Iron deficiency in micro-sized diatoms in the Oyashio region of the Western subarctic Pacific during spring     

Ai Hattori-Saito  Jun Nishioka  Tsuneo Ono  R. Michael L. McKay  Koji Suzuki 《Journal of Oceanography》2010,66(1):105-115

In order to detect iron (Fe) stress in micro-sized (20–200 μm) diatoms in the Oyashio region, western subarctic Pacific during spring, immunological ferredoxin/flavodoxin assays were applied to samples collected from the surface layer in May 2005. Concomitantly, the community composition of the micro-sized phytoplankton and hydrographic conditions, including dissolved Fe and macronutrient concentrations, were also examined. Chlorophyll (Chl) a concentrations were <2 mg m⁻³ at all sampling stations, except at a station where the Chl a level was 9.0 mg m⁻³ and a micro-sized diatom bloom occurred. A high abundance of ferredoxin in micro-sized diatoms was detected only at a rather near-shore station where dissolved Fe and macronutrient concentrations were higher, indicating that the micro-sized diatoms did not suffer from iron deficiency. On the other hand, flavodoxin in micro-sized diatoms was often observed at the other stations, including the bloom station, where macronutrients were replete but dissolved Fe concentration was low (0.31 nM). A significant amount of chlorophyllide a, a degradation product of Chl a, was also observed at the bloom station, suggesting a decline of the diatom bloom. The micro-sized phytoplankton species at all the stations were mainly composed of the diatoms Thalassiosira, Chaetoceros, and Fragilariopsis spp. Our study indicates that micro-sized diatoms were stressed by Fe bioavailability during the spring season in the Oyashio region  相似文献   

Re-Estimation of Annual Anthropogenic Carbon Input from Oyashio into North Pacific Intermediate Water     

Tsuneo Ono  Katsuyuki Sasaki  Ichiro Yasuda 《Journal of Oceanography》2003,59(6):883-891

The annual transport of anthropogenic carbon (C_anth) to the North Pacific Intermediate Water (NPIW) from the Western Subarctic Gyre (WSG) has been re-estimated by using newly estimated Oyashio transport and C_anth concentration, the latter calculated by the recently-established “ΔC*” method with some modifications. Estimated annual C_anth transport through the nearshore Oyashio west of 146°E was 0.020 ± 0.010 GtC y⁻¹, closely approximating the previous estimation based on a 1-D model calibrated with the CFC vertical distribution. The present study, however, found that an additional 0.025 ± 0.010 GtC y⁻¹ of C_anth was transported into NPIW in the region east of 146°E. Total C_anth transport, 0.045 GtC y⁻¹, contributes about 35% of annual C_anth accumulation of the whole temperate North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

ASCA Observations of X-ray Emission from Ultra-luminous Infrared Galaxies     

Takao Nakagawa  Tsuneo Kii  Ryuichi Fujimoto  Toshiyuki Miyazaki  Hajime Inoue  Yasushi Ogasaka  Ryohei Kawabe 《Astrophysics and Space Science》1999,266(1-2):43-48

  相似文献   

河南省舞阳县贾湖遗址出土的鲤科鱼类咽齿研究     

中岛经夫  吕鹏  张居中  中岛美智代  模林启介  袁靖 《第四纪研究》2015,35(1)

本文对贾湖遗址出土的鲤科鱼类进行了研究,发现有11种可以确定到属或种的鲤科鱼类.现在生存在中国南方的鲤科鱼类在贾湖遗址的出土,证明当时这个地区的气候比现在要温暖.这些鲤科鱼类是当时居住在贾湖遗址的先民有选择性地进行捕捞的.该研究有助于推进考古遗址出土鱼类遗存的动物考古学研究.  相似文献   

Expected changes in future agro-climatological conditions in Northeast Thailand and their differences between general circulation models     

Yoshimitsu Masaki  Yasushi Ishigooka  Tsuneo Kuwagata  Shinkichi Goto  Shinji Sawano  Toshihiro Hasegawa 《Theoretical and Applied Climatology》2011,106(3-4):383-401

We have studied future changes in the atmospheric and hydrological environments in Northeast Thailand from the viewpoint of risk assessment of future cultural environments in crop fields. To obtain robust and reliable estimation for future climate, ten general circulation models under three warming scenarios, B1, A1B, and A2, were used in this study. The obtained change trends show that daily maximum air temperature and precipitation will increase by 2.6°C and 4.0%, respectively, whereas soil moisture will decrease by c.a. 1% point in volumetric water content at the end of this century under the A1B scenario. Seasonal contrasts in precipitation will intensify: precipitation increases in the rainy season and precipitation decreases in the dry season. Soil moisture will slightly decrease almost throughout the year. Despite a homogeneous increase in the air temperature over Northeast Thailand, a future decrease in soil water content will show a geographically inhomogeneous distribution: Soil will experience a relative larger decrease in wetness at a shallow depth on the Khorat plateau than in the surrounding mountainous area, reflecting vegetation cover and soil texture. The predicted increase in air temperature is relatively consistent between general circulation models. In contrast, relatively large intermodel differences in precipitation, especially in long-term trends, produce unwanted bias errors in the estimation of other hydrological elements, such as soil moisture and evaporation, and cause uncertainties in projection of the agro-climatological environment. Offline hydrological simulation with a wide precipitation range is one strategy to compensate for such uncertainties and to obtain reliable risk assessment of future cultural conditions in rainfed paddy fields in Northeast Thailand.  相似文献   

