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991.
992.
Camps M Briand JF Guentas-Dombrowsky L Culioli G Bazire A Blache Y 《Marine pollution bulletin》2011,62(5):1032-6755
Biofilm formation is a key step during marine biofouling, the natural colonization of immersed substrata, leading to major economic and ecological consequences. Consequently, bacteria have been used for the screening of new non-toxic antifoulants: the adhesion of five strains isolated on three French locations was monitored using a fluorescence-based assay and toxicity was also evaluated. Nine biocides including commercial, natural and natural-derived products were tested. The commercial antifoulants, TBTO and Sea Nine showed low EC50 but high toxicity. The non-commercial products TFA-Z showed significant anti-adhesion activities and appeared to be non-toxic, suggesting a specific anti-adhesion mechanism. In addition, the strains could be classified depending on their sensitivity to the molecules used even if strain sensitivity also depended on the molecules tested. In conclusion, TFA-Z would be a promising candidate as non-toxic antifoulant and our results strengthen the need to perform antifouling bioassays with a panel of strains showing different response profiles. 相似文献
993.
Pedro A. Dinis Álvaro Oliveira Fernando Rocha Manuel Vieira Pedro P. Cunha 《Chemie der Erde / Geochemistry》2011,71(3):267-278
Geochemical and mineralogical data from a Pliocene to Pleistocene alluvial sequence are integrated to access the factors that control rare earth elements (REE) geochemistry and the evolution and spatial differences in provenance. The studied alluvial system is situated in a tectonic active setting at the contact between the Variscan Massif, with several Paleozoic and Precambrian units that support a coastal range, and the Atlantic margin. REE and HREE abundances are generally higher in swamp-lake than in floodplain sediments. The majority of the REE in floodplain sediments is hosted by Y and Th-bearing minerals and illite; in swamp-lake sediments is also probable an association with organic matter. The high Gd/Yb, Eu/Eu* and kaolinite content in older sediments suggest that during the earlier phases provenance was mainly from the hinterland (weathered granitic rocks and its sediment cover). The subsequent illite (Mg-rich) clay assemblages and REE patterns indicate mainly lateral input from the eastern basin edge (Palaeozoic and Precambrian metapelitic rocks). These sediments tend to have lower Gd/Yb and La/Sm than their source rocks. The analysis of the chemical index of alteration (CIA) indicates that although a north-directed fluvial axis existed at that time the “mature” basin edge units found to the south (Silurian) had a limited role in supplying sediments. This shift in provenance is attributed to the uplift of the coastal range. Afterwards, the contribution of recycled Cretaceous and Cenozoic sedimentary units increased progressively. This is demonstrated by the increase is SiO2/TiO2, CIA and kaolinite/illite when the climatic conditions are expected to have become less chemically aggressive. 相似文献
994.
Yavuz Özdemir Jon Blundy Nilgün Güleç 《Contributions to Mineralogy and Petrology》2011,162(3):573-597
Süphan is a 4,050 m high Pleistocene-age stratovolcano in eastern Anatolia, Turkey, with eruptive products consisting of transitional
calc-alkaline to mildly alkaline basalts through trachyandesites and trachytes to rhyolites. We investigate the relative contributions
of fractional crystallization and magma mixing to compositional diversity at Süphan using a combination of petrology, geothermometry,
and melt inclusion analysis. Although major element chemistry shows near-continuous variation from basalt to rhyolite, mineral
chemistry and textures indicate that magma mixing played an important role. Intermediate magmas show a wide range of pyroxene,
olivine, and plagioclase compositions that are intermediate between those of basalts and rhyolites. Mineral thermometry of
the same rocks yields a range of temperatures bracketed by rhyolite (~750°C) and basalt (~1,100°C). The linear chemical trends
shown for most major and trace elements are attributed to mixing processes, rather than to liquid lines of descent from a
basaltic parent. In contrast, glassy melt inclusions, hosted by a wide range of phenocryst types, display curved trends for
most major elements, suggestive of fractional crystallization. Comparison of these trends to experimental data from basalts
and trachyandesites of similar composition to those at Süphan indicates that melt inclusions approximate true liquid lines
of descent from a common hydrous parent at pressures of ~500 MPa. Thus, the erupted magmas are cogenetic, but were generated
at depths below the shallow, pre-eruptive magma storage region. We infer that chemical differentiation of a mantle-derived
basalt occurred in the mid- to lower crust beneath Süphan. A variety of more and less evolved melts with ≥55 wt% SiO2 then ascended to shallow level where they interacted. The presence of glomerocrysts in many lavas suggests that cogenetic
plutonic rocks were implicated in the interaction process. Blending of diverse, but cogenetic, minerals, and melts served
to obscure the true liquid lines of descent in bulk rocks. The fact that chemical variation in melt inclusions preserves deep-seated
chemical differentiation indicates that inclusions were trapped in phenocrysts prior to shallow-level blending. Groundmass
glasses evolved after mixing and display trends that are distinct from those of melt inclusions. 相似文献
995.
