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世界上最古老的化石(pp554-557) 人们知道,今天的大气中含有大量的氧。但是,地球并不总是被包裹在富含氧的大气层中。事实上,在地球的发展历史上,由蓝藻通过光合作用来生产氧是一个具有决定意义的时期,因为氧的供应为需氧生物的进化铺平了道路。在本期《自然》杂志上,澳大利亚地质调查机构的一组科学家发表文章称,他们找到了蓝藻活动的最早证据。他们将其在澳大利亚西部McRae山页岩中发现的25亿年前的沉积岩称为“分子化石”。这些所谓的化石实际上是有机化合物,尽管经过了这么长时间,它们仍然与当时由蓝藻留下的化合物很相似。(联系人:Roger E Summons; E-mail:Roger.Summons@agso.gov.au) 氮和磷哪一个是海洋中的生长限制因子(pp525-531) 氮对海洋中浮游植物的生长来说非常重要,但海洋中氮的数量与磷的数量密切相关。海洋学家有一个长期未能解决的问题,即氮和磷到底哪一种是海洋中的生长限制因子?这一问题的答案在环保上具有重要意义,因为沿海水域由于人为原因氮和磷的含量都过高,导致浮游植物生长
The oldest fossils in the world (pp554-557) People know that today’s atmosphere contains a lot of oxygen. However, the Earth is not always surrounded by oxygen-rich atmospheres. In fact, in the history of the earth, the production of oxygen by photosynthesis by cyanobacteria is a decisive period, as the supply of oxygen paves the way for the evolution of aerobic organisms. In this issue of Nature, a team of scientists from the Australian Geological Survey published an article saying they found the earliest evidence of cyanobacteria activity. They described the 2.5 billion-year-old sedimentary rocks that they found in the McRae shale in western Australia as “molecular fossils.” These so-called fossils are actually organic compounds that, despite being so long, are still very similar to the compounds left by the cyanobacteria at the time. (Contact: Roger E Summons; E-mail: Roger.Summons@agso.gov.au) Nitrogen and Phosphorus Which is a limiting factor for growth in the oceans (pp525-531) Nitrogen is not unusual for the growth of phytoplankton in the oceans Important, but the amount of nitrogen in the ocean is closely related to the amount of phosphorus. Oceanographers have a long-standing problem that can not be solved: which one is the limiting factor for the growth of the ocean? The answer to this question is of great environmental importance because of the man-made causes of nitrogen and phosphorus in coastal waters The content is too high, resulting in phytoplankton growth