彩虹明樱蛤的耗氧率与排氨率研究

研究了不同水温和不同规格下处于标准代谢状态的彩虹明樱蛤耗氧率与排氨率,并测定了窒息点.结果表明:在20℃时,水中DO大于临界值5.00mg/dm3时,彩虹明樱蛤的耗氧率和排氨率处于相对稳定的状态,分别为2.01×10-3(m/m)/h和16.73μmol/(g.h);当DO低于此值,则代谢出现异常,耗氧率随DO下降而下降,直到窒息为止,其窒息点为1.22mg/dm3,而排氨率也呈直线下降,随着耗氧停止而停止。     

盐度对菲律宾蛤仔摄食率和清滤率的影响

实验室条件下,对15、20、25、30和35五个盐度梯度下菲律宾蛤仔(Ruditapes philippinarum)的摄食率RI和清滤率RC进行了测定。结果表明,在15~25的盐度条件下,蛤仔的摄食率RI和清滤率RC随着盐度的升高而增大,在25时达到最大值,而在25~35盐度条件下,随盐度的增加而减小。     

盐度对双齿围沙蚕耗氧率和排氨率的影响

为优化双齿围沙蚕养殖条件,促进沙蚕资源的合理开发和利用,作者探讨了不同盐度下(8、16、24、32、40、45)双齿围沙蚕(Perinereis aibuhitensis)耗氧率和排氨率的情况。结果表明:盐度对双齿围沙蚕的耗氧率和排氨率均有显著性影响(P0.05)。在盐度为8~32时,耗氧率随着盐度的升高呈先下降后上升的趋势;在盐度为24时耗氧率最低(0.22 mg/(g·h)±0.01 mg/(g·h));在盐度为32时耗氧率达到最大值(0.37 mg/(g·h)±0.05 mg/(g·h))。在盐度为8~40条件下,沙蚕的排氨率随着盐度的升高呈先降低后上升的趋势;在盐度为24时,双齿围沙蚕的排氨率最低(0.10μmol/(g·h)±0.02μmol/(g·h));当盐度为40时排氨率达到最大值(0.94μmol/(g·h)±0.11μmol/(g·h))。盐度为8~40时,沙蚕的O︰N比值随着盐度的上升呈先升高后降低的趋势,在盐度24和32时,沙蚕的O︰N比值分别为130.84和126.47,且变化较小,当盐度40时,O︰N比值急剧下降到13.3,然后再度上升。综合上述结果,双齿围沙蚕生活的最适盐度为24~32。     

Calculation of littoral sand transport rate

An energy-related littoral sand transport rate formula is presented, based on extensive laboratory tests and on a broad set of known field data. An example of application of the new expression to an actual measured field situation is also given.     

香港巨牡蛎对3种浮游植物摄食率和滤清率的研究

本文在室内条件下研究了大、中、小3种规格的香港巨牡蛎（Crassostrea hongkongensis）对牟氏角毛藻（Chaetoceros muelleri）、亚心形扁藻（Platymonas subcordiformis）、球等鞭藻（Isochrysis galbana）3种浮游植物在同等密度、同等生物量条件下的摄食率和滤清率,探讨了香港巨牡蛎对3种浮游植物的摄食差异及其影响因素。结果表明,在28℃水温条件下,香港巨牡蛎的单位个体滤清率和单位体质量滤清率分别为1.40~8.94 L/（ind·h）和0.86~3.17 L/（g·h）,等密度和等生物量浮游植物条件下香港巨牡蛎均表现出单位个体滤清率由高到低依次为:大规格、中规格、小规格;不同规格香港巨牡蛎的单位体质量滤清率相近。相同藻类密度条件下,香港巨牡蛎的单位体质量滤清率由高到低依次为:亚心形扁藻、球等鞭金藻、牟氏角毛藻;相同生物量条件下,香港巨牡蛎对3种浮游植物单位体质量滤清率由高到低依次为:球等鞭金藻、亚心形扁藻、牟氏角毛藻。香港巨牡蛎对不同浮游植物种类和密度的滤清率、摄食率差异主要是受饵料的大小、营养质量和密度等因素影响。     

海塘越浪量风险分析

根据现有规范公式计算的海塘越浪量存在一定程度的风险,它主要来自越浪量计算参数的不确定性。对影响海塘越浪量计算不确定性的3种主要因素进行了分析,在此基础上给出了用M on te C arlo方法进行海塘越浪量风险模拟的步骤。一个实例海塘的计算结果表明:按《浙江省海塘工程技术规定》(1999)公式计算的海塘越浪量存在很大的不确定性,海塘越浪量分布在0.044~0.069 m3/(s.m),大于最大允许海塘越浪量[0.05 m3/(s.m)]的概率为88.93%。因此,对重要海塘的越浪量进行物理模型试验验证是十分必要的。     

