U.S. Mussel Watch: 1977–1978 results on trace metals and radionuclides     

Edward D. Goldberg  Minoru Koide  Vern Hodge  A.Russel Flegal  John Martin 《Estuarine, Coastal and Shelf Science》1983,16(1):69-93

The results of the U.S. Mussel Watch Monitoring Program for the period 1976–1978 for trace metals and artificial radionuclides in bivalves are presented. The substances analysed included Ag, Cu, Zn, Cd, Ni, Pb, ²³⁸Pu, ^239+240Pu and ²⁴¹Am. The analyses of organic substances will be presented elsewhere. The concentrations of these substances in the bivalves may reflect upwelling processes, anthropogenic inputs or natural levels. Off the California coast, mussels show markedly elevated Pu and Cd concentrations in coastal areas adjacent to the most intensive upwelling zones. Elevated levels of Pb, for example, are found in organisms living adjacent to highly urbanized places. The general patterns of distribution repeat themselves year after year at a given site. Thus, it is concluded that annual monitoring activities may not be necessary and that a frequency of sampling of several or so years may be more appropriate to identify pollution problems. Finally, national or regional baselines for metal concentrations in bivalves from unpolluted waters are proposed. National baselines for Pb in the west coast mussels of 1·0 parts 10^?6 and for Ag in east coast mussels of 0·05 parts 10^?6 are suggested.  相似文献   

ASCA Observation of the Quiescent X-Ray Counterpart to SGR 1627-41     

Hurley K  Strohmayer T  Li P  Kouveliotou C  Woods P  van Paradijs J  Murakami T  Hartmann D  Smith I  Ando M  Yoshida A  Sugizaki M 《The Astrophysical journal》2000,528(1):L21-L23

We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1627-41. A quiescent X-ray source, whose position is consistent both with that of a recently discovered BeppoSAX X-ray source and with the Interplanetary Network localization for this soft gamma repeater, was detected in this observation. In 2-10 keV X-rays, the spectrum of the X-ray source may be fit equally well by a power-law, blackbody, or bremsstrahlung function, with unabsorbed flux approximately 5x10-12 ergs cm-2 s-1. We do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both of which were noted in the earlier BeppoSAX observations.  相似文献   

Age model, physical properties and paleoceanographic implications of the middle Pleistocene core sediments in the Choshi area, central Japan     

Koji  Kameo  Makoto  Okada  Moamen  El-Masry  Toshio  Hisamitsu  Saneatsu  Saito  Hiroomi  Nakazato  Naohiko  Ohkouchi  Minoru  Ikehara  Hisato  Yasuda  Hiroshi  Kitazato  Asahiko  Taira 《Island Arc》2006,15(3):366-377

Abstract   A continuous, well-preserved core was obtained from the Choshi area, on the Pacific side of Japan, to investigate paleoceanographic and paleoclimatic changes around the northwestern Pacific region during the middle Pleistocene. Siliciclastic sequences in the core are divided into five formations – the Obama, Yokone, Kurahashi and Toyosato Formations in the Inubo Group and the Katori Formation, in ascending order. Examination of calcareous nannofossils and magnetic polarities detected four datums in the core sediments of the Inubo Group: the top of Reticulofenestra asanoi , the base of Helicosphaera inversa , the top of Pseudoemiliania lacunosa and the Brunhes–Matuyama boundary. Fourteen marine isotope stages (MIS24–MIS11) were identified in the δ¹⁸O and δ¹³C records based on detected datums and the graphic correlation with the standard stack oxygen isotope curve. Magnetic susceptibility and gamma-ray attenuation porosity evaluator density were also measured and low values characterize the glacial intervals. Biogenic sedimentation by primary production may be larger during the glacial periods because of invasions of nutrient-rich northern surface-waters related to the southward shift of the Kuroshio front in the Choshi area.  相似文献   

Shear Zones of Southern India: Implications for the Proterozoic Tectonics of East Gondwana     

K.M. Shaju  M. Yoshida  M. Santosh 《Gondwana Research》1998,1(3-4):420-421

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Oxygen isotope fractionation factors between anhydrite and water from 100 to 550°C     

Hitoshi Chiba  Minoru Kusakabe  Shin-Ichi Hirano  Sadao Matsuo  Shigeyuki Somiya 《Earth and Planetary Science Letters》1981,53(1):55-62

Oxygen isotope exchange between anhydrite and water was studied from 100 to 550°C, using the partial equilibrium method. The exchange rate was extremely low in NaCl solution. In the lower-temperature range, acid solutions were used to produce sufficient reaction to determine the oxygen isotope fractionation factors. The fractionation factors obtained in the present study are definitely different from those given by Lloyd [8]. They are similar to those for the HSO₄^?-water system studied by Mizutani and Rafter [19], and are consistently 2‰ higher than those of the barite-water system by Kusakabe and Robinson [5]. The temperature dependence of the oxygen isotope fractionation factors was calculated by the least squares method in which the weight was taken to be inversely proportional to the experimental error. The fractionation is given by:10³lnαanhydrite-water=3.21×(10³/T)²?4.72Available δ¹⁸O values of natural anhydrite were used to test the validity of this expression. It is shown that this newly revised geothermometer can be successfully applied to natural hydrothermal anhydrite.  相似文献   

