1,721,209 research outputs found
Dimethylsulfoniopropionate-derived compound concentrations, volatile organic compound concentrations, and microorganism abundances over diel cycles in the tropical ocean and in a coral back reef lagoon of Moorea (French Polynesia)
No full text<p><span>These data belong in the paper: </span></p>
<p>Marta Masdeu-Navarro, Jean-François Mangot, Lei Xue, Miguel Cabrera-Brufau, DavidJ. Kieber, Pablo Rodríguez-Ros, Stephanie G. Gardner, Kristin Bergauer, Gerhard J. Herndl, Cèlia Marrasé<span> </span>and Rafel Simó (2024)<span>. </span>Diel variation of seawater volatile organic compounds, DMSP-related compounds, and microbial plankton inside and outside a tropical coral reef ecosystem. Frontiers in Marine Science.</p>
<p>Concentrations of DMSP, acrylate, DMSO, DMS, DMDS, COS, CS2, isoprene, CH3I, CH2ClI, CH2Br2 and CHBr3 in seawater samples at two sampling sites, one inside (named BR) and one outside (named OO), of <span>the northern coral reef of Mo'orea, French Polynesia. Along with the afore mentioned compounds, the data set contains a</span><span>bundances of heterotrophic prokaryotes, Prochlorococcus, Synechococcus, picoeukaryotes and nanoeukaryotes as determined by flow cytometry, as well as concentrations of nutrients, chlorophyll a, DOC, DON, POC and FDOM. The data set is subdivided into two data sets, one per sampling site, each being composed of a time series of measurements done every 6h over a period of 36h. </span><span>All samples were collected in April 2018.</span></p>
Relación entre el Dimetilsulfuro y la Fotofisiología del Fitoplancton en la Superficie del Océano: Patrones Geográficos y Variabilidad a Corto Plazo
No full textMemoria de tesis doctoral presentada por Sarah-Jeanne Royer para obtener el título de Doctora en Ciencias del Mar por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. Rafel Simò Martorell del Institut de Ciències del Mar (ICM-CSIC).-- 345 pages[EN] Dimethylsulfide (DMS) and its algal precursor, dimethylsulfopropionate (DMSP), are major players in the oceanic and atmospheric sulfur cycle. DMS is the most abundant volatile organic sulfur compound in the upper ocean and its global emission accounts for ca. 28 Tg S per year, thus representing the main natural source of sulfur to the troposphere and about 30% of the global (including anthropogenic) sulfur emissions. [...][CAT] El dimetilsulfur (DMS) i el seu su precursor algal dimetilsulfoniopropionat (DMSP) són part fonamental del cicle del sofre als oceans i l'atmosfera. El DMS és el compost volàtil de sofre més abundant a l'oceà superficial, que n'emet a l'atmosfera una
quantitat aproximada de 28 Tg S l'any. [...]Peer Reviewe
Interactive effects of vertical mixing, solar radiation and microbial activity on oceanic dimethylated sulfur cycling
No full textMemoria de tesis doctoral presentada por Martí Galí Tàpias para optar al grado de Doctor en Ciencias del Mar en el Departament d'Enginyeria Hidràulica, Marítima i Ambiental de la Universitat Politécnica de Catalunya (UPC), realizada bajo la dirección del Dr. Rafel Simó Martorell del Departament d'Enginyeria Hidràulica, Marítima i Ambiental de la Universitat Politècnica de Catalunya (UPC) y del Institut de Ciències del Mar (ICM-CSIC),-- 214 pagesMicroscopic plankton thriving in the sunlit upper ocean play a key role in the biogeochemical functioning of the biosphere. The production and subsequent emission of volatile compounds is one of the numerous ways by which they participate in the cycling of elements and in uence the Earth's climate. Dimethylsulde (DMS), produced by enzymatic decomposition of the algal intracellular compound dimethylsulfoniopropionate (DMSP), is the more abundant organic volatile in the upper ocean. Its global emission amounts ca. 28 Tg S per year, and represents the main biogenic source of sulfur to the troposphere and about 30% of the total S emission (anthropogenic, biogenic and volcanic). Atmospheric oxidation of DMS contributes to atmospheric acidity, and is believed to promote the formation and growth of aerosols. Furthermore, DMS-derived sulfate aerosols have been suggested to cool the climate by reducing the amount of shortwave solar radiation reaching the Earth's surface by scattering solar radiation and, more important, by acting as cloud condensation nuclei. The `CLAW' hypothesis postulates that, if oceanic DMS emission was in turn stimulated by