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1.
The development process of wind-waves of which spectral peak distributes from 0.6 cps to 9.3 cps will be discussed on the basis of the wind tunnel experiments and of the field observations performed at Lake Biwa. The characteristics of power and slope spectra are here presented. The development process of these wind-waves is characterized by three stages;i.e. initial-wavelets, transition stage and sea-waves. In the wind tunnel experiments, the transition from the stage of the initial-wavelets to the transition stage occurs when the wave spectral peak arrives at the line 6.40×10–4 k –2cm2·sec (wherek is wave number) or when the slope spectral density at the frequencyf max becomes larger than 6.40×10–4 sec. In the stage of sea-waves, the component wave of a wave-spectral peak is steepest in the component waves. And the wave spectral peak develops along the line 1.02×102 f –6 cm2·sec (wheref is the frequency corresponding to the wave numberk) untill it reaches the line 33.3f –4cm2·sec, and thereafter develops along the latter line, which indicates the constant density of slope spectrum. It is suggested that the nonlinearity of wind-waves must become stronger as wind-waves develop. The effective momentum flux ws from the air flow to wind-waves in this stage is evaluated to be about 49% of the total stress 0.  相似文献   

2.
Analyses of gallium content were made by the fluorometric method on 57 samples of seaweeds which were composed of 30 species. As the result of it, the gallium content was found ranging from 0.02 to 0.64g g–1 and the average was 0.14g g–1 in the dried seaweeds.Generally, the gallium content in seaweeds had a close relationship to the aluminium and iron contents. The average weight ratio of Ga/Al was 3.8×10–4 and one of Ga/Fe was 4.0×10–4. The average Ga/Al weight ratio (3.8×10–4) was very similar to that reported for shallow-water deposits (2.1×10–4), but was definitely lower than that in sea water (1.5×10–2).  相似文献   

3.
Chlorophylla concentrations (Chla) of size-fractionated phytoplankton samples were measured in the western North Pacific Ocean, the Bering Sea, and the Gulf of Alaska during the summer of 1986. Among samples collected in the upper 100 m (total of 210 samples), 207 samples were dominated by micro- (>10 m) or picoplankton (<2 m) and only three samples were represented by nanoplankton (2–10 m). These 207 samples were classified based on the total Chla content into three types: Type H (>1.0 g l–1), Type M (0.5–1.0 g l–1), and Type L (<0.5 g l–1). These types further divided into two subtypes (-p and-m), depending upon dominancy of pico (-p) and microplankton (-m). The phytoplankton community was represented by Type L-p in the Gulf of Alaska, where 80% of the samples fell into this type. It was represented by Type M-p in the western North Pacific and the Oceanic Domain in the Bering Sea, where 53 and 41% of samples were identified as this type, respectively. In the Middle Domain of the Bering Sea, 68% of samples collected below the nitracline was Type H-m, which indicates blooms of microplanton. This type was also observed in the neritic waters near the Aleutian Islands. These types described above are consistent with a general trend that an increase in phytoplankton abundance is attributed to the growth of microplankton. An unusual type occurred above the nitracline of the Middle Domain, where microplankton prevailed, although the total Chla was less (Type L-m). This type represents a feature of late phase of an ice edge bloom. Another unusual type was found mainly in the Outer Domain of the Bering Sea, where the total Chla was high and picoplankton prevailed (Type H-p). The predominance of picoplankton seems to result from the heavy grazing intensity of large calanoid copepods upon microplankton but not upon picoplankton  相似文献   

4.
The selectivity of amino acid assimilation by marine bacteria was examined using seven kinds of14C-amino acids and the acid hydrolysate of14C-labelled proteins. It was found that the net assimilation and respiration by marine bacteria followed MICHAELIS-MENTEN kinetics for all of amino acids used in our experiments. Maximum velocities of amino acids were 0.01 to 0.19g carbon/hour per 2×107 cells for net assimilation and less than 0.18g carbon/hour per 2×107 cells for respiration at 20C. The velocity of gross assimilation was found with the following order: phenylalanine>valine, glutamic acid>serine, arginine>tryptophan>glycine. The assimilation velocities of amino acids in these laboratory works showed almost the same order as those in field experiments. The assimilation velocity of an amino acid was influenced by coexisting another amino acids or glucose. The assimilation velocity in lower substrate range of amino acids was directly proportional to the number of bacterial cells in the range from 6×102 to 3×104 cells per ml. No linear relation between the assimilation velocity of amino acids and reciprocal of absolute temperature was found, but a marked bending was observed at 15 to 20C. The velocity at the optimum temperature was three to six times of that at 5C.  相似文献   

