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1.
From 1979 to 1989, the current Qingshuigou course of the Huanghe River formed a sub - delta which resembles a beak extending into the Laizhou Bay. It covers 618 km2 in area. To meet the needs of developing and constructing the Huanghe River Delta and under the presupposition of keeping the current course for 15-20 a, we forecast mainly by using the OM (1, 1) model that the front border of the sub-delta will be close to 119°30'E and its area will become 923 km2by the end of the year 2000. The Huanghe River will make land 760 km2 in area.  相似文献   

2.
The Nampo dike, which is located at the west coast of Korea, was destroyed by wave overtopping during the storms on 30 August and 17 September in 1959. In this paper, is performed the probabilistic assessment of wave overtopping of Nampo dike by use of Owen model, Van der Meer & Janssen model and Hedges & Reis model for wave overtopping of seawall. Based on the available tidal and wave data for storm surges in 1989, the risk assessment of wave overtopping of the Nampo dike has been carried out by both Level Ⅱ and Level Ⅲ reliability methods. The calculated resuhs show the general agreement of failure probability between the two methods. By utilizing the rehabilitated cross section of Nampo dike, the failure probability of wave overtopping for the Nampo dike after rehabilitation will be rapidly reduced to that of initial design at crest level of 9.0 m with the improved slope from 1 : 2 to 1 : 4 at seaside. Since the sea level may only rise 1.0 m in the next few decades, the failure probability of Nampo dike will be still in the safe range.  相似文献   

3.
The Aral Sea is an important water area both for monitoring and oceanological studies, because its salinity and salt composition strongly differ from the oceanic. We offer a semiempiric calculation method of electric conductivity and the coefficient of its temperature dependence k judging from the ionic composition of water. The properties of the solution are considered as the sum of properties of seven binary salts taken based on the ionic composition of the solution. The MgSO4 concentration is thought to be the highest possible, which makes the salt concentration nearly unambiguous. In a salinity range of 46–120‰ and temperature range of 5–25°C (2002–2009), the standard deviation of the calculated and measured electric conductivity was 2.9%. To refine the calculation of salinity from electric conductivity measurements using the “oceanic” formula, we suggest its preliminary reduction to a constant temperature (20°C) using the measured or calculated coefficient k.  相似文献   

4.
INTRODUCTIONTheradionuclidesofnaturaluraniumandthoriumseriescanbeusedtotracemarinepro cessofvarioustemporalandspatialscaleandpropertiesthatprovideplentifulinformationaboutphysics,chemistry ,geoscienceandbiologyofoceanbecausetheyhavedifferentchemicalpro…  相似文献   

5.
ThisworkisfundedbyagrantfromtheNationalKeyTaskProjectsof8thand9thFive-yearplanprogram.INTRODUCTIONInthepastyears,studiesonthevirusesofpenaeidshrimpshavemadegreatprogressinvari-ouscountries.Rightnow,aboutl4virusesofpenaeidshrimpswerefound,i.e.BP(Baculoviruspenaei,Couch,1974),MBV(Penaeusmonndonbaculovirus,Lightneretal.,1983)orPBV(Penaeusplebejusbaculovirus,Lesteretal.,1987),BMN(Baculovirusmidgutglandnecrosisvirus,Sanaetal.,1981),PHRV(Penaeushybridrod-shapedvirus,Owensetal.,199l),…  相似文献   

6.
- By applying the theory of structural reliability, reliability analyses for the stability of a breast wall on the top of a sloping breakwater are carried out. Based on the analyses, the method for determining partial action / load factors and partial resistance factors of breast walls is expounded, and the design expressions with partial factors are given. The values of partial action / load factors and partial resistance factors are recommended preliminarily according to the computation for breast walls with typical cross-sections.  相似文献   

