马尾藻褐藻胶的研究 1.海蒿子(Sargassum pallidum)褐藻胶的提取条件

1881年Stanford首次自海带类海藻加碱提取出一种胶质,命名为“Algin”(褐藻胶),并对它的化学性质进行了初步研究。后来经过许多化学家对这种胶质的化组成和结构进行了多年的研究,才确定褐藻胶是一种主要由?-D甘露糖醛酸残基通过1,4位碳原子互相键合的多糖。"褐藻胶"这一名词在广义上包括水不溶性的褐藻酸、与多价金属离子构成的水不溶性褐藻酸盐类、以及与碱金属离子或铵基构成的水溶性褐藻酸盐类;狭义的说来,则指褐藻酸纳而言,因为市场上的商品主要是纳盐。     

Mathematical modeling of PCB bioaccumulation in Perna viridis

In the present work, we built a mathematical model of polychlorinated biphenyl (PCB) bioaccumulation in Perna viridis, namely, a one-compartment model with a time dependent incorporation rate R (μg g⁻¹ lipid per ppb water per day), with positive substrate cooperativity as the underlying physical mechanism. The temporal change of the PCB concentration Q (μg g⁻¹ lipid) in the soft tissues of the mussel depends on the competition of the input rate RW and the output rate kQ, where W is the concentration of PCB in water (ppb water) and k is the elimination rate (per day). From our experimental data, k=0.181±0.017 d⁻¹. The critical concentration in water W_c for positive substrate cooperativity was found to be 2.4 ppb. Below W_c, R is a constant. For a water concentration of 0.5 ppb Aroclor 1254, R=24.0±2.4 μg g⁻¹ lipid ppb⁻¹ d⁻¹. Above W_c, positive substrate cooperativity comes into effect and R becomes a function of time and dependent on the concentration Q in a form R=γQ/(Q+δ). This is the case for a water concentration of 5 ppb Aroclor 1254, where γ=15.1 μg g⁻¹ lipid ppb⁻¹ d¹ and δ≈200 μg g⁻¹ lipid. From this model, the uptake is exponentially increasing when the PCB concentration in the mussel is small compared to 200 μg g⁻¹ lipid, and hyperbolically increasing when the concentration is large compared to 200 μg g⁻¹ lipid, which are consistent with the experimental data. The model is useful for understanding the true processes taking place during the bioaccumulation and for risk assessment with higher confidence. Future experimental data which challenge the present model are anticipated and in fact desirable for improvement and perfection of the model.     

Changes in the water regime of the caspian sea

The article deals with issues of structure and dynamics of the Caspian Sea water balance. On the base of historical, paleogeomorphological and other data the evolution history of the Caspian Sea and its basin has been observed for different time intervals down to 400 thous. years ago. Presented are computerized data on water balance components in the current centenary obtained from instrumental observations, revealed are causes of the sea-level fluctuations within that time interval and anthropogenic factor contribution to this process. Based on the analysis of this material, an attempt has been undertaken to present a scenarion of a possible sea-level position of the Caspian Sea with the expected versions of climatic changes at the end of the XX and beginning of the XXI centuries.     

Die Verwendung von orthogonalen Polynomen in der Meteorologie

Zusammenfassung Das Höhenfeld der 850 mb-Fläche über Mitteleuropa und dem Nordatlantik wird in einem Gitternetz aus 45 Punkten durch Orthogonalpolynome (Tschebytscheff-Polynome) dargestellt. Es wird ein Überblick darüber gegeben, welche Verwendungsmöglichkeiten dieser Darstellungsform künftighin untersucht werden sollen; es sind dies vor allem die objektive Klassifikation der Großwetterlagen, statistische Prognosen (besonders Mittelfristprognosen) und die Anwendung bei der numerischen Wettervorhersage. Als Beispiel für die Darstellung wird der Übergang von einer zonalen Wetterlage über eine meridionale wieder zu einer zonalen Lage an den Änderungen der Koeffizienten der Polynomkombinationen gezeigt.

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Summary The field of heights of the 850 mb-surface above Central Europe and the North Atlantic is represented in a grid of 45 points by means of orthogonal polynomials (Tchebycheff-polynomials). A general discussion is given which of the possible applications of this kind of representation shall further be investigated, i. e. first of all the objective classification of large scale weather situations (Großwetterlagen), statistical forecasts (especially medium range forecasts), and the application in numerical weather prediction. As an example of this representation, the variations of polynomial coefficients are given for the transition of a pressure field from zonal to meridional and back to zonal.

