Illite crystallinity study of the Cretaceous Shimanto Belt in the Akaishi Mountains, eastern Southwest Japan   总被引：1，自引：0，他引：1  

Hirotaka  Tanabe Ken-Ichi  Kano 《Island Arc》1996,5(1):56-68

Abstract Illite crystallinity (IC) analyses in the Upper Cretaceous Shimanto accretionary complex of the southern Akaishi Mountains, eastern Southwest Japan confirm the applicability of this technique for evaluating the grade of diagenesis/metamorphism in a sediment-dominated accretionary complex. Reproducibility analyses of IC values show a variance of about 15% from the mean. Data from three traverses, which transect across-strike sections of ∼25 km, clearly demonstrate that the IC distributions have specific overall trends. The IC values belong to the lQwer anchizone and the zone of diagenesis. The IC distributions may be controlled locally by structural features, but there are no distinct relationships with regional-scale geological structures. This may indicate that the heterogeneous geothermal rise affected the pre-existing structural and diagenetic/metamorphic framework of the accretionary sequence. Along-strike variations of grade tend to increase toward the northeast where a Middle Miocene granitoid occurs. Hence, the original diagenetic/metamorphic framework of this part of the Shimanto Belt was presumably overprinted during the Middle Miocene.  相似文献   

Organochlorine and butyltin residues in deep-sea organisms collected from the western North Pacific,off-Tohoku,Japan   总被引：4，自引：0，他引：4  

de Brito AP  Takahashi S  Ueno D  Iwata H  Tanabe S  Kubodera T 《Marine pollution bulletin》2002,45(1-12):348-361

Organochlorine (OCs) and butyltin (BTs) residues were determined in deep-sea organisms collected from the western North Pacific, off-Tohoku, Japan. Among OCs, concentrations of polychlorinated biphenyls (PCBs) and DDTs (DDTs and its metabolites) were the highest in deep-sea organisms (maximum concentrations of 6700 and 13,000 ng/g lipid wt, respectively). Chlordane compounds (CHLs) were the next most abundant OCs, and hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were the lowest. BTs were also detected at maximum concentrations of 570 ng/g wet wt. Concentrations of PCBs, CHLs and BTs in deep-sea organisms collected from the western North Pacific, off-Tohoku, were generally lower than those in deep-sea and shallow water organisms from Japanese coastal waters. On the other hand, considerable variations in the concentrations of OCs were found among deep-sea organisms analyzed. Several carnivorous fishes such as snubnosed eel, lanternshark and grenadiers accumulated some OCs such as PCBs, DDTs and CHLs at high concentrations of up to a few μg/g levels. In addition, the residue pattern of OCs and BTs in fishes showed a specific trend according to the sampling depth; higher concentrations of PCBs, DDTs and CHLs and lower concentrations of HCHs, HCB and BTs were found in fishes collected from greater depth (1000 m) compared to those from shallower waters. This trend is consistent with the results of our earlier study on mesopelagic myctophid fishes. Results of this study suggest vertical transport of hydrophobic OCs such as PCBs, DDTs and CHLs and its accumulation in benthic deep-sea organisms.  相似文献   

Reduction in the testosterone levels by PCBs and DDE in Dall''s porpoises of northwestern North Pacific     

An. Subramanian  S. Tanabe  R. Tatsukawa  S. Saito  N. Miyazaki 《Marine pollution bulletin》1987,18(12):643-646

The increasing residue levels of PCBs and DDE in the blubber of dalli-type Dall's porpoises were found to have a negative effect on the testosterone levels in blood. Decrease in the levels of testosterone was statistically significant with increase in DDE concentrations. The results obtained suggest that the present levels of environmental contamination by persistent organochlorines can cause an imbalance of sex hormones and subsequent reproductive abnormalities in wild. The other hormone measured, aldosterone, which has no sexual function, was independent of the effects of both PCBs and DDE.  相似文献   

