Study of the spatial and historical distribution of sediment inorganic contamination in the Toulon bay (France)   总被引：4，自引：0，他引：4  

Tessier E  Garnier C  Mullot JU  Lenoble V  Arnaud M  Raynaud M  Mounier S 《Marine pollution bulletin》2011,62(10):2075-2086

This study presents trace elements levels in surface and deep sediments of the Toulon bay (SE France) subjected to anthropogenic inputs (navy base, harbors, etc.). The studied elements (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) are defined as priority contaminants in aquatic systems. Fifty-five points scattered on the entire bay were sampled, allowing the determination of contaminants distribution with a high resolution. Several approaches were used to assess the degree of contamination and the potential toxicity of the Toulon bay sediments: comparison to the French legislation, surface-weighted average metal concentrations, enrichment factors (EF), geoaccumulation indices (Igeo), trace element stock calculation and comparison to sediment quality guidelines. A principal component analysis was performed to reveal common behavior of the studied contaminants. Results demonstrated the very high contamination of the small bay, especially in Hg (EF up to 1500), Cu, Pb and Zn, with export to the large bay further governed by hydrodynamics.  相似文献   

Influence of water mixing on the inhibitory effect of UV radiation on primary and bacterial production in Mediterranean coastal water     

Roberto Bertoni  Wade H. Jeffrey  Mireille Pujo-Pay  Louise Oriol  Pascal Conan  Fabien Joux 《Aquatic Sciences - Research Across Boundaries》2011,73(3):377-387

The scaling of the solar ultraviolet radiation (UVR, 280–400 nm) effect on phyto- and bacterio-plankton at the ecosystem level is difficult since its estimate is often based on short-time incubation experiments performed at fixed depths, neglecting the previous days’ radiation history and the variable radiation caused by vertical mixing. To examine this issue, we measured primary (PP) and bacterial (BP) production in samples from coastal water in the Northwest Mediterranean Sea incubated at fixed depths or moving vertically within the water column (0–8 m) with a periodicity of 22 min, exposed to full sun, PAR or maintained in dark. Three experiments were carried out on consecutive days to measure day-to-day variations in planktonic response. In surface waters, PP was inhibited by ~32 to 42% by UVR, and BP was inhibited by ~50 to 70% by solar radiation (UVR + PAR). We observed a general decrease in the integrated inhibition of PP due to UVR for both fixed and moving incubations over the 3 days from ~27% of inhibition to non-significant inhibition. In contrast, large discrepancies were observed in the integrated inhibition of BP due to solar radiation (UVR + PAR) between fixed and moving incubations. Whereas both type of incubations gave similar estimation of solar radiation inhibition on day 1 (~25%), inhibition became much higher for fixed incubation compared to moving incubation on days 2 and 3. Differences in responses between days suggest that light history, spectral quality, photoadaptation or acclimation may be important factors in daily observed responses. Our results also underline, for the first time, the importance of the vertical mixing in the BP inhibition by solar radiation.  相似文献   

A preliminary methods comparison for measurement of dissolved organic nitrogen in seawater   总被引：2，自引：0，他引：2  

Jonathan H. Sharp  Kathrine R. Rinker  Karen B. Savidge  Jeffrey Abell  Jean Yves Benaim  Deborah Bronk  David J. Burdige  Gustave Cauwet  Wenhao Chen  Marylo D. Doval  Dennis Hansell  Charles Hopkinson  Gerhard Kattner  Nancy Kaumeyer  Karen J. McGlathery  Jeffrey Merriam  Nick Morley  Klaus Nagel  Hiroshi Ogawa  Carol Pollard  Mireille Pujo-Pay  Patrick Raimbault  Raymond Sambrotto  Sybil Seitzinger  Georgina Spyres  Frank Tirendi  Ted W. Walsh  C. S. Wong 《Marine Chemistry》2002,78(4)

