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   

Succession of macrobenthic fauna and nitrogen budget at two artificial tidal flats in Osaka Bay, Japan   总被引：1，自引：0，他引：1  

Yamochi S 《Marine pollution bulletin》2008,57(1-5):137-141

Nitrogen budgets and predominant benthic organisms were examined at a matured artificial tidal flat of Osaka Nanko bird sanctuary and an artificial young tidal flat of Hannan Second District, Osaka Bay, Japan. At the Osaka Nanko bird sanctuary, indexes of the quality of the bottom sediment increased over the time course and no abiotic area was observed in the macrobenthic fauna. Dissolved inorganic nitrogen imported into the tidal flat changed its form and was exported in the form of dissolved organic nitrogen. As a result, total nitrogen was trapped at the tidal flat at an average rate of 138 mgN m(-2)day(-1). At the young tidal flat of Hannan Second District net exchange of nitrogen varied markedly among 2000, 2001, 2002 and 2003. In September 2000 when only 5 months had passed after construction, the tidal flat functioned as a site of source for nitrogen. However, it changed as a sink for nitrogen in 2001-2002 in relation to the growth of seaweeds (Ulva spp. and Gracilaria vermiculophylla) and clams (Tapes philippinarum). In 2003 nitrogen was again released from the artificial tidal flat due to the decrease of biomass of the dominant organisms. Comparing the nitrogen budget between the two sites on a per unit time and area basis, net exchanges of nitrogen by tidal exchange were apparently low and relatively constant at the tidal flat of Osaka Nanko bird sanctuary. This suggests that the aged artificial tidal flat of Osaka Nanko bird sanctuary has a stable ecosystem compared to the young artificial tidal flat of Hannan Second District.  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   

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

Nguyen Phuc Cam Tu  Nguyen Ngoc Ha  Tokutaka Ikemoto  Bui Cach Tuyen  Shinsuke Tanabe  Ichiro Takeuchi   《Marine pollution bulletin》2008,57(6-12):858

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     

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

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, ΣPBDEs and HBCDs, respectively.  相似文献   

Building damage concentrated in Longtoushan town during the 2014 Ms. 6.5 Ludian earthquake,Yunnan, China: examination of cause and implications based on ground motion and vulnerability analyses     

Xin Wang  Susumu Kurahashi  Hao Wu  Hongjun Si  Qiang Ma  Ji Dang  Dongwang Tao  Jiwei Feng  Kojiro Irikura 《Journal of Seismology》2017,21(5):1185-1200

Though the 2014 Ludian Earthquake had only a moderate magnitude (Ms 6.5), high-level ground motions of almost 1g occurred at Longtoushan Town (seismic station 53LLT), which located near the intersection of a conjugate-shaped seismogenic fault. The building damages on the pluvial fan and the river terrace at Longtoushan was clearly different. In order to examine the generation of the large acceleration at 53LLT, the focal mechanisms and the rupture processes of the conjugate-shaped seismogenic fault were determined. We found that there were two continuous impulsive waves in the records of 53LLT that were generated from two different faults, the Baogunao fault and the Xiaohe fault, respectively. Site effects on the pluvial fan and the river terrace at Longtoushan Town and their relations to different building damages were examined. We found that the predominant period at the pluvial fan was about 0.25 s, close to the fundamental natural period of multi-story confined masonry buildings. Ground motions on the pluvial fan and the river terrace were simulated through convolving synthesized bedrock motions with the transfer functions, which were analyzed using the one-dimensional underground velocity structures identified from H/V spectral ratios of ambient noise. Building collapse ratios (CRs) are estimated based on the vulnerability function of the 2008 Wenchuan Earthquake and are compared with the observed values. We found that the observed building CRs on the pluvial fan are much higher than the estimated values. High-level ground shaking that is far beyond the design level was a reason for serious building damage.  相似文献