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Martn J.,IAEA Marine Environment Laboratories | Miquel J.-C.,IAEA Marine Environment Laboratories
Geophysical Research Letters | Year: 2010

The northwestern Mediterranean is known to be a privileged area of deep water formation via dense shelf water cascading and offshore convection. The impact of the former in the sedimentary dynamics of the deep basin has been highlighted in recent years, while open sea convection has been solely studied from a hydrological perspective. Particle fluxes and hydrodynamics were monitored at the DYFAMED site (Ligurian Sea, western Mediterranean) at 200, 1000 m and near the seafloor (2350 m depth) during winter 2005-2006. From February to April 2006, and in coincidence with an unusual episode of deep water formation, a notable intensification of currents was observed in the entire water column and near-bottom particle flux increased up to two orders of magnitude. These observations suggest that offshore convection must be taken into account together with cascading as a major driving force for sedimentary dynamics in the deep western Mediterranean. © 2010 by the American Geophysical Union.

Reinardy H.C.,University of Plymouth | Teyssie J.-L.,IAEA Marine Environment Laboratories | Jeffree R.A.,IAEA Marine Environment Laboratories | Jeffree R.A.,University of Technology, Sydney | And 4 more authors.
Science of the Total Environment | Year: 2011

Understanding uptake and depuration of radionuclides in organisms is necessary to relate exposure to radiation dose and ultimately to biological effects. We investigated uptake and depuration of a mixture of radionuclides to link bioaccumulation with radiation dose in zebrafish, Danio rerio. Adult zebrafish were exposed to radionuclides ( 54Mn, 60Co, 65Zn, 75Se, 109Cd, 110mAg, 134Cs and 241Am) at tracer levels (<200Bqg -1) for 14d, either via water or diet. Radioactivity concentrations were measured in whole body and excised gonads of exposed fish during uptake (14d) and depuration phases (47d and 42d for aqueous and dietary exposures respectively), and dose rates were modelled from activity concentrations in whole body and exposure medium (water or diet). After 14-day aqueous exposure, radionuclides were detected in decreasing activity concentrations: 75Se> 65Zn> 109Cd> 110mAg> 54Mn> 60Co> 241Am> 134Cs (range: 175-8Bqg 1). After dietary exposure the order of radionuclide activity concentration in tissues (Bqg -1) was: 65Zn> 60Co> 75Se> 109Cd> 110mAg> 241Am> 54Mn> 134Cs (range: 91-1Bqg -1). Aqueous exposure resulted in higher whole body activity concentrations for all radionuclides except 60Co. Route of exposure did not appear to influence activity concentrations in gonads, except for 54Mn, 65Zn, and 75Se, which had higher activity concentrations in gonads following aqueous exposure. Highest gonad activity concentrations (Bqg -1) were for 75Se (211), 109Cd (142), and 65Zn (117), and highest dose rates (-Gyh -1) were from 241Am (aqueous, 1050; diet 242). This study links radionuclide bioaccumulation data obtained in laboratory experiments with radiation dose determined by application of a dosimetry modelling tool, an approach that will enable better linkages to be made between exposure, dose, and effects of radionuclides in organisms. © 2011 Elsevier B.V.

Guitart C.,CSIC - Institute of Chemical and Environmental Research | Guitart C.,CSIC - Institute of Marine Sciences | Garcia-Flor N.,CSIC - Institute of Chemical and Environmental Research | Miquel J.C.,IAEA Marine Environment Laboratories | And 2 more authors.
Journal of Marine Systems | Year: 2010

Several measurements of polycyclic aromatic hydrocarbons (PAHs) in coastal marine compartments (viz. atmosphere, sea surface microlayer, subsurface seawater, sinking particles and sediments), made nearly simultaneously at two stations in the north-eastern Mediterranean, were used to estimate the transport fluxes of individual and total PAHs through the air-seawater-sediment system. Diffusive air-sea exchange fluxes were estimated using both subsurface water (SSW) and sea surface microlayer (SML) concentrations. The air-SML fluxes ranged from 411 to 12,292 ng m- 2 d- 1 (absorption) and from - 506 to -13,746 ng m- 2 d- 1 (volatilisation) for total PAHs (Σ15). Air-seawater column transport of particle-associated PAHs was estimated from the analysis of particulate atmospheric and sediment interceptor trap materials. Air-sea particle deposition fluxes of total PAHs ranged from 13 to 114 ng m- 2 d- 1 and seawater particle settling fluxes (upper 5 m water column) ranged from 184 to 323 ng m- 2 d- 1. The results of this study indicate that both the magnitude and the direction of the calculated air-sea diffusive fluxes change when PAH concentrations in the SML are considered. As a result, PAHs accumulation in the SML could produce the so-called "flux capping effect". However, the high variability in the coastal air-sea PAHs flux estimations, mainly due to the parameters uncertainty, requires further experimental approaches, including improvement of parameterisations. © 2009 Elsevier B.V. All rights reserved.

