3.9±1.0 molO2 m?2, 1.53±0.43 molCm?2 and 38±155 mmolNm?2) were statistically higher for oxygen compared to BATS (?1.81±0.37 molO2 m?2, 1.52± 0.30 molCm?2 and 147±43 mmolNm?2). The lateral advective flux divergence of tracers, which was more significant at ESTOC, was responsible for the differences in estimated oxygen remineralization rates between both stations. According to these results, the differences in net production and shallow remineralization cannot fully explain the differences in the flux of sinking organic matter observed between both stations, suggesting an additional consumption of nonsinking organic matter at ESTOC.

Vistas auxiliares simples

[ES] Monografía dedicada al estudio de las Vistas Auxiliares Simples.

Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network

[EN] Here we present monthly, basin-wide maps of the partial pressure of carbon dioxide (pCO2) for the North Atlantic on a latitude by longitude grid for years 2004 through 2006 inclusive. The maps have been computed using a neural network technique which reconstructs the non-linear relationships between three biogeochemical parameters and marine pCO2. A self organizing map (SOM) neural network has been trained using 389 000 triplets of the SeaWiFSMODIS chlorophyll-a concentration, the NCEP/NCAR reanalysis sea surface temperature, and the FOAM mixed layer depth. The trained SOM was labelled with 137 000 underway pCO2 measurements collected in situ during 2004, 2005 and 2006 in the North Atlantic, spanning the range of 208 to 437atm. The root mean square error (RMSE) of the neural network fit to the data is 11.6?atm, which equals to just above 3 per cent of an average pCO2 value in the in situ dataset. The seasonal pCO2 cycle as well as estimates of the interannual variability in the major biogeochemical provinces are presented and discussed. High resolution combined with basin-wide coverage makes the maps a useful tool for several applications such as the monitoring of basin-wide air-sea CO2 fluxes or improvement of seasonal and interannual marine CO2 cycles in future model predictions. The method itself is a valuable alternative to traditional statistical modelling techniques used in geosciences.

Enunciados SAD Básico

[ES]Enunciados de los ejercicios de nivel básico del Sistema de Ayuda al Dibujo (SAD)