Routine determination of dissolved organic nitrogen (DON) is performed in numerous laboratories around the world using one of three families of methods: UV oxidation (UV), persulfate oxidation (PO), or high temperature combustion (HTC). Essentially all routine methods measure total dissolved nitrogen (TDN) and calculate DON by subtracting the dissolved inorganic nitrogen (DIN). While there is currently no strong suggestion that any of these methods is inadequate, there are continuing suspicions of slight inaccuracy by UV methods.This is a report of a broad community methods comparison where 29 sets (7 UV, 13 PO, and 9 HTC) of TDN analyses were performed on five samples with varying TDN and DIN concentrations. Analyses were done in a “blind” procedure with results sent to the first author. With editing out one set of extreme outliers (representing 5 out of 145 ampoules analyzed), the community comparability for analyzing the TDN samples was in the 8–28% range (coefficient of variation representing one standard deviation for the five individual samples by 28 analyses). When DIN concentrations were subtracted uniformly (single DIN value for each sample), the comparability was obviously worse (19–46% cv). This comparison represents a larger and more diverse set of analyses, but the overall comparability is only marginally better than that of the Seattle workshop of a decade ago. Grouping methods, little difference was seen other than inconclusive evidence that the UV methods gave TDN values for several of the samples higher than HTC methods. Since there was much scatter for each of the groups of methods and for all analyses when grouped, it is thought that more uniformity in procedures is probably needed. An important unplanned observation is that variability in DIN analyses (used in determining the final analyte in most UV and PO methods) is essentially as large as the variability in the TDN analyses.This exercise should not be viewed as a qualification exercise for the analysts, but should instead be considered a broad preliminary test of the comparison of the families of methods being used in various laboratories around the world. Based on many independent analyses here, none of the routinely used methods appears to be grossly inaccurate, thus, most routine TDN analyses being reported in the literature are apparently accurate. However, it is not reassuring that the ability of the international community to determine DON in deep oceanic waters continues to be poor. It is suggested that as an outgrowth of this paper, analysts using UV and PO methods experiment and look more carefully at the completeness of DIN conversion to the final analyte and also at the accuracy of their analysis of the final analyte. HTC methods appear to be relatively easy and convenient and have potential for routine adoption. Several of the authors of this paper are currently working together on an interlaboratory comparison on HTC methodology.  相似文献   

A model of dimethylsulfide dynamics for the subtropical North Atlantic     

Mireille Lefvre  Alain Vzina  Maurice Levasseur  John W. H. Dacey 《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(12)

Dimethylsulfide (DMS) is a volatile sulfur compound produced by the marine biota. The flux of DMS to the atmosphere may act on climate via aerosol formation. It is therefore important to improve our understanding of the processes that regulate sea surface DMS concentrations for eventual inclusion into climate models. In order to simulate the dynamics of DMS concentrations in the mixed layer, a model of DMS production was developed and calibrated against a 1 year time-series of DMS and DMSP (dissolved and particulate) data collected in the Sargasso Sea at Hydrostation ‘S’. The model reproduces the observed divergence between the seasonal cycles of particulate DMSP, the DMS precursor produced by algae, and DMS produced through the microbial loop from the cleavage of dissolved DMSP. DMSP_p (particulate) reaches its maximum in the spring whereas DMSP_d (dissolved) and DMS reach maximum concentrations in summer. Several parameters had to vary seasonally and with depth in order to reproduce the data, pointing out the importance of physiological and structural changes in the plankton food web. These parameters include the intracellular S(DMSp):N ratio, the C:Chl ratio and the sinking rates of phytoplankton and detritus. For the Sargasso Sea, variations in the solar zenithal angle, which co-vary with the seasonal variations in the depth of the mixed layer, proved to be a convenient signal to drive the seasonal variation in the structure and dynamics of the plankton. Variations of the temperature and photosynthetically active radiation also help to reproduce the short-term variability of the annual S cycle. Results from a sensitivity analysis show that variations in DMSP_p are dependent mostly on parameters controlling phytoplankton biomass, whereas DMS is dependent mostly on variables controlling phytoplankton productivity.  相似文献   

Spatio-temporal variation of suspended and sedimentary organic matter quality in the Bay of Marseilles (NW Mediterranean) assessed by biochemical and isotopic analyses     

Cresson P  Ruitton S  Fontaine MF  Harmelin-Vivien M 《Marine pollution bulletin》2012,64(6):1112-1121