solar radiation, a regulatory feedback mechanism could operate between marine plankton and the radiative budget over the oceans. However, the relationship between DMS emission and solar radiation is not straightforward, since a number of biochemical and photochemical transformations come into action from the moment DMSP is synthesized by phytoplankton until DMS is emitted. These transformations are intimately linked to the physical environment, the ecological setting and the microbial interactions, rendering the picture of dimethylated sulfur cycling a lot more complicated. Surprisingly, though, the seasonal cycle of seawater DMS concentration seems to follow that of solar radiation in the majority of oceanic regions, regardless their productivity regimes. This characteristic feature of oceanic DMS, while broadly accepted, is not yet well understood. The premise of this thesis is that, to understand this emerging pattern, we need to understand what regulates the DMS production and consumption processes and their balance (that is, DMS budgets). To this end, we have studied the response of biotic and abiotic DMS cycling to solar radiation by means of incubation experiments. At another level, we have studied the response of ecosystem DMS budgets to dierent radiation climates, and from polar to subtropical areas. Since the depth of the upper mixed layer regulates the amount and spectral composition of the `light' seen by the cells and molecules, our studies have been backed by a careful characterization of underwater radiation elds and vertical mixing dynamicsPeer Reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Marine aerosols, their precursors and their influence on clouds over the global ocean
No full textMemoria de tesis doctoral presentada por María Aránzazu Lana Celaya para optar al grado de Doctora en Ciencias del Mar en el Departament d'Enginyeria Hidràulica, Marítima i Ambiental de la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección del Dr. Rafel Simó Martorell del Institut de Ciències del Mar (ICM-CSIC) y del Dr. Jordi Dachs del Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA-CSIC).-- 207 pagesMarine aerosols have a large potential to influence the Earth’s climate through their effects on cloud properties. The CLAW hypothesis goes further, and suggests that marine aerosols formed by the sulphur cycle of the ocean and the atmosphere act as a mechanism for regulating the Earth's climate. This effect is produced through the influence of plankton emissions of sulphur compounds on cloud formation. Phytoplankton produces dimethylsulphide (DMS), a highly volatile sulphur compound. Once in the atmosphere, DMS is oxidized and becomes the main source of natural atmospheric sulphates. These sulphates act as condensation nuclei, particles that are essential for the formation of clouds. Those marine particles in the atmosphere play an important role in the Earth's radiation budget. Indirectly they produce a greater amount of cloud droplets. Higher cloud condensation nuclei imply smaller cloud droplets. The efficiency of smaller droplets in reflecting incident solar radiation is greater, resulting in an increase in cloud albedo, producing a cooling effect on the Earth's surface. To properly study the marine aerosols we need accurate knowledge of the global seawater distribution of the aerosol precursors. Our work focused on the ocean-to-atmosphere emissions of DMS and other biogenic gases that can have an impact on cloud microphysics. During the thesis we updated the monthly global DMS climatology taking advantage of the three-fold increased size and better resolved distribution of the observations available in the DMS database. The emerging patterns found with the previous versions of the database and climatology were explored with the updated version. The statistical relationships between the seasonalities of DMS concentrations and solar radiation doses and chlorophyll a concentrations were here re-examined. Analyses of nine years of satellite data suggested that there is a natural inverse correlation between the spatial cover of low marine clouds and the cloud droplet size, which is related to the presence of small aerosols. This coupled seasonality pushes cloud albedo to contribute higher negative radiative forcing in summer and lower in winter. This relation is disrupted in the marine atmosphere regions heavily impacted by