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1.
Flume experiments and numerical simulation were conducted to characterize the hydrodynamics of a trapezoid artificial reef. Measurements in particle image velocimetry were conducted to observe the formation of upwelling and vortices; and forces for the reef model were measured by load cell. The results of flume experiments agree well with the numerical data. In addition, the flow structure around a reef combining trapezoidal and cubic blocks was simulated numerically under two deployment schemes, showing a more complicated flow structure than that of a stand-alone reef. Relationship between drag coefficient and Reynolds number suggest that the degree of turbulence can be assessed from the value of drag coefficient downstream from the reef. The role of the reef in water flow is to reduce flow velocity and generate turbulence. 相似文献
2.
Particle image velocimetry and numerical simulations of the hydrodynamic characteristics of an artificial reef 总被引：2，自引：0，他引：2
This article reports a particle image velocimetry study and the comparative results of a numerical simulation into the hydrodynamic characteristics around an artificial reef.We reveal the process of flow separation and vortex evolution,and compare the force terms generated by our artificial reef model.The numerical simulation agrees well with experimental results,showing the applicability of computational fluid dynamics to the hydrodynamics of an artificial reef.Furthermore,we numerically simulate the hydrodynamics of the reef model for seven velocities.The results show that the drag coefficient is approximately 1.21 in a self-modeling region for Reynolds numbers between 2.123×104and 9×104.Therefore,the upwelling height and current width of the flow field do not change significantly when the inflow velocity increases.Our study indicates that computational fluid dynamics can be applied to study the hydrodynamics of an artificial reef and offer clues to its construction. 相似文献
3.
In this study, the ability of macroalgae Gracilaria sp. of removing eutrophication factors and toxic heavy metals Al, Cr, and Zn in a closed cultivation system is reported.
The results show that the concentration of the three heavy metals decreased significantly during the experimental period in
an algal biomass dependent manner. The biofiltration capacity of the alga for Al, Cr, and Zn is 10.1%–72.6%, 52.5%–83.4% and
36.5%–91.7%, respectively. Using more materials resulted in stronger heavy metal removal. Additionally, the concentration
of chl-a, TN, TP and DIN of water samples from aquariums involving large, medium, and small algal biomass cultivation increased first
and then decreased during the experiment. COD value of all three groups decreased with time and displayed algal biomass dependency:
more algae resulting in a greater COD value than those of less biomass. Furthermore, changes in COD reflect an obvious organic
particles deprivation process of algae. This is the first report on heavy metal removal effect by Gracilaria species. The results suggest that macroalgae can be used as a biofilter for the treatment of nutrient-enriched or heavy-metal
polluted water, to which an appropriate time range should be carefully determined. 相似文献
4.
AVAILABILITY OF PHOSPHORUS FROM SELECTED INORGANIC PHOSPHATES TO JUVENILE ABALONE, HALIOTIS DISCUS HANNAI INO 总被引：2，自引：0，他引：2
The availability of phosphorus to juvenile abalone,Haliotis discus hannai from primary, secondary and tertiary calcium phosphate, primary sodium or potassium phosphate separately or in combination
was determined in a 120-day feeding trial. Seven semi-purified diets were formulated to contain relatively constant dietary
phosphorus, ranging from 0.78%–0.82%. The concentrations of dietary phosphorus were presumed to be slightly below the requirement
for abalone. A brown alga,Laminaria japonica, was used as a control diet. Abalone juveniles of silimar size (average weight 1.18 g; average shell length 18.74 mm) were
distributed in a single-pass, flow-through system using a completely randomized design with eight treatments and three replicates
each treatment. The survival ranged from 71.1% to 81.1%, and was not significantly (P>0.05) related to dietary treatment.
