Discovery of ferromanganese hydrocarbon-related nodules associated with the Meknes mud volcano (Western Moroccan margin)

A suite of ferromanganese nodules were sampled during the MVSEIS-2008 cruise aboard of the R/V Hesp��rides in the flanks of Meknes mud volcano (Moroccan margin, NE Central Atlantic). The nodules were collected at water depths between 750-850 m within a seabed area characterized by high acoustic backscatter values. Debris of cold water corals and hydrocarbon-derived authigenic carbonate crusts were sampled at same time. The nodules show tabular morphology, up to 20 cm in maximum diameter and 2 kg of weight, brown-reddish external color and they are internally composed by a concentric to complex arrangement of laminae. The results of X-ray diffraction analysis show that these ferromanganese nodules are essentially composed of goethite and lepidocrocite, being Mn-oxides, silicates (quartz and clay minerals) and carbonates (calcite, dolomite and siderite) accessory to occasional minerals. All the samples display micritic to micro-sparitic mosaic under the petrographic microscope which forms massive, laminated or dendritic-mottled textures. The nodules show a high abundance of Fe, minor Mn and low contents of trace metals and REEs. Mature hydrocarbons, as n-alkanes derived from marine bacterial activity, and phenanthrene have been detected in all the ferromanganese nodules analyzed. These nodules display analogous characteristics (textural, mineralogical and geochemical) to the nodules studied by Gonz��lez et al (2009) in the carbonate mud-mounds in the Gulf of Cadiz, offshore Iberian margin. In this way, the same preliminary genetic model proposed for these nodules might be applicable to those find in the Meknes mud volcano. Therefore, the anaerobic oxidation of hydrocarbon-rich fluids within the mud-breccia sediments in the flanks of Meknes mud volcano would induce the formation of early diagenetic Fe-(Mn) carbonate nodules. Thus, the nodules were later exhumed by the erosive action of sea bottom currents generating the replacement of ferromanganese carbonates by Fe-Mn oxy-hydroxides. Thus, the hydrocarbon-rich fluid venting from deep seated reservoirs and erosive action of bottom currents must have been essential actors, as mineralization controls, for ferromanganese nodules generation and evolution. These findings imply that this type of nodules must be considered as new product as derived from the anaerobic/aerobic oxidation of hydrocarbons in areas of active seepages.

Arrecifes de corales de aguas fr��as como posibles indicadores de emisiones de hidrocarburos en el Golfo de C��diz

El presente documento trata de exponer la relaci��n existente entre los corales de aguas fr��as encontrados en el Golfo de C��diz (Atl��ntico NE) con los procesos tect��nicos y las estructuras relacionadas con la migraci��n y la emisi��n de fluidos ricos en hidrocarburos (principalmente metano). Para ello, desde el a��o 2000 hasta la actualidad, se han llevado a cabo diversas campa��as oceanogr��ficas en las cuales se han obtenido datos y muestras relacionadas con las emisiones de hidrocarburos al fondo marino. Gracias a los datos y las muestras recogidas durante las campa��as se han creado una base de datos, en la que se re��nen todos los datos significativos relacionados con las campa��as oceanogr��ficas y con el objeto de este trabajo. Para finalizar, tras la creaci��n de la base de datos, y con las muestras proporcionadas por el IGME recogidas durante la campa��a oceanogr��fica MVSEIS08, se han podido llevar a cabo diversos estudios de laboratorio como la racemizaci��n de amino��cidos, an��lisis de biomarcadores as�� como la dataci��n de los esqueletos aragon��ticos de los corales de aguas fr��as mediante la t��cnica de U-Th en un futuro, con el objetivo de esclarecer la relaci��n existente entre estas emisiones de fluidos a trav��s de diversas estructuras y los corales de aguas fr��as, su edad, y en ��ltima instancia determinar los cambios producidos en la composici��n qu��mica de la masa de agua atl��ntica as�� como la variaci��n de las corrientes en el Golfo de C��diz durante el ��ltimo periodo glaciar. ABSTRACT This project attempts to explain the relationship between cold-water coral found in the Gulf of Cadiz (NE Atlantic) with tectonic processes and structures related to migration and hydrocarbon-rich fluids emissions (mainly methane). Since 2000 until present, have conducted various oceanographic cruises in which data were obtained and samples related to hydrocarbon emissions to the seabed. Thanks to data and samples collected during the cruises, I have created a database in which all gather meaningful data related to oceanographic and the object of this work. Finally, after the creation of the database, and the samples provided by the IGME collected during the oceanographic cruise MVSEIS08 have been able to carry out laboratory studies of racemization of aminoacids, biomarkers analysis and dating of aragonitic skeletons of cold-water corals in a future by U-Th data , in order to clarify the relationship between these fluids emissions through various structures, ages cold-water corals, and ultimately determine changes in the chemical composition of Atlantic water mass and the change of currents in the Gulf of Cadiz during the last glacial period.