Mengyan Li Patrick Conlon Stephanie Fiorenza Rock J. Vitale Pedro J.J. Alvarez 《Ground Water Monitoring & Remediation》2011,31(4):70-76
An innovative micro‐extraction of aqueous samples coupled with gas chromatography/mass spectrometry in selected ion‐monitoring mode (GC/MS‐SIM) was developed to selectively analyze for 1,4‐dioxane with low part‐per‐billion detection sensitivity. Recoveries of 1,4‐dioxane ranged from 93% to 117% for both spiked laboratory reagent water and natural groundwater matrices, the later having elevated organic carbon content (8.34 ± 0.31 mg/L as total organic carbon). We observed that freezing the aqueous sample along with the extraction solvent enhanced the extraction efficiency, minimized physical interferences, and improved sensitivity resulting in a limit of detection for 1,4‐dioxane to approximately 1.6 μg/L. This method substantially reduces the labor, time, reagents and cost, and uses instruments that are commonly found in analytical laboratories. This method requires a relatively small sample volume (200 μL), and can be considered a green analytical method as it minimizes the use of toxic solvents and the associated laboratory wastes. 相似文献
996.
In this study, graft copolymerization of itaconic acid (IA) and crotonic acid (CA) onto the crosslinked chitosan beads were carried out using ammonium persulfate as initiator. Grafted chitosan beads were characterized by FT‐IR analysis and grafting percentage determination. Grafting efficiency and add‐on percentages values of grafted chitosan beads were determined as 23–29 and 32–47%, respectively. Then, equilibrium isotherms and kinetics of brilliant green adsorption onto grafted chitosan beads were investigated. The results indicated that the pseudo‐second‐order kinetic model fitted better than the data obtained from pseudo‐first‐order model for the adsorption of brilliant green onto grafted chitosan beads. The fit of data for brilliant green (BG) adsorption onto grafted chitosan beads suggested that the Langmuir model gave closer fittings than the Freundlich model. 相似文献
997.
Pedro Filipe de Oliveira Cordeiro José Affonso Brod Roberto Ventura Santos Elton Luiz Dantas Claudinei Gouveia de Oliveira Elisa Soares Rocha Barbosa 《Contributions to Mineralogy and Petrology》2011,161(3):451-464
The Late-Cretaceous Catalão I contains stockworks of thin dykes of phoscorite-series rocks, which can be subdivided into P1 (olivine-bearing, phoscorites) and P2/P3 (olivine-lacking, nelsonites). Dolomite carbonatites (DC) are intimately associated with nelsonites, as pockets and dykes. The P2 apatite nelsonite, the P3 magnetite nelsonite, and, to a lesser extent DC, host the Catalão I niobium mineralization. C–O isotopes signatures in carbonates reveal several distinct magmatic and post-magmatic processes. Limpid carbonates with stable isotopic mantle-like composition show Rayleigh fractionation and are interpreted as primary, while those with brittle-turbid aspect, and higher oxygen isotope composition, probably underwent recrystallization by interaction with H2O-rich fluids. A group of samples shows higher oxygen compositions and lower carbon values, which could be explained by degassing of carbonatite magma during cooling. A degassing pattern, parallel to magmatic degassing but at higher oxygen and lower carbon compositions, observed in carbonate veins, may indicate degassing of fracture filling fluids. Furthermore, C–O isotopes of carbonate from monazite-bearing carbonatite have a positive correlation, indicating a distinct, late-stage carbo-hydrothermal event. Though the Catalão I nelsonites and phoscorites are of igneous origin, they underwent several post-magmatic events, which sometimes overprinted partially or entirely the magmatic isotope signature. 相似文献
998.
I. Tonguç Uysal Massimo Gasparon Robert Bolhar Jian-xin Zhao Yue-xing Feng Greg Jones 《Chemical Geology》2011,280(1-2):154-169
Extensive Paleozoic sinter deposits occur at the surface associated with sub-surface quartz veining and epithermal Au mineralisation in the Drummond Basin, Australia. We investigated the trace element composition of the sinter deposits and quartz veins in an attempt to develop a new geochemical exploration guide for geological resources. The Drummond Basin hydrothermal silica deposits are unique in having anomalously enriched incompatible element (Cs, Li, Be, U, Th and REE) concentrations in comparison to hydrothermal quartz veins from various granitic-pegmatitic systems elsewhere. The development of relative Ce deficiencies (Ce/Ce*norm < 1) in silica deposits indicate preferential mobilisation of REE over Ce from source rocks by oxidised hydrothermal fluids, leading to relative Ce enrichment in the source material (e.g., rhyolite intrusions). Sinters and quartz veins and some volcanic source rocks show a conspicuous positive Y anomaly relative to REE. This is interpreted in terms of Y fractionation due to fluorine complexation with REE during hydrothermal activity. The majority of sinter and quartz samples within or near the Au mineralisation zone are more enriched in mobile elements (Cs, Li, Rb and Be) than the silica deposits from areas distal to the mineralised area. Normalised Y–REE patterns of the sinter deposits, quartz veins, and wall rocks provide important information on the physico-chemical environment of epithermal mineral deposition in geothermal systems. Trace element systematics as revealed in the current study, particularly in relation to the alkali element mobility, have significant implications for finding new prospect areas and evaluating the potential of existing prospect areas for epithermal metal deposits and active geothermal fields. 相似文献
999.
François Chabaux Lin Ma Peter Stille Eric Pelt Mathieu Granet Damien Lemarchand Raphael di Chiara Roupert Susan L. Brantley 《Applied Geochemistry》2011
The development of U-series nuclides for investigating weathering processes has been significantly stimulated by the analytical improvement made over the last decades in measuring the 238U series with intermediate half-lives (i.e., 234U–230Th–226Ra). It is proposed in this paper to present principles and methods that are now being developed to determine weathering rates from the study of U-series nuclides in soils and weathering profiles. Mathematical approaches, developed to calculate such rates, are based on some implicit assumptions that are also presented and must be kept in mind if one wants to correctly interpret the obtained ages. 相似文献
1000.