However, the weight gain rate (41.72%–65.02%), daily increment in shell length (36.87–55.07 μm) and muscle RNA-DNA ratio (3.44–4.69)
were significantly (P<0.05) affected by dietary treatment. Soft body alkaline phosphatase activity (10.9–19.8 U/g wet tissue)
and carcass levels of lipid (7.71%–9.33%) and protein (46.68%–49.35%) were significantly (P<0.05) responsive to available
phosphorus of the diets. Dietary treatment had significant effect (P<0.05) on concentrations of phosphorus in the whole body
(WB) and soft body (SB). Apparent digestibility coefficients (45%–97%) of phosphorus were also significantly (P<0.05) different
between dietary treatments. The results indicated that among these inorganic compounds, primary calcium, potassium and sodium
phosphates separately or in combination could be utilized effectively by juvenile abalone as dietary phosphorus sources (availability
ranging from 87%–97%). However, secondary and tertiary calcium phosphates were found to be low in availability, the values
being 45% and 77%, repectively.
Project 39670572 supported by the Natural Science Foundation of China (NSFC). 相似文献
5.
In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum
condition for hatching fertilized eggs of burrow fish mudskipper,Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests
were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of
the nest-spawned eggs varied from 17.3% to 80.8%. Females could spawn after being artificially confined inside the nests with
males at ratios of 1∶1 or 1∶2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs
incubated in round plastic buckets were 32.7%–70.6%, and in the net cages, were 4.2%–20.5%, respectively. Mean hatching rates
of nest-fertilized eggs incubated in the round plastic buckets were 33.6%–76.3%, and in the net cages, were 5.9%–25.2%. Results
showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper. Keeping the hatching seawater
flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs.
Supported by the NSFC (No. 30170739), and also supported by the Provincial Natural Science Foundation of Fujian Province (No.
B0210003). 相似文献
6.
1 INTRODUCTIONIt is well known that wind-generated wavestorm surge and atmospheric circulation as impor-tant ocean weather events are closely related tomomentum exchange between sea and atmosphere(Oncley and Dudhia, 1995). For this reason, in thepast 20 years, attention has been directed towardshow to better describe momentum exchange throughsea surface. In general, to precisely determine theexchange, improvement should be made in the as-pects of reasonably depicting the roughness de-pend… 相似文献
7.
Effects of alginate gel at different concentrations on rheological properties of hair-tail (Trichiurus lepturus) surimi were investigated. Alginate gel (1% - 3%) exhibited enhanced effects, especially when alginate gel concentration increased. The rheological properties of mixture samples were studied by the time sweep, frequency sweep and temperature sweep. The critical strain values of the mixture samples for the onset of non-linear viscoelasticity were about 5%. The storage modulus G’ of the mixture samples increased with time for 4 h. The frequency sweep showed that G’ was greater than G" for all the mixture gels with different alginate gel concentrations, and values of both n’ and n" for all samples were low (<0.2), these constants corresponding to G’ and G", and indicating the elasticity of mixture gels. The values of storage modulus G’ decreased during heating process and increased with decreasing temperature. 相似文献
8.
Wetland stores substantial amount of carbon and may contribute greatly to global climate change debate. However, few researches have focused on the effects of global climate change on carbon mineralization in Zoigê al-pine wetland, Qinghai-Tibet Plateau, which is one of the most important peatlands in China. Through incubation ex-periment, this paper studied the effects of temperature, soil moisture, soil type (marsh soil and peat soil) and their in-teractions on CO2 and CH4 emission rates in Zoigê alpine wetland. Results show that when the temperature rises from 5℃ to 35℃, CO2 emission rates increase by 3.3-3.7 times and 2.4-2.6 times under non-inundation treatment, and by 2.2-2.3 times and 4.1-4.3 times under inundation treatment in marsh soil and peat soil, respectively. Compared with non-inundation treatment, CO2 emission rates decrease by 6%-44%, 20%-60% in marsh soil and peat soil, respec-tively, under inundation treatment. CO2 emission rate is significantly affected by the combined effects of the tempera-ture and soil type (p < 0.001), and soil moisture and soil type (p < 0.001), and CH4 emission rate was significantly af-fected by the interaction of the temperature and soil moisture (p < 0.001). Q10 values for CO2 emission rate are higher at the range of 5℃-25℃ than 25℃-35℃, indicating that carbon mineralization is more sensitive at low temperature in Zoigê alpine wetland. 相似文献
9.