Arrecifes de corales de aguas fr��as como posibles indicadores de emisiones de hidrocarburos en el banco de Galicia y determinaci��n de su edad mediante racemizacion de amino��cidos

Este proyecto tiene como objetivo analizar la posible relaci��n entre los corales de aguas fr��as encontrados en el Banco de Galicia con los procesos tect��nicos y las estructuras relacionadas con la migraci��n y la emisi��n de fluidos ricos en hidrocarburos (debido a su inter��s econ��mico), as�� como la creaci��n de un algoritmo que establezca una relaci��n entre el grado de racemizaci��n sufrido por los amino��cidos de las muestras y la edad de estas. Para ello, se han recopilado datos y muestras en el ��rea de estudio, gracias a los cuales se ha creado una base de datos que contiene una clasificaci��n de las muestras recogidas junto a los datos m��s relevantes de que est��n relacionados con el objetivo de este trabajo. Estas muestras han sido proporcionadas por el IGME y fueron recogidas mayoritariamente en la campa��a oceanogr��fica DIVA ARTABRIA II. Con estas muestras se han llevado a cabo an��lisis de laboratorio como el estudio de racemizaci��n de amino��cidos, el an��lisis de biomarcadores y la dataci��n por uranio-torio de los esqueletos aragon��ticos de los corales de aguas fr��as. Para finalizar, se han estudiado dichos datos con el objeto de comprobar la hip��tesis de que los corales de aguas fr��as colonizan zonas con emisiones de hidrocarburos, conocer su edad y en ��ltima instancia crear un algoritmo capaz de datar dichos corales a partir del grado de racemizaci��n de sus amino��cidos. Palabras clave: corales de aguas fr��as, Banco de Galicia, campa��a oceanogr��fica, DIVA ARTABRIA II, base de datos, racemizaci��n, amino��cidos, biomarcadores, dataci��n uranio-torio, hidrocarburos, algoritmo. ABSTRACT This project studies the relationship between cold-water corals found in the Galicia Bank with tectonic processes and with the structures related to migration and hydrocarbon-rich fluids emissions. Firstly, data and samples in the study were collected, through to classify the collected samples with the most relevant characteristics to our research scope. Sampling and data collection provided by the IGME were collected in the DIVA ARTABRIA II oceanographic cruise. Secondly, the current work presents a systematic laboratory analysis that allowed the study of aminoacid racemization as well as the analysis of biomarkers and the uranium-thorium dating of aragonitic cold-water coral skeletons. Finally, this data was studied to test the hypothesis that cold-water corals colonize areas with emissions of hydrocarbons, know its age and ultimately create and algorithm capable of dating these corals from the degree of racemization in its amino acids. Keywords: cold-water corals, Galicia Bank, oceanographic cruise, DIVA ARTABRIA II, database, racemization, amino acids, biomarkers, uranium-thorium datation, hydrocarbons, algorithm.

Conductancia del mes��filo en especies forestales: implicaciones en la respuesta fotosint��tica a la disponibilidad de agua y luz