5.
Early diagenetic properties of Amazon shelf muds are dominated by nonsulfidic Fe and Mn cycling, resulting in relatively little S deposition compared to previously studied marine margin environments. Despite abundant potential reactants typical of sulfidic deposits, authigenic sulfides represent only ~ 10% of diagenetically reduced Fe, and DOP (degree of pyritization) is only ~0.02. The average C/S (wt wt–1) ratio of buried sediment below the zone of SO4 2- reduction is ~ 7.4, ~ 2.6 times more than the commonly assumed modern shelf average of ~ 2.8. The deltaic burial rate forS is ~ 0.65 × 106 tons yr–1. Relatively lowS deposition is promoted by terrestrial weathering that delivers reactive oxide debris, but apparently depends most strongly on reoxidation and rapid burial by intense physical reworking and fluid-mud formation. Diagenetic models of S distributions demonstrate rapid sediment reworking (~ 10–100 cm yr–1 as apparent advection), substantialS reoxidation (84–98%), and in one case, massive sediment deposition of up to ~ 5 m of sediment in ~ 1 year. Extremely low DOP coupled with dominance by nonsulfidic reduced-Fe minerals and lack of biogenic sedimentary structures may be an indicator in marine organic-rich muds of intense physical reworking under oxygenated waters.  相似文献   

6.
Momentum and heat flux were measured with a sonic anemometer at the Marine Observation Tower in the port of ItÔ. Under unstable conditions (T w -T a =3C4C), using the eddy correlation method, results show thatCd=(1.2±0.3)×10–3 andCh=(1.5±0.3)×10–3 at 5.5 m above mean sea level except for the case of weak winds.An unexpected relationship betweenCd and (–z/L) was observed, that is,Cd decreases as (–z/L) increases. If roughness variation over the sea is taken into account, we can explain the decrease in the range of (–z/L) less than 1, but not in the range greater than 1. This is due to a strong instability effect and the change of roughness class, from moderately rough to smooth.  相似文献   

7.
The Alaskan Stream is the westward boundary current of the North Pacific subarctic gyre. In the central region of the North Pacific, the Alaskan Stream serves as a connection between the Alaskan gyre, Western subarctic gyre and Bering Sea gyre. Its volume transport is very important in estimating the magnitude of the subarctic circulation in the North Pacific. In order to clarify its seasonal and interannual variation, we conducted observations along a north-south section at 180° during June from 1990 to 1997. Moorings were deployed from 1995 to 1997. Hydrographic casts were made at intervals of 37 km to a depth of 3000 m. Moorings were set between CTD stations, with Moor1 (Moor2) at the center (southern edge) of the Alaskan Stream. Geostrophic volume transport (referred to 3000 m) revealed large interannual variability in the Alaskan Stream. Average volume transport over the 8 years was 27.5 × 106 m3s-1 with a standard deviation of 6.5 × 106 m3s-1. Maximum transport was 41.0 × 106 m3s-1 (1997) and minimum was 21.7 × 106 m3s-1 (1995). Stable westward flows were observed at Moor1 1500 m (259°, 11.7 cm s-1) and 3000 m (240°, 3.7 cm s-1, 1996–1997 year average). The ratio of eddy to mean kinetic energy (KE/ ) was very small (<0.6) throughout the year. A relatively weak and unstable westward flow was observed at Moor2 at 3000 m depth. Conversely, the average flow direction at Moor2 5000 m was eastward.  相似文献   

8.
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.  相似文献   

9.
Dissolved Fe and ligand concentrations and the Fe-binding strength of the organic ligands were measured in samples from the upper water column (150 m) of the oligotrophic waters of the Canary Basin (eastern North Atlantic Ocean). Concentrations of major nutrients, phytoplankton abundance and photosynthetic characteristics were also measured in the same samples.The concentrations of dissolved Fe and dissolved organic ligands were low with mean values of 0.31 ± 0.18 nM Fe and 1.79 ± 0.73 nEq of M Fe(n = 47), respectively. The conditional binding constant varied between 1019.8–1022.7 (n = 47). The largest variation with depth in the ligand concentrations (between 4.78 and 1.1 nEq of M Fe) was observed in the upper layer, above the Deep Chlorophyll Maximum (DCM located between 80 and 100 m), with high surface values in stations at 18 and 34.At the DCM where Fe was depleted, the ligand concentrations were still relatively high showing the same trend with depth as the amount of phytoplankton cells. Here 62% of the vertical variation in ligand concentrations can be explained by parameters describing phytoplankton cell abundance or biomass and orthosilicic acid concentration, which could reflect diatom growth. Ligand concentrations below the maximum of the DCM (n = 4) showed good linear positive relationships with the total phytoplankton biomass as well as with 2 out of 4 distinguished groups of phytoplankton (Synechococcus and pico-eukaryote I).In the maximum of the DCM and below this maximum the phytoplankton origin of the dissolved organic ligands of Fe is very probable. Data suggest a release of ligands by cell lysis and not by an active production. However, the origin in the surface layer is more difficult to explain. Although the amount of phytoplankton cells in the surface layer is reduced, it is still  25% of the cell concentration observed in the DCM. High concentrations of organic ligands could then be a remnant of past blooms or present production under nutrient depleted conditions. Input of Sahara dust can be another source of ligands.  相似文献   