STUDY ON EMBRYONIC DEVELOPMENT AND EARLY GROWTH OF TRIPLOID AND GYNOGENETIC DIPLOID LEFI—EYED FLOUNDER, PARALICHTHYS OLIVACEUS （T. et S. ） 总被引：1，自引：0，他引：1
The early effects of chromosomal manipulation of eggs and sperm on the yields of trip-loid and gynogenefic diploid larvae of Paralichthys olivaceus were investigated. Triploidy was achieved by cold shocking fen.ilized eggs at 0 - 2℃ for 45 minutes duration 5 minutes after fen.ilization, and the in-duced triploidy rates were 31.2% - 50% and the relative hatching rates were 53.3% - 99%. Gynnge-aetic diploids were obtained when eggs were inseminated with irradiated sperm and cold shocked at 0 -2℃ for 45 minutes duration 5 minutes after fertihzation. The induced gynogenetic diploid rates and the relative hatching rates were 94 % - 96 % and 48.5 % - 68.5 % respectively. The embryonic development of the triploid experimental group and of the gynogenetic diploid experimental group was delayed at first compared with the control group. But from the gastrula stage, it was not delayed anymore. There were no significant differences in the growth of the triploid experimental group larvae and the control group larvae, and in the growth of the gynogenetic diploid experimental group larvae and the control group larvae ac-cording to Student‘s t-test (α = 0.05). The relationship between the early growth of the triploid experi-mental group larvae and that of gynogenetic diploid experimental group larvae was also studied. 相似文献
10.
This research on the influence of sediment resuspension on the flux of materials in the margin of the East China Sea showed
that the sediment resuspension rates, was 47.40%–79.18% in the surface layers, and 72.75%–96.96% in the bottom layers. The
research confirmed that the Changjiang River runoff and the eddy area upwelling flow near 125°E were two important factors
affecting the sediment resuspension in summer; the transformation of DOC to POC through the flocculation in the transitional
region (123°–124°E) was also confirmed by comparison of the resuspension rate. The sediment resuspension was shown to be influenced
by the seasonal factor, especially in the surface layer.
Contribution No. 4017 from the Institute of Oceanology, Chinese Academy of Sciences.
Project 49636210 supported by NSFC. 相似文献
11.
Fatty acid composition and total lipid content of 8 strains of marine diatoms (Nitzschia frustrula, Nitzschia closterium, Nitzschia incerta, Navicula pelliculosa, Phaeodactylum tricornutum, Synedra fragilaroides) were examined. The microalgae were grown under defined conditions and harvested at the late exponential phase. The major
fatty acids in most strains were 14∶0 (1.0%–6.3%), 16∶0 (13.5–26.4%), 16∶1n−7 (21.1%–46.3%) and 20∶5n−3 (6.5%–19.5%). The
polyunsaturated fatty acids 16∶2n−4, 16∶3n−4, 16∶4n−1 and 20∶4n−6 also comprised a significant proportion of the total fatty
acids in some strains. The characteristic fatty acid composition of diatoms is readily distinguishable from those of other
microalgal groups. Significant concentration of the polyunsaturated fatty acid 20∶5n−3 (eicosapentaenoic acid) was present
in each strain, with the highest proportion in B222 (19.5%).
Project supported by the Hi-Tech “863” Programs of the China Ministry of Science and Technology (863-819-02-01). 相似文献
12.
