Tokaido — megalopolis of Japan

The Tokaido east coast road has been the main road of Japan since Mediaeval times, and the journey from Tokyo at one end to Kyoto or Osaka at the other, which used to take a fortnight, can now be completed in about three hours by bullet train, and an even faster linear-motor car is likely to be in operation in the near future.Already during the 18. cent., Edo (Tokyo) was the largest city in the world, with a population over a million, and the rapid urbanization of Japan's population since Meiji times, and particularly during the post-WW II period, has been quite unprecendented. In 1950, the median size of place was 13,000 and by 1975 it was 140,000. About 60 million lived in the Tokaido zone.The Kanto, Nobi and Osaka plains, adjacent to the good harbours of Tokyo, Ise and Osaka bays, enjoying the relatively mild climate of the Pacific coast, and being within 600 km of each other, have been the focii of urban and industrial development in Japan. The emergence of Tokaido megalopolis was boosted by capital investment in this zone, and was contingent upon the industriousness and high level of education of the people.The concept of megalopolis in Japan is popularly associated with rapid urbanization, poly-nuclear and linear form, and concentration of population, capital and information, all of which elements are typified by the Tokaido zone. The linear megalopolis pattern has been postulated as a more efficient growth form for high-dense society than the radial metropolitan pattern. It has even been suggested that megalopolis is a concept perceived by the intellect, its physical structure determined by information networks, metropolis being perceived by the eye and its physical structure being determined by transport and energy networks.Quite irrespective of the concept of megalopolis, there can be no denying that Japan's society is a high-dense society. In 1975, 57% of the population lived in Densely Inhabited Districts (DIDs) at minimum densities of 40 persons per hectare, and these DIDs covered only 2.2% of the land area of Japan. The current trend is for more and more people to live in DIDs, but for overall DID densities to decrease. During the past 25 years, there has been a huge influx of population into the Tokaido zone, and while until 1960 the greatest increases were in the three main metropolitan centres, as these became saturated, rapid urbanization spread into the neighbouring prefectures. Since the mid-sixties, the central metropolitan wards have begun to lose residents, but the daytime population has continued to increase, giving rise to increasingly complex commuting patterns. To give an example, the commuting field of Yokohama includes almost all the prefectures of Tokaido megalopolis.Like the image of megalopolis itself, life in Tokaido megalopolis has its good and bad aspects. Although per capita space in dwellings is increasing somewhat, housing is extremely expensive and people commute long distances. Incomes are high but environmental problems persist. There is a U-turn phenomenon, but metropolitan suburbs remain a popular choice of residence.Central management functions and knowledge and information oriented occupations are predominantly concentrated in Tokyo and Osaka, the two main nodes of Tokaido megalopolis. In the intermediate cities, new employment opportunities are stimulated by the expansion of second-level managerial functions. The transport and communications networks of Tokaido are becoming congested as mobility and information flow increase.Planning in the eighties will be affected by the switch from industries dependent on raw materials to knowledge intensive industries; from investment in production to investment in public facilities and pollution control. Within Tokaido megalopolis, there is room for local governments to expand efforts to improve the existing situation, and at its fringes to avert some of the less desirable consequences of rapid urbanization.     

Spin rates of fast-rotating asteroids and fragments in impact disruption

We present a new experimental result of fragment spin-rate in impact disruption, using a thin glass plate. A cylindrical projectile impacts on a side (edge) of the plate. Dispersed fragments are observed using a high-speed camera and the spin rates of fragments are measured. We find that the measured fragment spin-rate decreases with increasing size. Assuming that the rotational energy of fragments is supplied from the residual stress, the spin rate ω decreases with increasing fragment size r as ω∼r−1, which explains the above experimental results. This size-dependence is similar to that of the observed spin rates of small fast-rotating asteroids. Our results suggest that spin rates of fragments of small asteroids immediately after disruption may have a similar size-dependence, and can provide constraints on the subsequent spin-state evolution of small asteroids due to thermal torques.     

