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1.
A preliminary theoretical and experimental study was conducted on internal wave modes and their weak nonlinear resonant interaction
in a nonlinearly stratified fluid. An asymptotical solution of the modes and a dispersion relation of internal waves in a
stratified fluid with density profile
similar to that in our experiment were obtained theoretically. The resonant-interaction mechanism to 2nd order approximation
is also discussed. The resonant interaction of the 3rd and 4th mode internal waves excited by the unstable 1st mode wave is
analyzed on the basis of data obtained by conductivity probes. The resonant-interaction condition, i.e.,
,k
1+k
3+k
4=0, is examined. It is shown that the resonant instability increases with pycnocline thickness and wave maker driving frequency.
This work is supported by the National Natural Science Foundation of China. 相似文献
2.
Microstructure profiling measurements taken on a shallow Black Sea shelf and in Lake Banyoles and Boadella reservoir (Both in Spain) are analyzed to investigate the influence of boundary-layer-induced turbulence of various sources on mixing in the water interior. The state of turbulence in shallow waters is examined and details of microstructure data processing and error analysis are discussed. The dependence between averaged activity parameter AG and buoyancy Reynolds number Reb for the shelf turbulence indicates that for Reb < 1 the state of turbulence can be described by the fossil turbulence model, which postulates AG-Reb1/2. For Reb> 1, however, the influence of Reb on AG is weak, signifying that the buoyancy Reynolds number can no longer serve as the governing parameter for active turbulent mixing. The generation of turbulence by a one-minute long wind bursts (the Boadella reservoir) increases the averaged dissipation rate (e) of the surface mixed layer by more than 5 times (up to 3×10-6 W kg-1). The influence of the wind bursts was also traced below the ther-mocline, where turbulent patches with 相似文献
3.
Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate （^vSiO3-Si,^vPO4-P, ^vNH4-N, ^vNO2-N and ^vNO3-N） at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater （Cpw）, water and clay contents, and grain size of the sediments （CH2O, Cclay and GSsed）. The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area. 相似文献
4.
Results of a series of experiments (on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of
different composition and block structure) conducted in this systematic study of the effects of the composition and structure
of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption
to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of
the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity
coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of theM/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu2+ ion decrease with the increase of the G-block or the average length of the G-block
and the total adsorption capacity of alginic acid is found to vary in the same order as theF
MM(diad frequency) in alginate in the mixed solution of Sr2+, Ba2+ and Cd2+.
Contribution No. 2166 from the Institute of Oceanology, Chinese Academy of Sciences. 相似文献
5.
With the application of electronic computers, the extraction of harmonic constants from high and low waters becomes an extremely
simple process as compared with Doods’n’s technique. The phenomenon of aliasing is examined by supposing the samples are taken
at intervals of exactly 6 lunar hours. The constituents with frequencies satisfying the relation
are inseparable and the coefficient determinant of the normal equations will be singular if the heights only are used. When
the values of the first derivatives and the irregularity of the sampling are taken into consideration the condition of the
determinant is improved. Large diurnal tides can cause irregularity of sampling and so we are in favour of the separation
of the aliased constituents. For tidal current data, if the slack times are available, the results of analysis can be much
improved. The results for major constituents derived from the observed high and low waters agree satisfactorily with those
from hourly data.
This paper was published in Chinese inOcean. Limn. Sinica
17(4):318–328, 1986. 相似文献
6.
Kang Xinglun 《中国海洋湖沼学报》1990,8(4):348-353
To make surface seawater flow, the shear stress of the wind blowing on the sea must overcome the work of cohesion of seawaterW
c. Oil film on the sea will drift along the wind direction so long as the shear stress of the wind overcomes the work of adhesion
between the water and the oilW
a or the work of cohesion of oil Wt,o.
Experiments bear out the theory that surface tension of seawater is more than twice that of oils generally, so that the wind
influenced drift velocity of the oil film is over two times that of the wind-driven surface current. The wind factor for surface
current in Jiaozhou Bay is 0.025, while those for the drift velocities of O-diesel oil film and the used light crude oil film
are 0.070 and 0.052 respectively.
Generally the primary factors influencing the movement velocity of oil film on the sea are current, wind, and the physicochemical
properties of the oil. The drift velocity of oil film is determined from analysis of the work of adhesion between seawater
and oil. Experiments and actual observations agree with the theoretical analysis.
Contribution No. 1831 from the Institute of Oceanology, Academia Sinica 相似文献
7.
