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421.
422.
Norio Ogura Yoshiharu Tanaka Jun-ichi Itoh Katsufumi Takahashi 《Journal of Oceanography》1984,40(3):184-191
Behaviour of dissolved and particulate proteinaceous substances in the estuary of the Tama River was investigated through field observations and laboratory experiments. Concentrations of dissolved proteinaceous substances in estuarine water were determined at eight stations between the mouth of the Tama River (TA-15) and a point 16km upstream (TA-8), using the colorimetric method of Lowryet al. (1951) that employs Folin phenol reagent. The results were expressed in terms of Folin phenol active substances (FPAS). It was found that FPAS decreased with increasing salinity and that the proportion of high molecular weight FPAS (molecular weight greater than 100,000) decreased rapidly in the estuary.The shapes, sizes and numbers of amorphous particulate substances stained by Amido Black 10B, called Amido Black active substances (ABAS), were determined under a microscope. The numbers of ABAS retained on Millipore HA filters (mean diameter: 10–80µm) amounted to 450ml–1 in the estuarine water about 6km from the mouth of the estuary (Station TA-12M). Some of these aggregates are considered to be producedin situ by flocculation of high molecular weight FPAS during estuarine mixing. ABAS were also produced in experiments by mixing filtered river water with sea water. 相似文献
423.
Masayuki Takahashi Toshisuke Nakai Takashi Ishimaru Hiroshi Hasumoto Yoshihiko Fujita 《Journal of Oceanography》1985,41(2):73-80
Continuous distribution of the subsurface chlorophyll maximum (SCM) was confirmed in the Kuroshio and neighbouring areas in observations at 15 to 40 km intervals. Chlorophyll amounts occurring in and immediately around the SCM constituted 60 to 80% of the total chlorophyll in the water column above the 1% light level. The SCM zone received 1 to 10% of the surface irradiance at its center and contained sufficient macronutrients to support approximately one doubling of the existing phytoplankton biomass at most stations. There were several stations where there were higher nutrient concentrations that would support more than one doubling of the existing biomass around the SCM zone, and this was interpreted as resulting from uplift of the SCM zone due to upwelling. 相似文献
424.
Photosynthetic pigment system of picophytoplankton of cyanophytes was examined with five strains isolated from the Kuroshio
water at the depth of 70 m. Examination was made for the absorption spectra of intact cells of each strain. Analysis of pigment
composition was also made withSynechococcus NIBB 1059 and 1071, which were isolated from surface waters of the Gulf Stream and Kuroshio area, respectively. Results indicated
that (1) all strains contain phycoerythrin with a very high concentration, and (2) the phycoerythrin in these strains contains
two chromophores, phycoerythrobilin and phycourobilin, and (3) a large abundance of phycoerythrin and phycourobilin in the
phycoerythrin enablesSynechococcus picophytoplankton to absorb effectively the light in the blue-green region at the subsurface depth. These characteristics
suggest that cyanophytes in the subsurface water can collectt the blue-green light and perform actively photosynthesis even
at the bottom of euphotic layer. 相似文献
425.
High Ash Content in Net-Plankton Samples from Shallow Coastal Water: Possible Source of Error in Dry Weight Measurement of Zooplankton Biomass 总被引:2,自引:0,他引:2
Norio Nagao Tatsuki Toda Kazutaka Takahashi Koji Hamasaki Tomohiko Kikuchi Satoru Taguchi 《Journal of Oceanography》2001,57(1):105-107
Annual examination of net-plankton biomass in dry weight, ash-free dry weight, organic carbon, and nitrogen weight at the Manazuru harbor, central Japan revealed that net-plankton samples from shallow coastal water contained considerable amount of ash (53±13% of dry weight) which would be caused by contamination of inorganic materials from re-suspendion of sediments, terrestrial runoff and chain-forming diatoms. Therefore, in coastal water, dry weight is inadequate fro determination of zooplankton biomass in volving the possibility of over-estimation. Practical estimation of net-plankton biomass in shallow coastal waters, ash-free dry weight, organic carbon, and/or nitrogen are more adequate. 相似文献
426.
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
427.
Tatsuki Toda Tomoko Okashita Takeshi Maekawa Bin Abdul Adzis Kee Alfian Mohd Kushairi Mohd Rajuddin Ryota Nakajima Wenxi Chen Kunio T. Takahashi Bin Haji Ross Othman Makoto Terazaki 《Journal of Oceanography》2007,63(1):113-123
Coral community structures at eleven fringing reef sites were investigated along the coast of Peninsular Malaysia. Estimated
coverage of coral communities is examined by applying quantitative digital image analysis to the line transect method. Four
coral community types were characterized by dominant genera and lifeforms: Acropora branching community, Montipora-Acropora community, Porites massive community, and Heliopora community. Live coral coverage in all study sites ranged from 17.9% to 68.6%. Most reefs were in “fair” condition while some
reefs were shown to be in “poor” condition. Coral community structures among the study sites were divided into the west coast
of Peninsular Malaysia with a dominant Porites massive lifeform, and the east coast with a variety of lifeform categories of Montipora and Acropora. Physical effects such as the monsoon wind regime and sedimentation are likely to influence the formation of dominant coral
communities around Peninsular Malaysia. 相似文献
428.