The chemical composition of a Greenland glacier     

Herbert Weiss  Kathe Bertine  Minoru Koide  Edward D. Goldberg 《Geochimica et cosmochimica acta》1975,39(1):1-10

Chemical analyses on water from dated strata of a south Greenland permanent ice sheet revealed that there is a larger amount of sulfate in samples accumulated during the past decade than in those 60 or more years older. This increase is attributed to combustion of fossil fuel. With the exception of mercury, cadmium and possibly copper, the heavy metal distributions in the glacial waters are similar to those in atmospheric dusts. Previously reported higher mercury values in recently deposited strata were not confirmed.  相似文献   

Lead-210 and pollen geochronologies on Lake Superior sediments     

Kenneth W. Bruland  Minoru Koide  Carl Bowser  Louis J. Maher  Edward D. Goldberg 《Quaternary Research》1975,5(1):89-98

Rates of sedimentation in two Lake Superior deposits were determined by both ragweed pollen and ²¹⁰Pb geochronologies. The former yields an average rate over the time since the first appearance of enhanced concentrations of the pollen as a consequence of human settlement. Sedimentation rates derived on these two bases can be brought into accord if the first appearance of ragweed pollen in the sediments was around 1830 and if the sedimentation rates have been uniform over the past century.  相似文献   

Depositional history of artificial radionuclides in the Ross Ice Shelf,Antarctica     

Minoru Koide  Robert Michel  Edward D. Goldberg  Michael M. Herron  Chester C. Langway 《Earth and Planetary Science Letters》1979,44(2):205-223

The annual fluxes of artificial radionuclides (²³⁸Pu,^239+240Pu,²⁴¹Am,¹³⁷Cs,⁹⁰Sr and³H) from the atmosphere to the Ross Ice Shelf in Antarctica were determined from measurements in strata dated by²¹⁰Pb. Recognizable sources include the U.S. tests (Mike-Ivy and Castle Hill) in the early 1950s, the U.S.S.R. tests of the early 1960s, the SNAP-9A burnup of 1964 and the French and Chinese tests in the late 1960s and 1970s. There are several problems still awaiting resolution: the differences in atmospheric chemistries of fission products and of transuranics produced in weapons tests and the anomalous fluxes of²³⁸Pu to the ice shelf which do not appear to reflect a one-year stratospheric residence. There is no evidence for a smearing of the fallout record as a consequence of diffusion of these radionuclides in the glacial column.  相似文献   

Identification of a one-dimensional model for a soil-layer–bedrock system during an earthquake     

Minoru Tomizawa 《地震工程与结构动力学》1980,8(3):251-265

The propriety of adopting a multi-degree-of-freedom lumped mass–spring–dampers system driven by white noise support excitation as a one-dimensional model for a soil-layer–bedrock system during an earthquake is investigated by means of statistical system identification of the model with noisy measurement of the earthquake ground velocity. The present discussion also suggests that this model may not be applicable to all observed earthquake records, since the model itself depends on the statistical nature of the earthquake motion. For appropriate earthquake records, the system identification procedure may be accomplished; then dynamical properties of the soil-layer and the power spectral density for white noise excitation acting upon the bedrock can be estimated as shown in a numerical example.  相似文献   

Resonance capacity method for earthquake response analysis of hysteretic structures     

Minoru Yamada  Hiroshi Kawamura 《地震工程与结构动力学》1980,8(4):299-313

The Resonance Capacity Method is proposed for the earthquake response analysis of hysteretic structures. Resonance Capacity is a physical quantity of structures which is related to the hysteretic energy absorbed by structures in one cycle and is equated to the acceleration, velocity and displacement amplitudes α₀, d₀ and d₀ of earthquake ground motions at resonance.¹ According to the idealized trapezoidal approximation of earthquake ground motions in the logarithmic period–velocity plane as proposed by Veletsos and Newmark,⁸ the Resonance Capacity property applies in each period range, short, medium and long, where α₀, v₀ and d₀ respectively are approximately constant. In the medium range of periods, the energy dissipated in hysteretic loops and the deformation amplitudes of a single-degree system with elasto–plastic force–deformation relationships are calculated for the case of El Centro 1940, 18 May earthquake, by this Resonance Capacity Method. The result is compared with results from conventional numerical response analyses obtained by Berg and Thomaides,¹⁴ Kato and Akiyama¹² and Veletsos and Newmark,⁸ and the general agreement is seen to be good. Therefore, it may be possible to apply this Resonance Capacity Method over the entire range of periods. By means of this method the earthquake response analysis of hysteretic systems can be performed easily, and the hysteretic energy and fatigue characteristics of structures may be taken into account directly, up to the point of fracture.  相似文献