Carbon dioxide stored and acidified low oxygen bottom waters in coastal seas,Japan

Recently carbon dioxide fluxes between sea water and air have been measured in many coastal seas to clarify whether the coastal seas are source or sink of CO₂. In this study behavior of CO₂ within the water column was studied in a semi-enclosed coastal sea: the Seto Inland Sea, Japan. It was found that seasonal formation of hypoxic water mass is highly related to CO₂ dynamics in coastal seas. Bacterial remineralization of organic matter consumes dissolved oxygen (DO) and releases dissolved CO₂ in the bottom water when summertime thermal stratification develops. The CO₂ accumulates within the low DO bottom water (hypoxic water) and causes increasing of carbonic acid content which results in low pH. Concentrations of dissolved CO₂ and pH are highly correlated with DO concentration. The summertime low DO and acidification (low pH) occur in the lower layer every year. The accumulated CO₂ during the summer season is dispersed to the atmosphere at the beginning of mixing season.     

Seasonal changes in runoff characteristics on a permafrost watershed in the southern mountainous region of eastern Siberia

We attempted to clarify the runoff characteristics of a permafrost watershed in the southern mountainous region of eastern Siberia using hydrological and meteorological data obtained by the State Hydrological Institute in Russia from 1976 to 1985. We analysed seasonal changes in the direct runoff ratio and recession gradient during the permafrost thawing period. Thawing depth began to increase from the beginning of May and continued to increase until the end of September, exceeding 150 cm. Annual precipitation and discharge were in the range 525–649 mm and 205–391 mm respectively. The sum of the annual evapotranspiration and changes in water storage ranged from 235 to 365 mm. The mean daily evapotranspiration in June, July, August and September was 1·5 mm day^?1, 1·7 mm day^?1, 1·5 mm day^?1, and 0·5 mm day^?1 respectively. The direct runoff ratio was highest in June, decreasing from 0·8 in June to 0·2 in September. The recession gradient also decreased from June to September. Since the frozen soil functioned as an impermeable layer, the soil water storage capacity in the thawing part of the soil, the depth of which changed over time, controlled the runoff characteristics. Copyright © 2005 John Wiley & Sons, Ltd.     

Culture-dependent and independent analyses of subsurface microbial communities in oil-bearing strata of the Sagara oil reservoir

Abstract   Culture-dependent and independent methods were used to evaluate the microbial communities in cores collected at depths up to 200 m in oil-bearing and oil-free strata near the Sagara oil reservoir near Shizuoka, Japan. Direct microbial counts revealed much higher numbers (2.2 × 10⁴−7.9 × 10⁶/g) of microbes in the oil-bearing strata than in the oil-free zones, where counts were uniform at approximately 1.0 × 10⁴/g. Molecular taxonomic analyses via 16S rRNA gene sequence comparisons showed that the oil-free strata were dominated by members of the γ-Proteobacteria including Pseudomonas , Stenotrophomonas and Sphingomonas , whereas the oil-bearing strata were dominated by a single species closely related to Pseudomonas stutzeri . All archaeal clones were phylogenetically affiliated with the uncultured soil group in Crenarchaeota with the exception of a single phylotype that belonged to the genus Thermococcus . Culture-dependent analysis was carried out by most-probable-number culturing as well as direct plating to determine viable cell counts, using both complex organic substrates or native oil and autotrophic media. Both culture-dependent and independent methods revealed the abundant cultivable member was the aerobic oil-degrading bacterium Pseudomonas stutzeri and neither autotrophs nor anaerobic heterotrophs could be detected in the oil-bearing strata.     