La fotos��ntesis es el proceso biol��gico que permite la producci��n primaria y, por tanto, la vida en nuestro planeta. La tasa fotosint��tica viene determinada por la ���maquinaria��� bioqu��mica y las resistencias difusivas al paso del CO2 desde la atm��sfera hasta su fijaci��n en el interior de los cloroplastos. Hist��ricamente la mayor resistencia difusiva se ha atribuido al cierre estom��tico, sin embargo ahora sabemos, debido a las mejoras en las t��cnicas experimentales, que existe tambi��n una resistencia grande que se opone a la difusi��n del CO2 desde los espacios intercelulares a los lugares de carboxilaci��n. Esta resistencia, llamada normalmente por su inversa: la conductancia del mes��filo (gm), puede ser igual o incluso superior a la resistencia debida por el cierre estom��tico. En la presente tesis doctoral he caracterizado la limitaci��n que ejerce la resistencia del mes��filo a la fijaci��n de CO2 en diversas especies forestales y en distintos momentos de su ciclo biol��gico. En la fase de regenerado, hemos estudiado tres situaciones ambientales relevantes en el mayor ��xito de su supervivencia, que son: el d��ficit h��drico, su interacci��n con la irradiancia y el paso del crecimiento en la sombra a mayor irradiancia, como puede suceder tras la apertura de un hueco en el dosel forestal. En la fase de arbolado adulto se ha caracterizado el estado h��drico y el intercambio gaseoso en hojas desarrolladas a distinta irradiancia dentro del dosel vegetal durante tres a��os contrastados en pluviometr��a. Para cada tipo de estudio se han empleado las t��cnicas ecofisiol��gicas m��s pertinentes para evaluar el estado h��drico y el intercambio gaseoso. Por su complejidad y la falta de un m��todo que permita su cuantificaci��n directa, la gm ha sido evaluada por los m��todos m��s usados, que son: la discriminaci��n isot��pica del carbono 13, el m��todo de la J variable, el m��todo de la J constante y el m��todo de la curvatura. Los resultados m��s significativos permiten concluir que la limitaci��n relativa a la fotos��ntesis por la conductancia estom��tica, del mes��filo y bioqu��mica es dependiente de la localizaci��n de la hoja en el dosel forestal. Por primera vez se ha documentado que bajo estr��s h��drico las hojas desarrolladas a la sombra estuvieron m��s limitadas por una reducci��n en la gm, mientras que las hojas desarrolladas a pleno sol estuvieron m��s limitadas por reducci��n mayor de la conductancia estom��tica (gsw). Encontramos buena conexi��n entre el aparato fotosint��tico foliar y el sistema h��drico debido al alto grado de correlaci��n entre la conductancia hidr��ulica foliar aparente y la concentraci��n de CO2 en los cloroplastos en distintas especies forestales. Adem��s, hemos mostrado diferentes pautas de regulaci��n del intercambio gaseoso seg��n las particularidades ecol��gicas de las especies estudiadas. Tanto en brinzales crecidos de forma natural y en el arbolado adulto como en pl��ntulas cultivadas en el invernadero la ontogenia afect�� a las limitaciones de la fotos��ntesis producidas por estr��s h��drico, resultando que las limitaciones estom��ticas fueron dominantes en hojas m��s j��venes mientras que las no estom��ticas en hojas m��s maduras. La puesta en luz supuso un gran descenso en la gm durante los d��as siguientes a la transferencia, siendo este efecto mayor seg��n el grado de sombreo previo en el que se han desarrollado las hojas. La aclimataci��n de las hojas a la alta irradiancia estuvo ligada a las modificaciones anat��micas foliares y al estado de desarrollo de la hoja. El ratio entre la gm/gsw determin�� la mayor eficiencia en el uso del agua y un menor estado oxidativo durante la fase de estr��s h��drico y su posterior rehidrataci��n, lo cual sugiere el uso de este ratio en los programas de mejora gen��tica frente al estr��s h��drico. Debido a que la mayor��a de modelos de estimaci��n de la producci��n primaria bruta (GPP) de un ecosistema no incluye la gm, los mismos est��n incurriendo en una sobreestimaci��n del GPP particularmente bajo condiciones de estr��s h��drico, porque m��s de la mitad de la reducci��n en fotos��ntesis en hojas desarrolladas a la sombra se debe a la reducci��n en gm. Finalmente se presenta un an��lisis de la importancia en las estimas de la gm bajo estr��s h��drico de la refijaci��n del CO2 emitido en la mitocondria a consecuencia de la fotorrespiraci��n y la respiraci��n mitocondrial en luz. ABSTRACT Photosynthesis is the biological process that supports primary production and, therefore, life on our planet. Rates of photosynthesis are determined by biochemical ���machinery��� and the diffusive resistance to the transfer of CO2 from the atmosphere to the place of fixation within the chloroplasts. Historically the largest diffusive resistance was attributed to the stomata, although we now know via improvements in experimental techniques that there is also a large resistance from sub-stomatal cavities to sites of carboxylation. This resistance, commonly quantified as mesophyll conductance (gm), can be as large or even larger than that due to stomatal resistance. In the present PhD I have characterized the limitation exerted by the mesophyll resistance to CO2 fixation in different forest species at different stages of their life cycle. In seedlings, we studied three environmental conditions that affect plant fitness, namely, water deficit, the interaction of water deficit with irradiance, and the transfer of plants grown in the shade to higher irradiance as can occur when a gap opens in the forest canopy. At the stage of mature trees we characterized water status and gas exchange in leaves developed at different irradiance within the canopy over the course of three years that had contrasting rainfall. For each study we used the most relevant ecophysiological techniques to quantify water relations and gas exchange. Due to its complexity and the lack of a method that allows direct quantification, gm was estimated by the most commonly used methods which are: carbon isotope discrimination, the J-variable, constant J and the curvature method The most significant results suggest that the relative limitation of photosynthesis by stomata, mesophyll and biochemistry depending on the position of the leaf within the canopy. For the first time it was documented that under water stress shaded leaves were more limited by a reduction in gm, while the sun-adapted leaves were more limited by stomatal conductance (gsw). The connection between leaf photosynthetic apparatus and the hydraulic system was shown by the good correlations found between the apparent leaf hydraulic conductance and the CO2 concentration in the chloroplasts in shade- and sun-adapted leaves of several tree species. In addition, we have revealed different patterns of gas exchange regulation according to the functional ecology of the species studied. In field grown trees and greenhouse-grown seedlings ontogeny affected limitations of photosynthesis due to water stress with stomatal limitations dominating in young leaves and nonstomatal limitations in older leaves. The transfer to high light resulted in major decrease of gm during the days following the transfer and this effect was greater as higher was the shade which leaves were developed. Acclimation to high light was linked to the leaf anatomical changes and the state of leaf development. The ratio between the gm/gsw determined the greater efficiency in water use and reduced the oxidative stress during the water stress and subsequent rehydration, suggesting the use of this ratio in breeding programs aiming to increase avoidance of water stress. Because most models to estimate gross primary production (GPP) of an ecosystem do not include gm, they are incurring an overestimation of GPP particularly under conditions of water stress because more than half of An decrease in shade-developed leaves may be due to reduction in gm. Finally, we present an analysis of the importance of how estimates of gm under water stress are affected by the refixation of CO2 that is emitted from mitochondria via photorespiration and mitochondrial respiration in light.