10.
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   

11.
Back-pressured, constant-rate-of-deformation consolidation, and permeability tests were conducted on 21 undisturbed samples from Eckernförde Bay in the Baltic Sea. The soft fine-grained sediments have very high in-situ void ratios and are highly compressible. The compression index decreases slightly in the upper 40 cm but remains essentially unchanged below 40 cm at an average value of 3.5 to a depth of 260 cm. Recompression indices range from 5 to 19% of the virgin indices. The preconsolidation stress is consistently higher than the overburden stress, particularly near the surface. Permeabilities at in situ void ratios vary between 3 × 10–4 and 10–6 cm s–1, with the relationship between void ratio and the logarithm of permeability being linear.  相似文献   

12.
The vertical distributions of suspended particles in Osaka Bay were measured by using anin situ beam attenuation meter. The concentration of suspended particles near the bottom increases rapidly toward the bottom where size of sediment is in a range of silt. The settling velocity of suspended particles near the bottom was measured with the use of a settling tower in the laboratory. The settling velocity of the suspended particles with diameter from 10 to 100m is 2×10–3cm s–1 to 5×10–2cm s–1. The density of the particles ranges from 2.0 to 1.1 and decreases with increasing particle diameter.  相似文献   

13.
Different estimates were used to assess the diversity of the total macrofauna and its major taxonomic groups separately from a broad bathymetric range at a site in the NE Atlantic. In the Goban Spur region, a transect was sampled from the shelf to the abyssal plain over a depth range from 200 to 4500 m and in the Porcupine Sea Bight two stations were sampled (at 3670 m and 4115 m). Species diversity (the number of species per number of individuals) increased with increasing water depth, both when expressed as Hurlbert's E(Sn) and as Shannon's H′log e. The expected number of species in a 100-individual sample E(S100) of total macrofauna increased from 30 on the shelf to 68 on the abyssal plain. Evenness (the proportional abundance of species), estimated with Shannon's J′, also increased with water depth from 0.66 to 0.91, whereas dominance (Simpson's D) decreased from 0.09 to 0.01. Species richness (the number of species per unit of area), however, showed a parabolic pattern with a peak at the upper slope. The largest number of species was found at the slope station at 1425 m (232 species within 0.66 m2). It is argued that species richness is not a synonym of species diversity, but that species richness depends both on species density (which decreases with increasing water depth) and on species diversity. Across the whole bathymetric range (200 to 4500 m) a total of 696 species within 8327 specimens in a total sampled area of 4.12 m2 were counted, yielding mean values of 12 individuals per species and 169 species per m2. Different communities were found to exist on the shelf, slope and abyss. It is suggested that this could have been caused by different selection processes. Differences in life-history strategies and organic-matter supply could (at least partly) explain the different community structures and diversity patterns found along the depth gradient.  相似文献   

14.
Radiocarbon and total carbonate data were obtained near the 1973 GEOSECS stations in the North Pacific along 30°N and along 175°E between 1993 and 1994. In these stations, we estimated radiocarbon originating from atomic bomb tests using tritium, trichlorofluoromethane and silicate contents. The average penetration depth of bomb radiocarbon during the two decades has deepened from 900 m to 1300 m. Bomb radiocarbon inventories above the average value for the whole North Pacific were found widely in the western subtropical region around 30°N both in the 1970s and 1990s, and its area in the 1990s was broader than that in the 1970s. In most of the North Pacific, while the bomb radiocarbon has decreased above 25.4, the bomb radiocarbon flux below 25.4 was over 1 × 1012 atom m-2yr-1 in the subtropical region around 30°N. In the tropical area south of 20°N, the bomb radiocarbon inventory below 25.4 increased from zero to over 10 × 1012 atom m-2 during the last three decades. These distributions suggest that the bomb radiocarbon removed from the surface is currently accumulated with bomb 14C flux of over 1 × 1012 atom m-2yr-1 below 25.4 in the subtropical region, mainly by advection from the higher latitude, and that part of the accumulated bomb 14C gradually spread southward with about 30 years.  相似文献   

