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451.
We used a one dimensional, multi-element model to simulate the primary production (PP), recycling and export of organic matter at Stn. ALOHA, near Hawaii. We compared versions of the model with and without the cycling of dissolved organic matter (DOM) via the Microbial Food Web (MFW). We incorporated recently published measurements of high C:N ratios for uptake by diazotrophs. For other phytoplankton we included a formulation for overflow production of dissolved organic carbon (DOC), which occurs under nutrient-limited, light-replete conditions. We were able to match the observed mean DOC profile near the surface with both models, by tuning only the fraction of overflow DOC that is labile. The simulated bulk C:N remineralization ratio from the MFW model agreed well with a data-based estimate for the North Pacific subtropical gyre, but that from the Base model was too low. This is because the MFW model includes bacteria, with their low-C:N biomass. Simulated mean PP was lower than observed by 10% (Base) and 27% (MFW). This is consistent with the expectation that the 14C-method measures something greater than net production. DOC accounted for approximately half of simulated PP, most of this being overflow DOC. We find that overflow production and the MFW are key processes for reconciling the various data and PP measurements at this oligotrophic site. The impact of bacteria on the C:N remineralization ratio is an important link between ecosystem structure and the cycling of carbon. 相似文献
452.
Akihiko Murakami Tokio Matsuda Nobuhiro Watanabe Shinichi Nagasawa 《Journal of Oceanography》1976,32(5):242-248
The ability to degraden-paraffin mixture of two bacterial strains,Caulobacter sp. andFlavobacterium sp., isolated from sea water of Tokyo Bay was studied experimentally in the enriched seawater (ESW) medium. These bacteria degraded actively the mixture ofn-tridecane,n-tetradecane,n-pentadecane andn-hexadecane. The maximum rate of degradation was observed after a lag period of 2 to 8 day and these bacteria were found to degrade then-paraffin mixture at rates calculated to be in a range from 3.3×10?12 to 3.4×10?11 mg-oil cell?1 h?1 at 20°C. The maximum degradation rate,r m mg-oil l?1 h?1, was correlated with the amount of the initial totaln-paraffin,S mg-oil l?1, as expressed by the following equation: $$rm = (rm)\max \left( {\frac{S}{{S + Km}}} \right)$$ where (r m )max denotes the largest value ofr m whenn-paraffin exists in large excess andK m is a constant and represents the amount ofn-paraffin at which the degradation rate,r m , reaches 1/2 of its largest value, (r m )max. The values of (r m )max andK m were calculated to be as follows: In the case ofCaulobacter sp. (strain KM-1), (r m )max=6.0 mg-oil l?1 h?1 andK m =191 mg-oillesw ?1; in the case ofFlavobacterium sp., (r m )max=5.47 mg-oil l?1 h?1 andK m =152 mg-oillesw ?1. 相似文献
453.
Nutrient requirements of a red tide flagellate,Chattonella antiqua, were investigated in a laboratory culture experiment. Growth ofC. antiqua was supported by nitrate and ammonium, and by urea to a limited extent, but not by glycine, alanine and glutamate. Orthophosphate served as a good phosphorus source but glycerophosphate did not. Fe3+ (1µM) fully promoted the flagellate's growth in the presence of 80µM of EDTA. The addition of Mn2+ (0–20µM), Zn2+ (0–10µM) and Co2+ (0–0.4µM) did not show any effect. Among three vitamins tested, only B12 (6 ng 1?1) served as a growth factor. Glucose, acetate and glycolate did not improve growth in the light nor did they support growth in darkness. The minimum cell quotas for nitrogen, phosphorus, iron and B12 were estimated to be 11 pmoles ce?1, 1.0, ~0.09 and 1.1 fg cell?1, respectively. 相似文献
454.
Estimates of Energy Dissipation Rates in the Three-Dimensional Deep Ocean Internal Wave Field 总被引:2,自引:0,他引:2
Using the “Eikonal Approach” (Henyey et al., 1986), we estimate energy dissipation rates in the three-dimensional Garrett-Munk internal wave field. The total energy dissipation rate within the undisturbed GM internal wave field is found to be 4.34 × 10−9 W kg−1. This corresponds to a diapycnal diffusivity of about 0.3 × 10−4 m2s−1, which is less than the value 10−4 m2s−1 required to sustain the global ocean overturning circulation. Only when the high vertical wavenumber, near-inertial current shear is enhanced can diapycnal diffusivity reach ∼10−4 m2s−1. It follows that the energy supplied at low vertical wavenumbers and low frequencies is efficiently transferred to high vertical wavenumbers and near-inertial frequencies in the mixing hotspots in the real ocean. 相似文献
455.
