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Registros recuperados: 32 | |
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Castrillejo, Maxi; Casacuberta, Nuria; Christl, Marcus; Vockenhuber, Christof; Synal, Hans-arno; Garcia-ibanez, Maribel; Lherminier, Pascale; Sarthou, Geraldine; Garcia-orellana, Jordi; Masque, Pere. |
Pathways and timescales of water mass transport in the subpolar North Atlantic Ocean (SPNA) have been investigated by many studies due to their importance for the meridional overturning circulation and thus for the global ocean. In this sense, observational data on geochemical tracers provide complementary information to improve the current understanding of the circulation in the SPNA. To this end, we present the first simultaneous distribution of artificial 129I and 236U in 14 depth profiles and in surface waters along the GEOVIDE section covering a zonal transect through the SPNA in spring 2014. Our results show that the two tracers are distributed following the water mass structure and that their presence is largely influenced by the global fallout (GF)... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00457/56873/58725.pdf |
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Long, Marc; Holland, Aleicia; Planquette, Helene; Gonzalez Santana, David; Whitby, Hannah; Soudant, Philippe; Sarthou, Geraldine; Hégaret, Helene; Jolley, Dianne F. |
The dinoflagellate Alexandrium minutum produces toxic compounds, including paralytic shellfish toxins, but also some unknown extracellular toxins. Although copper (Cu) is an essential element, it can impair microalgal physiology and increase their toxic potency. This study investigated the effect of different concentrations of dissolved Cu (7 nM, 79 nM and 164 nM) on A. minutum allelochemical potency, here defined as negative effects of a protist on competing protists through the release of chemicals. This was studied in relation to its physiology. The effects of Cu were assessed on A. minutum growth, reactive oxygen species level, photosynthesis proxies, lipid metabolism, exudation of dissolved organic compounds, allelochemical potency and on the... |
Tipo: Text |
Palavras-chave: Alexandrium; Copper; Toxicity; Allelopathy; Physiology; Exudate. |
Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59612/62629.pdf |
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González-santana, David; Planquette, Helene; Cheize, Marie; Whitby, Hannah; Gourain, Arthur; Holmes, Thomas; Guyader, Vivien; Cathalot, Cecile; Pelleter, Ewan; Fouquet, Yves; Sarthou, Geraldine. |
Hydrothermal vents are a recognized source of trace elements to the ocean inventory. Nevertheless, the contribution of slow-spreading ridges remains poorly resolved. To address this, high-resolution dissolved (<0.45 μm) iron (dFe) and manganese (dMn) samples were collected during the GEOTRACES HERMINE GApr07 process study at the Mid Atlantic Ridge. Samples were collected at nine stations, from the TAG vent site to 75 km south-southwest following the neutrally buoyant plume. Concentrations of dMn and dFe ranged from 71 ± 6 and 51 ± 2 nmol kg–1 right above the vent site to 0.43 ± 0.01 and 1.56 ± 0.02 nmol kg–1 at the most distal station, respectively. Using a 5-box model coupled with our data, we show that as the plume traveled away from the vent,... |
Tipo: Text |
Palavras-chave: Iron; Manganese; Hydrothermal; TAG; Mid Atlantic Ridge; GEOTRACES. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75530/76431.pdf |
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Whitby, Hannah; Bressac, Matthieu; Sarthou, Geraldine; Ellwood, Michael J.; Guieu, Cécile; Boyd, Philip W.. |
Iron is a key micronutrient in seawater, but concentrations would be negligible without the presence of organic ligands. The processes influencing the ligand pool composition are poorly constrained, limiting our understanding of the controls on dissolved iron distributions. To address this, the release of iron and iron‐binding ligands during the microbial remineralisation of sinking particles was investigated by deploying in situ particle interceptor/incubator devices at subsurface sites in the Mediterranean Sea and Subantarctic. Analyses revealed the pool of released ligands was largely dominated by electroactive humic substances (74 ± 28%). The release of ligands during remineralisation ensured that concurrently released iron remained in solution, which... |
Tipo: Text |
Palavras-chave: Iron; Ligand; Humic; Remineralisation; Particle; Degradation. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00618/72981/72055.pdf |
