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51.
Norikazu Kinoshita Yuko Sato Takeyasu Yamagata Hisao Nagai Akihiko Yokoyama Takashi Nakanishi 《Journal of Oceanography》2007,63(5):813-820
In order to estimate the deposition rate of extraterrestrial material onto a manganese crust in a search for supernova debris,
we analyzed the contents of 10Be, 230Th, 231Pa, and 239,240Pu in a sample of manganese crust collected from the North Pacific Ocean. On the basis of the depth profile of 10Be, the growth rate of the manganese crust was determined to be 2.3 mm Myr−1. The uptake rates of 10Be, 230Th, and 231Pa onto the manganese crust were estimated to be 0.22–0.44%, 0.11–0.73%, and 1.4–4.5%, respectively, as compared to the deposition
rates onto the deep-sea sediments near the sampling station, while that for 239,240Pu was 0.14% as compared to the total inventory of seawater and sediment column. Assuming that sinking particles represent
0.11–4.5% of the uptake rates, the deposition rate of extraterrestrial material onto the manganese crust was estimated to
be 2–800 μg cm−2Myr−1 according to the uptake of 10Be onto the manganese crust. Further, our estimate is similar to the value of 9–90 μg cm− 2Myr−1 obtained using the integrated global production rate of 10Be and the deposition rate of 10Be onto the manganese crust. 相似文献
52.
The diffusion coefficients of aquo metal ions (Mz+) and their EDTA complexes (M-EDTA(z−4)+) were compared to understand the effect of EDTA complexation on the diffusion of metal ions by the diffusion cell method for Co2+, Ga3+, Rb+, Sr2+, Ag+, Cd2+, Cs+, Th4+, , and trivalent lanthanides. Most studies about ionic diffusion in water have dealt with free ion (hydrated ion). In many cases, however, polyvalent ions are dissolved as complexed species in natural waters. Hence, we need to study the diffusion behavior of complexes in order to understand the diffusion phenomenon in natural aquifer and to measure speciation by diffusive gradient in thin films (DGT), which requires the diffusion coefficients of the species examined. For many ions, the diffusion coefficients of M-EDTA(z−4)+ are smaller than those of hydrated ions, but the diffusion coefficients of M-EDTA(z−4)+ are larger than those of hydrated ions for ions with high ionic potentials (Ga3+ and Th4+). As a result, the diffusion coefficients of EDTA complexes are similar among various metal ions. In other words, the diffusion of each ion loses its characteristics by the complexation with EDTA. Although the difference is subtle, it was also found that the diffusion coefficients of EDTA complexes increase as the ionic potential increases, which can be explained by the size of the EDTA complex of each metal ion. 相似文献
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56.
Matheus Carvalho de Carvalho Ken-ichi Hayashizaki Hisao Ogawa 《Journal of Oceanography》2008,64(5):705-712
Through 2004 and 2005, δ
34S of sinking material from Otsuchi Bay was measured at the center and rocky shore of the bay. At the center of the bay δ
34S was high (18∼21‰) in the material collected from April to November. However, δ
34S was low (9∼14‰) in the material collected from December to March. The increase in δ
34S in April was attributed to an increase in phytoplankton biomass because marine phytoplanktonic δ
34S is high. When δ
34S of sinking material was low, input of riverine material or bottom sediment resuspension were considered as the probable
causes, because their δ
34S is low. Marine sulfur was always high (more than 70%) at both stations. The difference between the δ
34S of sinking material collected from the different sampling stations indicates that marine macroalgae contribute to sinking
material near the shore when phytoplankton is scarce. In conclusion, the relative influence of different material sources
to sinking materials could be successfully estimated using δ
34S. 相似文献
57.
Toshitaka Suzuki Yoshinori Iizuka Teruo Furukawa Kenichi Matsuoka Kokichi Kamiyama Okitsugu Watanabe 《极地研究(英文版)》2003,14(1)
1 IntroductionAntarcticicesheetisaburialgroundforatmosphericdeposition .Sincethereiscon tinuousinteractionbetweentheicesheetandtheatmosphere,variousatmosphericsub stancesareinjectedtotheicesheetsequentiallyintimeandspace.Therefore,verticalanalysesoftheicesheetprovideuswithinformationaboutpastclimaticchange (Delmas1 992 ;LegrandandMayewski 1 997)andhorizontalanalysesoftheicesheetprovideuswithknowledgeregardinglong rangetransportofairbornematerials (Kamiyamaetal.1 989;KreutzandMayewski 1 999)… 相似文献
58.
A preliminary study was made of the magnetic stratigraphy of the Pliocene and Lower Pleistocene marine sediments in Le Castella area, Calabria, Southern Italy. Microbiostratigraphic evidence of the measured sediments provides a basis for tentative correlation with the standard magnetic chronology. The Gilsa Event in the Matuyama Reversed Polarity Epoch is estimated to be a little older than the lower limit of the Calabrian in Le Castella area. 相似文献
59.
Koichiro Fujimoto Hidemi Tanaka Takayuki Higuchi Naoto Tomida Tomoyuki Ohtani Hisao Ito 《Island Arc》2001,10(3-4):401-410
Abstract Mineralogical and geochemical studies on the fault rocks from the Nojima–Hirabayashi borehole, south-west Japan, are performed to clarify the alteration and mass transfer in the Nojima Fault Zone at shallow depths. A complete sequence from the hornblende–biotite granodiorite protolith to the fault core can be observed without serious disorganization by surface weathering. The parts deeper than 426.2 m are in the fault zone where rocks have suffered fault-related deformation and alteration. Characteristic alteration minerals in the fault zone are smectite, zeolites (laumontite, stilbite), and carbonate minerals (calcite and siderite). It is inferred that laumontite veins formed at temperatures higher than approximately 100°C during the fault activity. A reverse component in the movement of the Nojima Fault influences the distribution of zeolites. Zeolite is the main sealing mineral in relatively deep parts, whereas carbonate is the main sealing mineral at shallower depths. Several shear zones are recognized in the fault zone. Intense alteration is localized in the gouge zones. Rock chemistry changes in a different manner between different shear zones in the fault zone. The main shear zone (MSZ), which corresponds to the core of the Nojima Fault, shows increased concentration of most elements except Si, Al, Na, and K. However, a lower shear zone (LSZ-2), which is characterized by intense alteration rather than cataclastic deformation, shows a decreased concentration of most elements including Ti and Zr. A simple volume change analysis based on Ti and Zr immobility, commonly used to examine the changes in fault rock chemistry, cannot account fully for the different behaviors of Ti and Zr among the two gouge zones. 相似文献
60.