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481.
Aliphatic and aromatic hydrocarbons in sediments of Santos and Cananéia, SP, Brazil. 总被引:2,自引:0,他引:2
Sediment samples from Santos and Cananéia, S?o Paulo Brazil were analysed by GC-FID and GC-MS for aliphatic and aromatic hydrocarbons in order to gather information on the degree of contamination by oil and other biogenic contributions. Concentrations of total n-alkanes in Santos varied from 1.05 to 4.29 microg g(-1) and aromatic hydrocarbons from 0.08 to 42.39 microg g(-1). In Cananéia total n-alkanes varied from 4.37 to 157.90 microg g(-1). However, aromatic hydrocarbons were not detected. In Cananéia n-alkanes of terrestrial plants with high molecular weight predominate (n-C25, n-C27, n-C29, n-C31 and n-C33). In Santos, a more uniform distribution of the n-alkanes and aromatic hydrocarbons was found at all the sediment stations. The hydrocarbon data from stations close to the Saboó Wharf, at Alemoa and in the COSIPA Channel revealed alarming levels of acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene and chrysene. 相似文献
482.
Florence Le Hébel Olivier Vidal Jean-Robert Kienast Denis Gapais 《Comptes Rendus Geoscience》2002,334(3):205-211
The so-called ‘Porphyro??des’ Unit of South Brittany is located below units marked by an early HP–LT event (blueschists from the Île de Groix) and above units marked by Upper Carboniferous HT metamorphism. P–T estimates in the Porphyro??des (at Belle-Île-en-Mer), using the phengite–chlorite thermobarometer, indicate pressures around 8 kbar and temperatures of 350–400 °C. These new estimates suggest that the early tectonic history of the ‘Porphyro??des’ should be linked to that of the overlying Blueschists, and imply a much larger areal extension of the HP–LT domain in this part of the Hercynian Belt. To cite this article: F. Le Hébel et al., C. R. Geoscience 334 (2002) 205–211. 相似文献
483.
Combining consecutive short arcs into long arcs for precise and efficient GPS Orbit Determination 总被引:1,自引:1,他引:0
G. Beutler E. Brockmann U. Hugentobler L. Mervart M. Rothacher R. Weber 《Journal of Geodesy》1996,70(5):287-299
The final products of theCODE Analysis Center (Center for Orbit Determination in Europe) of theInternational GPS Service for Geodynamics (IGS) stem fromoverlapping 3-day-arcs. Until 31 December, 1994 these long arcs were computedfrom scratch, i.e. by processing three days of observations of about 40 stations (by mid 1995 about 60 stations were used) of the IGS Global Network in our parameter estimation program GPSEST. Becauseone-day-arcs have to be produced first (for the purpose of error detection etc.) the actual procedure was rather time-consuming. In the present article we develop the mathematical tools necessary to form long arcs based on the normal equation systems of consecutive short arcs (one-day-solutions in the case of CODE). The procedure in its simplest version is as follows:
- Each short arc is described bysix initial conditions and a number of dynamical orbit parameters (e.g. radiation pressure parameters). The resulting long arc in turn shall be based onn consecutive short arcs and described bysix initial conditions and again the same number of dynamical parameters as in the short arcs..
- By asking position and velocity to be continuous at the boundaries of the short arcs we obtain a long arc which is actually defined by one set of initial conditions andn sets of dynamical parameters (ifn short arcs are combined)..
- By asking the dynamical parameters to be identical in consecutive short arcs, the resulting long arc is characterized by exactly the same number of orbit parameters as each of the short arcs.
- This procedure isnot yet optimized becauseformally all n sets of orbit parameters have to be set up and solved for in the long arc solution (although they are not independent). In order to allow for an optimized solution we derive all necessary relations to eliminate the unnecessary parameters in the combination. Each long arc is characterized by the actual number of independent orbit parameters. The resulting procedure isvery efficient.
484.
Species-specific elimination of polychlorinated biphenyls in estuarine animals and its impact on residue patterns 总被引:1,自引:0,他引:1
Elimination kinetics of tetra-, penta- and hexachlorobiphenyls (IUPAC Nos. 44, 52, 87, 95, 101, 153) were investigated by laboratory experiments in three species of different phyla: Nereis diversicolor (Polychaeta), Palaemon longirostris (Crustacea) and Platichthys flesus (Pisces). Half-lives were species-specific and structure-dependent. Palaemon longirostris eliminated all components fastest. N. diversicolor was faster than Platichthys flesus except for components 95 and 153. Contrary to the fish species, the two invertebrates contained significant amounts of polar transformation products of No. 52, which had been applied as 14C labelled. Therefore, the faster elimination by Palaemon longirostris and N. diversicolor was assumed to be generally due to increased biotransformation. Elimination was in accordance with polychlorinated biphenyl (PCB) residue patterns obtained from field samples of the species. Congeners with vicinal H atoms in m,p positions were under-represented in Palaemon longirostris and so were congeners with > or = 7 Cl in N. diversicolor, while the PCB residue pattern in Platichthys flesus was similar to that of Clophen A60. By comparing percentages of the experimental congeners in sigma PCB and their elimination half-lives in the three species, it was revealed that residue patterns were also influenced by species-dependent uptake, e.g. feeding habits. Extractable organic matter-based sigma PCB levels increased with trophic levels of the three species. 相似文献
485.