Problems of the New Towns in Japan     

Prof. Hiroshi Tanabe 《GeoJournal》1978,2(1):39-46

The new town in Japan is a sort of dormitory settlement in the metropolitan suburbs. Its main developer is the Japan Housing Corporation, whose representative achievement is the Tama New Town. The settlement is, however, too narrow, too expensive and too far away from the places of employment for the inhabitants to feel themselves as members of the community. The new town is a settlement of transients, which generates the condition of many commuting to the city without solving the problems of excessive urban growth. We should make a further inquiry into the new town as a contemporary type of urban settlement in this country.  相似文献   

Millennial‐scale stratigraphy of a tide‐dominated incised valley during the last 14 kyr: Spatial and quantitative reconstruction in the Tokyo Lowland,central Japan          下载免费PDF全文

Susumu Tanabe  Toshimichi Nakanishi  Yoshiro Ishihara  Rei Nakashima 《Sedimentology》2015,62(7):1837-1872

Spatial and quantitative analysis of infilling processes of the tide‐dominated incised valleys beneath the Tokyo Lowland during the last 14 kyr was undertaken by using data from 18 sediment cores, 467 radiocarbon dates and 6100 borehole logs. The post‐Last Glacial Maximum valley fills consist of braided river, meandering river, estuary, spit and delta systems in ascending order. The boundary between the estuary and delta systems is regarded as the maximum flooding surface. The maximum flooding surface beneath the Tokyo Lowland is dated at 8 ka in the Arakawa Valley and 7 ka in the Nakagawa Valley. This age difference is due to the migration of the Tone River from the Arakawa Valley to the Nakagawa Valley at 5 ka, and suggests that the widely held view that the global initiation of deltas coincided with the abrupt rise of sea‐level at 9 to 8 ka is true only where there has been steady sediment supply from major rivers. The meandering river system is dominated by sheet‐like sands that were deposited during lateral migration of channels during the Younger Dryas and isolated vertical sands within muds that reflect vertical aggradation of channels before and after the Younger Dryas. The transition between these channel geometries is controlled by a threshold sea‐level rise of 4 to 7 mm yr^?1. Before migration of the Tone River at 5 ka, the tide‐dominated bay in the Nakagawa Valley was filled by upward‐fining laterally accreting muds. The muds accreted from the margin to the axis of the bay. Such lateral accretion of suspended particles derived from outside the bay has been documented in other tide‐dominated coastal environments and is probably common in other similar settings. After the migration of the Tone River, the bay was filled by upward‐coarsening deltaic sediments.  相似文献   

慢地震与深部不连续颤动和慢滑事件同时发生     

Yoshihiro Ito  Kazushige Obara  Shutaro Sekine  Hitoshi Hirose  乔迎春 《国际地震动态》2009,(10):23-27

我们对日本西南部南海俯冲板块界面过渡带发生的超低频地震进行报道。由矩震级为3.1～3.5的超低频地震引起的地震波显示其卓越长周期约为20s。超低频地震活动伴随深源低频颤动和慢滑事件同时发生,并随之移动。慢地震一直被认为会增加向上倾斜的大型逆冲地震断裂带上的应力,而这3种现象的同时发生提高了人们对慢地震的探测和特性鉴定水平。  相似文献   

Regional variations in trace element concentrations in tissues of black tiger shrimp Penaeus monodon (Decapoda: Penaeidae) from South Vietnam     

Tu NP  Ha NN  Ikemoto T  Tuyen BC  Tanabe S  Takeuchi I 《Marine pollution bulletin》2008,57(6-12):858-866

The goal of the present study was to examine the specific bioaccumulation of 22 trace elements in muscle, exoskeleton and hepatopancreas of black tiger shrimp Penaeus monodon from the Mekong River Delta (MRD), and the South Key Economic Zone (SKEZ), South Vietnam. The general tendency in most trace element concentrations among different tissues were hepatopancreas>exoskeleton>muscle. Comparisons of trace element levels in tissues between the two regions showed that concentrations of Se in muscle and As in all three tissues were higher in SKEZ; whereas in MRD, the higher concentrations of most elements such as Mn, Cu, Cd, Ba, Hg, were observed in tissues. These geographical variations in trace element levels may reflect the differences in human activities between the two regions of South Vietnam. The target hazard quotient (THQ) values for trace elements (<1) indicate that local residents are not exposed to potential health risks via the consumption of shrimp.  相似文献   

