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61.
To study biological effects on the particulate removal of chemical elements from seawater, sediment trap experiments were carried out successively ten times throughout the spring phytoplankton bloom in Funka Bay. Sediment traps were deployed every one to two weeks at 1, 40 and 80 m depths. The settling particles obtained were analyzed for trace metals, phosphate and silicate. The propagation of diatoms in spring results in larger particulate fluxes than that of dinoflagellates. The biogenic silicate concentration is higher in the earlier period, when diatoms are predominant, than in the subsequent period, when dinoflagellates are predominant. The concentrations of aluminum, iron, manganese and cobalt in the settling particles comprising largely biogenic particles are lower during phytoplankton bloom. The concentration of copper is not reduced by the addition of biogenic particles, and its vertical flux is approximately proportional to the total flux, indicating that its concentration in the biogenic particles is nearly equal to that in the non-biogenic particles. The results for nickel and lead show the same tendency as for copper. Cadmium is more concentrated in biogenic particles than in non-biogenic particles, and the concentration of cadmium in the settling particles decreases with depth, similarly to phosphate and organic matter. Thus, metals in seawater are segregated by biological affinities, and the degree of incorporation into biogenic particles is in the order Cd > Pb, Ni, Cu > Co > Mn, Fe, Al. Biogenic particles are the most important agent controlling the vertical distribution of metals in the ocean. They remove the metals from the surface water, transport them through the water column, and regenerate them in the deep. 相似文献
62.
Each about 400 l of seawater sample was collected in the northern North Pacific and filtered through a membrane filter. Four radioisotopes of thorium,232Th,230Th,228Th and234Th, were determined for the two FractionsF (filtrate) andP (particles on the filter). In the percentages of FractionP in the subsurface water,230Th was significantly larger than other 3 isotopes, and232Th was significantly smaller than other 3 isotopes. The former finding can be explained by the slower rates in the reversible change between the FractionsF andP. The latter one, however, cannot be explained if thorium isotopes in the FractionF are truly dissolved with the same chemical form. This suggests that major part of the FractionF of232Th is not identical with those of other radiogenic thorium isotopes, and it should not be composed of simple dissolved ions. The removal of radiogenic234Th was related to the biological activity, but there was a deviation, between the FractionP and radioactivity deficiency of234Th in their vertical profiles. The deviation was similar to that between the chlorophylla and phaeo-pigments contents including their maximum depths. 相似文献
63.
A practical method has been developed for the simultaneous determination of226Ra,234Th,210Pb and210Po in seawater. In the method, the samples are spiked with228Ra,230Th,208Po and common lead to determine chemical yield. These nuclides are coprecipitated with calcium carbonate and ferric hydroxide from 20 to 50 l of seawater and separated from one another by using coprecipitation and ion exchange techniques. Counting sources of Ra and the other nuclides are prepared by electrodeposition onto silver discs. Their radioactivities are counted with an-spectrometer and a low background-counter. This method gives a standard deviation of about 5% for replicate determination of226Ra and the other nuclides. 相似文献
64.
Vertical profiles of tritium in seawater were determined for samples collected during the period from 1988 to 1990 at fourteen stations in the northwestern North Pacific (the Oyashio region) including the Okhotsk Sea and the Bering Sea. The profiles usually had a maximum in the surface layer and decreased gradually with depth down to 1,000 m. The water column inventory of tritium averaged 63% of the total atmospheric input in this region.The horizontal distribution of tritium showed a maximum in the region facing the Okhotsk Sea near 45°N for every isopycnal surface of
0
ranging from 26.60 to 27.40. The ages of the intermediate water were calculated for the respective isopycnal surfaces in the maximum region. This calculation assumed that the intermediate water was formed by the isopycnal mixing of two water masses—the Okhotsk Sea and the Bering Sea Component Waters, which had been produced in wintertime by the diapycnal mixing of the surface and the deep waters in the respective marginal seas. The results show that the intermediate water in this region was formed in the late 1980's for the water which has
0
of 26.60 to 26.80 and about 1970 for the water which has
0
of 27.00 to 27.40. Although we have estimated the mean ages of the intermediate water, the horizontal profile of dissolved oxygen suggests that the Okhotsk Sea Component Water is younger than the mean age. 相似文献
65.
Shuichi Watanabe Hiroshi Yamamoto Shizuo Tsunogai 《Journal of Atmospheric Chemistry》1995,22(3):271-283
The concentrations of DMS were simultaneously measured in both water and air at the sea surface on board a vessel during a trans-Pacific cruise around 40° N in August 1988. Those in the surface seawater varied widely with a mean of 162 ng S/1 and a standard deviation of 134 ng S/1 (n=37), but the variation was not a mere fluctuation and the high concentration (376 ng S/1) was found in the area between 145° W and 170° W. The atmospheric DMS concentration varied more widely with a mean value of 177 ng S/m3 and a standard deviation of 203 ng S/m3 (n=23). The diurnal variation of DMS was not significant in the air near the sea surface. However, the concentrations in the surface water was fairly well correlated with those in the surface air. The correlation coefficient (r
2=0.86) was larger than that between the atmospheric concentration and outflux of DMS (r
2=0.64). These findings mean that the turnover time of DMS in the atmosphere is not extremely short. Based on the linear relation between the atmospheric and seawater DMS, the turnover time of the atmospheric DMS has been calculated to be 0.9 days with an uncertainty of around 50%. The oxidation rate agrees fairly well with that expected from the OH radical concentration in the marine atmosphere. 相似文献
66.