Garcia-Ruiz S.,European Commission | Petrov I.,European Commission | Petrov I.,Free University of Colombia | Vassileva E.,European Commission | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

The cadmium content in surface water is regulated by the last European Water Framework Directive to a maximum between 0.08 and 0.25 μg L -1 depending on the water type and hardness. Direct measurement of cadmium at this low level is not straightforward in real samples, and we hereby propose a validated method capable of addressing cadmium content below μg L-1 level in natural water. It is based on solid-phase extraction using TiO2 nanoparticles as solid sorbent (0.05 g packed in mini-columns) to allow the separation and preconcentration of cadmium from the sample, combined to direct isotope dilution and detection by inductively coupled plasma mass spectrometry (ID-ICP-MS). The extraction setup is miniaturised and semi-automated to reduce risks of sample contamination and improve reproducibility. Procedural blanks for the whole measurement process were 5.3 ± 2.8 ng kg-1 (1 s) for 50 g of ultrapure water preconcentrated ten times. Experimental conditions influencing the separation (including loading pH, sample flow rates, and acid concentration in the eluent) were evaluated. With isotope dilution the Cd recovery rate does not have to be evaluated carefully. Moreover, the mathematical model associated to IDMS is known, and provides transparency for the uncertainty propagation. Our validation protocol was in agreement with guidelines of the ISO/IEC 17025 standard (chapter 5.4.5). Firstly, we assessed the experimental factors influencing the final result. Secondly, we compared the isotope ratios measured after our separation procedure to the reference values obtained with a different protocol for the digested test material IMEP-111 (mineral feed). Thirdly, we analysed the certified reference material BCR-609 (groundwater). Finally, combined uncertainties associated to our results were estimated according to ISO-GUM guidelines (typically, 3-4% k = 2 for a cadmium content of around 100 ng kg -1). We applied the developed method to the groundwater and wastewater samples ERM-CA615 and BCR-713, respectively, and results agreed with certificate values within uncertainty statements. [Figure not available: see fulltext.] © 2011 Springer-Verlag.

Quetel C.R.,European Commission | Vassileva E.,European Commission | Vassileva E.,IAEA Marine Environment Laboratories | Petrov I.,European Commission | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2010

This paper describes the application of TiO2 nano-particles (anatase form) for the solid-phase extraction of iron from coastal seawater samples. We investigated the adsorption processes by infra-red spectroscopy. We compared in batch and on-(mini)column extraction approaches (0.1 and 0.05 g TiO2 per sample, respectively), combined to external calibration and detection by inductively coupled plasma mass spectrometry at medium mass resolution. Globally, this titania phase was slightly more efficient with seawater than with ultra-pure water, although between pH 2 and pH 7, the Fe retention efficiency progressed more in ultra-pure water than in seawater (6.9 versus 4.8 times improvement). Different reaction schemes are proposed between Fe(III) species and the two main categories of titania sites at pH 2 (adsorption of [FeL x ](3-x)+ via possibly the mediation of chlorides) and at pH 7 (adsorption of [Fe(OH)2]+ and precipitation of [Fe(OH)3]0). Under optimised conditions, the inlet system was pre-cleaned by pumping 6% HCl for ∼2 h, and the column was conditioned by aspirating ultra-pure water (1.7 g min-1) and 0.05% ammonia (0.6 g min-1) for 1 min. Then 3 g seawater sample was loaded at the same flow rate while being mixed on-line with 0.05% ammonia at 0.6 g min-1 to adjust the pH to 7. The iron retained on the oxide powder was then eluted with 3 g 6% HCl (<0.002% residual salinity in the separated samples). The overall procedural blank was 220 ± 46 (2 s, n = 16) ng Fe kg-1 (the titania was renewed in the column every 20 samples, with 2-min rinsing in between samples with 6% HCl at 1.5 g min-1). The recovery estimated from the Canadian certified reference material CASS-2 was 69.5 ± 7.6% (2 s, n = 4). Typically, the relative combined uncertainty (k = 2) estimated for the measurement of ∼1 μg Fe kg-1 (0.45 μm filtered and acidified to pH 1.5) of seawater was ∼12%. We applied our method to a similar sample, from the coastal region of the North Sea. The agreement well within stated uncertainties of our result with the value obtained independently by isotope dilution mass spectrometry further validated our method. © 2010 Springer-Verlag.

