Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.     

DNA倍体分析技术在诊断妇科肿瘤中的研究进展

Aerosol samples were collected at altitudes from 584 m a.s.l.to 3,804 m a.s.l.at seven sites of the eastern Tianshan.The occurrence,distribution,and possible sources of 47 trace metals—including alkali metals and alkali earth metals,transition metals,lanthanoids,and heavy metals—were investigated.It was found that four sampling sites(Shuinichang,1,691 m a.s.l.;Urumqi City,809 m a.s.l.;Fu Kang Station,584 m a.s.l.;and Bogeda Glacier No.4,3,613 m a.s.l.)were contaminated mainly by heavy metals.Other three high-altitude sites(Urumqi Glacier No.1,3,804 m a.s.l.;Wang Feng road-maintenance station,3,039 m a.s.l.;and Tianshan Glaciology Station,2,135 m a.s.l.)were not polluted.The aerosol particles were clustered into two dominant types:crust-originated particles and pollution-derived particles.Aerosols from UG1,WF,and TGS were characterized by crust-originated particles such as clay,plagioclase,dolomite,alkali feldspar,and biotite;while those from SNC,Urumqi,FK,and BG4 were characterized by high content of Cl-rich particles,S-rich particles,and soot.The backward-trajectories results indicated that air masses arriving at SNC,Urumqi,FK,and BG4 were identified as the more polluted source,when compared to the short-range air mass transport from the North to UGI and WF.Relatively lower altitude,as well as terrain blocking,might be another important reason for the gradient difference in pollution influence among these seven places in the Urumqi River Basin.     

Turbulent structure in the upper layer of the western Equatorial Pacific Ocean

The Richardson number dependence of vertical eddy diffusion coefficients in the western Equatorial Pacific Ocean was examined on the basis of a Microstructure Profiler (MSP) observations during the cruise of Natsushima (JAPACS-89). The Richardson numberR _i was estimated by using the mean shear of velocity profile measured by an Acoustic Doppler Current Profiler (ADCP) with the vertical interval of 15 meters within one or two hours of the each MSP cast. The raw data plot of the vertical eddy diffusion coefficientK _p shows a large scatter with increasing tendency belowR _i =0.5. The relation between the mean vertical eddy diffusion coefficientK _p and the Richardson numberR _i , averaged over every 0.025 in theR _i , supports the model of Pacanowski and Philander (1981) in the range ofR _i >0.5, but coincides with the result of Peterset al. (1988) in the range ofR _i <0.5.     

Species and concentrations of selenium and nutrients in Tanabe Bay during red tide due toGymnodinium nagasakiense

A red tide due toGymnodinium nagasakiense was observed in August 1988 in Tanabe Bay, Wakayama Prefecture, Japan. The maximum cell concentration ofG. nagasakiense reached 1×10⁵ cells ml^–1 at the surface water. From May to September 1988, the following were monitored: water temperature, salinity, chlorophylla, D.O., dissolved nutrients (NO₂–N, NO₃–N, NH₄–N, PO₄–P DON, DOP), particulate nutrients (PON, POP) and three dissolved selenium species [Se(IV), Se(VI), Organic Se]. Dissolved inorganic nitrogen (NO₃–N, NH₄–N) decreased but PON, POP, DON, DOP and inorganic phosphate increased at the peak of the bloom. The concentration of organic selenium increased up to the bloom initiation period which started on 5 July, and then the concentration of Se(IV) increased as the concentration of organic selenium decreased at the peak of the bloom (3 August). The strong relationship was found between the concentration of Se(IV) and the cell concentration ofG. nagasakiense (r ²=0.98). The Se(IV) requirement ofG. nagasakiense was 2.89×10^–17 moles cell^–1, which was agreed well with 4.4×10^–17 moles cell^–1 found in a laboratory experiment onG. nagasakiense using selenium spiked artificial sea water medium. The average ratio of Se(IV) to dissolved inorganic nitrogen (DIN) during the red tide bloom was 11441, the ratio of Se(IV) to DIN at the surface with the maximum cell concentration ofG. nagasakiense of 1×10⁵ cells ml^–1 was 1137. These results suggested that selenium may play an important role in red tide outbreak ofG. nagasakiense.     

Centrifugal forces estimated from trajectories of drifting buoys in winding paths of the Kuroshio

Radii and angular velocities in the motions of drifting buoys deployed in the Kuroshio are estimated by fitting circles to the trajectories of two drifting buoys, one with a drogue at 300 m depth and the other at 800 m depth. The buoys were deployed in the Kuroshio where it was flowing counter-clockwise around the large cold water mass south of Honshu. The same technique was applied to two drifting buoys with drogues at 300 m depth placed in the Kuroshio where it flowed clockwise around Oshima Island in Sagami Bay. The centrifugal forces were 7% and 6% as large as the Coriolis forces in the Kuroshio around the cold water mass, and they were –56% and –42% as large as the Coriolis forces in the current around the Oshima Island. The temperature gradient observed in the Oshima-West Channel suggested that the pressure gradient there was smaller due to the centrifugal force acting against the Coriolis force than the pressure gradient to be balanced with the Coriolis force.     

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

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.     

Trench triple junction off Central Japan—preliminary results of French-Japanese 1984 Kaiko cruise, Leg 2

Leg 2 of the French-Japanese 1984 Kaiko cruise has surveyed the trench triple junction off central Japan, where the Japan, Izu-Bonin and Sagami Trenches intersect. The Izu-Bonin Trench is deeper than the Japan Trench and filled by a thick turbiditic series. Its anomalous depth is explained by the westward retreat of the edge of the northwestward moving Philippine Sea plate. On the contrary to what happens in the Japan Trench, horst and graben structures of the Pacific plate obliquely enters the Izu-Bonin Trench, suggesting that the actual boundary between these two trenches is located to the north of the triple junction. The inner wall of the Izu-Bonin Trench is characterized in the triple junction area by a series of slope basins whose occurrence is related to the dynamics of this area. The northernmost basin is overthrust by the edge of the fore-arc area of the Northeast Japan plate. The plate boundary is hardly discernible further east, which makes it impossible to locate precisely the triple junction itself. These features suggest that large intra-plate deformation occurs there due to the interaction of the plates involved in the triple junction and the weak mechanical strength of the wedge-shaped margin of the overriding plates.     

On the Prediction of the Kurtosis of Velocity Derivatives in a Turbulent Field

The prediction of the values of non-dimensional fourth-order moment (kurtosis) of the velocity derivative in a turbulent field is made under the assumption that the values of kurtosis depend on both the turbulence Reynolds number and the intermittency factor. The method consists of modeling a suitable probability density of the variable in a given turbulence Reynolds number and the intermittency factor. A crude model of the probability density function is derived, and the numerical calculations based on the model show excellent agreement with many of the experimental data. The analysis shows that the values of kurtosis depend strongly on the intermittency factor, and that depending on the value of the intermittency factor, it is entirely possible to have values of kurtosis as low as five in a flow with a turbulence Reynolds number of 5000.     

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