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71.
72.
It is well known that heavy oil (HO) on the sea surface causes serious problems in the aquatic environment. In particular, some species of teleosts which develop on the sea surface are thought to be affected by the HO which flows out from tankers or coastal industry. However, the toxicological effects of HO are not fully understood. We performed exposure experiments using the Pleuronectiformean fish, spotted halibut (Verasper variegatus), which is an important fishery resource in Japan. In course of the development, HO-exposed embryos showed remarkable delay in developmental processes including somite formation. We further observed abnormal development of the head morphology. Notably, treated embryos had relatively small eyes and craniofacial structures. These findings strongly suggest that HO seriously affects the cell proliferation and differentiation of the embryo. In addition, HO-exposed embryos showed abnormal neuronal development. We also performed the exposure in the larval stage. Treatment of post-hatching larvae with HO resulted in significantly greater mortality compared with controls. Through these observations, we finally conclude that HO is strongly toxic to halibut in their early life stages.  相似文献   
73.
It is well known that heavy oil (HO) on the sea surface causes serious problems in the aquatic environment. In particular, some species of teleosts which develop on the sea surface are thought to be affected by the HO which flows out from tankers or coastal industry. However, the toxicological effects of HO are not fully understood. We performed exposure experiments using the Pleuronectiformean fish, spotted halibut (Verasper variegatus), which is an important fishery resource in Japan. In course of the development, HO-exposed embryos showed remarkable delay in developmental processes including somite formation. We further observed abnormal development of the head morphology. Notably, treated embryos had relatively small eyes and craniofacial structures. These findings strongly suggest that HO seriously affects the cell proliferation and differentiation of the embryo. In addition, HO-exposed embryos showed abnormal neuronal development. We also performed the exposure in the larval stage. Treatment of post-hatching larvae with HO resulted in significantly greater mortality compared with controls. Through these observations, we finally conclude that HO is strongly toxic to halibut in their early life stages.  相似文献   
74.
75.
The -ray and white-light flare of 13 May, 1981 is used for a study of spatial distributions of energetic electrons and high-temperature plasma.  相似文献   
76.
77.
All of the available hydrographic station data (temperature, salinity, dissolved oxygen, phosphate and nitrate) taken in various seasons from 1964 to 1985 are analyzed to show where the upper portion of the Japan Sea Proper Water (UJSPW) is formed and how it circulates. From vertical distributions of water properties, the Japan Sea Proper Water can be divided into an upper portion and a deep water at the 1 (potential density referred to 1000 db) depth of 32.05 kg m–3 surface. The UJSPW in the north of 40°N increases in dissolved oxygen contents and decreases in phosphate contents in winter, while no significant seasonal variation is seen in the south of 40°N. Initial nutrient contents calculated from relationships between AOU and nutrients on isopycnal surfaces show no significant regional difference in the Japan Sea; this suggests that the UJSPW has originated from a single water mass. From depth, dissolved oxygen and phosphate distributions on 1 32.03 kg m–3 surface, core thickness distribution and subsurface phosphate distribution, it is inferred that the UJSPW is formed by the wintertime convection in the region west of 136°E between 40° and 43°N, and advected into the region west of the Yamato Rise along the Continent; finally, it must enter into the Yamato Basin.  相似文献   
78.
The long-term variation of water properties in the upper portion of the Japan Sea Proper Water (UJSPW) is examined on the basis of hydrographic data at PM10, located on the northwestern Japan Sea, and at PM05, in the Yamato Basin, taken from 1965 through 1982. At PM10, located at the southern boundary of the UJSPW formation region, dissolved oxygen fluctuations on the UJSPW core showed negative correlation with phosphate variations, but showed no signficant correlation with salinity variations. At PM05 water properties fluctuated with smaller amplitudes than those at PM10 except for salinity. Dissolved oxygen variations at PM10 lead those at PM05 by 12–15 months, suggesting that the UJSPW near PM10 circulates into the Yamato Basin spending 12–15 months. Increases of dissolved oxygen contents in summer on relevant isopycnal surfaces at PM10 occurred after cold and/or windy winters except for two of eight; this suggests that larger volume of the UJSPW is formed in severa winter. Rough estimations of the formation rate and existing volume of the UJSPW are made on the basis of a climatological dataset; 1.5×104 km3 yr–1 and 27.3×104 km3, respectively. The ventilation time of the UJSPW, 18.2 years, is about one tenth or less of residence time for the entire Japan Sea Proper Water. This indicates that the UJSPW is renewed about ten times as quick as the deeper water.  相似文献   
79.
During November 2000–June 2002, both direct current measurements from deployment of a line of five moorings and repeated CTD observations were conducted along the Oyashio Intensive observation line off Cape Erimo (OICE). All the moorings were installed above the inshore-side slope of the Kuril-Kamchatka Trench. Before calculating the absolute volume transports, we compared vertical velocity differences of relative geostrophic velocities with those of the measured velocities. Since both the vertical velocity differences concerned with the middle three moorings were in good agreement, the flows above the continental slope are considered to be in thermal wind balance. We therefore used the current meter data of these three moorings, selected among all five moorings, to estimate the absolute volume transports of the Oyashio referred to the current meter data. As a result, we estimated that the southwestward absolute volume transports in 0–1000 db are 0.5–12.8 × 106 m3/sec and the largest transport is obtained in winter, January 2001. The Oyashio absolute transports in January 2001, crossing the OICE between 42°N and 41°15′ N from the surface to near the bottom above the continental slope, is estimated to be at least 31 × 106 m3/sec. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
80.
Observations were made to study the oceanographic structure of the dense water formation and its outflow from Funka Bay, Hokkaido, during early spring. The winter Funka Bay water, which was transformed from the warm water of the Tsugaru Current, due to cooling and deep convection during the winter, flowed from the bay, while forming a frontal structure. The width and inclination of the density front were about 3 n. miles and 1.4×10?2, respectively, during the early spring of 1982. These values roughly coincided with calculated values of 2.6 n. miles and 1.7×10?2 using the sill flow model proposed by Whiteheadet al. (1974). Observed current speeds and directions were also similar to those predicted by the model. The renewal time of bay water with this flow was estimated to be about 51 days, which is consistent with the results of previous studies.  相似文献   
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