Chlorophyll a concentrations of net (retained on 30 m mesh net) and total plankton in surface waters were determined along cruise tracks in an area of the northern North Pacific Ocean and the adjacent Bering Sea and the Gulf of Alaska from summer to autumn. Total chlorophyll a concentrations were high with a great areal and temporal variations in the western northern North Pacific compared to the eastern part. Chlorophyll a concentrations of netplankton varied from 0.001 to 0.230 g chl a l–1 (average, 0.029 ± 0.040 g chl a l–1), and showed a positive relation but a weak regression coefficient (r
2 = 0.551) against the "average total chlorophyll a" (average of total chlorophyll a at the beginning and at the end during sampling of netplankton). However there were several data points showing high "average total chlorophyll a" but low netplankton and vice versa. Average percentage share of netplankton in the total chlorophyll a was estimated to be as large as 4.26%. 相似文献
429.
A total of 33 elements (Ag, Al, Au, Bi, Br, Cd, Ce, Co, Cr, Cs. Eu, Fe, Ge, Hf, Ir, Lu, Na, Ni, Os, Pd, Rb, Re, Sb, Se, Se, Si, Sm, Tb, Te, Tl, U, Yb and Zn) were analyzed by radiochemical and instrumental neutron activation in four eucrites: Juvinas (brecciated), Ibitira (vesicular, unbrecciated) and Moore County and Serra de Magé (cumulate, un brecciated).When arranged in order of volatility. Cl—normalized abundance patterns allow nebular and planetary effects to be distinguished. The stepped lithophile pattern reveals the dominance of nebular processes; in Ibitira, refractory elements (Hf, Lu, Tb, Ce, Sm, Yb, U, Eu) are (13.1 ± 0.7) × Cl chondrites; volatile elements (Rb. Cs, Br, Bi) are (6.0 + 1.5) × 10?2 Cl. The depletion of Tl seems inherent to the eucrite parent body and is mirrored in the chalcophile elements by the marked deficit of Te relative to Se; apparently volatiles were accreted as a fractionated C3-like component. Consistent but subtle Cl-normalized abundance differences between eucrites (Serra de Magé < Moore County < Juvinas < Ibitira) result from crystal/liquid differentiation; Ibitira approximates the composition of an undifferentiated eucrite magma. The siderophile pattern retains little sign of nebular processes, but reflects planetary metal-silicate partition.The bulk composition of the eucrite parent body closely resembles that of H-chondrites, except for two features: moderately volatile elements (e.g. Na, K. Rb) are very much lower, apparently due to the accretion of more chondrule-like material; the metallic Fe-Ni content is only ~13%, even though total iron is very similar. 相似文献
430.
The authors report here halogen concentrations in pore waters and sediments collected from the Mallik 5L-38 gas hydrate production research well, a permafrost location in the Mackenzie Delta, Northwest Territories, Canada. Iodine and Br are commonly enriched in waters associated with CH4, reflecting the close association between these halogens and source organic materials. Pore waters collected from the Mallik well show I enrichment, by one order of magnitude above that of seawater, particularly in sandy layers below the gas hydrate stability zone (GHSZ). Although Cl and Br concentrations increase with depth similar to the I profile, they remain below seawater values. The increase in I concentrations observed below the GHSZ suggests that I-rich fluids responsible for the accumulation of CH4 in gas hydrates are preferentially transported through the sandy permeable layers below the GHSZ. The Br and I concentrations and I/Br ratios in Mallik are considerably lower than those in marine gas hydrate locations, demonstrating a terrestrial nature for the organic materials responsible for the CH4 at the Mallik site. Halogen systematics in Mallik suggest that they are the result of mixing between seawater, freshwater and an I-rich source fluid. The comparison between I/Br ratios in pore waters and sediments speaks against the origin of the source fluids within the host formations of gas hydrates, a finding compatible with the results from a limited set of 129I/I ratios determined in pore waters, which gives a minimum age of 29 Ma for the source material, i.e. at the lower end of the age range of the host formations. The likely scenario for the gas hydrate formation in Mallik is the derivation of CH4 together with I from the terrestrial source materials in formations other than the host layers through sandy permeable layers into the present gas hydrate zones. 相似文献