Deep-sea sediment cores ranging up to 30,000–80,000 yrs in age were taken from a southern region of the Japan Sea and subjected to analyses for 5 major and 11 trace elements by means of instrumental photon activation analysis with 30 MeV bremsstrahlung. These elements were Ca, Fe, Mg, Na, Ti, Ba, Ce, Co, Cr, Mn, Nb, Ni, Rb, Sr, Y and Zr. Additionally, Al was determined spectrophotometrically. Distribution patterns of these elements with depth in the sediment columns were derived. Enrichments of Ca and Sr by biogenous process were observed; these Ca maxima are well correlated with Mn maxima. Below the Holocene—Pleistocene boundary, continuous transportation of poorly degraded continental debris, which was low in metallic constituents, was noted. A distinct enrichment of the top layer of the sediments in Mn was observed. This is the result of post-depositional upward migration of Mn. Fe, Co and Ni were also enriched in the top layers. In the central part of the basin, the oxidized post-glacial zone appears to be a typical pelagic sediment. 相似文献
456.
Michio J. Kishi Hitoshi Motono Makoto Kashiwai Atsushi Tsuda 《Journal of Oceanography》2001,57(5):499-507
A vertical one-dimensional ecosystem model with vertical migration of zooplankton was constructed and applied to Station A-7
off Sanriku district of Japan in the northwest Pacific Ocean. The model consists of an eight-compartment ecosystem model coupled
with a physical model of the oceanic mixed layer. The transition of phytoplankton species responsible for the spring bloom
is well reproduced by this model with vertical migration of zooplankton but is not simulated by the model without vertical
migration. This new model also simulates an observed inter-annual variability of the spring bloom, with the timing and intensity
of the simulated bloom in a given year depending upon the strength of mixing during the preceding winter.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
457.
Kay I. Ohshima Genta Mizuta Motoyo Itoh Yasushi Fukamachi Tatsuro Watanabe Yasushi Nabae Koukichi Suehiro Masaaki Wakatsuchi 《Journal of Oceanography》2001,57(4):451-460
In the southwestern part of the Okhotsk Sea, oceanographic and sea-ice observations on board the icebreaker Soya were carried out in February 1997. A mixed layer of uniform temperature nearly at the freezing point extending down to a
depth of about 300 m was observed. This is much deeper than has previously been reported. It is suggested that this deep mixed
layer originated from the north (off East Sakhalin), being advected along the shelf slope via the East Sakhalin Current, accompanied
with the thick first-year ice (average thickness 0.6 m). This vertically uniform winter water, through mixing with the surrounding
water, makes the surface water more saline (losing a characteristic of East Sakhalin Current Water) and the water in the 100–300
m depth zone less saline, colder, and richer in oxygen (a characteristic of the intermediate Okhotsk Sea water). The oceanographic
structure and a heat budget analysis suggest that new ice zone, which often appears at ice edges, can be formed through preconditioning
of thick ice advection and subsequent cooling by the latent heat release due to its melting.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
458.
Takashi Yabuki Toshio Suga Kimio Hanawa Koji Matsuoka Hiroshi Kiwada Tomowo Watanabe 《Journal of Oceanography》2006,62(5):649-655
It has been inferred that the Prydz Bay region is one of the source regions of Antarctic Bottom Water (AABW) based on rather
indirect evidence. In order to examine this inference, we investigate the hydrographic condition of the bay based mainly on
XCTD data obtained during the Japanese Whale Research Program in the Antarctic (JARPA). The JARPA hydrographic data reveal
Circumpolar Deep Water (CDW), which is a salty, warm water mass approaching the shelf break, and capture Modified CDW (MCDW)
intruding into the shelf water. AABW production requires mixing of CDW and cold shelf water saltier than 34.6 psu, which is
a saltier type of Low Salinity Shelf Water (LSSW). Saltier LSSW is observed near the bottom over the shelf, being mixed with
MCDW. We further identify saltier LSSW near the shelf break. This saltier LSSW appears close enough to unmodified CDW to be
mixed with it over the continental slope, indicating a possible source of AABW in Prydz Bay. 相似文献
459.
The fall-rate of the T-5 expendable bathythermograph (XBT) produced by Tsurumi Seiki (TSK) Co., Ltd and that by Sippican Inc.,
are intercompared by a series of contemporaneous and colocated measurements with conductivity-temperature-depth (CTD) profilers.
It is confirmed that the fall-rates of the two manufacturers' T-5 differ by about 5 percent, despite the fact that they had
been believed to be identical for many years. The cause of the difference is discussed on the basis of a detailed cross-examination
of the two T-5 models. It is found for the first time that the two models are different in several respects. The manufacturer's
fall-rate equation is only applicable to the Sippican T-5, for which Boyd and Linzell's (1993) equation seems to be slightly
more accurate. Kizu et al.'s (2005) equation gives a clearly less biased depth than the manufacturers' equation for the TSK T-5. It is also found that
the fall-rates of both T-5 models are dependent on water temperature, perhaps because of viscosity. The temperature-dependency
of the fall-rate of the TSK T-5 is larger than that of the Sippican T-5. 相似文献
460.
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