Phytol and phytyldiol concentrations at DYFAMED time series station and sediment trap

Particulate samples from the water column were collected monthly from depths of 5-150 m, between May 1996 and March 1997, in the northwestern Mediterranean Sea (Ligurian Sea) as part of the DYFAMED project within the French JGOFS program. These samples were analyzed by gas chromatography-electron impact mass spectrometry for their phytol and 3-methylidene-3,7,11-trimethylhexadecan-1,2-diol (phytyldiol) content. The corresponding Chlorophyll Phytyl side chain Photodegradation Index, molar ratio of phytyldiol to phytol, was calculated and the mean amount of chlorophyll photodegraded within the euphotic zone estimated. Seasonal differences in the chlorophyll photodegradation process appear in the one-year study. The chlorophyll appeared more photodegraded in the surface water (generally more than 40% photodegraded at 5-10 m) than at the deep chlorophyll maximum (DCM) (40-50 m) observed in the summer stratified waters (about 20% photodegraded). This difference was attributed to the healthy state of the phytoplankton community (coincidence with the highest primary production levels) and to the lower intensity of irradiance at the DCM level. On the other hand, the bulk of the detrital chlorophyll (chlorophyll associated with phytodetritus, phaeopigments) undergoes photodegradation before it sinks out of the photic zone. However, in January (winter mixed water) the pigments exported towards the sea floor were less photodegraded. This is thought to result from a shorter period of residence of the pigments in the photic zone due to vertical convection and grazing activity of macrozooplankton (salps), which are producers of rapid sinking fecal pellets.

Atmospheric and seawater carbon dioxide at time series station DYFAMED

A time series of fCO2, SST, and fluorescence data was collected between 1995 and 1997 by a CARIOCA buoy moored at the DyFAMed station (Dynamique des Flux Atmospheriques en Mediterranée) located in the northwestern Mediterranean Sea. On seasonal timescales, the spring phytoplankton bloom decreases the surface water fCO2 to approximately 290 µatm, followed by summer heating and a strong increase in fCO2 to a maximum of approximately 510 µatm. While the DELTA fCO2 shows strong variations on seasonal timescales, the annual average air-sea disequilibrium is only 2 µatm. Temperature-normalized fCO2 shows a continued decrease in dissolved CO2 throughout the summer and fall at a rate of approximately 0.6 µatm/d. The calculated annual air-sea CO2 transfer rate is -0.10 to -0.15 moles CO2 m-2 y-1, with these low values reflecting the relatively weak wind speed regime and small annual air-sea fCO2 disequilibrium. Extrapolating this rate over the whole Mediterranean Sea would lead to a flux of approximately -3 * 10**12 to -4.5 * 10**12 grams C/y, in good agreement with other estimates. An analysis of the effects of sampling frequency on annual air-sea CO2 flux estimates showed that monthly sampling is adequate to resolve the annual CO2 flux to within approximately ±10 - 18% at this site. Annual flux estimates made using temperature-derived fCO2 based on the measured fCO2-SST correlations are in agreement with measurement-based calculations to within ± 7-10% (depending on the gas transfer parameterization used), and suggest that annual CO2 flux estimates may be reasonably well predicted in this region from satellite or model-derived SST and wind speed information.

Chemistry of pore water and solids, formation factors and salt-corrected porosities of DSDP Site 68-503

Recent discoveries relating to the circulation of fluids within the oceanic crust include the finding of both important fluxes of elements and isotopes into the oceans by ridge-crest hydrothermal convection and important fluxes of heat out of the oceanic crust by convection at ridge crests and at some distance from ridge crests. In the present chapter, I present isotopic, chemical, and physical data from sediments and pore waters of Deep Sea Drilling Project (DSDP) Holes 503A and 503B. These results are modeled in terms of pore-water diffusion, advection, and production to ascertain the relative contribution of these processes at this location, 7.5 m.y. removed from ridge-crest hydrothermal activity. The observations made here contribute to the understanding of chemical and heat transport in oceanic crust of moderate age.

Chemical and strontium isotopic compositions of interstitial waters from sediments of ODP Site 135-841

The depth variations in the major chemical components dissolved in interstitial waters from the Tonga margin (ODP Site 841) are much more pronounced than those usually observed in deep-sea sediments. The extensive alteration of volcanic Miocene sediments to secondary minerals such as analcime, clays, and thaumasite forms a CaCl2-rich brine. The brine results from a high exchange of Ca to Na, K, and Mg and an increase in Cl concentrations due to removal of H2O from the fluid during the authigenesis of hydrous minerals. The formation of thaumasite could have partly controlled the concentration of dissolved SO4, HCO3, and Ca in the Miocene sediments. The strontium isotopic signature of the interstitial water suggests that alteration of the volcanic Miocene sediments occurred a long time after sedimentation. A transient diffusion model indicates that molecular diffusion was not prevented by lithologic barriers and that the formation of secondary minerals in the Miocene sediment occurred over a short period of time (e.g.,

