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Desertification has been notably expanding in China in the recent decade, especially in North China where dust/sand storm (DSS) frequently assaulted local communities. Analyses in marine ecology found that the earth ecosystem could be able to complement nutrient silicon for keeping sustain- able development of marine ecosystem, and decreasing CO2 concentration in the atmosphere; as a result, the area of desertification would be enlarged. Modern human being activities have resulted in constant changes in the amount of silicon transport from land into sea, leading to oversupply of nitrogen and phosphorus but silicon in seawater. The proportion of nitrogen, phosphorus and silicon was seriously im- balanced and the limitation of silicon for phytoplankton growth has become more serious. The silicon de- ficiency has damaged the marine ecosystem in coastal regions and slowed down the carbon sedimentation in the atmosphere of the world. The authors believe that the continual discharge of CO2 into the atmos- phere is the cause for the global warming including marine water temperature rise. Consequently, the earth ecosystem would have to trigger its complementary action to resume to the silicon balance by algae bloom in seawater for reducing air and water temperatures. In order to complement nutrient silicon into the sea, the ecosystem would transport silicon via the atmosphere; therefore, the desertification in the in- ner land is a natural reaction. As marine phytoplankton booming can reduce the CO2 concentration in the atmosphere and further ease the green-house effect, during this process, a large amount of silicon are de- manded by the ecosystem, which human being are unable to stop desertification from happening but slow down the progress and ease the risk. Therefore, as an important role in earth ecosystem, people should reduce the CO2 discharge into the atmosphere first; then, the normal function of river transporting silicon must be restored. In this way, the CO2 in the atmosphere can be kept in balance, the global warming slowed down, marine ecosystem development sustained, the drought in inner land eased, and the desert gradually under-controlled. 相似文献
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用原子荧光法同时测定砷、锑、铋、汞 总被引：8，自引：0，他引：8
试样经王水分解 ,在HCl (1+ 9)介质中 ,用硫脲 抗坏血酸将 5价As、Sb还原为 3价 ,再用KBH4 还原为氢化物。在HCl (1+ 4 )介质中 ,与KBH4 作用生成AsH3、SbH3、BiH3和Hg ,以特制空心阴极灯为光源 ,用双道无色散原子荧光仪测定As、Sb、Bi、Hg的荧光强度 ,各元素的检出限分别为As 5 9× 10 - 10 ,Sb 5 0× 10 - 10 ,Bi 6 9× 10 - 10 ,Hg 2 9× 10 - 1 相似文献
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本文以研究压溃理论的适用性为目的,以有椭圆度的钢管为研究对象,采用理论、有限元、实验相结合的方式,进行均匀外压作用下管道结构压溃失效的研究。整理了目前运用较为广泛的三种压溃理论模型,分别为弹性压溃理论、塑性压溃理论与规范经验公式。并基于ABAQUS软件,建立有椭圆度的钢管模型进行外压压溃模拟,得到不同径厚比D/T钢管的极限压溃值,并进行实验验证了有限元模型的正确性。对比不同压溃理论模型的计算值与有限元结果确定不同理论模型的适用性,获得以下结论:弹性压溃理论适用于径厚比D/T≥40的情况;塑性压溃理论的计算结果偏于保守,计算值均小于有限元结果;DNVGL-ST-F101规范适用适用径厚比D/T≥15的压溃值预测,是目前适用范围最广的公式。本文可为海底管道的抗压溃分析的理论研究提供参考。 相似文献
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将现代信息技术引入海洋信息化建设从而提高海洋行政执法科学化水平,是保证合理开发利用海洋和海洋经济健康可持续发展的有效途径。文章研究新形势下的海洋行政执法信息化机制,以例行执法检查和专项执法行动为主线,以航空监察、案件报备、行政审批和法律法规等为辅助,集成各类执法数据信息,运用软件编程和网络技术建立具有海洋行政执法业务流转和地图服务综合功能的信息监管系统,逐步实现海洋行政执法工作由传统监管模式向科学化、标准化和规范化的现代空间管理方式过渡,推进海洋行政执法监管的信息化进程,提升执法效率和监管力度。 相似文献
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