The estimation of acid dissociation constants in seawater media from potentionmetric titrations with strong base. I. The ionic product of water — Kw

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:

where β_HSO4 and β_HF are the relevant association constants and S_T and F_T are the total concentrations of sulphate and fluoride, respectively.This approach was used to obtain values for the ionic product of water (K_W) in artificial seawater media at various temperatures and ionic strengths. These were fitted to give the equation (molal concentration units):

$\text{pK}{}_{\mathrm{w}}\text{=}\text{3441.0}\text{T}\text{+2.256-0.7091}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(}\text{rms deviation 0.01}\text{)}$

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.     

环渤海区域大气水份平衡特征的研究

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。     

海洋湍流的测量及相关分析

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。     

Assessment of imposex in the common whelk, Buccinum undatum (L.) from the Eastern Scheldt, The Netherlands

Several cruises were carried out on the Eastern Scheldt between September 1992 and March 1995 to study the frequency and appearance of imposex in the common whelk, Buccinum undatum L. Incidences of imposex were always > 90%. For the first time several stages of imposex in Buccinum undatum are reported. The evolution of imposex in the whelk seems to follow a similar route as in Hinia reticulata belonging to the same superfamily (Buccinacea). Tissue organotin concentrations of animals collected in February 1995 showed the highest organotin concentrations in the digestive gland and lowest in the foot of the animals. Concentrations of phenyltin compounds (up to 625 ngSn/g DW) were much higher than those of butyltin compounds (up to 40 ngSn/g DW).     

“Batfish” a depth controllable towed body for collecting oceanographic data

“Batfish” is a streamlined vehicle developed to house fast-responding oceanographic sensors. It is towed behind a ship or small vessel and its depth is controlled from the vessel by a manually or automatically produced command signal. Variable-angle wings permit the vehicle to be lowered and a novel control surface, which eliminates the need for heavy ballast, assures lateral stability. There are two models: the standard and the wide-wing Batfish. The standard Batfish has collected temperature and conductivity data at depths of up to 200 m when towed at 10–25 km/hr, and the wide-wing Batfish at depths to 400 m when towed at 10–16km/hr.     

平鲷♀与真鲷♂的杂交研究

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。     

Optical monitoring of coastal waters: Photic depth estimates

Measurements of underwater irradiance, transparency and Secchi disc depth were carried out in Liverpool Bay during 1974. The depth of the photic zone measured in the green portion of the spectrum ranged from 5 m to 50 m, depending on location and season. Inshore values of photic depth were smaller than those encountered offshore. By mid-summer the depth of the photic zone had reached or exceeded the depth of the sea bed over the whole study area.Consideration was given to the error terms associated with the optical measurements and to the problems of using standard optical relationships in coastal waters. The relationship between Secchi disc depth and the depth of the photic zone could not be taken as constant but was a function of the absorption and scattering properties of the water mass.     

La marge continentale Tunisienne: Résultats d'une étude par sismique réflexion: Sa place dans le cadre tectonique de la Méditerranée Occidentale

Résumé Une série de profils de sismique réflexion effectués au large de la Tunisie et dans le détroit sardano-tunisien aboutissent à l'élaboration d'un schéma géologique interprétatif dans lequel nous replaçons le socle paléozoïque et sa couverture autochtone (Eocène et plio-quaternaire) et allochtone (nappe numidienne). Nous discutons ensuite des manifestations néotectoniques (bassins d'effondrements plio-quaternaires-mouvement de flexure-surrections locales-venues intrusives). Enfin la nature du substratum du détroit sardano-tunisien est discutée en liaison avec les hypothèses dynamiques et statiques relatives à la formation de la Méditerranée occidentale.

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Serial seismic reflection profiles off Tunisia and between Sardinia and Tunisia are presented. Interpretation is given which includes paleozoïc basement and its autochtonous (Eocene and plioquaternary) and allochtonous (Numidian nappe) cover. Recent tectonic activity is discussed, (Plioquaternary foundered basins, flexure, local uplifts, intrusions). Then the nature of the basement of the Sardinia-Tunisia zone is discussed with respect to the various hypotheses on the region of the Western Mediterranean.

     

Comparison of oscillatory and stationary flow through porous media

Experiments were conducted in an oscillatory water tunnel to investigate what effects temporal inertia has on the resistance of a granular medium. The flow law governing stationary porous media flow is reasonably well accepted and understood but the effects of unsteady flow have commonly been neglected. The present research was designed to assess the magnitude of the acceleration effects on media of uniformly packed spheres of equal diameter and on one sample of randomly placed stone.Oscillatory flow tests were made in a large oscillatory flume tunnel with periods varying from 3 to 12 seconds. The influence of properties of the medium (grain size and porosity) were tested by using spheres with two different diameters and packing each size sphere in different geometric arrangements. Tests made on a stone sample provided a qualitative assessment of the effects of more random material properties.For the experiments described in this paper, the Forchheimer unsteady-stationary flow law described the oscillatory measurements well when velocities and energy losses were maximum. Empirical coefficients determined from steady-stationary flow were generally found to apply to the unsteady flow, however some evidence of dependency on the period of oscillation was noted.