15.
In the spring of 1988, time series of microstructure and ADCP current profiles were collected at four locations in the North Main Basin of Puget Sound, Washington. Depth and time averages of diapycnal diffusivity at the four stations (1.8−67.0×10−4 m2 s−1) were one to three decades above typical open-ocean thermocline levels. The buoyancy frequency-squared N2 was near open-ocean levels, but unlike the open-ocean where N2S2, finescale shear-squared S2 was three to six times N2 over significant portions of the water column at two of the stations. The time and space mean of all measurements ( ) is close to inferred vertical eddy diffusivity from a primitive equation model for Puget Sound (Kz=3×10−3 m2 s−1) (J. Geophys. Res. 96 (1991) 16779). Large time and space variability of Kρ was found, with differences of inter-station, depth–time means over one decade. A simple scaling argument using the observed Kρ suggests significant exchange of mass between the layers of the subtidal flow over the basin's residence time. Additionally, measurements show that local mixing may be comparable to volume-weighted sill mixing in modifying the Main Basin's stratification. Both are contrary to the “advective reach” simplification of fjord dynamics. The mixing levels were dominated by the passage of a mid-depth, southward-flowing density intrusion and what we interpret as a strongly advected, non-linear internal tide. These mechanisms elevated profile-averaged Kρ by more than 10 times background levels, with sustained patches of Kρ≥1×10−2 m2 s−1. Critical 8-m gradient Richardson numbers (Ri8<0.25) matching regions of overturns (>20 m) and strong turbulence suggest that shear instabilities dominated the turbulence production, though there was support for double-diffusive convection in the warm core of the density intrusion.  相似文献   

16.
The activity of234Th (t 1/2=24.1 days) in dissolved, particulate and sediment trap samples was determined in the water column off southwestern Taiwan during 2–4 October, 1993. Vertical234Th fluxes measured by the free-floating sediment traps ranged from 363 to 2290 dpm m–2 d–1 in the upper 450 m. Th-234 fluxes predicted from the irreversible scavenging model concur with those measured by the sediment traps. Comparison of the residence times of particulate234Th and particulate organic carbon showed that their respective values differ by a factor of approximately 23, which suggests organic carbon is preferentially recycled relative to234Th in the euphotic zone.  相似文献   

17.
The stability constants for sulfate, chloride and hydroxide ions with cerium (III) in the solution at ionic strength of 0.67 have been determined by cation exchange method, the values of 1 and 2 for sulfate complexes of cerium being 40±13 and 453±140, respectively and those for chloride complexes being 1.28±0.23 and 0.56±0.076, respectively. The values of 1, 2 and 3 for hydroxide complexes of cerium were (4.5±0.9)×107, (3.3±0.7)×1014 and (1.8±0.7)×1023, respectively.Using the above constants the ratios of individual chemical species of144Ce were calculated in a solution at ionic strength of 0.67 containing sulfate and chloride ions approximately the same as in seawater of 35 %. The result of calculation indicates that the dominant species of144Ce in this solution is Ce(OH)3 0 at pH 8.  相似文献   

18.
The effects of irradiance on the excystment of tintinids from marine sediments were examined by incubating sediment samples in filtered seawater under various light levels. The total incidence of tintinnid excystment over five days was significantly less at low irradiance at and less than 2.5 E m–2sec–1 comparing to that at higher irradiance, at and more than 6.9 E m–2sec–1 (p<0.01), indicating that excystment of tintinnids is inhibited under low irradiance conditions. These results imply that water depth, disturbance of surface sediments and vertical mixing of water influence the excystment of tintinnids in coastal areas because these factors determine the light levels to which the tintinnid cysts are exposed.  相似文献   

19.
The respiration rates of copepod larvae and a ciliate (Placus sp.) from a tropical sea were measured with an oxygen electrode method. The general range of body size of these animals was 40–161m (diameter equivalent to a sphere), and the respiration rate measured was 0.00076–0.00176l O2 (animal)–1h–1 (or 2.02–9.05l O2 (mg wet weight)–1h–1) at 25.5–29.2C. There was no marked difference observed between the respiration rates of copepod larvae and the ciliate. The respiration rates obtained here are relatively higher than the rates of other similar sized protozoans found in the literature, but lower than the rate extrapolated from larger planktonic copepods in tropical seas.The present results and other information available on microzooplankton biomass suggest that microzooplankton respiration is of near equal importance to that of net zooplankton in the study of energy flow through tropical, pelagic ecosystems.  相似文献   

20.
Dependences have been determined which connect the parameters of the dispersion relation of the lowest mode of internal waves with the integral characteristics of the seasonal thermocline when 10 min30 min, 20 mh150 m, and 0·4 m2/s2 Q5·2 m2/s2.Translated by Mikhail M. Trufanov.  相似文献   

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