大气臭氧层与生物的演化

在影响生物演化的诸因素中,大气臭氧层是一个重要因素。当臭氧层不完善或遭受破坏时,紫外线就会令生物致伤致死,在晚元古代时,大气臭氧层还很薄弱.吸收紫外线的能力不强。进入罗圈冰期,陆缘海变浅,寒冷又使藻类减少,海水的透明度增大,紫外辐射增强而导致埃迪卡拉动物群的绝灭,白垩纪末期的绝灭事件与臭氧层的破坏有关,这是由慧星冲击引起的并造成了恶劣的环境,深海沉积物中所记录的各种地球化学异常可以用臭氧层破坏所产生的地球化学效应来加以解释.图1,参9.

AIR OZONOSPHERE AND EVOLUTION OF ORGANISMS

The air ozonosphere is one of the important factors affecting the evolution of organisms. When ozonosphere is imperfect or has been destroyed, the solar ultraviolet rays can hurt or kill the organisms. In the late proterozoic, the ozonosphere was still imperfect, with a poor capacity of absorbing the solar ultraviolet rays. When it went into the Luo Juan glacial age, the marginalbsca bceamc very shallow, the algea were reduced by the coldness, the transparence of seawater increased and the solar ultraviolet rays became more intense and the killing effect of the ultraviolet rays caused the ediacare fauna to extirpate. The event of extinction at end of the cretaceous had something to do with the ozonosphere destruction. The ozonosphere destruction was caused by the impact of the comet and it brought about adverse environments. The recording of various geochemical abnormal in the deep-sea sediment can be exphined with the geochemical effect caused by the destruction of the air ozonosphere, lfig, 9refs.