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Lemaitre, Nolwenn; Planchon, Frederic; Planquette, Helene; Dehairs, Frank; Fonseca-batista, Debany; Roukaerts, Arnout; Deman, Florian; Tang, Yi; Mariez, Clarisse; Sarthou, Geraldine. |
In this study we report particulate organic carbon (POC) export fluxes for different biogeochemical basins in the North Atlantic as part of the GEOTRACES GA01 expedition (GEOVIDE, May–June 2014). Surface POC export fluxes were deduced by combining export fluxes of total Thorium-234 (234Th) with the ratio of POC to 234Th of sinking particles at the depth of export. Particles were collected in two size classes ( > 53 and 1–53µm) using in situ pumps and the large size fraction was considered representative of sinking material. Surface POC export fluxes revealed latitudinal variations between provinces, ranging from 1.4mmolm−2d−1 in the Irminger basin, where the bloom was close to its maximum, to 12mmolm−2d−1 near the Iberian Margin, where the bloom had... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00465/57664/59860.pdf |
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Gourain, Arthur; Planquette, Helene; Cheize, Marie; Lemaitre, Nolwenn; Menzel Barraqueta, Jan-lukas; Shelley, Rachel; Lherminier, Pascale; Sarthou, Geraldine. |
The GEOVIDE cruise (May–June 2014, R/V Pourquoi Pas?) aimed to provide a better understanding on trace metal biogeochemical cycles in the North Atlantic. As particles play a key role in the global biogeochemical cycle of trace elements in the ocean, we discuss the distribution of particulate iron (PFe), in light of particulate aluminium (PAl), manganese (PMn) and phosphorus (PP) distributions. Overall, 32 full vertical profiles were collected for trace metal analyses, representing more than 500 samples. This resolution provides a solid basis for assessing concentration distributions, elemental ratios, size-fractionation, or adsorptive scavenging processes in key areas of the thermohaline circulation. Total particulate iron (PFe) concentrations ranged from... |
Tipo: Text |
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Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00485/59676/62747.pdf |
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Lemaitre, Nolwenn; Planquette, Helene; Planchon, Frederic; Sarthou, Geraldine; Jacquet, Stephanie; Garcia-ibanez, Maria Isabel; Gourain, Arthur; Cheize, Marie; Monin, Laurence; Andre, Luc; Laha, Priya; Terryn, Herman; Dehairs, Frank. |
The remineralisation of sinking particles by prokaryotic heterotrophic activities is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100–1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L−1), which was attributed to an intense bloom averaging 6 mg Chl-a m−3... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00412/52308/53075.pdf |
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Whitby, Hannah; Planquette, Helene; Cassar, Nicolas; Bucciarelli, Eva; Osburn, Christopher L.; Janssen, David J.; Cullen, Jay T.; González, Aridane G.; Völker, Christoph; Sarthou, Geraldine. |
Primary production by phytoplankton represents a major pathway whereby atmospheric CO2 is sequestered in the ocean, but this requires iron, which is in scarce supply. As over 99% of iron is complexed to organic ligands, which increase iron solubility and microbial availability, understanding the processes governing ligand dynamics is of fundamental importance. Ligands within humic-like substances have long been considered important for iron complexation, but their role has never been explained in an oceanographically consistent manner. Here we show iron co-varying with electroactive humic substances at multiple open ocean sites, with the ratio of iron to humics increasing with depth. Our results agree with humic ligands composing a large fraction of the... |
Tipo: Text |
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Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00622/73388/72598.pdf |
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Mtshali, T.n.; Horsten, N.r.; Thomalla, S.j.; Ryan‐keogh, T.j.; Nicholson, S.‐a.; Roychoudhury, A.n.; Bucciarelli, Eva; Sarthou, Geraldine; Tagliabue, A.; Monteiro, P.m.s.. |
Seasonal progression of dissolved iron (DFe) concentrations in the upper water column were examined during four occupations in the Atlantic sector of the Southern Ocean. DFe inventories from euphotic and aphotic reservoirs decreased progressively from July to February, while dissolved inorganic nitrogen (DIN) decreased from July to January with no significant change between January and February. Results suggest that between July and January, DFe loss from both euphotic and aphotic reservoirs were predominantly in support of phytoplankton growth (Iron to carbon (Fe:C) uptake ratio of 16±3 μmol mol‐1) highlighting the importance of the “winter DFe‐reservoir” for biological uptake. During January to February, excess loss of DFe relative to DIN (Fe:C uptake... |