In this paper, the linear continuously stratified ntxiel of the abyssal circulation proposed by Pedlosky (1992) was emended to include the second order term - (γθm) in the vertical turbulent mixing pararneterization of - (ω‘θ‘）x = kvθxx- θxxx, in which kv is a vertical diffusion coefficient,and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ＜0 is only allcmed). The influence of the γ-tema on the baroclinic structure of the abyssal circulation driven by up-welling out of the abyss was investigated, It was found that the γ-term has a noticeable influence on thebaroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroelinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in thewest. In addition, this parameter was found to decrease the vertically averaging meridional velocity of theabyssal circulation frcrn the west to the east on the southern boundary. For upwelling localized near theeastern boundary, the γ - term favors baroclinic layering of the abyssal circulation in the whole basin.Especially, on the southern boundary the γ - term could strengthen the vertically averaging meridional ve-loeity in the west, but gready weaken it in the east. The ntntel presented here might be considered as anextension of the Pedlosky baroclinic ntntel of the abyssal circulation. 相似文献
8.
Sea bottom stress is conventionally assumed to be directly proportional to the square of the verticallyaveraged velocity,and the drag coefficient to be dependent on the speed and direction of the wind on the sea surface,the depth and dimension of the sea,the period of the tide and so on. In this paper a three-dimensional numerical model is used to discuss the relation the dragcoefficient and the above-mentioned factors.It can be shown from calculation that the relation, is valid,that the drag coefficient is a constant in a major part of a sea as thought conventionally,andthat there is a small area near the coast where the drag coefficient is far greater.We call it singular area. A number of conclusions on the relation between the drag coefficient and the speed and direction ofthe wind,the sea depth and so on,were obtained. 相似文献
9.
Four kinds of polysaccharides (FA, FB, FC and FD) were extracted and purified from a red alga Furcellaria lumbricalis. Their monosaccharide composition, average molecular mass
and structural feature were determined by gas chromatography (GC), high performance gel permeation chromatography (HPGPC)
and Fourier transform infrared spectroscopy (FTIR), respectively. The results showed that FA and FB were composed of galactose
(Gal), 3,6-anhydro-galactose (AnG) and 4-sulfated-galactose (G4S), which were structurally similar to β-carrageenan and κ-carrageenan.
FC was composed of sulfated galactose and small amount of AnG, indicating that it was a hybrid-sulfated galactan. FD was composed
of α-1,4-glucose and belonged to floridean starch. The respective yields of FA, FB, FC and FD were 4.84%, 33.74%, 8.76% and
13.5%, and the corresponding
were 537 kD, 432 kD, 513 kD and 51 kD respectively. Owning to its high content (>60%) of polysaccharide, F. lumbricalis will be a good source of marine sulfated polysaccharide and shows its potential utilization in food and medicine. 相似文献
10.
A study on the curves of the exchange ratioE(%)- pH on the liquid-solid interface of the systems Zn (II) with clay minerals, (Kaolinite, illite and montmorillonite),
Zn (II) with hydrous ferric oxides (amorphous ferric oxide, geothite and hematite), Zn (II) with hydrous manganese oxide (γ-MnOOH,
manganite and δ-MnO2) etc. in seawater resulted in the discovery of new plateau type exchange ratioE(%)-pH curves not yet reported in literature. The two factors that decide the growth, decline and the change of the “plateau
type” curve are: (1) the inherent characteristics of systems, which can be explained by the exchange constants
(i=1, 2, 3, etc.) of interfacial stepwise ion/coordination particle exchange between liquid and solid; and (2)
. The theory of interfacial stepwise ion/coordination particle exchange in seawater was applied to explain the experimental
results of the above study and a general formula was derived for the plateau type exchange ratioE(%)-pH curves. The theoretically simulated and calculated curves coincided well with the experimental results. This paper
provides new and powerful experimental basis to support the theory of interfacial stepwise ion/coordination particle exchange
in seawater.
The project was supported by the National Natural Science Foundation of China. 相似文献
11.
The perforated breakwater is an environmentally friendly coastal structure,and dissolved oxygen concentration levels are an important index to denote water quality.In this paper,oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted.The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na_2SO_3 and Co Cl_2.The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions.It was found that the oxygen transfer coefficient through wave surface,K_1a_1,is much lower than the oxygen transport coefficient through the perforated breakwater,K_2a_2.If the effect of K_1a_1 is not considered,the dissolved oxygen concentration computation for inner water body will not be greatly affected.Considering the effect of a permeable area ratio α,relative location parameter of perforations δ and wave period T,the aforementioned data of 30 experimental scenarios,the dimensional analysis and the least squares method were used to derive an equation of K_2a_2(K_2a_2=0.0042α~(0.5)δ~(0.2)T~(-1)).It was validated with 6 other experimental scenarios data,which indicates an approximate agreement.Therefore,this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater. 相似文献
12.
A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the
China SOLAS Project in 2005 and 2006, including data for the surface microlayer (SML), subsurface layer (SSL) and surface
layer (SL). The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order: pCO2 SML > pCO2 SSL > pCO2 SL. The highest values were found in March for all SML, SSL and SL, followed by those in April, and the lowest were in May.