Masahito Shigemitsu Hisashi Narita Yutaka W. Watanabe Naomi Harada Shizuo Tsunogai 《Marine Chemistry》2007,106(3-4):442-455
A sediment core covering the last 145 kyrs was collected in the western subarctic Pacific (WSAP), and analyzed for Ba, U, Al, Sc, La, Yb, Th, biogenic opal (Opal) and organic carbon (Corg) as well as its isotopic ratio (δ13C). This study examined the change of past biological production in WSAP with multiple proxies, together with understanding the relation between Loess from the Asian continent and the biological production. The Loess content was estimated from the metal components, Al, Sc, La, Yb and Th. In this high latitude core (50°N), the Loess content was generally high during the glacial periods, but it was also high even in some interglacial periods. The excess amount of Ba relative to the detrital material composition, Baex, showed the best correlation with the Vostok δD (r = 0.72, p < 0.001), indicating that the biological production was lower in the glacial periods than in the interglacials. This corroborates the pervasive correlation between Baex in the polar region, WSAP and the Antarctic Sea, and Antarctic temperature, combined with previous research. This correlation might be explained by the stratification caused by cooling. In addition, the time variations of Baex in WSAP were similar to those of Baex in the Okhotsk Sea and of other proxies (Corg and Opal) in both the Okhotsk and the Bering Sea, indicating the spatial homogeneity of Baex in WSAP including proximal marginal seas. The Opal content was more weakly correlated with the Vostok δD (r = 0.46, p < 0.001) than Baex, reflecting that Opal in WSAP including proximal marginal seas was spatially heterogeneous compared to Baex. While both the Corg content and Uex, the excess amount of U relative to the detritus composition, were not positively correlated with the Vostok δD, they behaved similarly in the sediments. The positive correlation between δ13C and the Vostok δD (r = 0.42, p < 0.001), between δ13C and Baex (r = 0.60, p < 0.001) and between δ13C and Opal (r = 0.36, p < 0.01) indicates that δ13C in WSAP may give some information on the phytoplankton growth rate. There was not a significant correlation between the spatially homogeneous Baex in WSAP and Loess (r = − 0.16, p > 0.01), suggesting that the increase of biological production with the increase of Loess supply during the glacial periods did not occur. 相似文献
67.
Masahide?WakitaEmail author Shuichi?Watanabe Yutaka?W.?Watanabe Tsuneo?Ono Nobuo?Tsurushima Shizuo?Tsunogai 《Journal of Oceanography》2005,61(1):129-139
The dissolved inorganic carbon (DIC) and related chemical species have been measured from 1992 to 2001 at Station KNOT (44°N, 155°E) in the western North Pacific subpolar region. DIC (1.3∼2.3 µ mol/kg/yr) and apparent oxygen utilization (AOU, 0.7∼1.8 µmol/kg/yr) have increased while total alkalinity remained constant in the intermediate water (26.9∼27.3σθ). The increases of DIC in the upper intermediate water (26.9∼27.1σθ) were higher than those in the lower one (27.2∼ 27.3σθ). The temporal change of DIC would be controlled by the increase of anthropogenic CO2, the decomposition of organic matter and the non-anthropogenic CO2 absorbed at the region of intermediate water formation. We estimated the increase of anthropogenic CO2 to be only 0.5∼0.7 µmol/kg/yr under equilibrium with the atmospheric CO2 content. The effect of decomposition was estimated to be 0.8 ± 0.7 µmol/kg/yr from AOU increase. The remainder of non-anthropogenic CO2 had increased by 0.6 ± 1.1 µmol/kg/yr. We suggest that the non-anthropogenic CO2 increase is controlled by the accumulation of CO2 liberated back to atmosphere at the region of intermediate water formation due to the decrease of difference between DIC in the winter mixed layer and DIC under equilibrium with the atmospheric CO2 content, and the reduction of diapycnal vertical water exchange between mixed layer and pycnocline waters. In future, more accurate and longer time series data will be required to confirm our results. 相似文献
68.
Uranium in coastal sediments of Tokyo Bay and Funka Bay 总被引:2,自引:0,他引:2
Shizuo Tsunogai Seiya Nagao Shintaro Watanabe Yoshiaki Takahashi Kazunari Suzuki Masatoshi Yamada Koh Harada 《Journal of Oceanography》1990,46(5):211-218
The sediment cores from Tokyo Bay and Funka Bay were analyzed for U and its isotopic ratio,234U/238U, after dissolving them in 0.1 M HCl, and 30% H2O2 in 0.05 M HCl. A small fraction of U in the anoxic sediments was dissolved in 0.1M HCl and even the added yield tracer,232U, was lost. The isotopic ratio of H2O2 soluble U in the sediments was equal to that of seawater, suggesting that the H2O2 soluble U in the sediments is authigenic. The 6M HCl solution dissolved part of the lithogenic U besides the authigenic U. The depth profiles of U from the two bays resembled each other. The authigenic U comprised more than half of the total U even at the surface and increased with depth down to 70 cm, showing small maxima at about 20 cm. The concentration of refractory U was nearly constant with depth and similar to that of the pelagic sediments. The highest U concentration, 6 µg g–1 which was about 5 times that of the pelagic sediments, was observed in the layer between 70 and 160 cm depth in Tokyo Bay. The annual sedimentation rates of U in the Tokyo Bay sediments were 2.6 tons at the surface and 7.0 tons at the 70–160 cm depth. The increase in U with depth should be due to the deposition of interstitial U either diffusing downward from the surface indicating the trapping of seawater U, or otherwise diffusing upward from the deeper layer indicating the internal cycling of U within the sediments. 相似文献