Sensitive response of desert vegetation to moisture change based on a near-annual resolution pollen record from Gahai Lake in the Qaidam Basin, northwest China

We present a 50-year pollen record at near-annual resolution from Gahai Lake in the Qaidam Basin on the northeastern Tibetan Plateau. Chronology of a 22-cm short core was established by ²¹⁰Pb and ¹³⁷Cs analysis. The pollen results at 0.5 cm intervals show large changes in Artemisia/Chenopodiaceae (A/C) ratios from < 0.2 to 0.95 in the last 50 years. High (low) A/C ratios represent increase (decrease) in steppe pollen production, which correspond to high (low) relative humidity observed at nearby Delingha weather station. On the basis of good correspondence with instrumental records and carbonate content from Gahai Lake, we conclude that A/C ratio is sensitive to moisture change and can be a very useful index in reconstructing paleoclimate of arid regions. Comparison with pollen and snow accumulation data from Dunde ice core suggests that effective moisture at low and high elevations shows the opposite relationship when mountain precipitation was extremely high, possibly due to topography-induced uplifting and subsiding air dynamics.     

The characteristic distribution of silica over the East China Sea shelf slope

The localized near-bottom water with silica content higher than that in the adjacent shelf water was observed to exist at the eastern margins of the East China Sea continental shelf. The core of the high silica water possessed the silica content corresponding to that in the Kuroshio at depths greater than on the shelf. The mixing analysis of water masses using temperature (T) and silica (Si) showed that the core water can be produced through the vertical mixing of intermediate water of the Kuroshio deeper than 100 m. This study provides us a conclusion that the intermediate water of the Kuroshio is strongly mixed on the shelf slope and then upwelled to form the ridge-like distribution of water masses with low temperature and high silica content at the shelf edge.     

Risk assessment of TBT in the Japanese short-neck clam (Ruditapes philippinarum) of Tokyo Bay using a chemical fate model

A risk assessment of Tributyltin (TBT) in Tokyo Bay was conducted using the Margin of Exposure (MOE) method at the species level using the Japanese short-neck clam, Ruditapes philippinarum. The assessment endpoint was defined to protect R. philippinarum in Tokyo Bay from TBT (growth effects). A No Observed Effect Concentration (NOEC) for this species with respect to growth reduction induced by TBT was estimated from experimental results published in the scientific literature. Sources of TBT in this study were assumed to be commercial vessels in harbors and navigation routes. Concentrations of TBT in Tokyo Bay were estimated using a three-dimensional hydrodynamic model, an ecosystem model and a chemical fate model. MOEs for this species were estimated for the years 1990, 2000, and 2007. Estimated MOEs for R. philippinarum for 1990, 2000, and 2007 were approximately 1–3, 10, and 100, respectively, indicating a declining temporal trend in the probability of adverse growth effects.A simplified software package called RAMTB was developed by incorporating the chemical fate model and the databases of seasonal flow fields and distributions of organic substances (phytoplankton and detritus) in Tokyo Bay, simulated by the hydrodynamic and ecological model, respectively.     

Depth distribution of radiolarians from the Chukchi and Beaufort Seas, western Arctic

The depth distributions of the radiolarian fauna in the Chukchi and Beaufort Seas, marginal seas of the western Arctic Ocean, were examined quantitatively in depth-stratified plankton tows from 4 or 5 intervals above 500 m and in surface sediments from various depths between 163 and 2907 m. The radiolarian assemblage from the water column in September 2000 was dominated by Amphimelissa setosa and followed by the Actinomma boreale/leptoderma group, Pseudodictyophimus gracilipes and Spongotrochus glacialis. These species are related to the Arctic Surface Water shallower than 150 m. This assemblage is similar to that in the Greenland Sea relating to the ice edge, but did not contain typical Pacific radiolarians in spite of the flow of water of Pacific origin in this region. The living depth of Ceratocyrtis historicosa was restricted to the relatively warm water between 300 and 500 m corresponding to the upper Arctic Intermediate Water (AIW) originating from the Atlantic Ocean. Radiolarian assemblages in the surface sediments are similar to those in the plankton tows, except for common Cycladophora davisiana in sediment samples below 500 m. C. davisiana is probably a deep-water species adapted to the lower AIW or the Canadian Basin Deep Water ventilated from the shelves.     

A review of the NEMURO and NEMURO.FISH models and their application to marine ecosystem investigations

The evolution of the North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO) family of models to study marine ecosystems is reviewed. Applications throughout the North Pacific have shown the models to be robust and to be able to reproduce 1D, 2D and 3D components of nutrient, carbon cycle and biogeochemical cycles as well as aspects of the lower trophic levels ecosystem (phyto- and zooplankton). NEMURO For Including Saury and Herring, an extension that includes higher trophic levels, can be run uncoupled or coupled to NEMURO. In the uncoupled mode, the growth and weight of an individual fish is computed using plankton densities simulated by NEMURO but with no feedback between fish consumption and plankton mortality. In the coupled mode, the feeding, growth and weight of a representative fish are computed, and prey removals due to feeding by fish appear as mortality terms on the prey. The NEMURO family of models continues to evolve, including effects of the microbial loop and iron limitation at lower trophic levels, and full life cycle, multi-species and multi-generational simulations at higher trophic levels. We outline perspectives for future end-to-end modeling efforts that can be used to study marine ecosystems in response to global environmental change.     

