976 resultados para 185-1149


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Chlorine isotope ratios were determined for volcanic gas, geothermal well, ash, and lava samples along the Izu-Bonin-Mariana volcanic front, serpentinite clasts and muds from serpentine seamounts (Conical, South Chamorro, Torishima), basalts from the Guguan cross-chain, and sediments from Ocean Drilling Program (ODP) Sites 800, 801, 802, and 1149. There is no systematic variation in d37Cl values along the volcanic front in either gas or ash samples. In contrast, distinct variations occur across the arc, implying variations in the fluid source at different depths within the subduction zone. Serpentinite clasts and serpentine muds from the seamounts tap a source of ~30 km depth and have d37Cl values of structurally bound chloride of +0.4 per mil +/- 0.4 per mil (n = 24), identical to most seafloor serpentinites, suggesting a serpentinite (chrysotile and/or lizardite to antigorite transition) fluid source. Tapping deeper levels of the subduction zone (~115-130 km depth), volcanic gases and ashes have d37Cl values averaging -1.1 per mil +/- 1.0 per mil (n = 29), precisely overlapping the range measured in sediments from ODP cores (-1.1 per mil +/- +0.7 per mil, n = 11) and limited altered oceanic crust (AOC). Both sediments and AOC are possible Cl sources in the volcanic front. The Guguan cross-chain basalts come from the greatest depths and have an average d37Cl value of +0.2 per mil +/- 0.2 per mil (n = 3), suggesting a second serpentine-derived source, in this case from antigorite breakdown at ~200 km depth.

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Re and Os concentrations and Os isotopic ratios were determined for composite samples prepared from volcanoclastics (VCL) and basaltic flows (FLO) from Jurassic oceanic crust (Ocean Drilling Program Leg 185, Site 801 in the western Pacific), with the aim of determining the effect of seafloor weathering on the Re-Os budget. A supercomposite sample, prepared from a proportionate mixture of the various composite powders, served to represent the average composition of the altered oceanic crust [Kelley, K.A., Plank, T., Ludden, J. and Staudigel, H., (2003). Composition of altered oceanic crust at ODP Sites 801 and 1149, Geochem. Geophys. Geosyst. 4(6) 8910, doi:10.1029/2002GC000435.]. Re contents vary from 0.2 to 1.3 ng/g, and from 2.2 to 3.1 ng/g in the VCL and FLO composites respectively. Os contents vary from 0.005 to 0.047 ng/g in the VCL, and from 0.008 to 0.027 ng/g in the FLO composites. The FLO composites have much higher Re/Os ratios and thus have more radiogenic Os compositions (187Os/188Os = 1.38 to 8.48) than the VCL composites (187Os/188Os = 0.32 to 4.40). The VCL composite from the upper section of the crust shows evidence for substantial Re loss and Os uptake, consistent with oxidative weathering processes. However, Re uptake during weathering processes under more reducing conditions, evident in the FLO samples from throughout the section and to a lesser extent in the lower VCL samples, more than compensates for this Re loss in the upper VCL. Os concentrations were essentially unchanged by these reductive processes. Model age calculations suggest that Re uptake continued for tens of millions of years after crust formation. Abundant secondary pyrite is found throughout the altered Hole 801C crust in zones of restricted seawater flow, and this may have accommodated an important part of the input Re. The Re content of the supercomposite (~2.2 ng/g) is about 1 ng/g higher than would be expected on the basis of its Yb content. If the results from Hole 801C are typical, they suggest that the Re concentration of at least the upper part of the oceanic crust may be nearly doubled during seafloor alteration. Such large extents of Re uptake would have a significant effect on the oceanic Re budget. Furthermore, assuming that they survive passage through the subduction zone, these elevated Re contents would greatly decrease the proportion of subducted oceanic crust required in the source region to explain the radiogenic Os compositions of many ocean island basalts.