Paraná y su región : Criterios básicos para proyectar políticas de gestión metropolitana

El propósito del presente trabajo es reconocer, cómo a partir de las tensiones globales y locales, de carácter socio - espacial e imbricadas en el proceso de metropolización que acusa el ámbito expandido de la ciudad de Paraná, es factible identificar y analizar los criterios básicos para proyectar una inédita gestión metropolitana dentro del espacio regional que constituyen tanto el ejido de la capital de la Provincia de Entre Ríos como el de sus tres municipios conurbados. En consecuencia y a tal fin, se intenta aquí establecer los nuevos desafíos incorporados a la gestión urbano-ambiental, tanto provincial como municipal, dentro de los que se platea articular la intervención estatal y la participación comunitaria, en el marco de un proceso de ordenamiento territorial del ámbito metropolizado en esas cuatro jurisdicciones en las que hoy habitan más de trescientos mil comprovincianos. Se trata, por tanto, de un proyecto estratégico que institucionalmente persiga la posibilidad de articular en simultáneo cuatro criterios políticos considerados aquí básicos para la gestión democrática del territorio metropolitano: la gobernabilidad, la competitividad, la sustentabilidad y la inclusión social. Criterios que, dentro de esa inteligencia, guiarán el análisis desarrollado sobre propuestas de actuación, jurídico-normativas y de gestión para abordar la compleja problemática del espacio urbano-regional. Es en tal contexto entonces, y dentro de esos principios primordiales para la intervención urbano-territorial, en el que se estima posible plantear, desde el ámbito institucional del Gobierno de la Provincia y de los gobiernos municipales, un acotado y preciso conjunto de políticas sectoriales básicas de ordenamiento que habiliten al despliegue de estrategias comunes y de consenso social posible, destinadas a transformar las críticas condiciones por las que atraviesa la conurbación en su conjunto, sin por eso vulnerar la autonomía de la jurisdicciones municipales incluidas en el espacio geográfico. Concluyendo, en el presente trabajo se analizan e identifican en forma iniciática, los criterios esenciales para el logro de los objetivos territoriales y las metas institucionales que dentro de la gestión metropolitana, puedan asumir el Estado Provincial y las jurisdicciones municipales, en tanto dispositivos gubernamentales destinados a que legal y orgánicamente, sean orientadas las políticas que tengan el propósito de afrontar tanto los procesos territoriales distorsivos como los déficit, las asimetrías y las carencias socio-ambientales que acusa la población del Gran Paraná

The observatory of intelligence and territorial development, tool for innovation in processes of territorial planning in municipalities of the province of Jujuy

El municipio es considerado como un espacio donde sus habitantes comparten no sólo el territorio sino también los problemas y los recursos existentes. La institución municipal -como gobierno local- es el ámbito en el cual se toman decisiones sobre el territorio, que implican a sus habitantes. En cuanto a los actores, estos pueden ser funcionarios, empleados y la comunidad (individual y organizada en ongs), todos aportan sus conocimientos y valores, pero tienen diferentes intereses y diferentes tiempos. Vinculada a las decisiones, encontramos que la forma en que se gestiona la información territorial, es determinante si se pretende apuntar hacia acciones con impacto positivo, y sustentables en lo ambiental y en el tiempo. Este trabajo toma tres municipios: San Salvador de Jujuy, capital de la provincia localizada en los Valles Templados; San Pedro de Jujuy, principal municipio de la región de las Yungas y Tilcara en la Quebrada de Humahuaca. El aporte de la Inteligencia Territorial, a través del observatorio OIDTe, permite analizar los modos de gestión de la información, especialmente mediante el uso de las tecnologías de la información y comunicación (pagina web municipal, equipamiento informático en las oficinas, estrategias de comunicación y vinculación con la población) y mediante la organización de las estructuras administrativas (organigrama) por las cuales circula la información municipal. Además, con la participación enriquecedora de equipos multidisciplinarios en las diferentes etapas. Se busca, a partir de un diagnóstico, generar estrategias para la introducción de innovaciones con los propios actores municipales, a partir de las situaciones y modos culturales propios de cada lugar, incorporando los marcos conceptuales de la Inteligencia Territorial. En este sentido el OIDTe al promover el entendimiento entre los actores, institucionales y la sociedad, facilita la coordinación de diferentes intereses propiciando la toma de decisiones por acuerdos. Asimismo, el método Portulano, puede orientar la introducción de innovaciones en la coordinación de la información cartográfica, para que las diferentes oficinas puedan complementar sus aportes y la comunicación hacia fuera de la institución. En la fase de diagnóstico, se aplicaron entrevistas a informantes claves, se realizó un workshop con técnicos de planta permanente y funcionarios de áreas que manejan información territorial, y de planificación. También por la importancia de la capacidad instalada de recursos humanos, se analizó el nivel de instrucción y la capacitación con que cuenta el personal de planta permanente de cada área