Temporal trends of brominated flame retardants in coastal waters of Japan and South China: retrospective monitoring study using archived samples from es-Bank, Ehime University, Japan     

Tanabe S 《Marine pollution bulletin》2008,57(6-12):267-274

The present paper is a summary of studies conducted at the Center for Marine Environmental Studies, Ehime University, on temporal trends of brominated flame retardants (BFRs) in coastal waters of Japan and South China. Archived marine mammal fat tissues and dated sediment cores were used to evaluate temporal trends of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in relation to their usage in the region. The results indicate that environmental concentrations of these BFRs in Japan and South China increased significantly during the last several decades. Temporal trends in the contaminant concentrations were consistent with historical consumption of the corresponding BFRs. PBDE levels in marine mammals and sediments from Japan, after showing peak concentrations in the 1990s, appear to be leveling off in recent years, in accordance with the discontinued usage of Tetra- and Octa-BDEs in Japan from the 1990s. The change in concentration levels was also accompanied by changes in PBDE congener profiles, i.e. shift towards increased proportion of higher brominated BDEs. Furthermore, in recent years HBCD concentrations in marine mammals from Japan appear to exceed those of PBDEs, presumably reflecting increasing usage of HBCDs over PBDEs. In finless porpoises from the South China Sea, PBDE levels were much higher than HBCD concentrations both in the past and recent years, implying consumption of HBCDs was not as high as that of PBDEs in China. In dated sediment cores from Tokyo Bay, concentrations increased exponentially with doubling times of 4.6-7.9 years, 6.1-12 years and 7.1-12 years for BDE-209, SigmaPBDEs and HBCDs, respectively.  相似文献   

Contamination status and accumulation profiles of organotins in sea otters (Enhydra lutris) found dead along the coasts of California, Washington, Alaska (USA), and Kamchatka (Russia)     

Murata S  Takahashi S  Agusa T  Thomas NJ  Kannan K  Tanabe S 《Marine pollution bulletin》2008,56(4):641-649

Organotin compounds (OTs) including mono- to tri-butyltins, -phenyltins, and -octyltins were determined in the liver of adult sea otters (Enhydra lutris) found dead along the coasts of California, Washington, and Alaska in the USA and Kamchatka, Russia. Total concentrations of OTs in sea otters from California ranged from 34 to 4100ng/g on a wet weight basis. The order of concentrations of OTs in sea otters was total butyltins>total octyltins> or = total phenyltins. Elevated concentrations of butyltins (BTs) were found in some otters classified under 'infectious-disease' mortality category. Concentrations of BTs in few of these otters were close to or above the threshold levels for adverse health effects. Total butyltin concentrations decreased significantly in the livers of California sea otters since the 1990s. Based on the concentrations of organotins in sea otters collected from 1992 to 2002, the half-lives of tributyltin and total butyltins in sea otters were estimated to be approximately three years.  相似文献   

Arsenic species and their accumulation features in green turtles (Chelonia mydas)     

Agusa T  Takagi K  Iwata H  Tanabe S 《Marine pollution bulletin》2008,57(6-12):782-789

Total arsenic (As) and its compounds were determined in liver, kidney, muscle, and stomach contents of green turtles (Chelonia mydas). Total As concentrations in the muscle were higher than those in the kidney and liver. Arsenobetaine (AB) was the predominant compound in all the three tissues and its levels were positively correlated with total As concentrations. This indicates that AB greatly contributes to As accumulation in green turtles. Higher concentrations of remaining As in the sample after extraction were detected in the liver, implying that lipid-soluble or protein bound As compounds accumulate in the liver of green turtles. Total As levels in tissues showed significant negative correlations with standard carapace length. The size-dependence of As accumulation in green turtles may be related to their feeding habit, shifting from carnivore to herbivore at different growth stages. Concentrations of AB and dimethylarsinic acid (DMA) were low in the stomach contents but high in the tissues, implying bioaccumulation of these arsenicals in green turtles.  相似文献