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11.
Shin Takahashi Tomoko Oshihoi Tomohiko Isobe Tsunemi Kubodera 《Marine pollution bulletin》2010,60(2):187-196
Twelve species of deep-sea fishes collected in 2005 from the western North Pacific, off-Tohoku, Japan were analyzed for organohalogen compounds. Among the compounds analyzed, concentrations of DDTs and PCBs (up to 23,000 and 12,400 ng/g lipid wt, respectively) were the highest. The present study is the foremost to report the occurrence of brominated flame retardants such as PBDEs and HBCDs in deep-sea organisms from the North Pacific region. Significant positive correlations found between δ15N (‰) and PCBs, DDTs and PBDEs suggest the high biomagnification potential of these contaminants in food web. The large variation in δ13C (‰) values observed between the species indicate multiple sources of carbon in the food web and specific accumulation of hydrophobic organohalogen compounds in benthic dwelling carnivore species like snubnosed eel. The results obtained in this study highlight the usefulness of deep-sea fishes as sentinel species to monitor the deep-sea environment. 相似文献
12.
In this report, the capabilities of the adaptively shifted integration (ASI)‐Gauss code in the analysis of the seismic responses of framed structures are verified and validated by comparing the results with detailed numerical simulations performed by the parallel finite element analysis code, E‐Simulator, and with experimental results obtained by E‐Defense. The numerical results obtained by both codes showed good agreement with the experimental results obtained by E‐Defense. Furthermore, seismic waves with unnaturally large magnitudes are applied to a high‐rise building model to demonstrate the ability of the ASI‐Gauss code to analyze the collapse behaviors of building frames. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
13.
This study has demonstrated a reliable method of quantifying the total mass of litter on a beach. It was conducted on Ookushi beach, Goto-Islands, Japan, and uses a combination of balloon-assisted aerial photography and in situ mass measurements. The total mass of litter over the beach was calculated to be 716 ± 259 kg. This figure was derived by multiplying the litter-covered area (calculated using balloon-assisted aerial photography) by the mass of litter per unit area. Light plastics such as polyethylene made up 55% of all plastic litter on the beach, although more work is needed to determine whether lighter plastics are transported to beaches more readily by winds and ocean currents compared with heavier plastics, or whether lighter plastics comprise a greater percentage of marine litter. Finally, the above estimates were used to calculate the total mass of metals released into coastal ecosystems via plastic litter on beaches. 相似文献
14.
Malarvannan G Takahashi S Isobe T Kunisue T Sudaryanto A Miyagi T Nakamura M Yasumura S Tanabe S 《Marine pollution bulletin》2011,63(5-12):172-178
Three species of sea turtles (green, hawksbill and loggerhead turtles) stranded along the coasts or caught (by-catch) around Ishigaki Island and Kochi, Japan were collected between 1998 and 2006 and analyzed for six organohalogen compounds viz., PBDEs, PCBs, DDTs, CHLs, HCHs and HCB. The present study is the first and foremost to report the occurrence of organohalogen compounds in the sea turtles from Japan. Among the compounds analyzed, concentrations of PCBs, DDTs and CHLs were the highest in all the turtle samples. PBDEs were ubiquitously present in all the turtle species. Comparing with the other two species, concentrations of organohalogens in green turtle were relatively low and decreasing trend in the concentrations were noted with increasing carapace length. Concentrations of OCs in sea turtles from the coasts of Ishigaki Island and Kochi were relatively low as compared to those from other locations in the world. 相似文献
15.
We have estimated close asteroid encounters with the Earth by numerical integrations of a system with the Sun, 9 planets, and 188 near-earth-asteroids during the period 1994–4600. Asteroids approach the Earth from directions within 30 around the Sun in more than 20% of encounters with the closest distance less than 0.01 AU. Since ground-based observations cannot detect these objects, we should develop space-borne and/or lunar observatories in a short time to allow enough warning time before a catastrophic collision. 相似文献
16.