A study of Mg and K isotopes in Allende CAIs: Implications to the time scale for the multiple heating processes

Abstract— The measurements of magnesium and potassium isotopic compositions of refractory minerals in Allende calcium‐aluminum‐rich inclusions (CAIs), 7R‐19–1, HN3–1, and EGG3 were taken by secondary ion mass spectrometry (SIMS). The 7R‐19–1 contains ¹⁶O‐rich and ¹⁶O‐poor melilite grains and define a single isochron corresponding to an initial ²⁶Al/²⁷Al ratio of (6.6 ± 1.3) × 10^?5. The Al‐Mg isochron, O isotope measurements and petrography of melilite in 7R‐19–1 indicate that ¹⁶O‐poor melilite crystallized within 0.4 Myr after crystallization of ¹⁶O‐rich melilite, suggesting that oxygen isotopic composition of the CAI‐forming region changed from ¹⁶O‐rich to ¹⁶O‐poor within this time interval. The ¹⁶O‐poor melilite is highly depleted in K compared to the adjacent ¹⁶O‐rich melilite, indicating evaporation during remelting of 7R‐19–1. We determined the isochron for ⁴¹Ca‐⁴¹K isotopic systematics in EGG3 pyroxene with (4.1 ± 2.0) × 10^?9 (2s?) as an initial ratio of ⁴¹Ca/⁴⁰Ca, which is at least two times smaller than the previous result (Sahijipal et al. 2000). The ratio of ⁴¹Ca/⁴⁰Ca in the EGG3 pyroxene grain agrees within error with the value obtained by Hutcheon et al. (1984). No evidence for the presence of ⁴¹K excess (decay product of a short‐lived radionuclide ⁴¹Ca) was found in 7R‐19–1 and HN3–1. We infer that the CAI had at least an order of magnitude lower than canonical ⁴¹Ca/⁴⁰Ca ratio at the time of the CAI formation.     

新疆北部晚古生代埃达克岩、富铌玄武岩组合：古亚洲洋板块南向俯冲的证据

地球化学研究结果表明，新疆北部富蕴县境内的晚古生代下泥盆统托让格库都克组的安山质岩石具有与埃达克岩非常相似的地球化学特征，它们具有较高的Al2O3，Na2O和Sr含量以及Sr/Y比值；明显亏损重稀土和Y，它们的MORB标准化微量元素蛛网图表现为明显的Nb，Ta负异常和Sr正异常，同时强烈亏损高场强元素。与埃达克岩共生的玄武岩的地球化学特征则与富铌玄武岩一致，表现为Si过饱和及富Na的特征，同时具有较高的Nb，TiO2和P2O5含量，并富集高场强元素。由于埃达克岩和富铌玄武岩的形成均与板块俯冲有关，因此，它们的存在表明，古亚洲洋在早-中泥盆世向南(哈萨克斯坦-准噶尔板块)发生了一次洋壳俯冲作用。     

Oxygen Isotope Evidence for Chemical Interaction of Ki lauea Historical Magmas with Basement Rocks

Klauea historical summit lavas have a wide range in matrix ¹⁸O_VSMOWvalues (4·9–5·6) with lower values in rockserupted following a major summit collapse or eruptive hiatus.In contrast, ¹⁸O values for olivines in most of these lavasare nearly constant (5·1 ± 0·1). The disequilibriumbetween matrix and olivine ¹⁸O values in many samples indicatesthat the lower matrix values were acquired by the magma afterolivine growth, probably just before or during eruption. BothMauna Loa and Klauea basement rocks are the likely sources ofthe contamination, based on O, Pb and Sr isotope data. However,the extent of crustal contamination of Klauea historical magmasis probably minor (< 12%, depending on the assumed contaminant)and it is superimposed on a longer-term, cyclic geochemicalvariation that reflects source heterogeneity. Klauea's heterogeneoussource, which is well represented by the historical summit lavas,probably has magma ¹⁸O values within the normal mid-ocean ridgebasalt mantle range (5·4–5·8) based on thenew olivine ¹⁸O values. KEY WORDS: Hawaii; Klauea; basalt; oxygen isotopes; crustal contamination