南极沿海伯尔顿盐湖双刺镰状水蚤盐度耐性的季节变化

双刺镰状水蚤Drepanopus bispinosus为南极沿海伯尔顿盐湖(Burton lake)中的越冬种类之一,其雌性性成熟大约于每年的初冬季节,在随后8个多月的生活史中,经历了一个盐度从33(5月份)到39(11月份)的环境变化.本文报道了该水蚤雌性成体对环境盐度适应的季节差异,动物在冬季的耐低盐能力较夏季强,从冬季到夏季,动物对盐度的适应范围明显地向高盐度方向偏移,这与环境盐度对动物的驯化有关.在低盐水中,动物的呼吸率增高,且夏季大于冬季,因而进一步证实了环境盐度的变化对动物盐度适应性的影响.     

东部非洲低空急流的数值研究

一个三维的有限区域、原始方程的数值模式用来研究东部非洲急流和夏季西南季风。这个模式适用于24°S—48°N和30°E—110°E的范围,在E—W和S—N方向上水平分解分别为1°和2°。Arakawa C方案中、模式的格点是交错的。垂直方向上有5个σ层。有限差分为二阶。显示分离方法是利用时间积分。在一度分解表面高度的基础上、波包和5点平滑的地带包括在这个模式中。横向的边界条件是自由滑动和对正常风分量的展开。但是、总的质量守恒。在模式中,对于驱动季风所规定的对流加热率为7月份平均观测值的五倍。纬向平均温度通过用2天时间尺度的瑞利恢复而保持。七月份平均纬向流通过张驰逼近而初值化。根据莫宁-奥布霍夫的平稳相关总方程式把边界层参数化了。在6天时间内的各种条件下,模式积分处于准稳定状态。同时发现,东非急流的强度和季风环流的结构对于地形,对流加热和加热强度是非常敏感的。但对感热和非线性平流的敏感性却是很小的     

印度东南部海岸拉梅斯沃勒姆滨外保克湾底层水特征对底栖有孔虫的影响

有孔虫生活在海洋和半咸水环境。底栖有孔虫的存在很大程度上受物理因素（深度、温度、光量、水体扰动）、化学因素（盐度、溶解氧和可用元素）和生物因素（食物供给量和底层沉积物特征）的制约。研究人员对印度东、西岸现代底栖有孔虫生态学和分布状态进行了研究。Ｎａｉｄｕ等在对Ｖｉｓａｋｈａｐａｔｎａｍ港复合体有孔虫进行分析后提出 ,可以将有孔虫作为海洋污染的指示物。ＳｒｅｅｎｉｖａｓａＲａｏ等采用Ｑ模式系数分析对尼赞伯德讷姆湾有孔虫的分布进行了研究 ,确认此区域存在４种组合 ,受不同环境条件的影响。Ｋｈａｒｅ等对门格…     

白垩纪温度较冷的估价

白垩纪温度较冷的估价Ｂ．ｗ．Ｓｅｌｌｗｏｏｄ等有关白垩纪气候的概念部分基于详尽的地质证据，如不耐寒冷的古生物（如：珊瑚的分布比现在偏极地５－１５℃）和特殊气候条件的沉积相的广泛分布。这些资料的解释反映２１℃的等温线在纬度上至少向两极移动５°，全球的平...     

Irish on the move

Trends in emigration from Ireland over time are reviewed. "During the eighteenth and nineteenth centuries overseas migration to the United States and seasonal harvest migration to Britain were the main types of movement, but over the past 100 years the Irish have developed a special affinity for settling in British towns. Although the outflow was halted for a time during the 1970s, when return migration took over, the 1980s have seen a renewal of the exodus. This time, however, the character of the flow has changed from predominantly low-skill construction and factory workers to embrace better-educated emigrants, including many graduates. This shift reflects Ireland's changing position in the international market for labour."     

Interstellar water in meteorites?

D/H ratios of two meteorites (Renazzo CR and Semarkona LL3), which are known to exhibit the largest departures from the terrestrial hydrogen isotopic ratios, have been determined with the CRPG Nancy ion microprobe. Correlations between the D/H ratios and the chemical compositions (H2O, K, Si, C/H) of plausible hydrogen carriers were observed. From these correlations, it is possible to show that, contrary to previous interpretations, phyllosilicates are the carriers of the deuterium-rich hydrogen in Semarkona and Renazzo: 870 x 10(-6) > or = D/H > or = 670 x 10(-6) (+4600 > or = deltaD > or = 3300%) and > or = 320 x 10(-6) (deltaD > or = 1050%), respectively. Hydrogen is also present in the chondrules of these two deuterium-rich meteorites. The large differences in D/H ratios between matrix (up to 700 x 10(-6), deltaD up to +3500%) and chondrules (from 120 x 10(-6) (deltaD = -230%) to 230 x 10(-6) (deltaD = +475%)) show that hydrogen in chondrules cannot originate from the matrix by simple contamination or diffusion processes. The high D/H ratios measured in water-bearing minerals could not have been produced thermally within a dense solar nebula. Chemical reactions (i.e., involving ions or radicals), taking place in interstellar space or in the outer regions of the nebula at 110-140K are presently the only conceivable mechanisms capable of yielding such isotopic enrichments. Water in these meteorites should no longer be considered as a simple product of nebular condensation under equilibrium thermodynamic conditions at T > or = 160K.