The development and evolution of the persistent counterclockwise circulation in Suo-Nada have been studied in detail using
a three-dimensional numerical model. The realistic circulation has been reproduced from the monthly climatological fields
of salinity, temperature along the open boundary, wind, heat flux and buoyancy input from twenty-two major rivers surrounding
the basin. The seasonal variation of fresh-water discharge from the rivers proved to be the most important forcing mechanism
driving the circulation. The expansion and contraction of coastal low salinity water well corresponded with the development
of counterclockwise circulation from spring to summer and dissipation from autumn to winter. The circulation was found to
be vertically homogenous and quasi-barotropic. However, confined along the coastal zone is an estuarine flow (i.e., oppositely
directed currents in the upper and lower layers) whose horizontal dimension conforms to the period of maximum buoyancy flux
from the rivers. This indicates that the flow pattern in Suo-Nada can be separated into two distinct regions where the relative
dominance of estuarine circulation plays a significant role. Furthermore, the monthly water exchange capacity for autonomous
purification of the basin has been evaluated from the average residence time of conservative material based on the calculated
current field. It is demonstrated that the kinetic energy of the basin is directly responsible in promoting water exchange
in Suo-Nada.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
The wind-induced sea-level variations at Hakata tidal station in winter are reproduced realistically using a one-way nested
model. This nested model is constructed with a structured finite-difference Princeton Ocean Model (POM) for the Tsushima-Korea
Straits, and an unstructured Finite Volume Coastal Ocean Model (FVCOM) for Fukuoka Bay divided into triangular-cell grids.
The correlation coefficient and root-mean-square error between observed and modeled results are 0.742 and 1.88 [cm], respectively.
Moreover, the results show that the nested model with FVCOM is more accurate than the model in which FVCOM is replaced with
a high-resolution POM for Fukuoka Bay. This indicates that the nested model constructed with structured and unstructured models
works effectively in hindcasting the wind-induced sea-level variations. 相似文献
18.
Rolando S. Balotro Atsuhiko Isobe Manabu Shimizu Atsushi Kaneda Takatoshi Takeuchi Hidetaka Takeoka 《Journal of Oceanography》2002,58(6):759-773
An attempt was made to reproduce the circulation pattern in Suo-Nada, Japan during spring and summer season in order to elucidate
the water exchange mechanism in the basin. Two hydrographic surveys at the end of each season were conducted covering the
entire Suo-Nada area. A three-dimensional hydrodynamic Princeton Ocean Model (POM) was used to compute the current resulting
from the observed density and wind field. During spring, a very pronounced counter clockwise gyre is situated near the opening
of the basin. This is replaced by a clockwise circulation which seemed to occupy the whole domain during summer. Within each
season, however, the vertical distribution of current does not show any remarkable differences, indicating the dominance of
horizontal current and a very weak estuarine flow. These observational and numerical results were used to estimate the remnant
function and the corresponding average residence time of permanently dissolved matter (PDM) and transformable matter (TM).
The results revealed a small difference in the average residence times of materials within each season but a large seasonal
variability between spring and summer. Furthermore, calculations based on climatological density fields have indicated a similar
trend of variation between the seasonal values of average residence times.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
20.
Hirotaka Ito Motoki Kino Nozomu Kawakatu Naoki Isobe Shoichi Yamada 《Astrophysics and Space Science》2007,311(1-3):335-339
We investigate the total kinetic powers (L
j) and ages (t
age) of powerful jets of four FR II radio sources (Cygnus A, 3C 223, 3C 284, and 3C 219) by the detail comparison of the dynamical
model of expanding cocoons with observed ones. It is found that these sources have quite large kinetic powers with the ratio
of L
j to the Eddington luminosity (L
Edd) resides in 0.02<L
j/L
Edd<10. Reflecting the large kinetic powers, we also find that the total energy stored in the cocoon (E
c) exceed the energy derived from the minimum energy condition (E
min ): 2<E
c/E
min <160. This implies that a large amount of kinetic power is carried by invisible components such as thermal leptons (electron
and positron) and/or protons. 相似文献