Lake Sediment Core Records of Sulphur Accumulation and Sulphur Isotopic Composition in Central Ontario, Canada Lakes     

M. Catherine Eimers  Andrew M. Paterson  Peter J. Dillon  Sherry L. Schiff  Brian F. Cumming  Roland I. Hall 《Journal of Paleolimnology》2006,35(1):99-109

Stable isotopic compositions and concentrations of total sedimentary sulphur (S) were determined in cores from 6 lakes in the acid-sensitive Muskoka-Haliburton region of south-central Ontario. The isotopic composition of S in deep sediment (> ~ 20 cm) was approximately constant in all lakes, and indicated a pre-industrial δ ³⁴S value between +4.0 and +5.3‰, which is similar to current bulk deposition. Similarly, total S concentrations in deep sediment were relatively low (1.9–5 mg S g⁻¹ dwt) and approximately constant with depth within cores. All lakes exhibited up-core increases in total S and decreases in δ ³⁴S at a depth corresponding to the beginning of industrialization in the Great Lakes region ( ~ 1900), resulting in a generally reciprocal depth pattern between total S concentration and δ ³⁴S ratios. While initial shifts in total S and δ ³⁴S were likely due to enhanced SO₄ reduction of newly available anthropogenic SO₄, both the magnitude and pattern of up-core S enrichment and shifts in δ ³⁴S varied greatly among lakes, and did not match changes in S deposition post 1900. Differences between lakes in total S and δ ³⁴S were not related to any single hydrologic (e.g., residence time) or physical (e.g., catchment-area-to-lake area ratio) lake characteristic. This work indicates that sediment cores do not provide consistent records of changes in post-industrial S deposition in this region, likely due to redox-related mobility of S in upper sediment.  相似文献   

Physiography and tectonic setting of the subglacial lake district between Vostok and Belgica subglacial highlands (Antarctica)     

I. E. Tabacco  P. Cianfarra  A. Forieri  F. Salvini  A. Zirizotti 《Geophysical Journal International》2006,165(3):1029-1040

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Dual simulations of fluid flow and seismic wave propagation in a fractured network: effects of pore pressure on seismic signature   总被引：1，自引：0，他引：1  

S. Vlastos  E. Liu  I. G. Main  M. Schoenberg  C. Narteau  X. Y. Li  B. Maillot 《Geophysical Journal International》2006,166(2):825-838

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Haul-out pattern of itinerant male Antarctic fur seals (Arctocephalus gazella) at Laurie Island, South Orkney Islands     

Alejandro R. Carlini  Gustavo A. Daneri  Ricardo Casaux  María E. I. Márquez 《Polar research》2006,25(2):139-144

The seasonal haul-out pattern of itinerant male Antarctic fur seals ( Arctocephalus gazella ) was determined by regular counts at Mossman Peninsula, Laurie Island, South Orkney Islands, from 1996 to 2005. Small numbers of animals began to arrive at the beach in late December/early January (mean date 28 December Ø 15 days, n= 10). Peak numbers of animals ashore changed considerably between seasons. In 1996, 1998 and 2001, peak numbers were registered in March (6/3, 18/3 and 6/3, respectively). Numbers peaked in 1997, 1999 and 2005 at the end of January/beginning of February (26/1,2/2 and 28/1, respectively). In 2000, 2002, 2003 and 2004 peaks were registered in the third week of February (15/2, 22/2, 14/2 and 20/2, respectively). Peaks in numbers of seals ashore also varied between years, being minimum during 2001 (2531 individuals) and maximum during 2006 (16 610 individuals). In March 1998 the coasts of Laurie Island were surveyed by navigating inflatable boats near the shoreline; 18 haul-out places were identified. The big differences in peak numbers, as well as in the dates of peak events among years, suggest that local conditions could have an effect on the numbers of animals hauled out in a given year. It may therefore be difficult to predict trends from summer censuses in non-breeding places.  相似文献   

Mesoarchean island-arc association in the Central Karelian terrane, Fennoscandian shield: New Geochronological data     

S. A. Svetov  N. M. Kudryashov  Yu. L. Ronkin  H. Huhma  A. I. Svetova  T. N. Nazarova 《Doklady Earth Sciences》2006,406(1):103-106

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First find of the Tomakovka Beds in the Gerakleya Peninsula of Southwestern Crimea     

I. M. Barg 《Doklady Earth Sciences》2006,406(1):8-11

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Ge-bearing coals of the Luzanovka Graben, Pavlovka brown coal deposit, southern Primorye     