7.
Process-based modeling of morphodynamics of a tidal inlet system   总被引:1,自引:0,他引:1  
The morphodynamic evolution of an idealized inlet system is investigated using a 2-D depthaveraged process-based model,incorporating the hydrodynamic equations,Englund-Hansen’s sediment transport formula and the mass conservation equation.The model has a fixed geometry,impermeable boundaries and uniform sediment grain size,and driven by shore-parallel tidal elevations.The results show that the model reproduces major elements of the inlet system,i.e.,flood and ebb tidal deltas,inlet channel.Equilibrium is reached after several years when the residual transport gradually decreases and eventually diminishes.At equilibrium,the flow field characteristics and morphological patterns agree with the schematized models proposed by O’Brien (1969) and Hayes (1980).The modeled minimum cross-sectional entrance area of the tidal inlet system is comparable with that calculated with the statistical P-A relationship for tidal inlets along the East China Sea coast.The morphological evolution of the inlet system is controlled by a negative feedback between hydrodynamics,sediment transport and bathymetric changes.The evolution rates decrease exponentially with time,i.e.,the system develops rapidly at an early stage while it slows down at later stages.Temporal changes in hydrodynamics occur in the system;for example,the flood velocity decreases while its duration increases,which weakens the flood domination patterns.The formation of the multi-channel system in the tidal basin can be divided into two stages;at the first stage the flood delta is formed and the water depth is reduced,and at the second stage the flood is dissected by a number of tidal channels in which the water depth increases in response to tidal scour.  相似文献   

8.
Karyotypes of three species of the marine Veneroida molluscs   总被引:1,自引:0,他引:1  
INTRODUCTIONExceptforcorbiculalivinginfreshwater,themostVeneroidamolluscsliveinthesea .Theyarewidelydistributedwithlargequantityofcategories.Manyofthebivalvemolluscsareculturedfortheireconomicvalue .ThespeciesofSolengrandis,SaxidomuspurpuratusandMactrachinensisareaquaculturedinthenorthernseasofChina .Morphologyandcultivationbiologyofthebivalvemolluschavebeenreported (Qietal.,1 989;Weietal.,1 995;Wangetal .,1 984 ) .Asthefoundationofbivalvemollusccytogenetics ,chromosomestudyiscritical…  相似文献   

9.
There were 8 typhoons over the northwestern Pacific Ocean in August of 1985. Their movement characteristics were mainly northward or recurvature northward. At the same time, a complex movement of 3 typhoons clustering was observed. In this paper, the typhoon movement tendency is studied by using satellite cloud maps. The westward and northward tendencies can be distinguished clearly. Based on this rule, typhoon movement can be forecasted 12-48 h before. Some characteristics models of the typhoon moving northward or recurving northward on the satellite cloud maps are also given in this paper.  相似文献   

10.
On the basis of data of drifting bottles' tracks and the current measured in anchored stations, as well as temperature and salinity observed in cruise investigations and coastal stations, ADCP current data and AVHRR surface sea temperature (SST) data on the western coast of Guangdong, synthetic results of analysis showed that the coastal currents in the west of the mouth of the Zhujiang River were mainly westward in summer, which constituted the north branch of cyclonic gyre in the east of the Qiongzhou Straits. Part of its water flowed westward into the Beibu Gulf through the Qiongzhou Straits. The coastal current pattern was not identical with the traditional current system which flowed westward in the Qiongzhou Straits in winter and eastward in summer. The summertime's coastal current was always westward, maybe temporarily turning northeast only when the southwest wind was strong. The important characteristics of coastal current on the western coast of Guangdong, in the Qiongzhou Straits and in the north of the Beibu Gulf were analyzed and their mechanisms also were explained.  相似文献   

11.
Microplankton communities of three coastal sites of Qingdao, Shandong Province, China were investigated using RAPD (random amplified polymorphic DNA) molecular markers and morphological observations. Eight RAPDprimers were selected to amplify the DNA polymorphy. The genetic distances inferred from the pairwise similarities were calculated for the phylogenetic tree construction. Meantime, the traditional microscopic determination, a way of visualizing the species composition, was performed to detect the major taxa of microplanktons from all samples. Results showed that: (1) the band sharing index values were in the range of 0.504 2—0.763 2 among samples from the same sampling site at different time scales, while 0.406 5—0.685 7 among the samples from different stations at the same time scales, indicating that spatial variations of microplankton communities were more pronounced than temporal ones; (2) samples from the same station basically clustered together, corresponding to the geographic distribution of the sampling sites; (3) diversity derived from genetic and morphological data did not correspond with each other well.  相似文献   

