The temporal record and sources of atmospherically deposited fly-ash particles in Lake Akagi-konuma,a Japanese mountain lake

Fly-ash particles comprising spheroidal carbonaceous particles (SCP) and inorganic ash spheres (IAS), produced from industrial fossil-fuel combustion, are found in lake sediments throughout the world where they provide an historical record of atmospheric pollutant deposition. These particles have been widely used to assess the temporal and spatial distribution of industrial atmospheric pollution in both freshwater and terrestrial environments in Europe and the USA. However, there have been very few palaeolimnological fly-ash studies undertaken in Japan and none in Japanese mountain lakes. Here, we present the historical SCP and IAS records from a radiometrically dated sediment core taken from Lake Akagi-konuma (36°31′ 54″N, 139°11′ 32″E; elevation 1,470 m) located 100 km north-west of Tokyo. Meteorological data and back trajectory analyses confirm potential sources both within Japan and further afield in China and South Korea. SCP contamination began in the 1950s and increased rapidly to a peak in the mid-1980s. It is thought this represents contamination of Japanese origin, principally oil-fired power stations within 150 km of the lake. The profile of IAS, almost solely coal-derived, shows a rapid increase in the 1970s, in contrast to the record of coal consumption in Japan. The IAS record is therefore thought to reflect long-range transport from coal combustion sources in eastern China which started to expand in the 1970s. This raises concerns over the potential impact on Japanese mountain areas from recent rapid increases in, and predicted acceleration of, emissions from this industrial process. The scale of SCP contamination recorded in Lake Akagi-konuma is equivalent to moderately impacted mountain lakes in Europe, but is at the upper end of the range for remote lakes in the western United States.     

Paleoposition of Southwest Japan at 16 Ma: Implication from paleomagnetism of the Miocene Ichishi Group

New paleomagnetic data from shallow-marine sediments of the Ichishi Group suggest a clockwise tectonic rotation of Southwest Japan in the Middle Miocene. Samples have been collected from mud or tuff layers at 17 sites. Stability of remanent magnetization has been examined by using alternating field and thermal demagnetization. The polarity sequence, composed of four normal and seven reversed polarity sites, is correlated to Polarity Epoch 16 (15.2–17.6 Ma), based on micropaleontological assignment of the upper Ichishi Group to Blow's Zone N8. The mean paleomagnetic direction of the 11 sites shows an anomalous declination toward the northeast. This result suggests that Southwest Japan was subjected to a clockwise rotation through 45° since 16 Ma. The clockwise rotation can be explained by the drift of Southwest Japan associated with the spreading of the Japan Sea during the Middle Miocene.     

Pin‐supported walls for enhancing the seismic performance of building structures

An application of a pin‐supported wall‐frame system in retrofitting an eleven‐story steel reinforced concrete frame is introduced. The retrofit aims at enhancing integrity and avoiding weak story failure in an existing moment‐resisting frame. Seismic performance of the building before and after the retrofit is assessed through nonlinear dynamic analysis. The results show that the pin‐supported walls are effective in controlling the deformation pattern of the ductile frame and hence in avoiding weak story failure. With the well‐controlled deformation pattern, carefully arranged energy dissipating devices are able to concentrate energy dissipations so that damage to the rest of the structure can be significantly reduced. Copyright © 2012 John Wiley & Sons, Ltd.     

Shaking table tests on seismic response of steel braced frames with column uplift

Previous studies have suggested that rocking vibration accompanied by uplift motion might reduce the seismic damage to buildings subjected to severe earthquake motions. This paper reports on the use of shaking table tests and numerical analyses to evaluate and compare the seismic response of base‐plate‐yielding rocking systems with columns allowed to uplift with that of fixed‐base systems. The study is performed using half‐scale three‐storey, 1 × 2 bay braced steel frames with a total height of 5.3 m. Base plates that yield due to column tension were installed at the base of each column. Two types of base plates with different thicknesses are investigated. The earthquake ground motion used for the tests and analyses is the record of the 1940 El Centro NS component with the time scale shortened by a factor of 1/√2. The maximum input acceleration is scaled to examine the structural response at various earthquake intensities. The column base shears in the rocking frames with column uplift are reduced by up to 52% as compared to the fixed‐base frames. Conversely, the maximum roof displacements of the fixed and rocking frames are about the same. It is also noted that the effect of the vertical impact on the column associated with touchdown of the base plate is small because the difference in tensile and compressive forces is primarily due to the self‐limiting tensile force in the column caused by yielding of the base plate. Copyright © 2006 John Wiley & Sons, Ltd.     

Rates of net assimilation and respiration of amino acids by marine bacteria

The selectivity of amino acid assimilation by marine bacteria was examined using seven kinds of¹⁴C-amino acids and the acid hydrolysate of¹⁴C-labelled proteins. It was found that the net assimilation and respiration by marine bacteria followed MICHAELIS-MENTEN kinetics for all of amino acids used in our experiments. Maximum velocities of amino acids were 0.01 to 0.19g carbon/hour per 2×10⁷ cells for net assimilation and less than 0.18g carbon/hour per 2×10⁷ cells for respiration at 20C. The velocity of gross assimilation was found with the following order: phenylalanine>valine, glutamic acid>serine, arginine>tryptophan>glycine. The assimilation velocities of amino acids in these laboratory works showed almost the same order as those in field experiments. The assimilation velocity of an amino acid was influenced by coexisting another amino acids or glucose. The assimilation velocity in lower substrate range of amino acids was directly proportional to the number of bacterial cells in the range from 6×10² to 3×10⁴ cells per ml. No linear relation between the assimilation velocity of amino acids and reciprocal of absolute temperature was found, but a marked bending was observed at 15 to 20C. The velocity at the optimum temperature was three to six times of that at 5C.     