Ali B.A.,French National Center for Scientific Research | Garel M.,French National Center for Scientific Research | Cuny P.,French National Center for Scientific Research | Miquel J.-C.,IAEA Marine Environment Laboratories | And 3 more authors.
Chemistry and Ecology | Year: 2010

Marine luminous deep-sea bacteria may represent a potential source of signal perturbation for the ANTARES neutrino telescope installed between 2000 and 2475 m depth in the Mediterranean Sea. Using the CARD-FISH method, we have estimated the relative abundances of total prokaryotes of Bacteria, γ -proteobacteria and Vibrinoceae (domain, class and family affiliation of marine luminous bacteria, respectively) through the water column close to the ANTARES site. At 2200 m depth, Vibrionaceae appeared to be far from negligible, representing 40% of γ -proteobacteria, 25% of Bacteria and 9% of the total DAPI-stained cells, while Bacteria and Archaea represented 35% each. Furthermore, during a high luminous background period detected by the neutrino telescope, we isolated, from a 2200 m depth sample, a piezophilic luminous bacterium, phylogenetically determined as Photobacterium phosphoreum strain ANT-2200. We have used this strain to investigate the effect of hydrostatic pressure on bioluminescence by developing a new high-pressure apparatus. First assays showed that the bioluminescence intensity of Photobacterium phosphoreum strain ANT-2200 was 5 times higher at 22 MPa than at 0.1 MPa (atmospheric pressure). © 2010 Taylor & Francis.

Ternon E.,CNRS Oceanography Laboratory of Villefranche | Ternon E.,University Pierre and Marie Curie | Guieu C.,CNRS Oceanography Laboratory of Villefranche | Guieu C.,University Pierre and Marie Curie | And 6 more authors.
Biogeosciences | Year: 2010

Simultaneous measurements of atmospheric deposition and of sinking particles at 200 and 1000 m depth, were performed in the Ligurian Sea (North-Western Mediterranean) between 2003 and 2007, along with phytoplanktonic activity derived from satellite images. Atmospheric deposition of Saharan dust particles was very irregular and confirmed the importance of sporadic high magnitude events over the annual average (11.4 g m-2 yr-1 for the 4 years). The average marine total mass flux was 31 g m-2 yr-1, the larger fraction being the lithogenic one (∼37%). The marine total mass flux displayed a seasonal pattern with a maximum in winter, occurring before the onset of the spring bloom. The highest POC fluxes did not occur during the spring bloom nor could they be directly related to any noticeable increase in the surface phytoplanktonic biomass. Over the 4 years of the study, the strongest POC fluxes were concomitant with large increases of the lithogenic marine flux, which had originated from either recent Saharan fallout events (February 2004 and August 2005), from "old" Saharan dust "stored" in the upper water column layer (March 2003 and February 2005), or alternatively from lithogenic material originating from Ligurian riverine flooding (December 2003, Arno, Roya and Var rivers). Those associated export fluxes defined as "lithogenic events", are believed to result from a combination of forcing (winter mixing or Saharan events, in particular extreme ones), biological (zooplankton) activity, and also organic-mineral aggregation inducing a ballast effect. By fertilising the surface layer, mixed Saharan dust events were shown to be able to induce "lithogenic events" during the stratification period. These events would be more efficient in transferring POC to the deeper layers than the spring bloom itself. The extreme Saharan event of February 2004 exported ∼45% of the total annual POC, compared to an average of ∼25% for the bloom period. This emphasises the role played by these "lithogenic events", and in particular those that are induced by the more extreme Saharan events, in the carbon export efficiency in the North-western Mediterranean Sea.

Martin J.,IAEA Marine Environment Laboratories | Miquel J.-C.,IAEA Marine Environment Laboratories
Marine Ecology | Year: 2010

The DYFAMED sediment trap station in the Ligurian Sea (NW Mediterranean) has been active since 1986 and today comprises the longest time-series of downward particle flux in the Mediterranean Sea. As such, it provides valuable information on the interannual variability of the particle flux, and also documents possible recent changes in the NW Mediterranean pelagic ecosystems. We report an unprecedented episode of downward flux of mucilaginous material at the DYFAMED station during summer 2002 in association with singular hydrometeorological conditions. The rain of mucilaginous aggregates clogged a PPS5 sediment trap at 260 m depth and was also clearly detected at 1080 m depth. The possible factors governing the development and sinking of the mucilaginous material are discussed. A very sharp increase of sea surface temperature during June and the presence of freshened waters in the surface the following month resulted in a stronger than usual stratification of the upper water column throughout the summer season. We suggest that the steepness of the vertical density gradient was responsible for the unusual accumulation of mucous aggregates. Additionally, a diatom bloom took place during the nutrient-depleted conditions typical of summer, a factor which may have contributed to feed the pycnocline with transparent exopolymer substances. A storm occurring in the beginning of August relaxed the stratification and promoted the deposition of the mucilaginous aggregates accumulated in the upper water column during the preceding months. Important similarities of ambient conditions preceding the apparition of mucilaginous material in our open-sea site and those reported in the Adriatic Sea during major mucilage events, suggest that general climatic conditions, rather than local factors, drive the occurrence of major accumulations of mucilaginous material in the water column at both sub-basins of the Mediterranean Sea. In this regard, the strength of the air temperature increase during the onset of the stratified season is proposed as a major controlling factor. © 2010 Blackwell Verlag GmbH.

