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71.
GIS支持下的长江口拦门沙泥沙冲淤定量计算 总被引:23,自引:4,他引:23
依据1842~1997年10幅不同年代的长江口海图资料,利用地理信息系统和数字化仪进行处理,建立不同时期的长江口水下数字高程模型,以此作为基础资料,实现了从横剖面、深泓线纵剖面、平面变化等不同角度对长江口拦门沙地区滩槽演变、岸线侵蚀、沙岛形成与变迁等进行研究.通过计算河槽容积,实现了对不同时段泥沙冲淤量的计算.结果表明,155a来拦门沙总的趋势是不断淤积,但不同时期淤积速度大不一样,个别时期甚至会发生一定程度的冲刷,这主要与动力条件的波动有关.1842~1997年,共淤积泥沙38.10亿t,平均每年淤积0.246亿t,约占长江来沙的5%,年均淤厚为1.1cm泥沙淤积部位主要在九段沙、横沙及横沙东滩、崇明东滩三处.发生冲刷的范围较小,仅占总面积的21.4%,主要在北槽,北港上段和南槽局部也有轻微的冲刷发生. 相似文献
72.
Takushi?NikiEmail author Taiki?Fujinaga Mariyo?F.?Watanabe Junji?Kinoshita 《Journal of Oceanography》2004,60(5):913-917
Solid-phase microextraction (SPME) is a simple, sensitive and less destructive method for the determination of dimethylsulfide
(DMS) in seawater. Combined with detection by gas chromatography-mass spectrometry (GC-MS), the method had sufficient sensitivity
(minimum detectable concentration of DMS was 0.05 nM), and practical levels of reproducibility (relative standard deviation
≤7%) and linearity (r
2 > 0.995) over a wide concentration range (0.5 to 910 nM). The protocol developed was applied to a Sagami Bay water sample
to determine concentrations of DMS and DMSP, and in situ DMSP-lyase activity. 相似文献
73.
Eddy Shedding from the Kuroshio Bend at Luzon Strait 总被引:16,自引:1,他引:16
TOPEX/POSEDIENT-ERS satellite altimeter data along with the mean state from the Parallel Ocean Climate Model result have been used to investigate the variation of Kuroshio intrusion and eddy shedding at Luzon Strait during 1992–2001. The Kuroshio penetrates into the South China Sea and forms a bend. The Kuroshio bend varies with time, periodically shedding anticyclonic eddies. Criteria of eddy shedding are identified: 1) When the shedding event occurs, there are usually two centers of high Sea Surface Height (SSH) together with negative geostrophic vorticity in the Kuroshio Bend (KB) area. 2) Between the two centers of high SSH there usually exists positive geostrophic vorticity. These criteria have been used to determine the eddy shedding times and locations. The most frequent eddy shedding intervals are 70, 80 and 90 days. In both the winter and summer monsoon period, the most frequent locations are 119.5°E and 120°E, which means that the seasonal variation of eddy shedding location is unclear. 相似文献
74.
In this paper we analyze seismic regime and earthquake depth distribution and correlation of seismicity and mud volcanism in the Azerbaijan and the Caspian Sea region. For the present region we have calculated accurate source locations, seismic activity, earthquake repetition and released earthquake energy parameters. It is shown that the active tectonic processes in the region are concentrated within the thick sedimentary cover that we consider as a general source of contemporary stress and a main structural element responsible for the origin of regional earthquakes. The correlation of seismicity and mud volcanism is of paragenetic character. 相似文献
75.
76.
Molecular identification of bloom-forming species Phaeocystis globosa(Prymnesiophyta)and its dispersal based on rDNA ITS sequence analysis 总被引:3,自引:1,他引:3
Abstract-The colony-forming Phaeocystis species are causative agents of dense bloom occurrences incoastal waters worldwide. It is difficult to separate them because of the different morphologies associatedwith their colonial stages. In this study we applied molecular approaches to analyze the genetic variationof Phaeocystis globosa and Phaeocystis pouchetii from several geogrtaphic regions, and to assist in tracingthe dispersal of bloom-forming Phaeocystis species in coastal waters of China. The Sequences of the inter-nal transcribed sacers (ITS1 and ITS2) of rDNA and the 5.8S ribosomal RNA gene of Phaeocystisstrains were determined. Sequence comparison shows that P.globosa was the most divergent toP. pouchetii, exhibiting sequence divergence higher than 0.08. However, lower genetic divergences ex-isted between strains of P.globosa. The sequence comparison of the Phaeocystis rDNA ITS clearlyshows that the species isolated from the southeast coast of China is identified as P. globosa rather thanP. cf. po 相似文献
77.
Experimental Investigation of Instantaneous Properties of Wave Slamming on the Plate 总被引:1,自引:0,他引:1
The purpose of this paper is to investigate the instantaneous properties of wave slamming on the plate structure of an open structure.The advanced instantaneous measuring technique-Particle Image Velocimetry(PIV) is applied to acquire the instantaneous velocity field of wave slamming.From the cross-correlation analysis results of the images captured by the CCD camera,the flow fields of wave impacting on the structure are displayed visually,and the instantaneous whole-field fluid velocity vectors are obtained.The relation between the instantaneous peak impacting pressures and the instantaneous velocities of water particles is studied by probability analysis. 相似文献
78.
3种蛏类线粒体16SrRNA和COI基因片段的序列比较及其系统学初步研究 总被引:15,自引:0,他引:15
对3种蛏类大竹蛏(Solen grandis),长竹蛏(Solen strictus)和小刀蛏(Cultellus attenuatus)的线粒体16SrRNA和COI基因片段序列进行了比较并对其系统学进行了初步研究。得到的序列总长度分别为472-481bp(16S)和658bp(COI)。3种蛏序列的碱基组成均显示出较高的A+T比例(16SrRNA基因62.1%;COI基因62.8%)。对位排序比较表明,16SrRNA片段种内个体间变异较小,3种类间存在128个碱基变异位点(其中包括127个简约信息位点)和5个插入/缺失位点,总共12个碱基长;COI片段有200个碱基存在变异,其中包括191个简约信息位点,不存在任何插入/缺失位点。数据分析结果表明16SrRNA和COI基因片段大竹蛏与长竹蛏两片段的遗传距离分别为0.0856和0.1712,两竹蛏类与小刀蛏的遗传距离分别为0.3054,0.2798和0.2662,0.2933。作者认为小刀蛏与竹蛏之间的遗传距离已达到科之间的水平,结果支持将其提升为刀蛏科的分类观点。3种蛏类线粒体16SrRNA和COI基因在种间明显的多态性,证实了16SrRNA和COI基因序列均普遍适用于蛏类种及以上阶元的系统学分析。 相似文献
79.
80.
栉孔扇贝消化管的组织学观察 总被引:5,自引:0,他引:5
运用石蜡切片法和组织化学方法,对栉孔扇贝的消化管进行了研究,结果表明,整个消化管从腔内到腔外,都由黏膜上皮、黏膜肌层、结缔组织和外膜组成。黏膜上皮层由纤毛柱状细胞和杯状细胞组成,基膜很薄,皮下有一层有肌纤维,结缔组织中有丰富的血腔隙,除直肠的外膜为浆膜外,其余皆为纤维膜。纤毛和黏液在食物的运输中起重要作用。胃和晶杆囊上皮能分泌消化酶。胃上上有较弱的碱性磷酸酶和脂酶活性。胃和晶杆囊上皮及纤毛有酸性磷酸酶活性,晶杆囊上皮的核前细胞质中含铁,各部位不含钙。 相似文献