High-temperature and high-pressure equation of state for the hexagonal phase in the system NaAlSiO4 – MgAl2O4

Thermal equation of state of an Al-rich phase with Na_1.13Mg_1.51Al_4.47Si_1.62O₁₂ composition has been derived from in situ X-ray diffraction experiments using synchrotron radiation and a multianvil apparatus at pressures up to 24 GPa and temperatures up to 1,900 K. The Al-rich phase exhibited a hexagonal symmetry throughout the present pressure–temperature conditions and the refined unit-cell parameters at ambient condition were: a=8.729(1) Å, c=2.7695(5) Å, V ₀=182.77(6) Å³ (Z=1; formula weight=420.78 g/mol), yielding the zero-pressure density ρ₀=3.823(1) g/cm³ . A least-square fitting of the pressure-volume-temperature data based on Anderson’s pressure scale of gold (Anderson et al. in J Appl Phys 65:1534–543, 1989) to high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus K ₀=176(2) GPa, its pressure derivative K ₀ ^′ =4.9(3), temperature derivative (?K _T /?T) _P =?0.030(3) GPa K^?1 and thermal expansivity α(T)=3.36(6)×10^?5+7.2(1.9)×10^?9 T, while those values of K ₀=181.7(4) GPa, (?K _T /?T) _P =?0.020(2) GPa K^?1 and α(T)=3.28(7)×10^?5+3.0(9)×10^?9 T were obtained when K ₀ ^′ was assumed to be 4.0. The estimated bulk density of subducting MORB becomes denser with increasing depth as compared with earlier estimates (Ono et al. in Phys Chem Miner 29:527–531 2002; Vanpeteghem et al. in Phys Earth Planet Inter 138:223–230 2003; Guignot and Andrault in Phys Earth Planet Inter 143–44:107–128 2004), although the difference is insignificant (<0.6%) when the proportions of the hexagonal phase in the MORB compositions (～20%) are taken into account.     

Damage assessment after 2001 Gujarat earthquake using Landsat-7 satellite images

In this paper, we present a method of earthquake damage detection by comparing the optical images with panchromatic bands for the Gujarat, India earthquake, which occurred on January 26, 2001. The data used in this study are optical remote sensing images taken by Landsat-7 satellite on January 8 and February 29, 2001, before and after the earthquake. We have investigated the pre and post-earthquake satellite images calculating the differences in the reflection intensity (digital number) of the two images. The estimated affected area has been subtracted on a pixel unit based on the obtained frequency distributions of the differences in the optical sensor values, which show significant changes in the reflectance due to the earthquake disaster. We have investigated the accuracy of our analysis result using a classification method for the training areas with aerial photographs taken after the earthquake. The two damage detection methods show a very similar result.     

Estimation of strong motion distribution in the 1995 Kobe earthquake based on building damage data

The 1995 Kobe earthquake caused unprecedented damage to buildings and civil infrastructures in the city of Kobe and its surrounding areas. In order to evaluate the structural damage in this area due to the earthquake, it is important to estimate the distribution of earthquake ground motion. However, since the number of strong ground motion records is not enough in the heavily damaged areas, it is necessary to estimate the distribution using other data sources. In this paper, the fragility curves for low‐rise residential buildings were constructed using the recorded motions and the building damage data from the intensive field survey by the AIJ and CPIJ group. The fragility curves obtained were then employed to estimate the strong motion distribution in the district level for Kobe and the surrounding areas during the earthquake. The results may be useful to investigate the various damages caused by the earthquake. Copyright © 2001 John Wiley & Sons, Ltd.     

Correlation of JMA instrumental seismic intensity with strong motion parameters

The Japan Meteorological Agency (JMA) seismic intensity (I_JMA) has been used as a measure of strong shaking for many years in Japan, and it necessitates to know the correlation between the JMA seismic intensity and other strong motion indices, e.g. Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Spectrum Intensity (SI). In this study, two strong motion data sets were selected; in which, the first set consists of 879 three‐components non‐liquefied records selected from 13 major earthquake events that occurred in Japan, the United States, and Taiwan, and the second set consists of 17 liquefied records selected from 7 major earthquake events that occurred in Japan and the United States. The JMA seismic intensity and other ground motion indices were calculated using the selected data sets. The relationships between the JMA seismic intensity and PGA, PGV, and SI were then derived performing a two‐stage linear regression analysis. Results from the analysis show that the JMA instrumental seismic intensity shows higher correlation with SI than PGA or PGV, and it shows the highest correlation with the parameters such as the combination of PGA and SI or the product of PGA and SI. The obtained relationships are also compared with the ones obtained by other studies, which may be useful for the disaster management agencies in Japan and deployment of new SI‐sensors that monitor both PGA and SI. Copyright © 2002 John Wiley & Sons, Ltd.