Links between bacterial communities in marine sediments and trace metal geochemistry as measured by in situ DET/DGT approaches   总被引：1，自引：0，他引：1  

Gillan DC  Baeyens W  Bechara R  Billon G  Denis K  Grosjean P  Leermakers M  Lesven L  Pede A  Sabbe K  Gao Y 《Marine pollution bulletin》2012,64(2):353-362

Our current view about the relationship between metals and bacteria in marine sediments might be biased because most studies only use ex situ approaches to quantify metals. The aim of the present research was to compare ex situ and in situ methods of metal measurement (DET and DGT--diffusive equilibration or diffusive gradients in thin-films) and relate the results with two commonly used microbiological variables (bacterial biomass and bacterial diversity as revealed by DGGE). No previous studies have used such in situ approaches in microbial ecology. For biomass and most of the investigated trace metals (Ag, Cd, Sn, Cr, Ni, Cu, Pb, and Al) no significant correlations were found. The exceptions were Fe, Mn, Co, and As which behave like micronutrients. For bacterial diversity, no relevant relationships were found. We conclude that in situ methods are more adapted tools for microbial ecologists but that ex situ approaches are still necessary.  相似文献   

Physical and chemical control of the phytoplankton of Ahe lagoon, French Polynesia     

Charpy L  Rodier M  Fournier J  Langlade MJ  Gaertner-Mazouni N 《Marine pollution bulletin》2012,65(10-12):471-477

The environmental characteristics of Ahe deep lagoon (Tuamotu Archipelago, French Polynesia) were studied over 3 years with the aim of explaining the spatial and temporal variability of the natural food available for pearl oysters with a special focus on phytoplankton biomass and global photosynthesis/respiration ratio of the lagoon. Chlorophyll averaged 0.34±0.01 μg L(-1) and our findings did not confirm increased phytoplankton biomass in deep lagoonal waters. Phytoplankton production appears to be limited firstly by nitrogen and respiratory processes overpass photosynthetic processes at least in the north-eastern edge of the atoll. Grazing by pearl oysters in culture seems to decrease the POC concentration but not the phytoplankton biomass. Oysters graze mainly on non chlorophyllian particles.  相似文献   

Identification of stoichiometric iron-phosphorus colloids produced in a eutrophic lake     

Charles-Philippe Lienemann  Marc Monnerat  Janusz Dominik  Didier Perret 《Aquatic Sciences - Research Across Boundaries》1999,61(2):133-149

: Iron-rich colloids formed at the oxic-anoxic interface of a eutrophic lake (Lake Lugano; CH) were characterized by bulk chemical methods and analytical electron microscopy. Fractionation of raw waters showed that non-dissolved iron is particulate above the oxicline and mainly colloidal in the anoxic part of the hypolimnion, while non-dissolved ortho-phosphate is mostly colloidal through the water column. Because of these differences, filtration did not prove helpful for the determination of the role of iron-rich species in the scavenging of ortho-phosphate. On the other hand, analytical electron microscopy revealed that iron-rich nano-granules (ca. 50nm) are associated to the surface of bacterially produced fibrillar polysaccharides. Iron colloids in these complex entities contain important and constant amounts of phosphorus ([PO4]part:[Fe]part = 0.48 - 0.11, n = 1096 Fe-rich entities analyzed by electron microscopy), which suggests that phosphates are stoichiometrically incorporated into the hydrous iron oxide phase, with a tentative composition Fe2[OOH]1-x[(OH)3]x[PO4], during its genesis.  相似文献   

Structural investigations of (Ca,Sr)ZrO<Subscript>3</Subscript> and Ca(Sn,Zr)O<Subscript>3</Subscript> perovskite compounds     

Martine Tarrida  H. Larguem  M. Madon 《Physics and Chemistry of Minerals》2009,36(7):403-413