Tipo: Text |
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Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59914/63095.pdf |
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Shelley, Rachel; Landing, William M.; Ussher, Simon J.; Planquette, Helene; Sarthou, Geraldine. |
The fractional solubility of aerosol-derived trace elements deposited to the ocean surface is a key parameter of many marine biogeochemical models. Despite this, it is currently poorly constrained, in part due to the complex interplay between the various processes that govern the solubilisation of aerosol trace elements. In this study, we used a sequential two-stage leach to investigate the regional variability in fractional solubility of a suite of aerosol trace elements (Al, Ti, Fe, Mn, Co, Ni, Cu, Zn, Cd, and Pb) from samples collected during three GEOTRACES cruises to the North Atlantic Ocean (GA01, GA03-2010, and GA03-2011). We present aerosol trace element solubility data from two sequential leaches that provide a solubility window, covering a... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00439/55041/56473.pdf |
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Bowie, A. R.; Van Der Merwe, P.; Queroue, Fabien; Trull, Thomas; Fourquez, M.; Planchon, F.; Sarthou, Geraldine; Chever, Fanny; Townsend, A. T.; Obernosterer, I.; Sallee, Jean-baptiste; Blain, S.. |
Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO2 by the biological pump. The KEOPS-2 (KErguelen Ocean and Plateau compared Study 2) "process study", took place around the Kerguelen Plateau in the Indian sector of the Southern Ocean. This is a region naturally fertilised with iron on the scale of hundreds to thousands of square kilometres, producing a mosaic of spring blooms which show distinct biological and biogeochemical responses to fertilisation. This paper presents biogeochemical iron budgets (incorporating vertical and lateral supply, internal cycling, and sinks) for three contrasting sites: an upstream high-nutrient low-chlorophyll reference, over the plateau and in the... |
Tipo: Text |
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Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00276/38726/37233.pdf |
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Long, Marc; Tallec, Kevin; Soudant, Philippe; Le Grand, Fabienne; Donval, Anne; Lambert, Christophe; Sarthou, Geraldine; Jolley, Dianne F.; Hegaret, Helene. |
Allelochemical interactions are likely to be a contributing factor explaining the success of large blooms of the harmful marine dinoflagellate Alexandrium, however, the physiological mechanisms of allelochemical interactions remain poorly described. Here we investigated the sub-lethal effects (on an hourly scale) of a filtrate containing allelochemicals from Alexandrium minutum on the physiology of the common diatom Chaetoceros muelleri. The filtrate induced deleterious effects to the diatom physiology within only 30 min of exposure. Esterase activity and photosynthesis were drastically inhibited, with up to 34% of the population being metabolically inactive and up to 30% reduction in photosystem II quantum yield when exposed to the filtrate. In addition,... |
Tipo: Text |
Palavras-chave: Allelopathy; Alexandrium; Metabolism; Photoinhibition; Lipids; Pigments. |
Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00460/57133/59748.pdf |
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Zurbrick, Cheryl M.; Boyle, Edward A.; Kayser, Richard J.; Reuer, Matthew K.; Wu, Jinfeng; Planquette, Helene; Shelley, Rachel; Boutorh, Julia; Cheize, Marie; Contreira, Leonardo; Barraqueta, Jan-lukas Menzel; Lacan, Francois; Sarthou, Geraldine. |
During the 2014 GEOVIDE transect, seawater samples were collected for dissolved Pb and Pb isotope analysis. These samples provide a high-resolution "snapshot" of the source regions for the present Pb distribution in the North Atlantic Ocean. Some of these stations were previously occupied for Pb from as early as 1981, and we compare the 2014 data with these older data, some of which are reported here for the first time. Lead concentrations were highest in subsurface Mediterranean Water (MW) near the coast of Portugal, which agrees well with other recent observations by the US GEOTRACES program (Noble et al., 2015). The recently formed Labrador Sea Water (LSW) between Greenland and Nova Scotia is much lower in Pb concentration than the older LSW found in... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00456/56760/58607.pdf |
