锋与地形的相互作用

一、引 言 锋的地形效应的重要性,早已被天气学界所承认,但是至今尚未对这些效应作出动力学的研究。Bannon(1983)对于一些在表面地形上移动的处在伸展变形场中的准地转锋,求得了分析解。1984年,他得到了更普遍的半地转解,但这个解需要时变地形和低边界层条件部分初值化。Bannon(1983,1984)的研究结果表明,当一条锋在山坡上爬坡运动时,这个锋将减弱,而当它向下坡运动时,则加强。在文中我们将发展一个数值模式,这个模式将会消除Bannon(1984)所用到的近似值。这一模式是Williams(1972)对一个锋生研究的扩展模式的变形。将一个随地形起伏的垂直坐标引入到简化的地形内含中去。还要使用周期性边界条件,变形场的风分量变为正弦的形式,这些边界条件从数值方法的角度来说是比较好的处理办法,而变形场则给出了一个运动着的天气扰动更合情合理的描述。     

Genetic responses to metal contamination in two clams: Ruditapes decussatus and Ruditapes philippinarum

Coastal ecosystems are subjected to a wide variety of disturbances, including those due to xenobiotics of agricultural and industrial origin. These pollutants as heavy metals can modify the genetic diversity of populations by favouring or counter-selecting certain alleles or genotypes by differential mortality. In the present study, two genetic markers (phosphoglucomutase and glucosephosphate isomerase) and a protein marker (metallothionein) were monitored in order to determine the impact of heavy metals in different clam populations. Analysis of the genetic structure of the clam populations examined reveals that those inhabiting environments contaminated by heavy metals exhibit a higher allelic diversity and possess alleles at PGM loci that could be selected by the presence of heavy metals. The evaluation of metallothionein levels using a specific polyclonal antibody developed in the Pacific oyster (Crassostrea gigas) demonstrated the existence of a relationship between metallothionein concentrations and the level of metal pollution for clam populations sampled from different sites. An inter-specific difference was also detected between Ruditapes decussatus and Ruditapes philippinarum living in sympatry at the same site, suggesting a differential response of these two species upon exposure to an identical heavy metal concentration.     

对地球大气和表面研究的卫星数据处理和分析软件系统

一、引 言 在地球科学发展中现在正出现两个重要的趋势。一个是传统的研究地球部分的定向学科的方法。它正慢慢地让位於更全面的多学科的方法,该方法把地球和大气看成是一个动态的综合系统。另一个是空间观测方法,或更确切地说是卫星遥感,它正成为地球科学各学科如:海洋学、气象学、生物学、地质学和地球物理学的标准研究工具。 鉴于这种趋势,加州空间研究所一直都在开发卫星数据处理和分析软件系统,来支持多学科的及综合研究计划。该系统叫做OASIS(海洋大气卫星图象系统),它有助於处理地球的大气和表面(陆地和海洋)的科研及教学活动的开展。     

Implications of seasonal priming and reproductive activity on the interpretation of Comet assay data derived from the clam, Tapes semidecussatus Reeves 1864, exposed to contaminated sediments

We explore the use of the clam Tapes semidecussatus Reeves 1864 as an indicator for the presence of potentially genotoxic substances in estuarine sediments. The limitations associated with the interpretation of Comet assay data (expressed as % DNA in tail) in terms of clam reproductive state, size (age) and thermal exposure history following laboratory acclimation are discussed. Hatchery-reared clams, subjected to ambient temperature fluctuations during growth, were exposed in vivo under laboratory conditions for three weeks to sediment samples collected from a polluted site and a "clean" reference site. The DNA damage observed in haemocytes, gill and digestive gland cells was significantly higher in animals exposed to contaminated sediment compared to those exposed to sediment from the reference site. The extent of DNA damage recorded was not correlated with size (age). Spawning was not observed during the experiment. Nevertheless, clams with well-developed gonads showed a statistically higher degree of DNA damage in gill and digestive gland cells- but not haemocytes, demonstrating an increased sensitivity to potential genotoxic compounds, possibly caused by impaired DNA repair capacity due to reproductive activity. Furthermore, the degree of DNA damage in clams exposed to contaminated sediments was higher in autumn and winter compared to spring and summer, suggesting an effect of seasonal priming.     