(Ca _x ,Sr_1?x )ZrO₃ and Ca(Sn _y ,Zr_1-y )O₃ solid solutions were synthesized by solid-state reaction at high temperature before to be studied by powder X-ray diffraction and Raman Spectroscopy. Diffraction data allow the distortion of the ABO₃ perovskite structure to be investigated according to cations substitution on A and B-sites. It is shown that distortion, characterized by Φ, the tilt angle of BO₆ octahedra, slightly increases with decreasing y content in Ca(Sn _y ,Zr_1?y )O₃ compounds and strongly decreases with decreasing x content in (Ca _x ,Sr_1?x )ZrO₃ compounds. Such results are discussed in view of the relative A and B cation sizes. Raman data show that vibrational spectra are strongly affected by the cation substitution on A-site; the frequencies of most vibrational modes increase with increasing x content in (Ca _x ,Sr_1?x )ZrO₃ compounds, i.e. with the decreasing mean size of the A-cation; the upper shift is observed for the 358 cm^?1 mode (?ν/?r = ?60.1 cm^?1/Å). On the other hand, the cation substitution on B-sites, slightly affect the spectra; it is shown that in most cases, the frequency of vibrational modes increases with increasing y content in Ca(Sn _y ,Zr_1?y )O₃ compounds, i.e. with the decreasing mean size of the B-cation, but that two modes (287 and 358 cm^?1) behave differently: their frequencies decrease with the decreasing mean size of the B-cation, with a shift respectively equal to +314 and +162 cm^?1/Å. Such results could be used to predict the location of different elements such as trivalent cations or radwaste elements on A- or B-site, in the perovskite structure.  相似文献   

Climatic variability during the last 90 ka of the southern and northern Levantine Basin as evident from marine records and speleothems     

Ahuva Almogi-Labin  Miryam Bar-Matthews  Dan Shriki  Elina Kolosovsky  Martine Paterne  Bettina Schilman  Avner Ayalon  Zeev Aizenshtat  Alan Matthews   《Quaternary Science Reviews》2009,28(25-26):2882-2896

The influence of the northern Atlantic and tropical monsoonal systems, as recorded by the River Nile, on the climate variability of the southeastern Mediterranean was studied in two cores taken by the R/V Marion Dufresne: one core taken SE of Cyprus representing the northern Levantine Basin (core 9501, 980 m water depth) and the other located ˜380 km further south, represents the southeastern Levantine Basin in an area influenced by the River Nile plume (core 9509, 884 m water depth). The study was performed at relatively high resolution using several proxies: δ¹⁸O of Globigerinoides ruber, sediment characteristics and index colour parameters in core sections representing the last 86 ka. A low-resolution alkenone sea surface temperature record was also measured. The time frame in both cores was mostly constrained by ‘wiggle’ matching with the nearby well-dated δ¹⁸O and δ¹³C record of the Soreq Cave, which is mainly influenced by the eastern Mediterranean water vapor. The sedimentary record of the southern core is strongly influenced by the River Nile contribution throughout the last 86 ka, as evidenced by the higher sedimentation rates compared with the northern core (20 cm/ka vs. 5 cm/ka), continuously darker sediment colour, and higher TOC values (0.6–0.9 vs. 0.25 wt% not including sapropels). During sapropels S1 and S3, present in both cores, the influence of the River Nile became more widespread, reaching as far as Cyprus. Yet, the influence of the River Nile remained stronger in the south, as evident by the higher TOC values in the southern core throughout the entire 90 ka period and the longer duration of S1 in the southern core. An anomalous low δ¹⁸O interval that is not recorded in western Mediterranean occurred between 58 and 49 ka in the Levantine Basin and is more developed in the northern core. This period correlates with D-O interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle, suggesting that the warming mainly impacted the northern Levant.The Eastern Mediterranean Sea and land area was considerably warmer than the western Mediterranean throughout the LGM – Holocene transition, and the δ¹⁸O_{G. ruber} drop of 4.5‰ is significantly greater than the 3‰ shift found for the western Mediterranean δ¹⁸O_{G. bulloides}, both differences reflecting an increased continental effect from the western to eastern Mediterranean. Comparison between the marine and the land δ¹⁸O records suggests that the origin of rain over the land is composed of mixed signal from the southern and northern Levantine Basin. The study of Δδ¹⁸O_sea–land variations demonstrates that various factors have influenced the sea–land relationship during the last 90 ka. The ‘amount effect’ has an important influence on rainfall δ¹⁸O during interglacial periods (particularly sapropel periods), whereas during glacial periods, increased land distances and elevation differences arising from decrease in sea level may have brought about decrease in δ¹⁸O of rainfall due to Rayleigh distillation processes. These influences were superimposed on those of sea surface water δ¹⁸O changes brought about by continental ice melting, and the strong effects felt in the southern Levantine Basin of the high River Nile input during periods of enhanced monsoonal activity.  相似文献   

Economics of climate policy and collective decision making   总被引：1，自引：0，他引：1  

Beat Bürgenmeier  Andrea Baranzini  Catherine Ferrier  Céline Germond-Duret  Karin Ingold  Sylvain Perret  Peter Rafaj  Socrates Kypreos  Alexander Wokaun 《Climatic change》2006,79(1-2):143-162

This paper explores the reasons why economic instruments of climate change are reluctantly applied and stresses the need for interdisciplinary research linking economic theory and empirical testing to deliberative political procedures. It is divided in three parts. The first one recalls the main issues in implementing Cost-Benefit Analysis such as information problems, uncertainties, discounting the future and irreversibilities. The second part shows how these issues can be treated in integrated assessment and techno-economic models and presents a case study, which shows that

• The chosen scenario tends to stabilize atmospheric CO₂ concentration at around 550 ppm in the long run.
• Exclusion of possibility to trade CO₂ emission permits under a cap regime would increase the cost of emission abatement for OECD countries.
• Combining different flexibility instruments might lead to significant gains in the overall cost of climate policy.

