Ocean productivity before about 1.9 Gyr ago limited by phosphorus adsorption onto iron oxides
Ocean productivity before about 1.9 Gyr ago limited by phosphorus adsorption onto iron oxides
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DOI：
10.1038/417159a
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发表时间：
2002-05-09
期刊：
影响因子：
64.8
通讯作者：
Canfield, DE
中科院分区：
文献类型：
--
作者：
Bjerrum, CJ;Canfield, DE
产氧蓝藻在27亿年前的某个时候进化后(1)，地球上的氧气生产被认为依赖于海洋中营养物质的可获得性，例如磷(以正磷酸盐的形式)。在现代海洋中，磷的重要去除途径是通过其在氧化铁沉积物(2，3)上的吸附来实现的。过去，这种矿床被认为更为丰富，因为在低硫酸盐条件下，大量铁氧化物的形成导致了带状铁构造的沉积(4，5)。在这种情况下，氧化铁吸附除磷可以得到强化。在这里，我们分析了条带状铁建造中的磷和铁的含量，以表明32亿到19亿年前(太古代和早元古代)的海洋正磷酸盐浓度可能只相当于今天浓度的10%-25%。因此，我们认为，低磷有效性应该显著降低光合作用和碳埋藏的速率，从而减少地球早期的长期氧气生产--正如先前推测的那样(4)--并导致太古代晚期和早元古代大气中氧气浓度较低。
After the evolution of oxygen-producing cyanobacteria at some time before 2.7 billion years ago(1), oxygen production on Earth is thought to have depended on the availability of nutrients in the oceans, such as phosphorus (in the form of orthophosphate). In the modern oceans, a significant removal pathway for phosphorus occurs by way of its adsorption onto iron oxide deposits(2,3). Such deposits were thought to be more abundant in the past when, under low sulphate conditions, the formation of large amounts of iron oxides resulted in the deposition of banded iron formations(4,5). Under these circumstances, phosphorus removal by iron oxide adsorption could have been enhanced. Here we analyse the phosphorus and iron content of banded iron formations to show that ocean orthophosphate concentrations from 3.2 to 1.9 billion years ago (during the Archaean and early Proterozoic eras) were probably only similar to10-25% of present-day concentrations. We suggest therefore that low phosphorus availability should have significantly reduced rates of photosynthesis and carbon burial, thereby reducing the long-term oxygen production on the early Earth-as previously speculated(4)-and contributing to the low concentrations of atmospheric oxygen during the late Archaean and early Proterozoic.