Interstitial water d13C and sediment geochemistry of ODP Leg 166 sites

A review of interstitial water samples collected from Sites 1003-1007 of the Bahamas Transect along with a shore-based analysis of oxygen and carbon isotopes, minor and trace elements, and sediment chemistry are presented. Results indicate that the pore-fluid profiles in the upper 100 meters below seafloor (mbsf) are marked by shifts between 20 and 40 mbsf that are thought to be caused by changes in sediment reactivity, sedimentation rates, and the influence of strong bottom currents that have been active since the late Pliocene. Pore-fluid profiles in the lower Pliocene-Miocene sequences are dominated by diffusion and do not show significant evidence of subsurface advective flow. Deeper interstitial waters are believed to be the in situ fluids that have evolved through interaction with sediments and diffusion. Pore-fluid chemistry is strongly influenced by carbonate recrystallization processes. Increases in pore-fluid Cl- and Na+ with depth are interpreted to result mainly from carbonate remineralization reactions that are most active near the platform margin. A lateral gradient in detrital clay content observed along the transect, leads to an overall lower carbonate reactivity, and enhances preservation of metastable aragonite further away from the platform margin. Later stage burial diagenesis occurs at slow rates and is limited by the supply of reactive elements through diffusion.

Interstitial-water chemistry and stable isotope record of Prydz Bay sediments

Leg 119 of the Ocean Drilling Program (ODP) provided the first opportunity to study the interstitial-water chemistry of the eastern Antarctic continental margin. Five sites were cored in a northwest-southeast transect of Prydz Bay that extended from the top of the continental slope to within 30 km of the coastline. Geological studies of the cores reveal a continental margin that has evolved through terrestrial, glacial, and glacial-marine environments. Chemical and stable isotopic analyses of the interstitial-waters were performed to determine the types of depositional environments and the diagenetic and hydrologic processes that are operating in this unusual marine environment. Highly compacted glacial sediments provide an effective barrier to the vertical diffusion of interstitial-water solutes. Meteoric water from the Antarctic continent appears to be flowing into Prydz Bay sediments through the sequence of terrestrial sediments that lie underneath the glacial sediments. The large amounts of erosion associated with glacial advances appear to have had the effect of limiting the amount of marine organic matter that is incorporated into the sediments on the continental shelf. Although all of the sites cored in Prydz Bay exhibit depletions in dissolved sulfate with increasing depth, the greatest bacterial activity is associated with a thin layer of diatom ooze that coats the seafloor of the inner bay. Results of alkalinity modeling, thermodynamic calculations, and strontium analyses indicate that (1) ocean bottom waters seaward of Site 740 are undersaturated with respect to both calcite and aragonite, (2) interstitial waters at each site become saturated or supersaturated with respect to calcite and aragonite with increasing depth, (3) precipitation of calcium carbonate reduces the alkalinity of the pore waters with increasing depth, and (4) recrystallization of aragonite to calcite accounts for 24% of the pore-water strontium. Weathering of unstable terrestrial debris and cation exchange between clay minerals and pore fluids are the most probable chemical processes affecting interstitial water cation gradients.

Biomass and bioturbation in surface sediments of the Arctic Ocean

Little is known about the benthic communities of the Arctic Ocean's slope and abyssal plains. Here we report on benthic data collected from box cores along a transect from Alaska to the Barents Abyssal Plain during the Arctic Ocean Section of 1994. We determined: (1) density and biomass of the polychaetes, foraminifera and total infauna; (2) concentrations of potential sources of food (pigment concentration and percent organic carbon) in the sediments; (3) surficial particle mixing depths and rates using downcore 210Pb profiles; and (4) surficial porewater irrigation using NaBr as an inert tracer. Metazoan density and biomass vary by almost three orders of magnitude from the shelf to the deep basins (e.g. 47 403 individuals m**-2 on the Chukchi Shelf to 95 individuals m**-2 in the Barents Abyssal Plain). Water depth is the primary determinant of infaunal density, explaining 39% of the total variability. Potential food concentration varies by almost two orders of magnitude during the late summer season (e.g. the phaeopigment concentration integrated to 10 cm varies from 36.16 mg m**-2 on the Chukchi Shelf to 0.94 mg m**-2 in the Siberia Abyssal Plain) but is not significantly correlated with density or biomass of the metazoa. Most stations show evidence of particle mixing, with mixing limited to <=3 cm below the sediment-water interface, and enhanced pore water irrigation occurs at seven of the nine stations examined. Particle mixing depths may be related to metazoan biomass, while enhanced pore water irrigation (beyond what is expected from diffusion alone) appears to be related to total phaeopigment concentration. The data presented here indicate that Arctic benthic ecosystems are quite variable, but all stations sampled contained infauna and most stations had indications of active processing of the sediment by the associated infauna.