The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude, there was a significant negative correlation between it and latitude, i.e., ‘high latitude low pCO2’. By using four calculation models, the carbon dioxide fluxes (
) in spring in the Yellow and South China Seas, which were found to act as a ‘sink’ of atmospheric CO2, were preliminarily estimated on the basis of the pCO2 data in the SML to be −7.00×106t C and −22.35×106t C, respectively. It is suggested that the
calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL. 相似文献
13.
This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica (Magabuyo), Diplodiscus paniculatus (Balobo), Parashorea malaanonan (Bagtikan), and Swietenia macrophylla (Mahogany) in Mount Makiling Forest Reserve (MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate (SEE), coefficient of determination (R 2), mean bias \(( \bar E )\), and absolute mean difference (AMD). For the lack-offit statistics, SEE, \(\bar E\) and AMD were determined in different relative height classes. The results indicated that the Kozako2 stem taper model offered the best fit for the four tropical species in most statistics. The Kozako2 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, \(\bar E\) and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height, merchantable stem volumes and total stem volumes of standing trees belonging to the four species of the tropical forest in MMFR. 相似文献
14.
Distribution characteristics of boron and lithium in brine of Zhacang Caka salt lake,Xizang (Tibet), China 总被引：1，自引：0，他引：1
Zheng Xiyu 《中国海洋湖沼学报》1984,2(2):218-227
15.
This study examines oblique wave motion over multiple submerged porous bars in front of a vertical wall. Based on linear potential theory, an analytical solution for the present problem is developed using matched eigenfunction expansions. A complex dispersion relation is adopted to describe the wave elevation and energy dissipation over submerged porous bars. In the analytical solution, no limitations on the bar number, bar size, and spacing between adjacent bars are set. The convergence of the analytical solution is satisfactory, and the correctness of the analytical solution is confirmed by an independently developed multi-domain BEM (boundary element method) solution. Numerical examples are presented to examine the reflection and transmission coefficients of porous bars, C R and C T , respectively, for engineering applications. The calculation results show that when the sum of widths for all the porous bars is fixed, increasing the bar number can significantly improve the sheltering function of the bars. Increasing the bar height can cause more wave energy dissipation and lower C R and C T . The spacing between adjacent bars and the spacing between the last bar and the vertical wall are the key parameters affecting C R and C T . The proposed analytical method may be used to analyze the hydrodynamic performance of submerged porous bars in preliminary engineering designs. 相似文献
16.
The aim of this study was to investigate the effects of light intensity and enhanced nitrogen supply on the growth and photosynthesis of the green-tide macroalga, Ulva prolifera. Thalli of U. prolifera were grown in natural or NH 4 +-enriched seawater under two different light intensities for 7 days, and then the growth rate, pigmentation, and photosynthetic performance of the thalli were evaluated. The results show that the relative growth rate(RGR) was markedly higher under the high light level than under the low light level. Enrichment with NH 4 + enhanced the RGR under high light intensity, but did not affect RGR under low light intensity. In low light conditions, NH 4 +-enrichment resulted in a marked decrease in the maximal photosynthetic rate( P m) and the maximum carbon fixation rate( V max), but it did not affect the half saturation constant for carbon( K 0.5) or the ratio of V max to K 0.5, which reflects the carbon acquisition efficiency. In high light conditions, P m, K 0.5, and the dark respiration rate( R d) increased under NH 4 + enrichment, but V max and the V max / K 0.5 ratio decreased. Regardless of the light intensity, NH 4 +-enrichment did not affect the apparent photosynthetic efficiency( α), which refl ects the ability of the alga to use light energy at low light levels. Under both low and high light intensities, the chlorophyll a(Chl a), chlorophyll b(Chl b), and carotenoids(Car) contents in thalli were higher in NH 4 +-enriched than in natural seawater, except that there was a decrease in the Chl b content of thalli in NH 4 +-enriched seawater under low light intensity. Therefore, NH 4 + enrichment improved the growth and photosynthetic performance of U. prolifera under high light intensity, but not under low light intensity. We discuss the possible mechanisms underlying these physiological responses. 相似文献
17.
