Butyltin concentrations along the Japanese coast from 1997 to 1999 monitored by Caprella spp. (Crustacea: Amphipoda)     

Takeuchi I  Takahashi S  Tanabe S  Miyazaki N 《Marine environmental research》2004,57(5):397-414

The concentrations of butyltins along the Japanese coastline were investigated from 1997 to 1999, 7 to 9 years after implementation of legislation limiting the use of tributyltin (TBT) in Japan. Seawater was sampled at 0.5 m depth, and Caprella spp. were collected from Sargassum spp. and aquaculture facilities from 18 areas within four broad areas along the coastline of Japan, i.e., the Pacific coast of northern Japan, the coast along the Sea of Japan, Tokyo Bay and adjacent areas, and western Japan. Butyltins (MBT, DBT and TBT) were detected in 32 of the 63 seawater samples with average concentrations of 4.6 ng MBT/l, 4.5 ng DBT/l and 6.8 ng TBT/l, respectively. Butyltin concentrations in seawater from western Japan indicate "hot spots" even in unpopulated areas. Butyltins (MBT, DBT and TBT) were detected in all samples of Caprella spp., varying from 2.3 ng BTs /g wet wt in C. penantis R-type from Tobishima Island in the Sea of Japan to 464 ng BTs /g wet wt in C. decipiens Mayer from Amakusa, western Kyushu. The BT concentrations in Caprella spp. form western Japan were significantly higher than those from other areas, including Tokyo Bay and adjacent areas, where large scale industry and international ports are located. These results indicate that butyltin contamination still remains even in unpopulated areas after the regulation on TBT usage, and that the regulation governing TBT usage since 1990 has not been effective enough to concede recovery of shallow water ecosystems around Japan.  相似文献   

Hydrographic Structure and Transport of Intermediate Water in the Kuroshio Region off the Boso Peninsula, Japan   总被引：1，自引：1，他引：1  

Kosei Komatsu  Yutaka Hiroe  Ichiro Yasuda  Kiyoshi Kawasaki  Terrence M. Joyce  Frank Bahr 《Journal of Oceanography》2004,60(2):487-503

Hydrographic structure and transport of intermediate water were observed in the Kuroshio region south of Japan, focusing on the 26.6–27.5σ_θ density in six cruises from May 1998 through September 2001. In the section off the Boso Peninsula where the Kuroshio exfoliates eastward, the intermediate water was clearly clustered into three groups meridionally composed of the coastal water, the Kuroshio water and the offshore water. Compared with the Kuroshio water characterized by warm, salty water transported by the Kuroshio, the coastal and offshore waters significantly degenerated due to mixing with cold, fresh waters originated from the subarctic region: the former was affected by alongshore spread of the coastal Oyashio and the latter by direct intrusion of the new North Pacific Intermediate Water (NPIW) into the southern side of the Kuroshio current axis. Particularly the offshore water showed higher apparent oxygen utilization (AOU) in layers deeper than 26.9σ_θ while it showed lower AOU in layers shallower than 26.9σ_θ, which indicated that colder, fresher and higher AOU water was distributed on the southeastern side of the Kuroshio in deeper layers. In May 1998, the Oyashio-Kuroshio mixing ratio was estimated to be typically 2:8 for the offshore water on the assumption of isopycnal mixing. Moreover, northeastward volume transport of the Kuroshio water was obtained from geostrophic velocity fields adjusted to lowered acoustic Doppler current profiler (LADCP) data to yield 6.1 Sv at 26.6–26.9σ_θ and 11.8 Sv at 26.9–27.5 σ_θ. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Formation Process of North Pacific Intermediate Water Revealed by Profiling Floats Set to Drift on 26.7 σθ Isopycnal Surface     

Yugo Shimizu  Takanori Iwao  Ichiro Yasuda  Shin-Ichi Ito  Tomowo Watanabe  Kazuyuki Uehara  Nobuyuki Shikama  Toshiya Nakano 《Journal of Oceanography》2004,60(2):453-462