Seasonal variance of salinity tolerance of a copepod Drepanopus bispinosus in an Antarctic littoral saline lake (Burton Lake)

In Burton Lake (an Antarctic littoral saline lake), as one of the overwinter species, the female Drepanopus bispinosus reach adult form in autumn. and early winter.For the subsequent life period of more than eight months, the animals experience such changing environment as increasing salinities from approximately 33 (in May) to 39 (in November). There is a considerable difference of salinity tolerance of female adults between summer and winter populations.Winter collected copepods survived lower salinities than summer collected copepods in this experiment. The upward shift in their salinity tolerance range is related to the development of field acclimation to salinity. Respiration rates of the summer animals showed a visible increase over those of winter copepods in simitar salinity and temperature conditions, thus supporting the above conclusion.     

大陆边缘深水-超深水带油气潜力

考虑了世界大洋含油气盆地扩张到陆架和陆坡脚，在超深水盆地中已经发现了大量包括石油的烃类资源，这些盆地限于被动大陆边缘，具有相同的形成机制，优选出那些堆积在有利的裂谷和深水扇条件下的源岩和储层，描述了油气（这里指石油）的生成和聚集。膏盐化在圈闭形成和烃类运移中扮演了重要的作用。全球经验表明俄罗斯北部、东部和南部陆架以及陆坡和坡脚有巨大的石油潜力。     

210Pb沉积速率测定法在浅水动力环境中的应用

本文根据瓦登海(Waddensea)潮滩沉积物。~(210)Pb强度的测定和有关实验,讨论了~(210)Pb沉积速率测定法在浅水动力环境中应用所存在的一些问题和原因;提出了~(210)Pb“转换时间”和“沉降时间”概念;分析了泥沙运动与沉积物~(210)Pb强度的关系并依据粒度指标对某些不规则~(210)Pb剖面进行修正;发现Jade湾潮滩现代沉积速度为0.16—0.29cm/a,Greetsiel为0.16cm/a,Afsluitdfijk大坝附近达6.0cm/a,反映了大坝工程改变动力环境后出现的聚淤现象。     

三万五千年以来的海平面

美国大西洋陆架35,000年来的海平面曲线,是建立在80多个放射性碳年代的基础上,其中15个年代是老于15,000年代的。测年的材料包括浅水软体动物、鲕状岩、珊瑚藻、海滩岩和盐沼泥炭。30,000—35,000年前的海平面,曾经是接近于现在的海平面的。随后冰川发育,16,000年前海平面降低到负130米左右。全新世海侵可能开始于约14,000年前,并迅速地延续到约7,000年前。世界大多数大陆架的年代和这条曲线相一致,说明这条曲线大致是这个时期海平面升降的曲线。     

年轻洋底测年

年轻洋底测年Ｄ．Ｍ．Ｃｈｒｉｓｔｉｅ尽管火山熔岩空间分布令人满意且能大量取样，但是，由于缺乏其样品直接、准确的年龄数据，对洋中脊火山岩石学及其演变的详尽研究长期以来受阻。即使这些特定区域内通过潜艇观测或遥控摄像一录相技术得到的地质图都能够对熔岩流体积...     

人造放射性示踪砂在联合王国的应用

示踪砂技术已逐渐成为一种确定的工程泥沙研究方法，英国上世纪就进行了30次有关河流或沿岸泥沙运动的观测研究，如Harwell原子能研究所和Walingtord水利研究所等。这些研究很多是为商业机构进行的，故其研究成果很少在公开刊物上发表，现将其有关应用技术作摘录介绍。1放射性示踪砂可用于海岸研究的放射性同位素很多，其中，示踪同位素的选择主要依据勘测时间的长短及标记示踪砂的适应性。英国一些研究单位曾将‘’sc（半衰期以u）、““Ag（半衰期253d）、’‘Cr（半衰期27．sd）、‘”An（半衰期2．7d）和““La（半衰期40．Zh）等同…