Effects of polychlorinated biphenyls on liver function and sexual characteristics in Japanese medaka (Oryzias latipes)     

Nakayama K  Sei N  Handoh IC  Shimasaki Y  Honjo T  Oshima Y 《Marine pollution bulletin》2011,63(5-12):366-369

The effects of polychlorinated biphenyls (PCBs) on liver function and their differences between sexes were analyzed in Japanese medaka (Oryzias latipes) exposed to PCB126 or Kanechlor-400 (KC-400) using microarray. PCB exposure induced vitellogenin 1 expression in female medaka while suppressing choriogenin genes, which suggests that the effects of PCBs on estrogen-responsive genes do not occur directly through an estrogen receptor-mediated pathway. Reduction of androgen receptor alpha expression was also observed, and the gene expression pattern in PCB-exposed males changed to become more similar to that of females. Furthermore, changes in glycolysis-related genes indicate that PCB exposure might enhance glucose production via gluconeogenesis in the liver of medaka. Taken together, our results suggest that PCBs disrupt the endocrine system, especially androgen function, and may have the potential to cause demasculinizing effects. Additionally, induction of gluconeogenesis might be a response to maintain glucose levels consumed as a result of PCB exposures.  相似文献   

Distribution and dispersal of the early larval stages of the Japanese spiny lobster Panulirus japonicus in the East China Sea     

Taku Yoshimura  Kenji Morinaga  Seiji Oshimo  Yoshinobu Konishi  Tsuneo Goto 《新西兰海洋与淡水研究杂志》2013,47(2):591-604

The annual distribution and dispersal of early‐stage phyllosoma of the Japanese spiny lobster Panulirus japonicus were examined in the East China Sea and the Sea of Japan off western Japan. Early‐stage larvae were sampled mainly in summer and relatively near the coast off western Kyusyu Island. Few larvae were found in the other three seasons in the East China Sea and the Sea of Japan. This finding suggests that P. japonicus larvae are retained in coastal areas for a few months after hatching until stage V and are transported offshore until autumn, before they grow to stage VI. Examination of archival drifter data off western Kyusyu Island during the spawning season of P. japonicus supported the relatively rapid dispersal of the larvae from the East China Sea near Japan to the Pacific Ocean or the Sea of Japan. Larval transport from the East China Sea to the Pacific Ocean, which is considered to be a main distribution area of middle‐ and late‐stage larvae, would occur in the south at approximately 32–33°N in the East China Sea near western Kyusyu Island.  相似文献   

Effects of low pCO2 conditions on sea urchin larval size     

Ryota Suwa  Yukihiro Nojiri  Tsuneo Ono  Yoshihisa Shirayama 《Marine Ecology》2013,34(4):443-450

Ocean acidification results from an increase in the concentrations of atmospheric carbon dioxide (CO₂) impacts on marine calcifying species, which is predicted to become more pronounced in the future. By the end of this century, atmospheric pCO₂ levels will have doubled relative to the pre‐industrial levels of 280 ppm. However, the effects of pre‐industrial pCO₂ levels on marine organisms remain largely unknown. In this study, we investigated the effects of pre‐industrial pCO₂ conditions on the size of the pluteus larvae of sea urchins, which are known to be vulnerable to ocean acidification. The larval size of Hemicentrotus pulcherrimus significantly increased when reared at pre‐industrial pCO₂ level relative to the present one, and the size of Anthocidaris crassispina larvae decreased as the pCO₂ levels increased from the pre‐industrial level to the near future ones after 3 days' exposure. In this study, it is suggested that echinoid larvae responded to pre‐industrial pCO₂ levels. Ocean acidification may be affecting some sensitive marine calcifiers even at the present pCO₂ level.  相似文献   

Thermal effect of the sea breeze on the structure of the boundary layer and the heat budget over land   总被引：2，自引：1，他引：1  

Tsuneo Kuwagata  Junsei Kondo  Masatoshi Sumioka 《Boundary-Layer Meteorology》1994,67(1-2):119-144

The daytime boundary-layer heating process and the air-land heat budget were investigated over the coastal sea-breeze region by means of observations over the Sendai plain in Japan during the summer. In this area, the onset of the sea breeze begins at the coast around 0900 LST, intruding about 35 km inland by late afternoon. The cold sea breeze creates a temperature difference of over 10°C between the coastal and inland areas in the afternoon. On the other hand, warm air advection due to the combination of the counter-sea breeze and land-to-sea synoptic wind occurs in the layer above the cold sea breeze in the coastal region. Owing to this local warm air advection, there is no significant difference in the daytime heating rate over the entire atmospheric boundary layer between the coastal and inland areas. The sensible heat flux from the land surface gradually decreases as distance from the coastline increases, being mainly attributed to the cold sea breeze. The daytime mean cold air advection due to the sea breeze is estimated asQ _adv ^local =–29 W m^–2 averaged over the sea breeze region (035 km from the coastline). This value is 17% of the surface sensible heat fluxH over the same region. The results of a two-dimensional numerical model show that the value ofQ _adv ^local /H is strongly affected by the upper-level synoptic wind direction. The absolute value ofQ _adv ^local /H becomes smaller when the synoptic wind has the opposite direction of the sea breeze. This condition occurred during the observations used in the present study.  相似文献   

Large-scale freezing work for subway construction in Japan     

Michio Miyoshi  Tsuneo Tsukamoto  Shiro Kiriyama   《Engineering Geology》1979,13(1-4):397-415

  相似文献