12.
2019~2020年在三峡库区巫山(WS)、万州(WZ)、丰都(FD)、涪陵(FL)4个采样点采集到新建短颌鲚(Coilia brachygnathus)种群153尾个体,基于鳞片和10个微卫星DNA标记进行年龄结构、生长特征与遗传多样性分析。结果显示,短颌鲚种群体长分布范围为102.1~301.6mm,平均体长(196.6±40.0)mm;体重分布范围为1.90~79.70g,平均体重(17.70±13.06)g。短颌鲚种群年龄组为1~5龄,其中2龄和3龄为优势年龄组,占总个体数的82.35%。体长-体重呈幂函数指数关系,属于正异速生长类型。微卫星DNA标记分析结果显示,10个微卫星位点共检测到82个等位基因,各群体平均等位基因数(Na)为5.600 0~7.300 0,平均有效等位基因数(Ne)为3.541 4~3.831 5,平均观测杂合度(Ho)为0.617 7~0.700 0,平均期望杂合度(He)为0.682 3~0.702 9之间,平均多态信息含量(PIC)为0.628 5~0.648 4。4个群体的遗传多样性水平均较高,呈现出由三峡库区下游至上游逐渐减小的特点。遗传结构分析结果显示,群体间遗传分化水平很低,遗传变异主要来源于个体内部。结果表明,三峡库区短颌鲚种群处于快速扩张阶段,4个群体均具有较丰富的遗传多样性,遗传结构未发生显著群体分化,群体间基因交流频繁。由此提示,三峡库区短颌鲚很可能来源于三峡大坝下种群扩张迁入三峡库区水域而繁殖建群。  相似文献   

13.
Meiobenthos at the mouth of the Grevelingen and Oosterschelde Estuaries in the Southern Bight of the North Sea was monitored using meiobenthic abundance and nematode community structure. Hierarchical sampling included 54 subsamples nested within 18 cores within six stations within two transects. The spatial patterns of the meiofaunal populations and communities are presented in cm-scale (among subsamples), m-scale (among cores), km-scale (among stations) and 10 km-scale (between transects). The variance components analysis of meiofaunal abundances showed that km-scale and 10 km-scale represented 63–90% of total variance while m-scale and cm-scale provided only 10–37%. Different communities were found among stations rather than among cores or subsamples by detrended correspondence analysis ordination and clustering analysis. The main assemblage of meiofauna occurred at the km-scale. Nematode diversity was more powerful than meiofaunal abundance in detecting spatial variation at all scales. However, at least two replicates are required for monitoring when sampling using a 10 cm2 subsampling core.  相似文献   

14.
采用通用引物PCR扩增法,测定了辽东湾海域的白色霞水母(Cyanea nozakii)螅状体、碟状体及水母体的18S以及ITS-5.8S r DNA序列,同时利用Gene Bank数据库中已有同源序列对其进行序列分析及系统分析。结果显示,白色霞水母3个个体的18S和ITS-5.8S r DNA序列完全一致。白色霞水母样品的ITS-5.8S r DNA序列与Gen Bank中未知真核生物的序列高度相似(≥99%),推测该物种可能是早期发育阶段(卵、浮浪幼虫或碟状体)的白色霞水母样品。霞水母属不同种间18S r DNA序列经比对后同源序列长度为1709bp,多态位点数33个;比对后ITS1同源序列长度为368bp,其中变异位点203个,简约信息位点数178个,单变异位点21个。基于18S r DNA基因序列的霞水母属种内和种间平均遗传距离分别为0、0.008,而基于ITS1序列的霞水母属种内和种间平均遗传距离分别为0.019、0.284。基于ITS1的种间遗传距离是种内遗传距离的15倍,适合于进行物种鉴定。NJ系统树的结果也表明同种的不同个体各自聚枝,其聚类结果大致与形态分类吻合。研究表明,ITS基因片段在霞水母不同种间变异较大,更适于大型水母种类鉴定、检测及属内种间水平的系统进化研究。  相似文献   