Six newly developed floats, which were set to drift on the 26.7 σ_θ isopycnal surface and to profile temperature, salinity and pressure above 1000 dbar once a week, were deployed in the Oyashio and Kuroshio Extension (KE) in order to examine the circulation, formation site and time scale of newly formed North Pacific Intermediate Water (NPIW). The floats were deployed in February or May 2001, and the data from their deployments to December 2002 are analyzed here. Four of the six floats were deployed near the KE axis at around the first meander crest, and they moved eastward to 157°E–176°W at latitudes of 30°N–45°N. The other two floats deployed in the Oyashio water with low-potential vorticity near the south coast of Hokkaido moved southward to reach the KE front and then moved eastward to the same region as the first four floats. The temperature and salinity at 26.7 σ_θ measured by the profiling floats indicate that the source waters of NPIW, Oyashio and Kuroshio waters are drastically mixed and modified in the mixed water region west of 160°E. The floats were separated into the three paths east of 160°E between the Kuroshio Extension front and the north of Water-Mass front (nearly subarctic front). New NPIW is judged to be formed along these three paths since the vertical profiles of temperature and salinity are quite smooth, having a salinity minimum at about 26.7σ_θ along each path. Kuroshio-Oyashio isopycnal mixing ratios of the new NPIW are 7:3, 6:4 and 5:5 at 26.7σ_θ along the southern, middle and northern paths, respectively. Potential vorticity converges to about 14–15 × 10⁻¹¹ m⁻¹s⁻¹ along these paths. The time scale of new NPIW formation is estimated to be 1–1.5 years from the merger of Oyashio and Kuroshio waters to the formation of the new NPIW. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

X-ray topographic study of quartz crystals twinned according to japan twin law     

Toshikazu Yasuda  Ichiro Sunagawa 《Physics and Chemistry of Minerals》1982,8(3):121-127

Quartz crystals twinned according to Japan twin law were investigated by means of X-ray topography in order to understand the origin of characteristic morphology of twin crystals. It is demonstrated that the flattened and elongated morphology characteristic of quartz twins is due to preferential growth at twin junctions where dislocations with the Burgers vector direction 〈11 \(\overline {\text{2}} \) 1〉 concentrate, and that such preferential growth operates only when {10 \(\overline {\text{1}} \) 1} faces meet at the twin junction. Once {10 \(\overline {\text{1}} \) 0} faces appear at the twin junction due to the change of growth conditions, the effect diminishes sharply and the characteristic morphology becomes less pronounced. This leads to the conclusion that the characteristic morphology of quartz crystals twinned according to Japan twin law is formed at the earlier stage of growth and becomes less pronounced at the later stage of growth.  相似文献   

Thermal phase transition of potassium sulfate,K2SO4     

Michihiro Miyake  Ichiro Minato  Shin-ichi Iwai 《Physics and Chemistry of Minerals》1979,4(4):307-315

The thermal phase transition of K₂SO₄ has been investigated by high temperature polarized light microscopy. K₂SO₄ undergoes a first-order transition at 587° C where the orthorhombic low temperature form (Pmcn) transforms into a hexagonal high temperature modification (P6₃/mmc). Prior to the beginning of the phase transition, K₂SO₄ shows an anomalous optical behavior. The crystal apparently becomes optically uniaxial twice at 338° and 425° C, respectively, and truly optically uniaxial at 587° C. The phase transition propagates through an intermediate temperature form, which is sandwiched between the low and the high temperature forms and moves in a definite direction, 〈130〉 (orthorhombic indices), in the vicinity of the phase transition. Passing through the phase transition point on cooling, dark belts crossing each other are observed which are a result of the transformation twins parallel to {110} and {130}.  相似文献   

Investigation of excess argon in ultramafic rocks from the Kola Peninsula by the⁴⁰Ar/³⁹Ar method     

Ichiro Kaneoka 《Earth and Planetary Science Letters》1974,22(2):145-156

In several xenolithic ultramafic rocks from the Kola Peninsula, including a magnetic separate, abnormally high⁴⁰Ar/³⁹Ar ratios persisted at low and high temperatures. The lowest⁴⁰Ar/³⁹Ar ratio was consistently observed at intermediate temperatures (900–1100°C), indicating an apparent age of 2.8–3.1 b.y.; however, this may not indicate the formation age.The quantity of excess⁴⁰Ar was estimated at each temperature fraction, adopting ages inferred from published Rb-Sr ages or the minimum⁴⁰Ar/³⁹Ar age. Excess⁴⁰Ar is abundantly trapped both in mineral lattices and nonretentive trapping sites, but the trapping sites are different from those of in-situ radiogenic⁴⁰Ar. The high temperature component of excess⁴⁰Ar is considered to represent Ar dissolved during mineral formation in the upper mantle or the lower crust.A correlation between the amount of high temperature excess⁴⁰Ar and³⁶Ar exists for some samples. The⁴⁰Ar_excess/³⁶Ar ratios of the rocks of probable upper mantle or lower crust origin vary from about 10 000 to 35 000, which may suggest large fluctuations of this ratio in the deep interior of the earth. The high value implies that most³⁶Ar was already degassed from the earth's interior at least 2 or 3 b.y. ago.  相似文献   

Structure of Brazil twin boundaries in amethyst showing brewster fringes     

Lu Taijing  Ichiro Sunagawa 《Physics and Chemistry of Minerals》1990,17(3):207-211