Torpor in mice is induced by both leptin-dependent and -independent mechanisms

We tested the effect of chronic leptin treatment on fasting-induced torpor in leptin-deficient A-ZIP/F-1 and ob/ob mice. A-ZIP/F-1 mice have virtually no white adipose tissue and low leptin levels, whereas ob/ob mice have an abundance of fat but no leptin. These two models allowed us to examine the roles of adipose tissue and leptin in the regulation of entry into torpor. Torpor is a short-term hibernation-like state that allows conservation of metabolic fuels. We first characterized the A-ZIP/F-1 animals, which have a 10-fold reduction in total body triglyceride stores. Upon fasting, A-ZIP/F-1 mice develop a lower metabolic rate and decreased plasma glucose, insulin, and triglyceride levels, with no increase in free fatty acids or ��-hydroxybutyrate. Unlike control mice, by 24 hr of fasting, they have nearly exhausted their triglycerides and are catabolizing protein. To conserve energy supplies during fasting, A-ZIP/F-1 (but not control) mice entered deep torpor, with a minimum core body temperature of 24��C, 2��C above ambient. In ob/ob mice, fasting-induced torpor was completely reversed by leptin treatment. In contrast, neither leptin nor thyroid hormone prevented torpor in A-ZIP/F-1 mice. These data suggest that there are at least two signals for entry into torpor in mice, a low leptin level and another signal that is independent of leptin and thyroid hormone levels. Studying rodent torpor provides insight into human torpor-like states such as near drowning in cold water and induced hypothermia for surgery.

Total organic carbon, delta13C, biomarker, gas compilations and hopanoids analysis from IODP Sites 307-U1317 and 307-U1318

During the Integrated Ocean Drilling Program (IODP) Expedition 307 for the first time a cold-water coral carbonate mound was drilled down through its base into the underlying sediments. In the current study, sample material from within and below Challenger Mound, located in the Belgica carbonate mound province in the Porcupine Basin offshore Ireland, was investigated for its distribution of microbial communities and gas composition using biogeochemical and geochemical approaches to elucidate the question on the initiation of carbonate mounds. Past and living microbial populations are lower in the mound section compared to the underlying sediments or sediments of an upslope reference site. A reason for this might be a reduced substrate feedstock, reflected by low total organic carbon (TOC) contents, in the once coral dominated mound sequence. In contrast, in the reference site a lithostratigraphic sequence with comparatively high TOC contents shows higher abundances of both past and present microbial communities, indicating favourable living conditions from time of sedimentation until today. Composition and isotopic values of gases below the mound base seem to point to a mixed gas of biogenic and thermogenic origin with a higher proportion of biogenic gas. Oil-derived hydrocarbons were not detected at the mound site. This suggests that at least in the investigated part of the mound base the upward flow of fossil hydrocarbons, being one hypothesis for the initiation of the formation of carbonate mounds, seems to be only of minor significance.