The third part presents results of a survey conducted among the main economic and environmental associations in Switzerland. The survey reveals conflicting views on economic instruments. It shows how the social acceptability of these instruments can be improved in taking explicitly into account these opposing views of special interest groups. Therefore, policy scenarios should be selected in combining techno-economic models with empirical studies about their political and normative context.  相似文献   

Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs     

van den Brink NW  Riddle MJ  van den Heuvel-Greve M  van Franeker JA 《Marine pollution bulletin》2011,62(1):128-132

We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining.  相似文献   

Erratum: New constraints on the thickness of the Semail ophiolite in the Northern Emirates     

Charles Naville  Martine Ancel  Paul Andriessen  Patrice Ricarte  François Roure 《Arabian Journal of Geosciences》2011,4(3-4):687-687

  相似文献   

A Compilation of Silicon and Thirty One Trace Elements Measured in the Natural River Water Reference Material SLRS-4 (NRC-CNRC)   总被引：1，自引：0，他引：1  

Delphine Yeghicheyan  Jean Carignan  Michel Valladon  Martine Bouhnik Le  Coz  Florence Le Cornec  Maryse Castrec-Rouelle  Michel Robert  Luc Aquilina  Emmanuel Aubry  Carine Churlaud  Aline Dia  Samuel Deberdt  Bernard Dupré  Rémi Freydier  Gérard Gruau  Odile Hénin  Anne-Marie de  Kersabiec  Joël Macé  Luc Marin  Nicole Morin  Patrice Petitjean  Elodie Serrat 《Geostandards and Geoanalytical Research》2001,25(2-3):465-474

The natural river water certified reference material SLRS-4 (NRC-CNRC, National Research Council-Conseil National de Recherches Canada) has been routinely analysed for major and trace elements by six French laboratories. Most measurements were made using inductively coupled plasma-mass spectrometry. For silicon and thirty one trace elements (rare earth elements, Ag, B, Br, Cs, Ga, Ge, Li, P, Pd, Rb, Se, Th, Ti, Tl, W, Y and Zr), no certified values are assigned by NRC-CNRC. We propose some compilation values and related uncertainties according to the results obtained by the different laboratories.  相似文献   

Variations de l’âge des sédiments calcaires et « Culm » carbonifère dans la chaîne varisque du Sud de la France : migration de l’orogenèse varisque     

Jean-Jacques Delvolvé  Marie-France Perret 《Geodinamica Acta》2013,26(2):117-126

Résumé

Dans le Sud de la France et les Pyrénées espagnoles, les calcaires sous-jacents aux roches détritiques du Culm carbonifère ont fait l’objet d’une datation systématique par conodontes. Il en ressort que le dépôt de ces niveaux carbonates s’est poursuivi de plus en plus tardivement de l’Est vers l’Ouest : du Viséen inférieur (V3b) en Montagne Noire, au Namurien supérieur (G2) en Pays basque.

Les roches détritiques à caractère flyschoïde du Culm remanient, localement, des éléments de calcaire de plate-forme. La datation de ces éléments par foraminifères, algues, pseudo-algues et végétaux supérieurs montre qu’ils sont de plus en plus récents d’Est en Ouest : leur âge s’échelonne du Viséen 3bp-Namurien A en Montagne Noire, au Westphalien C (Kachirien) au Pays basque (Massif des Cinco-Villas).

Ces divers résultats montrent que les manifestations tectoniques, responsables des premiers épandages détritiques du Culm puis de la resédimentation des calcaires de plate-forme dans le bassin, ont commencé de plus en plus tardivement de la Montagne Noire au Pays basque.

Dans sa branche Sud, l’orogenèse varisque, si l’on s’en tient à la position actuelle de ses segments observables, a migré progressivement du Nord vers le Sud, en Montagne Noire et dans le Massif de Mouthoumet, puis vers l’Ouest, des Pyrénées centrales aux Pyrénées orientales.  相似文献