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Knowledge of the subduction input flux of nitrogen (N) in altered oceanic crust (AOC) is critical in any attempt to mass-balance N across arc-trench systems on a global or individual-margin basis. We have employed sealed-tube, carrier-gas-based methods to examine the N concentrations and isotopic compositions of AOC. Analyses of 53 AOC samples recovered on DSDP/ODP legs from the North and South Pacific, the North Atlantic, and the Antarctic oceans (with larger numbers of samples from Site 801 outboard of the Mariana trench and Site 1149 outboard of the Izu trench), and 14 composites for the AOC sections at Site 801, give N concentrations of 1.3 to 18.2 ppm and d15N_air of -11.6? to +8.3?, indicating significant N enrichment probably during the early stages of hydrothermal alteration of the oceanic basalts. The N-d15N modeling for samples from Sites 801 and 1149 (n=39) shows that the secondary N may come from (1) the sedimentary N in the intercalated sediments and possibly overlying sediments via fluid-sediment/rock interaction, and (2) degassed mantle N2 in seawater via alteration-related abiotic reduction processes. For all Site 801 samples, weak correlation of N and K2O contents indicates that the siting of N in potassic alteration phases strongly depends on N availability and is possibly influenced by highly heterogeneous temperature and redox conditions during hydrothermal alteration. The upper 470-m AOC recovered by ODP Legs 129 and 185 delivers approximately 800 kg/km N annually into the Mariana margin. If the remaining less-altered oceanic crust (assuming 6.5 km, mostly dikes and gabbros) has MORB-like N of 1.5 ppm, the entire oceanic crust transfers 5100 kg/km N annually into that trench. This N input flux is twice as large as the annual N input of 2500 kg/km in seafloor sediments subducting into the same margin, demonstrating that the N input in oceanic crust, and its isotopic consequences, must be considered in any assessment of convergent margin N flux.

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Purpose – The purpose of this paper is to present a selection of responses to the report Fashion Victims, published by War on Want in December 2006. It offers a range of viewpoints presented by members of the Editorial Advisory Board of CPOIB. These are presented in chronological order of submission. There is some cross-reference by contributors to the work of others, but no attempt is made to present a unified argument. Design/methodology/approach – Presents the full contributions of involved participants, without mediation or editorial change. Findings – A number of different perspectives are presented on the central issue that is summarised by the opening heading in War on Want’s report – “How cheap is too cheap?” It is seen that the answer to this question is very much dependent upon the standpoint of the respondent. Originality/value – In presenting this form of commentary, members of the CPOIB Editorial Board seek to stimulate debate about an issue of concern to contemporary society, without resort to the time delay and mediating processes of peer-review normally attached to academic writing. It is hoped that this discussion will provoke further contributions and a widening of the debate. Keywords Corporate social responsibility, Multinational companies, Conditions of employment, Trade unions

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Seasonal changes and flooding have an extraordinarily great influence on the drift of organisms. The free water space plays the main part in the provision of food for some fish (Salmo trutta - trout): drift and content of the stomach are balanced here (Simuliidae): whereas others (Thymallus vulgaris) only selectively chose certain animals living at the bottom (molluscs). The total drift, drift of organisms and drift of organic material and minerals, plays a main role in the rate of production in streams. Besides the biology of the organisms living on the river bed, also the geological and hydrographical situation of the area plays a very important role for the composition of the drift. During the years 1964-1966 three streams in the characteristical geological formations flysch, gneiss and chalk of lower Austria were studied in regard to their drift. The Tulln (above St. Christopen), the Krems (above Senftenberg) and the Schwarza (above Hirschwang) seemed to be ideal for this comparative study because they are easy to reach. After summarising the hydrography and chemistry of examined rivers, the author examines the relationship between water level and total drift and the stratification of the total drift before analysing the drift of living organisms. Also considered are seasonal changes of drift of organisms and drift of exuviae.

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This abbreviated translation summarises the chemical composition of Iraq water resources. Among the described water bodies are the River Euphrates, Shatt al Arab River and a number of standing waters.

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Here we reported the fatty-acids and their δ 13C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ∼540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ∼2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C16. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ 13C values (−39.99‰ to.32.36‰) of n-C12:0, n-C13:0, i-C14:0and n-C14:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C18:2 and C18:1Δ9 have the same δ 13C values, they may originate from theBeggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lowerδ 13C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.