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Tang, Weiyi; Wang, Seaver; Fonseca-batista, Debany; Dehairs, Frank; Gifford, Scott; Gonzalez, Aridane G.; Gallinari, Morgane; Planquette, Helene; Sarthou, Geraldine; Cassar, Nicolas. |
Marine N-2 fixation supports a significant portion of oceanic primary production by making N-2 bioavailable to planktonic communities, in the process influencing atmosphere-ocean carbon fluxes and our global climate. However, the geographical distribution and controlling factors of marine N-2 fixation remain elusive largely due to sparse observations. Here we present unprecedented high-resolution underway N-2 fixation estimates across over 6000 kilometers of the western North Atlantic. Unexpectedly, we find increasing N-2 fixation rates from the oligotrophic Sargasso Sea to North America coastal waters, driven primarily by cyanobacterial diazotrophs. N-2 fixation is best correlated to phosphorus availability and chlorophylla concentration. Globally,... |
Tipo: Text |
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Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59564/62548.pdf |
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Louropoulou, Evangelia; Gledhill, Martha; Browningi, Thomas J.; Desai, Dhwani K.; Barraqueta, Jan-lukas Menzel; Tonnard, Manon; Sarthou, Geraldine; Planquette, Helene; Bowie, Andrew R.; Schmitz, Ruth A.; Laroche, Julie; Achterberg, Eric P.. |
Heme b is an iron-containing co-factor in hemoproteins. Heme b concentrations are low (< 1 pmol L-1) in iron limited phytoplankton in cultures and in the field. Here, we determined heme b in marine particulate material (> 0.7 mu m) from the North Atlantic Ocean (GEOVIDE cruise - GEOTRACES section GA01), which spanned several biogeochemical regimes. We examined the relationship between heme b abundance and the microbial community composition, and its utility for mapping iron limited phytoplankton. Heme b concentrations ranged from 0.16 to 5.1 pmol L-1 (median = 2.0 pmol L-1, n = 62) in the surface mixed layer (SML) along the cruise track, driven mainly by variability in biomass. However, in the Irminger Basin, the lowest heme b levels (SML: median =... |
Tipo: Text |
Palavras-chave: Heme b; North Atlantic; Phytoplankton; Diatoms; Iron; Limitation; GEOTRACES; GEOVIDE. |
Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00508/61940/66029.pdf |
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Cossa, Daniel; Heimburger, Lars-eric; Perez, Fiz F; Garcia-ibanez, Maria Isabel; Sonke, Jeroen E.; Planquette, Helene; Lherminier, Pascale; Boutorh, Julia; Cheize, Marie; Barraqueta, Jan Lukas Menzel; Shelley, Rachel; Sarthou, Geraldine. |
We report here the results of total mercury (HgT) determinations along the 2014 GEOTRACES GEOVIDE cruise (GA01 transect) in the North Atlantic Ocean (NA) from Lisbon (Portugal) to the Labrador coast (Canada). Ninety-seven percent of the HgT concentrations of unfiltered samples (HgTUNF) ranged between 0.16 and 1.00 pmol L−1. The geometric mean was 0.51 pmol L−1 for the 535 samples analysed. The dissolved fraction (< 0.45 μm) of HgT, determined on 141 samples, averaged 78 % of the HgTUNF for the whole water column. HgTUNF concentrations increased eastwards and with depth from Greenland to Europe and from sub-surface to bottom waters, respectively. The Hg distribution mirrored that of dissolved oxygen concentration, with highest HgTUNF levels associated... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00412/52303/53071.pdf |
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Sarthou, Geraldine; Lherminier, Pascale; Achterberg, Eric P.; Alonso-perez, Fernando; Bucciarelli, Eva; Boutorh, Julia; Bouvier, Vincent; Boyle, Edward A.; Branellec, Pierre; Carracedo, Lidia I.; Casacuberta, Nuria; Castrillejo, Maxi; Cheize, Marie; Pereira, Leonardo Contreira; Cossa, Daniel; Daniault, Nathalie; De Saint-leger, Emmanuel; Dehairs, Frank; Deng, Feifei; De Gesincourt, Floriane Desprez; Devesa, Jeremy; Foliot, Lorna; Fonseca-batista, Debany; Gallinari, Morgane; Garcia-ibanez, Maribel I.; Gourain, Arthur; Grossteffan, Emilie; Hamon, Michel; Heimburger, Lars Eric; Henderson, Gideon M.; Jeandel, Catherine; Kermabon, Catherine; Lacan, Francois; Le Bot, Philippe; Le Goff, Manon; Le Roy, Emilie; Lefebvre, Alison; Leizour, Stephane; Lemaitre, Nolwenn; Masque, Pere; Menage, Olivier; Barraqueta, Jan-lukas Menzel; Mercier, Herle; Perault, Fabien; Perez, Fiz F; Planquette, Helene; Planchon, Frederic; Roukaerts, Arnout; Sanial, Virginie; Sauzede, Raphaelle; Schmechtig, Catherine; Shelley, Rachel U.; Stewart, Gillian; Sutton, Jill; Tang, Yi; Tisnerat-laborde, Nadine; Tonnard, Manon; Treguer, Paul; Van Beek, Pieter; Zurbrick, Cheryl M.; Zunino Rodriguez, Patricia. |