Jeffree R.A.,IAEA Marine Environment Laboratories | Oberhansli F.,IAEA Marine Environment Laboratories | Teyssie J.-L.,IAEA Marine Environment Laboratories
Science of the Total Environment | Year: 2010

Multi-tracer experiments determined the accumulation from seawater of selected radioactive trace elements (Mn-54, Co-60, Zn-65, Cs-134, Am-241, Cd-109, Ag-110m, Se-75 and Cr-51) by three teleost and three chondrichthyan fish species to test the hypothesis that these phylogenetic groups have different bioaccumulation characteristics, based on previously established contrasts between the carcharhiniform chondrichthyan Scyliorhinus canicula (dogfish) and the pleuronectiform teleost Psetta maxima (turbot). Discriminant function analysis on whole body: water concentration factors (CFs) separated dogfish and turbot in two independent experiments. Classification functions grouped the perciform teleosts, seabream (Sparus aurata) and seabass (Dicentrarchus labrax), with turbot and grouped the chondrichthyans, undulate ray (Raja undulata; Rajiformes) and spotted torpedo (Torpedo marmorata; Torpediniformes), with dogfish, thus supporting our hypothesis. Hierarchical classificatory, multi-dimensional scaling and similarity analyses based on the CFs for the nine radiotracers, also separated all three teleosts (that aggregated lower in the hierarchy) from the three chondrichthyan species. The three chondrichthyans were also more diverse amongst themselves compared to the three teleosts. Particular trace elements that were more important in separating teleosts and chondrichthyans were Cs-134 that was elevated in teleosts and Zn-65 that was elevated in chondrichthyans, these differences being due to their differential rates of uptake rather than loss. Chondrichthyans were also higher in Cr-51, Co-60, Ag-110m and Am-241, whereas teleosts were higher only in Mn-54. These contrasts in bioaccumulation patterns between teleosts and chondrichthyans are interpreted in the context of both proximate causes of underlying differences in physiology and anatomy, as well as the ultimate cause of their evolutionary divergence over more than 500. million years before present (MyBP). Our results and interpretation point to the possibility that radiation exposure regimes may be influenced by phylogeny, with implications for the adequacy of the marine reference organism approach in marine environmental protection. © 2010 Elsevier B.V.

Vassileva E.,IAEA Marine Environment Laboratories | Hoenig M.,Research Center
Analytica Chimica Acta | Year: 2011

This paper describes the determination of the total and extractable mass fractions of Cd and Pb in mineral feed test sample distributed by the Community Reference Laboratory for Heavy Metals in Feed and Food (CRL-HM), in the frame of the fifth interlaboratory comparison for the European Union National Reference Laboratories (NRL).The developed in this study protocol for the total and extractable mass fractions of Pb and Cd in mineral feed sample is based on isotope dilution inductively coupled plasma mass spectrometry (ID ICP-MS). The applied dual spiking approach reduced by 50% the number of analytical steps. The addition of hydrofluoric acid in the digestion step was found necessary to ensure a full decomposition and complete isotope equilibration. Quadrupole inductively coupled plasma mass spectrometer equipped with collision reaction interface (CRI) was employed for the measurements of Cd and Pb. Two methods for the determination of Cd were applied and compared. In the first one the high molybdenum content was reduced by introduction of matrix separation step followed by standard ICP-MS mode measurement, whereas in the second one CRI mode was used for the determination of Cd without preliminary matrix separation. The estimation of the combined uncertainty was performed according to the ISO guidelines. Uncertainty propagation was used as a tool for validation of proposed analytical procedure. Contributions from the correction for moisture content, sample homogeneity, procedural blank, instrumental background and dead time effects were evaluated in both cases. The largest uncertainty contributors for Cd and Pb is due to the within bottle homogeneity of the mineral feed sample - 50.3% and 90% respectively. The IUPAC data for isotope composition are the second major contributor to the combined uncertainty of the result for the total mass fraction of Cd in mineral feed - 43.3%. However, the ID ICP-MS results achieved from the two series of samples (partial and total extraction) were in excellent agreement within uncertainty, irrespective of the method used for extraction. The ID ICP-MS results for the total and extractable mass fractions of Cd and Pb in feed sample were compared with the results obtained with external calibration approach and routinely applied in the daily analytical practice of the Belgium National Reference Laboratory for trace elements in food and feed. © 2011 Elsevier B.V.

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