15.
Over 30 sea surface microlayer (SML) samples from two contrasting sites in the North Western Mediterranean -- Barcelona (Spain) and Banyuls-sur-Mer (France) -- were collected using three different sampling devices, namely, glass plate, metal screen (MS) and a surface slick sampler (SS), and compared with the corresponding underlying water (16 samples). The distributions of 41 polychlorinated biphenyl congeners (PCBs) were determined in the different phases: particulate (1.17-10.8 SigmaPCB ng L(-1)), truly dissolved (0.080-16.7 SigmaPCB ng L(-1)) and colloidal matter (1.17-43.0 SigmaPCB ng L(-1)), being the last two estimated from the analysis of the apparently dissolved phase. Concentrations of PCBs in the SML were higher than those in the underlying water (ULW), giving rise to enrichment factors (EF=[C](SML)/[C](ULW)) up to first-order of magnitude. The ANOVA statistical approach was used to assess differences of bulk data (e.g. dissolved organic carbon, DOC; particulate organic carbon, POC; suspended particulate matter, SPM) among sampling devices, whilst p-tailed t paired tests were used in order to compare the enrichments obtained for each sampling date. In this respect, no significantly different enrichment factors were found among sampling devices (p < 0.05), although the surface SS showed lower enrichments, probably due to the dilution of the SML with the ULW during sampling. The MS seemed to be the most suitable device for the determination of PCBs in the SML in terms of sampling efficiency under a variety of meteorological conditions.  相似文献   

16.
The aim of this study was to attempt to fill current knowledge gaps on midlittoral Mediterranean biodiversity at local and regional scales, by using benthic polychaetes as a model taxon. Two different data sets were analysed: (i) a quantitative data set from the two Natural Geography in Shore Areas (NaGISA) study sites in Crete and (ii) a qualitative data set from multiple sites across the Mediterranean. At the local scale, the results provide evidence that (i) discrete species communities are formed in midlittoral Mediterranean habitats, which vary by geographical location and year, depending on the scale of observation; (ii) macrophyte coverage and Chl‐a are the only environmental variables associated, albeit weakly, with the above pattern; (iii) although naturally disturbed, the Cretan NaGISA sites do not seem to experience any anthropogenic stress; (iv) environmental heterogeneity and history seem to be much less important in shaping the polychaete communities than inter‐specific interactions; however, it is not possible to specify at this stage whether local or regional processes or even their interactions may shape the polychaete communities. At the regional scale, the results indicate that (i) the only factor that seems to be involved in the regional pattern is the identity of the study providing the data sets, which implies variability and bias in how research projects are carried out, from the sampling design through to data collection and analysis; (ii) the Cretan NaGISA sites may be considered as representative of the habitat in the Mediterranean, under certain conditions.  相似文献   

17.
To test if environmental contamination acts as a selection force affecting genetic diversity at the population level, two intertidal invertebrate species, Mytilus galloprovincialis and Balanus glandula, were collected from seven different bay sites in southern California. Collections were made at three relatively pristine 'clean' sites and four 'impacted' sites exposed to heavy industrial or boating activity, and which had previously been identified as having measurable levels of pollution. Genetic diversity at each site was assessed by comparing fragment polymorphisms generated from genomic DNA by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). All populations retained a large amount of genetic diversity and were genetically similar to each other. However, several different measures of diversity indicated that, for most primers, the populations of both species from impacted sites had lower genetic diversity compared to those populations from clean sites. Individuals at impacted sites were more likely to share the same haplotypes than were those from clean sites. Few bands seen in the clean sites were absent from the impacted sites or vice versa, but a number of bands in the clean site populations were significantly less common in the impacted populations, while a few bands uncommon in clean site populations were more common at impacted sites. Together, these results suggest that pollution at the impacted sites may reduce genetic diversity among the resident invertebrate populations.  相似文献   