The GEOVIDE cruise, a collaborative project within the framework of the international GEOTRACES programme, was conducted along the French-led section in the North Atlantic Ocean (Section GA01), between 15 May and 30 June 2014. In this special issue (https://www.biogeosciences.net/special_ issue900.html), results from GEOVIDE, including physical oceanography and trace element and isotope cyclings, are presented among 18 articles. Here, the scientific context, project objectives, and scientific strategy of GEOVIDE are provided, along with an overview of the main results from the articles published in the special issue. |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00470/58178/60685.pdf |
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Lemaitre, Nolwenn; De Souza, Gregory F.; Archer, Corey; Wang, Ruo-mei; Planquette, Helene; Sarthou, Geraldine; Vance, Derek. |
In this study, we report seawater dissolved zinc (Zn) concentration and isotope composition (Zn) from the GEOTRACES GA01 (GEOVIDE) section in the North Atlantic. Across the transect, three subsets of samples stand out due to their isotopically light signature: those close to the Reykjanes Ridge, those close to the sediments, and those, pervasively, in the upper ocean. Similar to observations at other locations, the hydrothermal vent of the Reykjanes Ridge is responsible for the isotopically light Zn composition of the surrounding waters, with an estimated source Zn of -0.42 ‰. This isotopically light Zn is then transported over a distance greater than 1000 km from the vent. Sedimentary inputs are also evident all across the trans-Atlantic section,... |
Tipo: Text |
Palavras-chave: Zinc isotopes; North Atlantic; Zinc sources; GEOTRACES; GEOVIDE. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00618/73035/72166.pdf |
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Long, Marc; Tallec, Kevin; Soudant, Philippe; Lambert, Christophe; Le Grand, Fabienne; Sarthou, Geraldine; Jolley, Dianne; Hegaret, Helene. |
Harmful microalgal blooms are a threat to aquatic organisms, ecosystems and human health. Toxic dinoflagellates of the genus Alexandrium are known to produce paralytic shellfish toxins and to release bioactive extracellular compounds (BECs) with potent cytotoxic, hemolytic, ichtyotoxic and allelopathic activity. Negative allelochemical interactions refer to the chemicals that are released by the genus Alexandrium and that induce adverse effects on the physiology of co-occurring protists and predators. Releasing BECs gives the donor a competitive advantage that may help to form dense toxic blooms of phytoplankton. However BECs released by Alexandrium minutum are uncharacterized and it is impossible to quantify them using classical chemical methods.... |
Tipo: Text |
Palavras-chave: Harmful algal bloom; Alexandrium; Allelopathy; Cytotoxicity; PAM fluorometry; Bioassay. |
Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00453/56424/58116.pdf |
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Lemaitre, Nolwenn; Planquette, Helene; Dehairs, Frank; Planchon, Frederic; Sarthou, Geraldine; Gallinari, Morgane; Roig, Stéphane; Jeandel, Catherine; Castrillejo, Maxi. |
Vertical export of particulate trace elements (pTEs) is a critically underconstrained aspect of their biogeochemistry. Here, we combine elemental analyses on large (>53 μm) particles and 234Th measurements to determine downward export fluxes from the upper layers (40–110 m) of pTEs (Al, Cd, Co, Cu, Fe, Mn, Ni, P, Ti, V, Zn) and mineral phases (lithogenic, Fe- and Mn-oxides, calcium carbonate, and opal) in the North Atlantic along the GEOVIDE transect (Portugal–Greenland–Canada; GEOTRACES GA01 cruise). The role of lithogenic particles in controlling TE fluxes is obvious at proximity of the Iberian margin where the highest pTE export fluxes were estimated (up to 3912 μg/m2/d for pFe). However, high lithogenic and pTE fluxes are also observed up to 1700 km... |
Tipo: Text |
Palavras-chave: Particulate trace elements; Export fluxes; Multiple carrier phases; Residence times; GEOTRACES. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00656/76810/78174.pdf |
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Registros recuperados: 32 | |
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