Isotopic and biochemical features of suspended particulate organic matter (POM) in the water column and of sedimentary organic matter (SOM) were investigated seasonally in the Bay of Marseilles. Biochemical compounds (carbohydrates, lipids and proteins) were consistently more concentrated in POM than in SOM, with SOM mainly composed of insoluble carbohydrates. POM displayed lower δ(13)C and higher δ(15)N values than SOM. Phytoplanktonic production represented the major contributor of POM year-round with spatial and seasonal variations. Climatic parameters and wind-induced currents created differences in POM contributions, with more important inputs of terrestrial OM at one sampling site. Spatial and seasonal variations were lower for SOM. The composition of this pool appeared to be linked with the permanent inputs of phytoplankton and Posidonia oceanica detritus. The combined use of biochemical and isotopic analyses was a useful tool to characterize OM pools and would help understanding the trophic functioning of this coastal environment.  相似文献   

Multi-Elemental Analysis of ATHO-G Rhyolitic Glass (MPI-DING Reference Material) by Femtosecond and Nanosecond LA-ICP-MS: Evidence for Significant Heterogeneity of B,V, Zn,Mo, Sn,Sb, Cs,W, Pt and Pb at the Millimetre Scale     

Anastassia Y. Borisova  Rémi Freydier  Mireille Polvé  Klaus Peter Jochum  Frederic Candaudap 《Geostandards and Geoanalytical Research》2010,34(3):245-255

This paper reports on the application of variants of LA-ICP-MS – including infrared femtosecond laser ablation (fs-LA) inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and nanosecond laser ablation (ns-LA) coupled with single-collector sector-field (SF-) ICP-MS – to the in situ determination of trace elements in different splits of the reference material (RM) ATHO-G (MPI-DING). Analyses of the materials performed by fs- and ns-LA-ICP-MS demonstrated the efficiency of the techniques with typical accuracy at a level of ≤ ± 20%. One ‘anomalous’ split, however, displayed a significant discrepancy from the reference concentrations for B, V, Zn, Mo, Sn, Sb, Cs, W and Pb. Three- to six-fold enrichment of V, Mo, Cs and Pt relative to the reference contents in this split is likely to have been due to direct contact of the silicate melt with Pt crucible walls and ceramics. Boron, Zn, Sn, Sb, W and Pb depletion relative to the reference concentrations is probably due to siderophile element adsorption by the Pt walls and/or related to the formation of volatile-depleted compositional cords during the preparation process. Our results imply that additional precautions should be taken against volatile/siderophile element heterogeneity in marginal/surface layers (≤ 10 mm) during the preparation of RMs by the fusion technique.  相似文献   

Dynamics and sources of suspended particulate organic matter in the Marennes-Oléron oyster farming bay: Insights from stable isotopes and microalgae ecology     

Nathalie Malet  Pierre-Guy Sauriau  Mireille Ryckaert  Pascale Malestroit  Gael Guillou 《Estuarine, Coastal and Shelf Science》2008

The aim of this study was to distinguish between sources of the complex variety of Marennes-Oléron Bay suspended particulate organic matter (SPOM) contributing to the tropho-dynamics of the Marennes-Oléron oyster farming bay. Basic biomarkers (Chl a, C/N and POC/Chl a ratios), carbon and nitrogen stable isotopes from SPOM were analyzed and the microalgae community was characterized. The sampling strategy was bimonthly from March 2002 to December 2003; samples were taken from an intertidal mudflat. Four main sources contributed to the SPOM pool: terrigenous input from rivers, neritic phytoplankton, resuspended microphytobenthos and periodic inputs from intertidal Zostera noltii meadows. Seasonal fluctuations were observed in both years of the study period: (1) SPOM collected in the spring of 2002 (δ¹³C = −25‰ to −23‰) was mainly composed of fresh estuarine inputs; (2) SPOM from the summer and fall of 2002 and 2003 was predominantly neritic phytoplankton (δ¹³C = − 22‰ to −19‰); (3) SPOM from the winter of 2002, spring of 2003 and winter of 2003 (δ¹³C = −21 to −23‰) was composed of a mixture of decayed terrigenous river inputs and pelagic phytoplankton, which was predominantly resuspended microphytobenthos. In the summer of 2003—the warmest summer on record in southern France and Europe—SPOM was particularly enriched for ¹³C, with δ¹³C values ranging from −14‰ to −12‰. Pulses in δ¹³C values, indicative of ¹³C-enriched decaying materials, extended into the fall. These were attributed to benthic intertidal inputs, including both resuspended microphytobenthos and Z. noltii detritus. Changes in SPOM sources in Marennes-Oléron Bay may lead to differences in the quality of the trophic environment available for reared oysters.  相似文献   