V. V. Seredin  Yu. A. Danilcheva  L. O. Magazina  I. G. Sharova 《Lithology and Mineral Resources》2006,41(3):280-301

Results of the study of a new Ge-bearing area of the Pavlovka brown coal deposit are presented. Ge is accumulated in bed III₂ lying at the bottom of the Late Paleogene-Early Neogene coal-bearing sequence adjacent to the Middle Paleozoic granite basement. The Ge content in coals and coal-bearing rocks varies in different sections from 10 to 200–250 ppm, reaching up to 500–600 ppm in the highest-grade lower part of the bed. The metalliferous area reveals a geochemical zoning: complex Ge-Mo-W anomalies subsequently grades along the depth and strike into Mo-W and W anomalies. Orebodies, like those at many Ge-bearing coal deposits, are concentric in plan and dome-shaped in cross-section. Coals in their central parts, in addition to Ge, W, and Mo, are enriched in U, As, Be, Ag, and Au. Distribution of Ge and other trace elements in the metalliferous sequence and products of gravity separation of Ge-bearing coals is studied. These data indicate that most elements (W, Mo, U, As, Be) concentrated like Ge in the Ge-bearing bed relative to background values are restricted to the organic matter of coals. The electron microscopic study shows that Ge-bearing coals contain native metals and intermetallic compounds in association with carbonates, sulfides, and halogenides. Coal inclusions in the metalliferous and barren areas of the molasse section strongly differ in contents of Ge and associated trace elements. Ge was accumulated in the coals in the course of the interaction of ascending metalliferous solutions with organic matter of the buried peat bogs in Late Miocene. The solutions were presumably represented by N₂-bearing thermal waters (contaminated by volcanogenic CO₂) that are typical of granite terranes.  相似文献   

Cryogeochemical processes in the oxidation zone of sulfide deposits: Experimental data     

A. B. Ptitsyn  T. I. Markovich  V. A. Pavlyukova  E. S. Epova 《Doklady Earth Sciences》2006,411(9):1398-1400

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The chemical composition of HR 1512, a peculiar helium-weak star     

T. M. Rachkovskaya  L. S. Lyubimkov  S. I. Rostopchin 《Astronomy Reports》2006,50(2):123-133

We have used high-resolution spectra to study the chemical composition of HR 1512, a star with effective temperature T _eff = 15 200 K, atmospheric gravity log g = 3.52, microturbulence parameter V _t = 1.5 km/s, and rotation rate v sin i = 17 km s^?1. We confirm the presence of a helium deficiency (?0.6 dex), indicating that HR 1512 is a helium-weak star. Its considerable phosphorus excess (1.6 dex) testifies that the star belongs to the PGa subtype. We suggest that the He and P abundances increase with height; i.e., that there is stratification of He and P in the star’s atmosphere. Among the CNO elements, nitrogen demonstrates an underabundance of ?0.4 dex, while the abundances of carbon and oxygen are solar. Deficits of about ?0.5 or ?0.6 dex were also found for Mg, Si, and S. A neon excess of 0.4 dex was derived from our non-LTE analysis of NeI lines. The largest excess among the iron-peak elements (Cr, Mn, Fe, and Ni) is 0.6 dex, for manganese; the abundances of chromium and nickel display excesses of 0.5 and 0.3 dex, respectively, while the iron abundance is almost normal. The chemical anomalies of HR 1512 generally agree with those for mercury-manganese stars. This supports the hypothesis that PGa stars represent an extension of HgMn stars to higher temperatures.  相似文献   

Managanese and iron in the White Sea: Sedimentation and diagenesis     

A. G. Rozanov  I. I. Volkov  N. M. Kokryatskaya  M. V. Yudin 《Lithology and Mineral Resources》2006,41(5):483-501

Iron and manganese in bottom sediments studied along the sublatitudinal transect from Kandalaksha to Arkhangelsk are characterized by various contents and forms depending on sedimentation environments, grain size of sediments, and diagenetic processes. The latter include redistribution of reactive forms leading to enrichment in Fe and Mn of the surface sediments, formation of films, incrustations, and ferromanganese nodules. Variations in the total Fe content (2–8%) are accompanied by changes in the concentration of its reactive forms (acid extraction) and the concentration of dissolved Fe in the interstitial water (1–14 μM). Variations in the Mn content in sediments (0.03–3.7%) and the interstitial water (up to 500 μM) correspond to a high diagenetic mobility of this element. Changes in the valence of chemical elements results in the redox stratification of sediment strata with maximum concentrations of Fe, Mn, and sulfides. Organic matter of sediments with a considerable terrestrial constituent is oxidized by bottom water oxygen mainly at the sediment surface or in anaerobic conditions within the sediment strata. The role of inorganic components in organic matter oxidation changes from surface sediments, where manganese oxyhydroxide dominates among oxidants, to deeper layers, where sulfate of interstitial water serves as the main oxidant. Differences in river runoff and hydrodynamics are responsible for geochemical asymmetry of the transect. The deep Kandalaksha Bay serves as a sediment trap for manganese (Mn content in sediments varies within 0.5–0.7%), whereas the sedimentary environment in the Dvina Bay promotes its removal from sediments (Mn 0.05%).  相似文献