光合色素标记法测定不同类群浮游植物的光合速率和生长速率

尝试利用放射性同位素14C示踪方法测定浮游植物不同类群的光合速率和生长速率,并通过实验室和现场海域的培养实验来初步评估该技术的可行性.通过高效液相色谱法分离光合色素,手动收集并测定各对应光合色素峰的放射性活度,依据Redalje-Laws法并结合类胡萝卜素标记法计算出各大类群浮游植物的光合速率和生长速率.实验结果表明,在实验室纯种培养的4株藻光合速率范围为347.73~678.98 mg/（dm3.d）,最高的为绿藻的小球藻,最低的为定鞭金藻的球石藻.其生长速率范围为0.12~0.24 d-1,最高的为球石藻,最低的为小球藻.在现场海域各类群的光合速率相对较低,变化范围为0.63~68.78 mg/（dm3.d）,生长速率在0.07~1.68 d-1之间.本研究首次在我国海域通过现场原位测定得到不同类群浮游植物的光合速率和生长速率.但在测定过程中存在的样品含量和放射活度较低等问题还有待于进一步解决.     

Oceanic spreading rate and crustal thickness

Examination of oceanic seismic refraction results indicates a correlation between total crustal thickness and spreading rate, with slower spreading producing thinner crust. The effect is seen at spreading rates less than about 20 mm yr^–1. The crustal thickness and its dependence on spreading rate are predicted by theoretical modelling of flow and melting beneath mid-ocean ridges.     

Erosion of cohesive sediments as a rate process

The problems associated with the erosion of cohesive sediment in the marine environment are well recognized. However, the mechanisms of controlling erosion are not well understood. The research to be presented was directed at characterizing the erosion resistance of cohesive sediment through the application of rate process and double layer theories. Additionally, relationships between erodability and temperature, salinity, pore water content and erosional shear stress were studied.A total of 50 tests were conducted in a refrigerated water tunnel. These included tests in which temperature was incremented at constant erosional shear stress and tests within which the erosional stress was varied at constant temperature.The material tested was a remoulded illitic-silt (Grundite). Tests were performed at constant pH and at five different water contents ranging from 40 to 80%. For each water content, samples were tested at five different salinities varying from 0 to 10% NaCl.Results are as follows: (1) the erosional response of cohesive sediments can be described with rate process and double layer throries, (2) the magnitude of experimental activation energies suggest solid-to-solid bonding and are essentially independent of salinity and water content, (3) experimental flow volumes were essentially invariant with water content, but decreased with salinity in accordance with the double layer theory, which suggest that the dominant interparticle forces in surface cohesive erosion are physico-chemical rather than mechanical.     

Impact of global warming rate on permafrost degradation

The IAP RAS climate model of intermediate complexity is used to analyze the sensitivity of the area of continuous potential permafrost S _cont to the rate of global temperature variation T _gl in experiments with greenhouse-gas increases in the atmosphere. The influence of the internal variability of the model on the results is reduced by conducting ensemble runs with different initial conditions and analysis of the ensemble means. Idealized experiments with a linear or exponential dependence of the concentration of carbon dioxide in the atmosphere have revealed an increase in the magnitude of the temperature-sensitivity parameter of the area of continuous potential permafrost, k _cont (= S _{cont, 0} ^t-1 dS _cont/dT _gl, where S _{cont, 0} is the present value of S _cont). With a decrease in the linear trend coefficient of T _gl from about 3 to about 2 K/100 yr, this parameter varies from approximately ?0.2 to ?0.4 K^?1. With an even slower change in global temperature, k _cont virtually does not vary and remains close to the value obtained from paleoreconstructions of the past warm epochs. Such a dependence of k _cont on the rate of global warming is related mainly to the fact that the more rapid increase in T _gl leads to a slower response over high-latitude land. The contribution from changes in the annual temperature cycle, though comparable in the order of magnitude, is about one-third as large as the contribution from the variation of the latitudinal structure of the response of annual mean temperature. The total reduction in the annual cycle of temperature during warming partly compensates for the effect of the annual mean temperature rise, thus decreasing the magnitude of k _cont. In numerical experiments with greenhouse gas changes in accordance with SRES scenarios A2 and B2 and scenario IS92a, there is also a monotonic increase in the magnitude of the normalized parameter of temperature sensitivity of the area of continuous permafrost with a decrease in the growth rate of global temperature. For scenarios A2-CO2, IS92a-GHG, IS92a-CO2, B2-GHG, and B2-CO2, its value is almost indistinguishable from the steady-state asymptotic value of ?0.4 K^?1. For A2-GHG, the magnitude of k _cont turns out to be far less (k _cont ≈ ?0.3 K^?1).     

