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901.
The Lagrangian diffusion equation appropriate for the dispersion of current followers (e. g., floats, drogues, drifters) is proposed. The analytical solution to the equation is obtained for a uniform deformation field, characterized by Lagrangian deformations and anisotropic eddy diffusivities both varying with time. Expressions are derived for the patch area and its elongation and rotation. For small values of elapsed time after the initial release the patch area can be accounted for by the exponential of the cumulative value of the horizontal divergence; the relative rate of change of the patch area can be accounted for by the horizontal divergence.  相似文献   
902.
Investigations of short term acute exposure of bay scallops, Argopecten irradians and two scallop predators, the oyster drill Urosalpinx cinerea and the common starfish Asterias forbesi, to oil, dispersant, and oil-dispersant mixtures (Kuwait Crude Oil and Corexit 9527) suggested that predator and prey have different lethal susceptibilities. Scallops were most sensitive to dispersant and dispersant mixed with oil, starfish were only sensitive to dispersant while the oyster drill seemed unaffected even though all were exposed to dilutions of identically prepared stock solutions. Scallops were least susceptible during winter months and most susceptible at summer temperatures. Treatment had less effect on predators than on scallops at summer temperatures. Sublethal concentrations of dispersant and oil-dispersant mixtures diminished the behavioural ability of scallops to recognise drills and starfish. The degree of effect increased with temperature. Predator detection of prey at the same concentrations was more complex. The feeding response or posturing reflex of starfish was significantly slowed by all treatments. In contrast, drills were unaffected in their recognition of scallop effluent in a choice chamber after treatment.  相似文献   
903.
根据1986—1990中美热带西太平洋海气相互作用8个航次合作综合调查资料,分析了1987年10月赤道中西太平洋165°E(10°N-6°S)次表层水形成溶解氧最大值的原因。1986-1987年E1Nino衰退时期,该海域赤道附近在E1Nino强盛时期下沉的次表层水开始回升,短时期内形成了类似于中、高纬度海域的理化环境,使浮游生物在混合层内聚集生长,最终导致溶解氧含量在次表层出现最大值和过饱和含量。  相似文献   
904.
中国对虾(Penaeus chinensis)四倍体诱导研究   总被引:13,自引:0,他引:13  
利用光控和行为学原理,控制中国对虾在适当时候产卵,在一定的时刻以温度休克和细胞松弛素的方法诱导受精卵发育成为四倍体。作者发展了对虾染色体制备技术,以中肠和触角腺、精巢为材料,从后期幼体直到8~9cm左右次成虾均获得较好的分裂中相。染色体倍性检测结果表明,最好的四倍体诱导成功率达66.7%。共获得10cm左右的实验对虾几千尾。初步观察表明,四倍体中国对虾具有一定的生长优势。  相似文献   
905.
The various assumptions implicit in the calculation of acid dissociation constants (based on ionic medium standard states) from potentiometric titrations using a cell with liquid junction (i.e. a pH measuring cell) have been examined. It was concluded that results can be obtained having an accuracy commensurate with the experimental precision. It has been shown that although the precise composition of the medium is a function of the hydrogen ion concentration (because of the protolytic nature of some of the ions in the media, e.g., sulphate and fluoride), the effect of such variations in the medium composition can be compensated for when defining the activity of hydrogen ion on an ionic medium standard state by defining the concentration of hydrogen ion as:
[H]SWS=h(1 + βHSO4ST + βHFET)
where βHSO4 and βHF are the relevant association constants and ST and FT are the total concentrations of sulphate and fluoride, respectively.This approach was used to obtain values for the ionic product of water (KW) in artificial seawater media at various temperatures and ionic strengths. These were fitted to give the equation (molal concentration units):
pKw= 3441.0T+2.256-0.709112 (rms deviation 0.01)
where I is the formal ionic strength of the artificial seawater medium and T is the absolute temperature. The values obtained are in reasonable agreement with those found by previous workers.  相似文献   
906.
利用1981 ̄1990年环渤海地区的地面气象资料,探空资料和土地利用资料,计算了该地区大气水份平衡方程中各分量,分析了其变化特征,并对它们之间的相互关系进行了研究。  相似文献   
907.
对海洋湍流速度脉动的一维概率密度作了测量,并把测量结果与高 斯分布进行了比较。比较的结果表明,一个接近于高斯分布而另一个却差别较 大。计算到直至五阶湍流相关函数并与网格湍流进行了比较,结果都表明小时 间间隔中测量结果与网格湍流的结果近似一致,而大时间间隔中却相差很大。 以上结论说明了较长的测量时间的必要性。  相似文献   
908.
平鲷♀与真鲷♂的杂交研究   总被引:14,自引:0,他引:14  
研究了不同盐度,温度,pH对平鲷Rhabdosargus sarba♀和真鲷Pagrosomus major♂清子活力的影响,确立了人工授精与孵化的条件参数。平鲷♀与真鲷♂杂交的受精率达95%以上,胚胎发育与其亲本的相似。经过超低温保存的真鲷精子的激活率,活力与鲜精的接近,其杂产的受精率也可达95%以上。实验获得了杂产仔鱼,但杂交的孵化率比对照组低。  相似文献   
909.
The prevalence of dermal neoplasia among neotenic tiger salamanders (Ambystoma tigrinum) collected from the Reese Air Force Base sewage lagoon far exceeded that among salamanders from nearby uncontaminated lagoons. Perylene was the predominant pglycyclic aromatic hydrocarbon contaminant in this lagoon. Perylene was shown to be a substrate for monooxygenases in skin and liver homogenates and formed DNA-binding metabolites. Perylene exposure appeared to augment subsequent perylene metabolism by dermal enzymes but it was not a strong inducer of hepatic monooxygenases. Aroclor 1254 induced benzo(a)pyrene and perylene metabolism by both skin and liver enzymes. However, perylene apparently was not activated by salamander enzymes, as suggested by its lack of in vitro mutagenicity and failure to induce tumors.  相似文献   
910.
A simulation of a chronic input of petroleum into an estuarine environment was investigated using the facilities at the Marine Ecosystems Research Laboratory at the University of Rhode Island. An oil-water dispersion of No. 2 fuel oil was added to the system (twice weekly for 24 weeks) and the saturated hydrocarbons from this oil were measured in suspended material and sediments. After the initial chronic oil addition, trace amounts of hydrocarbons were detected in the sediments within two weeks, but substantial accumulation was not detected for approximately 135 days. The oil appeared to enter the sediment via the suspended material, with most of the saturated hydrocarbons associated with smaller size sediment particles (< 45 μm to > 0·3 μm). With time, the fuel oil saturated hydrocarbons in the sediments were mixed to a depth of 3 to 4 cm. Although only 12% of the total saturated hydrocarbons added to the system were found in the sediments, these hydrocarbons appear to be relatively stable and were still detectable in these sediments for at least six months after the last oil addition.  相似文献   
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