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41.
Seasonal and annual variations of marine sinking particulate flux during 1993~1996 in the central South China Sea 总被引:1,自引:0,他引:1
CHEN Ronghu WIESNER M G ZHENG Yulong CHENG Xinrong JIN Haiyan ZHAO Qingying ZHENG Lianfu 《海洋学报(英文版)》2007,26(3):33-43
A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993~1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species (Globigerinoides sacculifer, G. ruber, Globigerinita glutinata, Neogloboquadrina dutertrei) and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution. 相似文献
42.
43.
In order to accurately design a sand compaction pile (SCP) with low replacement area ratio, it is important to understand the mechanical interaction between the sand pile and clay ground and its mechanism during consolidation process in composite ground. In this article, therefore, a series of numerical analyses on composite ground improved by SCP with low replacement area ratio were carried out. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, were confirmed by comparing the results obtained from a series of laboratory model tests with the composite ground improved by SCP. Through the results of the numerical analyses, mechanical behavior of the sand pile and clay in composite ground during consolidation is elucidated, together with a stress sharing mechanism between sand pile and clay. 相似文献
44.
More and more researches show that neither the critical downward acceleration nor the critical slope of water waves is a universal constant. On the contrary, they vary with particular wave conditions. This fact moders the models either for the probability of wave breaking B or for the whitecap coverage W based on these criteria difficult to apply. In this paper and the one which follows we seek to develop models for the prediction of both B and W based on the kinematical criterion. First, several joint probabihstic distribution functions (PDFs) of wave characteristics are derived, based on which the breaking properties B and W are estimated. The estimation is made on the assumption that a wave breaks ff the horizontal velocity of water particles at its crest exceeds the local wave celerity, and whitecapping occurs in regions of fluid where water particles travel faster than the waves. The consequent B and W depend on wave spectral moments of orders 0 to 4.Then the JONSWAP spectrum is used to represent the fetch-limited sea waves in deep water, so as to relate the probahility of wave breaking and the whitecap coverage with wind parameters. To this end, the time-averaging technique proposed by Glazman (1986) is applied to the estimation of the spectral moments involved, and furthermore, the theoretical models are compared with available observations collected from published literature. From the comparison, the averaging time scale is determined. The final models show that the probability of wave breaking as well as the whitecap coverage depends on the dimensionless fetch. The agreement between these models and the database is reasonable. 相似文献
45.
46.
郑平胜 《海洋学报(英文版)》1986,5(3):456-456
Some unusual features have been analysed in this paper on the sea conditions ofnorthwestern East China Sea and the fisheries of Mackerel, Round Scad, Sardines off Zhejiangin the autumn of 1983, based on the data of the past years. The findings are as follows: 1. The low-salinity water area formed by the Changjiang River runoff emptying intothe sea expanded by three times as campared with that of 1978 (a poor runoff year). The 相似文献
47.
中国台湾地区地处欧亚板块与菲律宾海板块之间,地震活动频繁.本文报道了 我国台湾地区及其邻近海域1985~2002年间5.5级以上地震的条带内外频度比分 布,并着重研究了1999—2002年中发生的3次7.5级以上地震前的条带现象.其结 果表明:台湾地区近期发生的3次7.5级以上大地震前,5.5级以上地震呈条带分 布.这些条带符合条带内地震个数Nin≥6的条件,符合条带内、外频度比Nin/(Nin Nout)≥75%的条件,也符合条带长宽比大于5的要求,只是与板内地震条带相比,条 带的长度较短. 相似文献
48.
氮磷营养盐与有机汞联合作用对微氏海链藻生长的影响 总被引:1,自引:1,他引:1
探讨在高营养盐(氮、磷、硅分别为浮游植物生长的营养盐阚值≥40、50、9倍)条件下,氮浓度及氮磷摩尔比值[n(N)/n(P)]变化、汞(甲基汞和乙基汞)对微氏海链藻(Thalassiosira weissflogii)生长的影响。结果表明,高营养盐区海链藻的生长遵循营养盐限制的唯一因子论;氮浓度和氮磷比提高促进生长,当n(N)/n(P)=64则呈抑制效应;生长初期,甲基汞和乙基汞均产生毒性抑制作用,生长中后期,适量甲基汞(浓度≤1.0μg/L)、乙基汞(浓度≤0.5μg/L)却呈兴奋效应,促进生长;汞形态不同,剂量-效应关系不同。氮和有机汞是海链藻生长的刺激因子。适度有机汞污染与氮富营养化对微氏海链藻的生长产生协同效应。 相似文献
49.
MECHANISM OF URANIUM ADSORPTION ON AMIDOXIME RESIN 总被引:1,自引:0,他引:1
The mechanism of uranium adsorption from seawater by polyacrylamidoxime resin is investigated by means of the experiments of adsorption isotherm and adsorption rate. The uranium uptake increases with the adsorption temperature and varies with the pH of seawater. Thermochemical and kinetic calculation show that the enthalpy change (△H) and the activation energy (E) of the uranium adsorption are 42.4 42.4 kJ mol-1 and 41.2 kJ mol-1 respectively, indicating that the uranium adsorption on the resin proceeds via a certain complex chemical reaction in which the amidoxime group in the resin chelates uranyl ions. 相似文献
50.
Cu2+、Zn2+、SDS、DBS对脊尾白虾的毒性试验 总被引:4,自引:0,他引:4
选用铜、锌2种常见重金属和十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(DBS)2种阴离子表面活性剂对脊尾白虾Palaemon carincauda仔虾进行96h急性毒性试验。结果表明,Cu2 、Zn2 、SDS、DBS对脊尾白虾仔虾的96h LC50分别为0.34、0.82、14.3和14.4 mg.L-1。将脊尾白虾仔虾对这4种毒物的敏感性与文献报道的其它动物进行了比较,结果认为可以将其作为毒性测试的标准试验生物。 相似文献