New, very high-resolution (25 cm) seismic profiles have revealed the internal architecture of the infilling of a macrotidal bay, the Marennes-Oléron Bay, France. Within this geometry, a major seismic unconformity has been correlated with core data. This correlation provides evidence that the seismic unconformity corresponds to a sharp grain-size decrease. Both seismic and core data indicate that this change of grain size can be interpreted as a record of a recent (around 1,000 years b.p.) decrease in hydrodynamical energy with time and/or a larger supply of fine-grained material. This recent environmental change can be related to natural infilling of the Marennes Oléron Bay, and to tidal prism decrease, increasing human activities (e.g. land reclamation, deforestation, agricultural land use) and climate fluctuations during the late Holocene, such as the transition between the cold period of the Dark Ages (1,550–1,050 years b.p.) and the Medieval warm period (1,050–550 years b.p.). 相似文献
486.
A few months-old storm-generated turbidite deposited in the Capbreton Canyon (Bay of Biscay, SW France) 总被引:1,自引:1,他引:1
A gravity core taken in the canyon of Capbreton shows a succession of sedimentary facies which can be interpreted as three superimposed Bouma sequences. The turbiditic sequences are covered by an oxidised layer which contains live benthic foraminiferal faunas indicating a reprisal of hemipelagic deposition. Activities of 234Th and 210Pb suggest that the most recent turbidite was deposited between early December 1999 and mid-January 2000. During this period, the most probable natural event able to trigger a turbidity current was the violent storm which affected the French Atlantic coast on 27 December 1999. The turbidity current could have been caused by a sediment failure due to an excess in pore pressure generated by the storm waves, an increase of the littoral drift, or the dissipation of the along-coast water bulge through the canyon. This sub-recent turbidite shows that the canyon experiences modern gravity processes, despite the lack of a direct connection with a major sediment source. 相似文献
487.
A set of 103 997 free air gravity anomalies in 6′x 10′ blocks has been compiled covering Europe including the Mediterranean Sea, North Sea, Norwegian Sea, Baltic Sea and parts of the North Atlantic Ocean. Concerning sea areas, this data set is based on a collection of point free air gravity anomalies. Anomalies for land areas have been compiled resp. computed from free air gravity anomaly maps or Bouguer anomaly maps and partly from supplied mean values of convenient small block size. Remaining gaps have been interpolated by means of least squares prediction filtering. The precision of the compiled mean free air gravity anomalies is estimated to ±7 mgal, verified by a comparison of independent gravity anomaly sets. 相似文献
488.
Alfred Bentz A. Meyer-Gürr Helmut Fahrion Walter Rühl Wilhelm Kehrer Hermann Deecke H. Schlüter Rolf Behrmann Hans Weber Herbert Lögters Oswald Schmidt 《International Journal of Earth Sciences》1948,35(2):167-170
Ohne Zusammenfassung 相似文献
489.
Priv.-Doz. Dr. Max Weber 《Pure and Applied Geophysics》1961,49(1):119-128
Zusammenfassung Es wird im Anschluss an «Die Laufzeifunktion und ihre Interpretation in der Refraktionsseismik des einachsig inhomogenen Körpers» (4) die Interpretation von seismischen Refraktionsmessungen im Grenzfallc
o=0 eingehend behandelt.
Summary In pursuance of «Die Laufzeifunktion und ihre Interpretation in der Refraktionsseismik des einachsig inhomogenen Körpers» (4) the special interpretation problem withc o=0 is generally treated.相似文献
490.
Bodo Weber Alexander Iriondo Wayne R. Premo Lutz Hecht Peter Schaaf 《International Journal of Earth Sciences》2007,96(2):253-269
The histories of the pre-Mesozoic landmasses in southern México and their connections with Laurentia, Gondwana, and among
themselves are crucial for the understanding of the Late Paleozoic assembly of Pangea. The Permian igneous and metamorphic
rocks from the Chiapas massif as part of the southern Maya block, México, were dated by U–Pb zircon geochronology employing
the SHRIMP (sensitive high resolution ion microprobe) facility at Stanford University. The Chiapas massif is composed of deformed
granitoids and orthogneisses with inliers of metasedimentary rocks. SHRIMP data from an anatectic orthogneiss demonstrate
that the Chiapas massif was part of a Permian (∼ 272 Ma) active continental margin established on the Pacific margin of Gondwana
after the Ouachita orogeny. Latest Permian (252–254 Ma) medium- to high-grade metamorphism and deformation affected the entire
Chiapas massif, resulting in anatexis and intrusion of syntectonic granitoids. This unique orogenic event is interpreted as
the result of compression due to flat subduction and accretionary tectonics. SHRIMP data of zircon cores from a metapelite
from the NE Chiapas massif yielded a single Grenvillian source for sediments. The majority of the zircon cores from a para-amphibolite
from the SE part of the massif yielded either 1.0–1.2 or 1.4–1.5 Ga sources, indicating provenance from South American Sunsás
and Rondonian-San Ignacio provinces. 相似文献