Suspended sediment and Cs fluxes during the exceptional December 2003 flood in the Rhone River, southeast France     

Christelle Antonelli  Frdrique Eyrolle  Benoît Rolland  Mireille Provansal  Franois Sabatier 《Geomorphology》2008,95(3-4):350-360

At the beginning of December 2003, one of the biggest floods for at least 150 yr was recorded on the Rhone River. In the lower part of the river, the peak flood reached 11,000 m³ s⁻¹. The geomorphological and radioecological consequences of such an event were investigated downstream all the nuclear installations by using measured and calculated fluxes and the total export of suspended sediment and associated ¹³⁷Cs. Results pointed out the major role played by large floods in the annual suspended sediment load, as 3.70 × 10⁶ tons of silts, 0.85 × 10⁶ tons of sands, and 0.84 × 10⁶ tons of clays were transferred towards the coastal environment. Nevertheless, these solid loads were found to be lower than those expected as regards the liquid discharge reached during this event and suggested that previous floods that occurred on the river and on its main tributaries during the last decade have probably led to the removal of available sediment from the channels and their banks. Besides, the ¹³⁷Cs activity measured within the suspended load was estimated at 14.9 ± 0.4 Bq kg⁻¹, which is a level characteristic of the suspended sediments from the Rhone catchment area and demonstrated that nuclear installations located along the Rhone valley did not significantly contribute to any increase in ¹³⁷Cs activity in the water during the flood. The total ¹³⁷Cs particulate export amounted to 77 ± 17 GBq and was mainly associated with the silt fraction that contributes to around 70% of the total ¹³⁷Cs export.  相似文献   

Remarques sur la matrice des chondrites ordinaires d'apres l'observation de quelques chondrites a bronzite peu ou pas choquees     

Mireille Christophe Michel-Levy 《Earth and Planetary Science Letters》1977,34(1):155-158

Microscopic investigations have been done on the chondrites Sena and Nadiabondi (H5, not shocked), Ste. Marguerite en Comines (H4, very slightly shocked), Allegan (H5, slightly shocked). Only in such cases can the matrix be easily observed and compared to those of type 3 chondrites. The <100 μm debris found in types 4 and 5 that we have observed are not the result of the metamorphism of type 3 fines.The abundance of tiny debris is in direct relation with the intensity of the shock though this shock was insufficient to provoke either the induration of the stones or a significant loss of rare gases. The bulk of the fines are the result of local disaggregation of the most brittle parts from chondrules and fragments.A low-temperature matrix has not been observed in these meteorites but only in H3 chondrites, as a coating around the chondrules. The accretion modelists should take into account the absence or the scarcity of fine particles in their calculations.  相似文献   

Some clues to the history of the H-group chondrites     

Mireille Christophe Michel-Levy 《Earth and Planetary Science Letters》1981,54(1):67-80

SEM, optical and chemical observations have been performed on 12 H3-6 chondrites, 9 of them being also studied by other groups. Morphological features of chondrules and crystals (growth steps) are shown; the significance of the finely crystallised troilite in Menow and Ambapur Nagla is discussed in the light of the discovery that the NiFe blebs associated with it are Ni-rich (50–60% Ni). Sulphur should have been mobilized without shock evidence possibly as a result of solar heating. Pre-chondritic relict material is recognized by anomalous or variable mineral compositions, and in some cases, by the presence of overgrowths on relict cores. After short notes on individual chondrites, a tentative history of H chondrites is proposed. The chondrule-forming episode is considered as a remelting of pre-existing material. The accretion would immediately follow this event for type 6 (around 1000°C), and would occur at progressively lower temperature for types 5 and 4. Type 3 would represent material coming from an extended source region, an hypothesis consistent with the broader range composition of the particles and with their cooling before accretion to much lower temperatures (below 350°C).  相似文献