We analyzed the survival data of the offspring from 21 sires and 42 dams of turbot. The results show that the cumulative survival
rates for turbot from 2 to 18 months range from 17.5% to 28.5%; main mortality occurred during months 2–5; and the highest
survival rates of families were 97.9%, 98.8%, 99.4%, 99.7% during months 2–5, 5–6, 6–8, 8–11, and 11–18, respectively, and
99.5%, being 53.5%, 23.8%, 19.5%, 14.9%, and 13.2% higher, respectively, than the mean values in each period. In all periods,
the estimated heritabilities for survival were very low without significant difference from zero (P≫0.05) (values ranged from 0.06 to 0.12), indicating low additive genetic effects. The genetic correlations of survival among
families in different periods were all positive, but low in magnitude (values range from 0.03 to 0.31). Genetic correlations
between long-term survival and other periods’ survival had negative values (−0.06 and −0.15) and three positive values (0.16,
0.12 and 0.14). Genetic correlations between survival and weight were all positive, except for survival at months 2–5 and
weight at 18 months, which was not significantly negative (−0.18). 相似文献
13.
DONG Weihua YIN Xiuqin 《中国地理科学(英文版)》2007,17(2):166-172
Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation. 相似文献
14.
The myosin heavy chain (MyHC) is one of the major structural and contracting proteins of muscle. We have isolated the cDNA
clone encoding MyHC of the grass carp, Ctenopharyngodon idella. The sequence comprises 5 934 bp, including a 5 814 bp open reading frame encoding an amino acid sequence of 1 937 residues.
The deduced amino acid sequence showed 69% homology to rabbit fast skeletal MyHC and 73%–76% homology to the MyHCs from the
mandarin fish, walleye pollack, white croaker, chum salmon, and carp. The putative sequences of subfragment-1 and the light
meromyosin region showed 61.4%–80% homology to the corresponding regions of other fish MyHCs. The tissue-specific and developmental
stage-specific expressions of the MyHC gene were analyzed by quantitative real-time PCR. The MyHC gene showed the highest
expression in the muscles compared with the kidney, spleen and intestine. Developmentally, there was a gradual increase in
MyHC mRNA expression from the neural formation stage to the tail bud stage. The highest expression was detected in hatching
larva. Our work on the MyHC gene from the grass carp has provided useful information for fish molecular biology and fish genomics. 相似文献
15.
Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry.
Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities
remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction
to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm.
A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef
sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria (Alpha-, Beta-, Gamma-, Delta-, and Epsilonproteobacteria), Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from
other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes
because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested
that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest
diversity found in the anoxic layer (15–25 mm) and the least diversity in the suboxic layer (3–5 mm). Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the
anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution
of bacterial communities in sandy reef sediments. 相似文献
16.
By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning
system under combined actions of wind and waves is studied. The numerical simulation is conducted by the method of nonlinear
time domain coupled analysis, and the mooring forces are calculated by the piecewise extrapolating method. The scale in the
model experiment is 1:100, and the mooring system of the model is designed with the method of equivalent water-depth truncation
by comparing the numerical and the experimental results, the platform motion and mooring forces subject to wind and waves
are investigated. The results indicate that the numerically simulated mooring forces agree well with the experimental results
in static equivalent field, but show some difference in dynamic equivalent field; the numerically simulated platform motions
coincide well with the experimental results. The maximum motion of the platform under operating conditions is 20.5 m. It means
that the horizontal displacement is 2% less than the water depth, which satisfies the operating requirements. 相似文献
17.
Heat shocks effectively produced triploids inPenaeus chinensis. Fertilized eggs heat shocked (28–32°C) for 8 to 16 minutes, starting from 8 to 20 minutes after spawning, resulted in triploidy
induction rates of 39%–75%. Several triploid populations were cultured to 10 cm. In a triploid population, two kinds of ovaries
were observed. Histological examination showed apparent differences between these two kinds of ovaries, whereas among male
shrimp, there were no such differences.
Contribution No. 3465 from the Institute of Oceanology. Chinese Academy of Sciences.
The study was supported by the International Foundation for Science, Asian Fisheries Society and Chinese Climbing Project
PDB 6–2, and Chinese National 863 Project (No. 863-819-01-05). 相似文献
18.