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Résumé Les hauteurs de la surface isobarique de 850 mb au dessus de l'Europe Centrale et de l'Océan Atlantique du Nord sont représentées dans un carrelage de 45 points par des polynoms orthogonaux (polynoms de Tchebycheff). Un aperçu est donné quel emploi possible de cette manière de représentation sera à examiner dans l'avenir; ce sont avant tout la classification objective des situations météorologiques générales (Großwetterlagen), les prévisions statistiques (particulièrement les prévisions à moyenne échéance) et l'application à la prévision numérique. Comme exemple de cette représentation la transition d'une situation météorologique zonale à une situation méridionale et vice versa à une situation zonale est montrée au moyen des variations des coefficients des combinaisons des polynoms.

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Herrn Prof. Dr.R. Inzinger, dem Vorstand des Mathematischen Labors der Technischen Hochschule Wien, sei an dieser Stelle gedankt, daß er für die rechnerischen Vorarbeiten die Maschinen seines Instituts und einen seiner Assistenten für deren Programmierung zur Verfügung stellte.     

A study of the subarctic boundary region in the Western North Pacific

During autumn 1968 an oceanographic investigation was conducted in the region of the Subarctic boundary between 155°E and 180°. The geostrophic flow of the upper 500 m was remarkably similar in direction; hence the salinity-minimum, Intermediate water must have the same path of flow as water at the surface. A water mass analysis revealed a decrease in the percentage of Subarctic water to the south and east, plus an increase in the homogeneity of water to the east, which supports Reid's conclusions that the salinity minimum results mainly from lateral mixing in the pycnocline in this region. Salinity at the minimum increases toward the south and east, and the density at this level also increases slightly from the western to the central Pacific, perhaps as a result of unequal vertical mixing above and below the minimum.     

Radium and lead-210 in marine barite

Measurements of ²²⁶Ra and ²¹⁰Pb in barite samples separated from different depths of a piston core from the eastern equatorial Pacific are reported. ²²⁶Ra is enriched in the barite as would be expected from the chemistries of Ra and Ba; the ${}^{226}\text{Ra}\text{Ba}$ ratio centers around 1.5 · 10¹⁴ atoms/mole. The results suggest that barite is concentrating Ra at a rate comparable to its decay rate, viz. 5.78 · 10^?3 yr^?1. The gross ²¹⁰Pb depletion with respect to ²²⁶Ra is indicative of ²²²Rn loss due to the smallness of the barite crystals.     

Organic contaminants and characteristics of sediments from Oso Bay,south Texas,USA

The Oso Bay, Texas, sediments from nine sites were analyzed by GC-MS for organics to measure contamination in the bay. In most of the sites sediments contained tetrachloroethene (87–1433 g/kg), bis (2-ethylhexyl)phthalate (40–193 g/kg), and aliphatic hydrocarbons, C₈-C₁₃ (720–2491 g/kg). Sources of these contaminants include a landfill, military facilities, and municipal and industrial discharges. Size analysis of the sediments indicates they contain a high percentage of muddy sand (50–75 percent), which suggests that Oso Bay consists of common bay margin sediments.     

The possible connection between ionization in the atmosphere by cosmic rays and low level clouds

Recent analysis of monthly mean cloud data from the International Satellite Cloud Climatology Project uncovered a strong correlation between low cloud and the cosmic ray flux for extensive regions of the Earth. Additional data have been recently released covering the period up to September 2001 with which we have made a new study of the geographical variation of the correlation between low cloud and predicted ionization level from cosmic rays at an altitude of 2 km. When analysed globally, we find that the correlations do not correspond to the latitude variation of cosmic ray flux and they are not field significant. Nonetheless they appear to be marginally field significant over broad latitude and longitude bands with a peak positive correlation at 50 degrees North and South and a tendency to negative correlation at lower latitudes. The correlation is strongest over the North and South Atlantic. Several of these features are consistent with the predictions of the electroscavenging process.We use a simple model to calculate the climatic impact should the correlation be confirmed. We show that, under the most favorable conditions, a reduction in low cloud cover since the late 19th century, combined with the direct forcing by solar irradiance can explain a significant part of the global warming over the past century, but not all. However, this computation assumes that there is no feedback or changes in cloud at other levels.     

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