18.
Staggered nested sampling designs are virtually unknown in biology, but are widely used in manufacturing because they are highly efficient. I used a staggered nested design to address variation in the abundance of an intertidal clam Austrovenus stutchburyi (Gray) at four spatial scales. The scales were addressed by sampling cells containing five samples spaced at 50, 5, 0.5, and 0.05 m from one another. Estimates of variation from staggered nested designs can be made via ANOVA and principal component methods. ANOVA and principal component methods estimated roughly equal variability among those four spatial scales of abundance, and at all but the smallest scales variances were estimated very imprecisely. Staggered nested designs are highly efficient, applicable to any nested design, and deserve to be investigated more widely.  相似文献   

19.
The soft sediment fish communities below 20 m depth were studied at two sites on the west coast of Scotland (Irvine Bay, Firth of Clyde and the Lynn of Lorne) using small meshed beam trawls. In both cases the emphasis was on the small demersal fish (<15 cm) within these communities. The Irvine Bay community was studied between May 1978 and December 1979 and the Lynn of Lorne community between February 1975 and October 1976.Twenty-seven fish species were recorded in Irvine Bay and 32 in the Lynn of Lorne. In both communities four species constituted more than 78% of the total annual abundance, two gobies (Lesueurigobius friesii and Pomatoschistus norvegicus) were high in the dominance ranking for both sites. The species abundance lists were similar for both sites (0·62 level of similarity) but the species lists for each site were different (0·36 level of similarity). The overall mean density of small demersal fish was similar for both sites (Irvine Bay = 0·045 individuals m?2 and the Lynn of Lorne = 0·047 individuals m?2). There were two periods of high abundance for both communities (late autumn to winter and late spring). There was, however, a low repeatability between successive years. The species richness (D) was relatively high (Irvine Bay = 1·5-3·08, Lynn of Lorne = 1·4-3·34) as was the species diversity (H′) (Irvine Bay = 1·17-1·97, Lynn of Lorne = 1·23-1·95). The proportional representation (J′) of each species within the community was greater in Irvine Bay (J′ = 0·57-0·77) than in the Lynn of Lorne (J′ = 0·50-0·72). Therefore these two communities of small demersal fish appeared to be similar at the community level but the way in which this was achieved was different.  相似文献   

20.
Evidence suggests that patterns of benthic community structure are functionally linked to estuarine processes and physical characteristics of the benthos. To assess these linkages for coarse-sediment shorelines, we used a spatially nested sampling design to quantify patterns of distribution and abundance of both macroinfauna and macroepibiota. We examined replicate beach segments within a site (∼1 km), sites within areas of relatively uniform salinity and temperature (∼10 km), and areas (∼100 km) in the two major basins of Puget Sound, Washington. Because slight variations in physical characteristics of a beach can lead to significant alterations in biota, we minimized confounding physical influences by working only in the predominant shoreline habitat type in Puget Sound, a mixture of sand, pebbles and cobbles. Species richness decreased steadily from north to south along gradients of declining wave energy, increasing temperature and decreasing salinity. A few taxa were confined to the South Basin, but many more were found in the North. Most of the variability in population abundance was captured at the smaller spatial scales. Physical conditions tend to become increasingly different with distance among sites. Communities became more different from north to south as species intolerant of more estuarine conditions dropped out. There was significant spatial autocorrelation among populations on neighboring beach segments for 73 of the 172 species sampled. Populations of these benthic species may be connected via dispersal on scales of at least km in Puget Sound. Our results strengthen prior conclusions about the strong linkages between the biota and physical patterns and processes in estuaries. It is important for monitoring and impact-detection studies to account for natural variation of physical gradients across the sampling scales used. Nested, replicated sampling designs can facilitate the detection of environmental change at spatial scales ranging from global (e.g., warming or El Niño), to regional (e.g., estuary-wide changes in salinity patterns), to local (e.g., from development at a site).  相似文献   

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