Temporal variations in multimodal structures of diurnal (D 1) and semidiurnal (D 2) internal tides were investigated on the continental slope of the Dongsha Plateau, based on 2-month moored acoustic Doppler current profiler observations. Harmonic analysis indicated that the D 1 components (K 1 and O 1) dominated the internal tide field. The vertical structure of the K 1 constituent presented a first-mode structure while the M 2 constituent seemed to exhibit a high-mode structure. Amplitude spectra analysis of the current data revealed differences in baroclinic current amplitudes between different water depths. Temporal variations in modal structures ware analyzed, based on the D 1 and D 2 baroclinic tides extracted from the baroclinic velocity field with band-pass filters. Analysis showed that the magnitude of the D 1 internal tide current was much larger than the D 2 current, and temporal variations in the modal structure of the D 1 internal tide occurred on an approximately fortnightly cycle. The EOF analyses revealed temporal transformation of multimodal structures for D 1 and D 2 internal tides. The enhancement of the D 1 internal tide was mainly due to the superposition of K 1 and O 1, according to the temporal variation of coherent kinetic energy. 相似文献
18.
Effects of nitrogen (N) and phosphorus (P) from different sources and at different concentrations on the growth of Levanderina fissa (= Gyrodinium instriatum) were studied in laboratory conditions. The findings might explain the recurrent blooms of this species in Pearl River Estuary, China. Results showed that nutrient limitation significantly inhibited the growth of L. fissa. The values of specific growth rate (μ max) and half-saturation nutrient concentration (K S) were 0.37 divisions/d and 8.49 μmol L?1 for N, and 0.39 divisions/d and 1.99 μmol L?1 for P, respectively. Based on K S values, dissolved inorganic N level in PRE was sufficient to support the high proliferation of L. fissa, while dissolved inorganic P concentration was far lower than the minimum requirement for its effective growth. L. fissa was not able to utilize dissolved organic N (DON) compounds such as urea, amino acids, and uric acid. However, it grew well by using a wide variety of dissolved organic P (DOP) sources like nucleotides, glycerophosphate, and 4-nitrophenylphosphate. The results from this study suggested that the ability in DOP utilization of L. fissa offers this species a competitive advantage in phytoplankton communities. The high level and continuous supply of DIN, enrichment of DOP, together with warm climate and low salinity in the Pearl River Estuary provided a suitable nutrient niche for the growth of L. fissa, and resulted in the recurrent blooms in the estuary. 相似文献
19.
Euphausia pacific is an important source of natural astaxanthin.Studies were carried out to assess the extractability of astaxanthin from E.pacific using subcritical 1,1,1,2-tetrafluoroethane(R134a).To examine the effects of multiple process variables on the extraction yield,astaxanthin was extracted under various conditions of pressure(30-150 bar),temperature(303-343 K),time(10-50 min),flow rate(2-10 g min-1),moisture content(5.5%-63.61%),and particle size(0.25-0.109 mm).The results showed that the extraction yield increased with temperature,pressure,time and flow rate,but decreased with moisture content and particle size.A maximum yield of 87.74% was obtained under conditions of 100 bar,333 K,and 30 min with a flow rate of 6 g min-1 and a moisture content of 5.5%.The substantial astaxanthin yield obtained under low-pressure conditions demonstrates that subcritical R134a is a good alternative to CO 2 for extraction of astaxanthin from E.pacific. 相似文献
20.
The effects of environmental Na+/K+ ratio on the gill ion-transport enzyme activity, plasma osmolality and growth of Cynoglossus semilaevis juveniles were investigated. The results showed that, plasma osmolality was similar among flounder adapted to different Na+/K+ ratios of saline groundwaters (P>0.05), while the growth, gill Na+, K+-ATPase and HCO3
−-ATPase activities were affected by Na+/K+ ratio significantly (P<0.05). The gill Na+, K+-ATPase activity reached its maximum on day 3, then decreased gradually from day 3 to day 9 and remained constant from day
9 to day 15. The peak values of gill Na+, K+-ATPase activity were detected on day 3 for all Na+/K+ ratios of saline groundwaters, then the enzyme activities descended, and on day 9 the enzyme activities achieved steady state,
and the gill HCO3
−-ATPase activity increased rapidly and achieved steady state after one day. During steady state, the gill Na+, K+-ATPase and HCO3
−-ATPase activity of Na+/K+ ratios 20 and 40 treatments were significantly higher than those in the control group (Na+/K+ ratio 27.5), while there were no significant differences between the Na+/K+ ratio 30 treatment and the control group; the gill Na+, K+-ATPase activity of Na+/K+ ratio 20 and 40 treatments were significantly higher than that for ratio 30 treatment, but there were no significant differences
of gill HCO3
−-ATPase activity among these treatments. At the end of the 15-day experiment, the weight gain (%) and specific growth rate
(SGR) of flounders maintained in seawater were significantly higher than those in groundwaters; significant differences also
occurred among the treatments; Na+/K+ ratio 30 treatment had the highest values (33.7% and 1.94 respectively), which were significantly higher than those under
Na+/K+ ratios 20 and 40 treatments. Therefore, for the saline groundwater used in this experiment, it is suggested that the Na+/K+ ratio be adjusted to approximately 30, i.e., as close to that of natural seawater as possible in the culture of flounder. 相似文献