Effect of sampling rate on wave height statistics

This paper examines the effects of digital processing, and therefore discretisation or sampling, of sea surface elevations that are, in reality, continuous. Using random linear wave theory, probability distributions for the measured (as opposed to actual) wave amplitudes and heights have been obtained which are conditional on the sampling rate. It is shown that with low sampling rates there are significant departures from the usual Rayleigh distribution. Rates of 1 Hz or less may lead to significant underestimation of the probability of very large waves. An analysis of full-scale measurements obtained from a platform in the North Sea supports these results.     

浅色黄姑鱼幼鱼耗氧率、排氨率及窒息点的初步研究

呼吸和排泄是鱼类代谢活动的重要特征,是鱼类生物能量学研究的重要内容之一,对于评估鱼类在水生态系统中的作用、物质循环、能量流动以及养殖容量等具有十分重要的意义。通过了解耗氧率和排氨率与各种因素的相互关系及变化规律可以了解鱼体的代谢水平和活动规律等,可为鱼类的养殖生产、新品种培育、移植驯化、养殖水体水质调控和活体运输等提供科学依据。有关鱼类耗氧率的研究,国内已有许多文献[1-11],但关于排氨率的研究相对较少,目前已见有牙鲆、犬齿牙鲆、大西洋鲆等种类的报道[12-14]。     

臭氧对西施舌胚胎孵化率和幼虫摄食生长与成活的影响

研究了臭氧处理后的海水对西施舌(Coelomactra antiquata)胚胎孵化率、幼虫摄食率、生长率和成活率的影响。结果表明,臭氧处理后的海水的化学耗氧量(COD)及NH 4-N的浓度明显下降。西施舌胚胎在通入臭氧(4.17mg/L)10min的海水中,孵化率最高,为97%,在充入臭氧25min的海水中孵化率最低,为72.7%;西施舌幼虫在充入臭氧10～15min的海水中和未经处理的海水中生长较快;幼虫在充入臭氧5min和10min的海水中成活率有所提高。将幼虫放在多次充入臭氧的海水中培养,再放回未经臭氧处理的海水进行17h和30h恢复,30h后其死亡率达85%,而在充入臭氧时间短的的海水中死亡率较低,为33.3%,表明西施舌幼虫的生理机能受到了臭氧的不可恢复破坏。     

What causes the adiabatic lapse rate?

The adiabatic lapse rate is commonly explained as being proportional to the work done on a fluid parcel as its volume changes in response to an increase in pressure. According to this explanation the adiabatic lapse rate would increase with both pressure and the fluid's compressibility, but this is not the case. Rather, the adiabatic lapse rate is proportional to the thermal expansion coefficient and is independent of the fluid's compressibility. Here we show that the adiabatic lapse rate is independent of the increase in the internal energy that a parcel experiences when it is compressed. We explain what is missing from the traditional explanation of the adiabatic lapse rate and we explore the thermodynamic cause of the adiabatic lapse rate. In particular, we seek to explain how the adiabatic lapse rate can be negative in cool fresh water.     

Transport rate under irregular sheet flow conditions

This paper presents the results of experiments conducted on sand transport in sheet flow conditions under nonlinear asymmetric irregular oscillations with different frequency spectrums. Two methods are proposed for estimation of the transport rate. The first method which is based on a wave by wave analysis of the irregular velocity profile gives very accurate predictions. The second method, which uses a representative single wave, is less computing time consuming and still gives satisfactory results. The measured net transport rates do not show any dependence on the spectral shape.     

盐度及规格对管角螺耗氧率和排氨率的影响

海水温度28℃的条件下,实验室中研究了不同盐度(12,17,22,27,32)对管角螺(Hemifusus tuba Gmelin)耗氧率和排氨率的影响。实验结果表明:盐度、个体大小对管角螺的耗氧率和排氨率均有显著的影响。盐度为12～27时,单位体质量管角螺耗氧率随着盐度的升高而增加,并在27时达到最大值;盐度为27～32时,随着盐度的升高管角螺的耗氧率降低。管角螺的软体部干质量与单位体质量耗氧率之间的关系符合幂函数方程,呈负相关关系;盐度范围在12～27时,单位体质量的管角螺排氨率随着盐度的升高而增加,并在27时达到最大;盐度为27～32时,随着盐度的升高管角螺的排氨率降低。管角螺的软体部干质量与单位体质量排氨率之间的关系也符合幂函数方程,呈负相关关系。不同规格管角螺的耗氧率、排氨率及O:N值随着盐度的升高而逐渐增大,并在27达到最大值,然后随着盐度的升高逐渐减少。