Adsorption of tributyltin by tributyltin resistant marine Pseudoalteromonas sp. cells

The isolate, Pesudoalteromonas sp. TBT1, could grow to overcome the toxicity of tributyltin chloride (TBTCl) up to 30 μM in the absence of Cl⁻ in the medium until the cells reached an exponential phase of growth. The viability, however, was reduced after the cells reached a stationary phase. The degradation products, such as dibutyltin (DBT) and monobutyltin (MBT), were not detected in the growth medium, indicating that the isolate has no ability to degrade TBT into less toxic DBT and MBT. Up to about 10^7.5 TBT molecules were adsorbed by a single cell. The observation of morphological changes with an electron microscope showed that the cell surface became wrinkled after exposure to the lethal concentration of 10 mM TBTCl. These results indicate that the resistance of the isolate toward the toxicity of TBTCl is not related to the unique cell surface, which seems to play an important role in preventing the diffusion of TBTCl into the cytoplasm.     

Chemical composition of Coscinodiscus wailesii and the implication for nutrient ratios in a coastal water, Seto Inland Sea, Japan

Chemical compositions of Coscinodiscus wailesii were determined for four samples of natural cells. Results revealed that the cellular Si:N ratio of C. wailesii cell was 2.4:1.0-5.2:1.0. The impacts of C. wailesii on surrounding coastal water were evaluated from hydrographic observations, in which C. wailesii cell density, nutrients concentrations and temperature were monitored from November 2001 to February 2005 in Harima-Nada, the Seto Inland Sea, Japan. In low temperature periods, from October to December, two peaks of C. wailesii cell density were observed and nutrient concentrations were depleted. The draw-down ratio of Si(OH)(4) and DIN (Si(OH)(4):DIN ratio) in the water column were similar to the cellular Si:N ratio of C. wailesii cells, which have high Si contents. In addition the effects of different Si(OH)(4):DIN ratio were determined for in situ bottle incubation experiments. In the culture experiments, picoplankton (0.2-2.0 microm) which consisted of small flagellates became dominant under low Si(OH)(4):DIN ratios. These results suggested that the sizes distribution shifted to small size and the phytoplankton community was changed to small flagellates after the C. wailesii bloom. These changes would influence predators at higher trophic levels in its coastal ecosystem.     

Quantification of the effect of forest harvesting versus climate on streamflow cycles and trends in an evergreen broadleaf catchment

ABSTRACT

A new method known as Unobserved Components–Dynamic Harmonic Regression (UC-DHR) was applied to a 39-year record of rainfall and streamflow for three sub-catchments of the Sarukawa Experimental Watershed in southwestern Japan. Some 25% of the timber was harvested from one of the sub-catchments in May–July 1982 and the objective was to quantify the magnitude of this effect relative to the effects of climate cycles (e.g. Southern Oscillation Index). The observed effects of inter-annual climate cycles (i.e. 0.89–1.36 mm/d) were seen to be comparable (i.e. 0.70–1.17 mm/d) to the effects of harvesting 25% of the standing timber. This result underlines the importance of always quantifying the effect of climate on streamflow response when harvesting impacts are studied.

Editor D. Koutsoyiannis; Associate editor T. Okruszko     

The Meteoritical Bulletin,No. 96, September 2009

Abstract— The Meteoritical Bulletin No. 96 contains a total of 1590 newly approved meteorite names with their relevant data. These include 12 from specific locations within Africa, 76 from northwest Africa, 9 from the Americas, 13 from Asia, 1 from Australia, 2 from Europe, 950 from Antarctica recovered by the Chinese Antarctic Research Expedition (CHINARE), and 527 from the American Antarctic program (ANSMET). Among these meteorites are 4 falls, Almahata Sitta (Sudan), Sulagiri (India), Ash Creek (United States), and Maribo (Denmark). Almahata Sitta is an anomalous ureilite and is debris from asteroid 2008 TC3 and Maribo is a CM2 chondrite. Other highlights include a lunar meteorite, a CM1 chondrite, and an anomalous IVA iron.     

Oblique and near collision subduction, Sagami and Suruga Troughs —preliminary results of the French-Japanese 1984 Kaiko cruise, Leg 2

Leg 2 of the French-Japanese 1984 Kaiko cruise has surveyed the Suruga and the Sagami Troughs, which lie on both sides of the northwestward moving and colliding Izu-Bonin Ridge, the northernmost part of the Philippine Sea plate. The transition from the Nankai Trough to the Suruga Trough is characterized by northward decrease in width of the accretionary prism, in good agreement with the increasing obliquity between the through axis and the direction of the convergence, as the strike of the convergent boundary changes from ENE-NNE to south-north. South of the area, the southern margin of the Zenisu Ridge shows contractional deformations. This supports the interpretation made by the team of Leg 1 who studied the western extension of the area we studied, that it is an intra-oceanic thrusting of the ridge over the Shikoku Basin. In the Sagami Trough, where the relative motion is highly oblique to the plate boundary, active subduction is mostly confined in the east-west trending portions of the trough located south of the Boso Peninsula and along the lower Boso Canyon, near the TTT triple junction. In between, the present motion is mainly right-lateral along the northwest trending Boso escarpment. However, an inactive but recent (Pliocene to lower Pleistocene) accretionary prism exists south of the Boso escarpment, which suggests that the relative motion was more northerly than at present before about 1 Ma ago.