anthropogenic aerosols. Consequently, the potential influence the aerosol precursors have on marine clouds was next analysed over unpolluted and polluted ocean, separately. The 9 years of global satellite data and ocean climatologies were used to derive parameterizations of the production fluxes of secondary aerosols formed by oxidation of DMS and other biogenic organic volatiles. Further, the emission fluxes of biogenic primary organic and sea salt aerosols ejected by wind action on sea surface were also globally studied. Series of weekly estimates of these fluxes were correlated to series of cloud droplet effective radius. The outcome of the statistical analyses indicated that sulphur and organic secondary aerosols might be important in seeding cloud nucleation and droplet activation over mid and high latitude unpolluted oceanic regions. Conversely, primary aerosols (organic and sea salt) showed that, despite contributing to large shares of the marine aerosol mass, they do not seem to be major drivers of the variability of cloud microphysics. Our results provide partial support for the feasibility of the CLAW hypothesis at the seasonal scale. Despite that DMS has drawn much of the attention on the links between marine biota and climate regulation, the implication of other biogenic precursors on cloud formation provides and suggests a wider scope on the formulation of such hypothesisPeer Reviewe
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Mar, gel i cel (Ciència i poesia en temps de canvis)
No full textCiclo de conferencias Bosc Ancestral realizadas en el Institut de Ciències del Mar (ICM-CSIC) de BarcelonaPensem en el científic com un personatge curiós, que es pregunta contínuament com són i funcionen les «coses», que troba plaer a descriure i comprendre. M’hi apunto. Però encara m’apunto més al científic que troba plaer a descobrir, a revelar connexions noves entre fenòmens aparentment inconnexos. Ho visc en la pròpia pell: el pinyol de fer ciència és un procés creatiu, no sols descriptiu, que no l’allunya gaire de l’art. Com aquest, parteix d’un deliri d’exploració, s’alimenta de la fascinació per l’entorn, i fa ressonar l’observació amb el món interior per generar coneixement, transformació.
Quin lloc, l’Antàrtida, per viure-hi integradament les dues experiències, la científica i l’artística. És un lloc que t’atrapa com pocs al món. Sobretot, perquè la natura hi té tot el protagonisme i es desplega amb tot l’esplendor. Però també perquè és un lloc on han confluït i conflueixen moltes coses: atrocitats, ambicions, proeses, acords geopolítics excepcionals, troballes científiques determinants. Anem a l’Antàrtida perquè guarda bona part de les claus del funcionament del nostre planeta. Però també perquè, avui, mirar-se el món des de l’Antàrtida és una invitació a l’esperit de col·laboració, a llançar preguntes genuïnes, a l’admiració i l’agraïment, tan necessaris, a sentir-se part d’una vida ancestral, poderosa, dinàmica, que ens fa tots iguals, del pes just d’un floc de neuPeer Reviewe
BIOCOMPLEXITY 2004 : Estudi del cicle del sofre a les capes superficials de l'oceà. Mar dels Sargassos
No full textDiario de la campaña oceanográfica BIOCOMPLEXITY, a bordo del buque oceanográfico Seward Johnson durante el mes de julio de 2004, publicado en la página web de ICM Divulga.-- 17 pages, figuresL'objectiu de la campanya Biocomplexity és dur a terme l'estudi més complet i detallat que mai s'ha fet del cicle del sofre a la capa més superficial de l'oceà, per tal d'esbrinar els factors ambientals i biològics que controlen l'emissió de l'atmosfera. La campanya s'ha portat a terme en juliol 2004 a bord del vaixell oceanogràfic nord-americà Seward Johnson. Rafel Simó, investigador principal de la campanya Biocomplexity, escriu des del vaixell per a explicar el que hem vingut a estudiar fins al Mar dels Sargassos.
- Projecte i participants: · El paper de l'oceà en el clima · L'objectiu principal de la campanya · On es troba i quines característiques té el Mar dels Sargassos? - Diari de campanya: · El vaixell, la seva tripulació i el DIMETILSULFUR · Els efectes dels corrents marins · Els secrets de la producció primària · El nostre treball a bord · Els falsos deserts com el Mar dels Sargassos · Trichodesmium · Llum, radiació, reaccions fotoquímiques i el paper dels organismes · ParèntesisPeer reviewe
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