April to October, 1997 comparative studios on the nitrogen budgets of closed shrimp polyculture systems showed that, in all the studied polyculture systems, nitrogen from feeds and fertilizers were the main input items, which comprised 70.7% - 83.9% of the total input nitrogen, 3.2% - 7.4% of which was provided by nitrogen fixation. It was in monoculture enclosures (Y-4, Y-11 and Y-12) that the percentage reached the maximum value. The output nitrogen in harvested products comprised 10.8% - 24.6% of total input nitrogen, and the highest percentage, 24.6%, was found in shrimp-fish-tagelus polyculture systems. In shrimp monoculture and shrimp-fish polyculture systems, they were 19.1% and 21.9%, respectively. The nitrogen utilization efficiency was different and varied from 12.2% to 20.1%. The highest, 20.1%, was found in shrimp-fish-tagelus polycultttre systems, and the average of 20.0% was found in shrimp-tagelus polyculture systems. The lowest, 12.2%, was found in shrimp monoculture systems.All the nitrogen utilization efficiencies in shrimp-fish systems or shrimp-scallop systems seemed to be higher than that of the monoculture system, but they showed little statistical difference. The main outputs of nitrngen were found in sediment mud, and comprised 48.2% -60.8% of the total input, the lowest percentage was found in shrimp-fish-tagelus polyculture systems, and the highost percentage in shrimp-scallop systems.During the experiment, nitrogen lost through denitrification and ammonia volatilization comprised 1.9% - 6.2%, averaged 2.8%, of the total input, and the loss through seepage comprised 5.9% - 8.9% of the total.The estimated nitrogen attached to the enclosure wall comprised 3.7% - 13.3% of the total, and was highest in shrimp monoculture systems. Compared with the classic shrimp farming industry, the closed shrimp polycul-ture systems may improve the nitrogen utilization efficiency, and hence reduce the environmental impacts on coastal waters. The nitrogen discharging rates for all the studied polyculture systems ranged from 3.0% to 6.0% of total input nitrogen. 相似文献
19.
1INTRODUCTIONIntheHuanghe(Yellow) Riverbasin, soilerosionisaseriousproblem,whilerunoffandsedimentyieldsim-ulation hasnotbeenextensivelystudiedonthebasisofGIS(GeographicInformationSystem) and dis-tributedhydrologicalmodel.Inthisstudy,theLushiwatershed,whichislocatedattheupstreamoftheLushiHydrologicalStationintheLuoheRiver—thebiggesttributary oftheHuanghe Riveranddown-streamofXiaolangdiDam,isselectedasthestudyarea.ThelevelofsoilerosioninLushiwatershedismoderatein theHuangheRiverbas… 相似文献
20.
岩溶含水层中的地下水是重要的可饮用水来源, 由于其复杂的水文地质特征, 采用数值模型分析和评价含水层中地下水环境极具挑战性。采用变饱和度流动方程描述含水层基质中的饱和-非饱和流动, 采用管道流方程描述岩溶管道中的层流及紊流流动, 基于流动解采用对流弥散方程分别描述基质与管道中的溶质迁移过程。根据相关实验数据以及MODFLOW-CFP程序的模拟结果对流动模拟的准确性进行验证, 并基于此开展了岩溶管道以及非饱和参数对地下水流动及污染物迁移影响的模拟。结果显示, 数值模型能很好地重现含水层中饱和区与非饱和区以及岩溶管道的地下水动态, 岩溶管道对含水层的渗流场产生了较大的影响。管道中快速流动的特性使得周围的水向其中汇集, 影响了局部流动场, 进而使得泄露的污染物质随水流进入管道, 快速向管道出口处(泉点)迁移, 突破曲线显示管道出口处的污染物浓度响应速度远快于基质中对应的位置, 非饱和参数对管道中污染物浓度的响应速率有着不同程度的影响。建立的模型完善了岩溶含水层中非饱和区地下水流动、污染物运移以及基质-管道流动与溶质运移耦合模拟等方面的工作, 加深了对岩溶含水层地下水动力学以及污染物迁移过程的认识, 对岩溶水文地质及地下水环境等方面具有重要意义。 相似文献