Optical investigations of Brewster fringes in natural amethyst crystals have indicated that the fringes are Brazil twin boundaries consisting of McLaren and Pitkethly type zig-zag structures and closed parallelograms. The two types of Brazil twin boundaries appear alternately in the successive fringes and in different orientations in one fringe. The Brewster fringes develop by a process of incorporation of many Brazil twin lamellae, when growth conditions are stabilized after this process. If perturbation occurs in growth conditions, distinct growth banding with and without Brazil twin lamellae will develop, and not Brewster fringes.  相似文献   

Rectangular parallellepiped resonance method for piezoelectric crystals and elastic constants of alpha-quartz     

Ichiro Ohno 《Physics and Chemistry of Minerals》1990,17(5):371-378

A theory is presented on the free osculations of a rectangular parallelepiped of piezoelectric crystal, by extending the theory of the rectangular parallelepiped resonance (RPR) method to determine elastic constants of crystals, as exemplified by an alpha-quartz specimen. The piezoelectric contribution to resonance frequencies was examined numerically on the specimen, and it was revealed that piezoelectricity causes approximately 5 kHz increase around 1 MHz. The resonance frequencies of the specimen were measured and inverted to elastic constants by least squares inversion. The inversion was by both the previous non-piezoelectric or elastic theory and by the present piezoelectric theory. The use of the non-piezoelectric theory resulted in an overestimate of 2σ or 0.6% in c ₁₁ and underestimate of σ or 6% in c ₁₂. These are the constants expected to be most affected by piezoelectricity. Errors are less than σ in the other constants. During measurement, it was found that the force applied to hold the specimen caused deviations from free oscillation and experimental errors of 5 kHz. The correction for this force is of some importance in RPR studies of piezoelectric crystals.  相似文献   

Rare gas isotopes and mass fractionation: An indicator of gas transport into or from a magma     

Ichiro Kaneoka 《Earth and Planetary Science Letters》1980,48(2):284-292

A simple model of mass fractionation may explain the isotopic ratios of rare gases in volcanic materials. Single-stage mass fractionation of atmospheric rare gases predicts an upper limit for²⁰Ne/²²Ne of 10.3 and a lower limit for⁴⁰Ar/³⁶Ar of 280. The rare gas data in volcanic materials seem to support this interpretation.Relatively low⁴⁰Ar/³⁶Ar ratios, as low as 282, have been observed in recent Japanese volcanic rocks. Such a low⁴⁰Ar/³⁶Ar ratio may be explained by mass fractionation of the atmospheric value if the rare gases represent those which were transported into the magma chamber with other volatile elements.Both the amounts and the fractionated rare gas abundance pattern of lighter elements which are observed in pumices from the recent eruption of Mt. Usu, Southern Hokkaido, Japan, suggest the possibility of air injection into its magma chamber. Thus, the fractionation of rare gases in volcanic materials may be a common occurrence, and it must be considered in models for the origin of isotopic differences between rare gases in volcanic materials and the atmosphere.  相似文献   

Temperature variation of elastic constants of quartz across the α - β transition     

Ichiro Ohno  Kazumi Harada  Chihiro Yoshitomi 《Physics and Chemistry of Minerals》2006,33(1):1-9

The α − β transition of quartz was successfully observed with using a single sample by means of the rectangular parallelepiped resonance (RPR) method. An oriented rectangular parallelepiped of α-quartz single crystal was prepared and the resonant frequencies of 30–11 vibrational modes were measured from room temperature to 700°C. The softening of quartz crystal was observed as the significant reduction of resonant frequencies near the α–β transition. The present study is the first application of the RPR method to the study of phase transition. The complete set of elastic constants of α- and β-quartz were determined as a function of temperature by the least-squares inversion of the measured frequency data obtained by a single run. This is a merit yielded by the RPR method. It is shown near the α − β transition in both α- and β-quartz that the elastic parameters decrease proportionally to |T−T ₀|⁻ⁿ , where T is temperature and T ₀ is the transition temperature, 573.0°C for α-quartz and 574.3°C for β-quartz. It was also seen that linear incompressibilities K ₁ = (C ₁₁ +C ₁₂ +C ₁₃)/3 and K ₃ = (C ₃₃ +2C ₁₃)/3 decrease rapidly toward the transition, whereas, shear moduli C ₄₄, C _S1 = (C ₁₁ +C ₃₃ -2C ₁₃)/4 and C _S3 = (C ₁₁ -C ₁₂)/2 = C ₆₆ decrease only slightly. The shear modulus C _S3 = C ₆₆ increased slightly in α-quartz. The elastic properties of isotropic aggregate of quartz were calculated, and it is shown that the longitudinal wave velocity significantly decreases at the α − β transition, whereas, the shear wave velocity decreases only slightly.  相似文献