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Enhanced carbon pump inferred from relaxation of nutrient limitation in the glacial ocean

机译：从放松冰河中营养物质限制推断出增强的碳泵

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The modern Eastern Equatorial Pacific (EEP) Ocean is a large oceanic source of carbon to the atmosphere. Primary productivity over large areas of the EEP is limited by silicic acid and iron availability, and because of this constraint the organic carbon export to the deep ocean is unable to compensate for the outgassing of carbon dioxide that occurs through upwelling of deep waters. It has been suggested that the delivery of dust-borne iron to the glacial ocean could have increased primary productivity and enhanced deep-sea carbon export in this region, lowering atmospheric carbon dioxide concentrations during glacial periods. Such a role for the EEP is supported by higher organic carbon burial rates documented in underlying glacial sediments, but lower opal accumulation rates cast doubts on the importance of the EEP as an oceanic region for significant glacial carbon dioxide drawdown. Here we present a new silicon isotope record that suggests the paradoxical decline in opal accumulation rate in the glacial EEP results from a decrease in the silicon to carbon uptake ratio of diatoms under conditions of increased iron availability from enhanced dust input. Consequently, our study supports the idea of an invigorated biological pump in this region during the last glacial period that could have contributed to glacial carbon dioxide drawdown. Additionally, using evidence from silicon and nitrogen isotope changes, we infer that, in contrast to the modern situation, the biological productivity in this region is not constrained by the availability of iron, silicon and nitrogen during the glacial period. We hypothesize that an invigorated biological carbon dioxide pump constrained perhaps only by phosphorus limitation was a more common occurrence in low-latitude areas of the glacial ocean.
机译：现代的东赤道太平洋（EEP）海洋是向大气排放碳的大型海洋资源。 EEP大面积地区的初级生产力受到硅酸和铁可用性的限制，并且由于这一限制，有机碳向深海的出口无法补偿因深水上升而产生的二氧化碳放气。有人提出，将粉尘载铁输送到冰河海洋可以增加该地区的初级生产力，并增加该地区的深海碳出口，从而降低冰河时期大气中的二氧化碳浓度。潜在的冰川沉积物中所记录的较高的有机碳埋藏率支持了EEP的这种作用，但较低的蛋白石积累速率使人们怀疑EEP作为海洋区域对冰川二氧化碳大量减少的重要性。在这里，我们提出了一个新的硅同位素记录，表明冰川EEP中蛋白石积累速率的反常下降是由于在粉尘输入增加而铁利用率提高的条件下，硅藻硅与碳吸收率的降低所致。因此，我们的研究支持在上一个冰川时期在该地区加强生物泵的想法，这可能导致冰川二氧化碳的减少。此外，根据硅和氮同位素变化的证据，我们推断，与现代情况相比，该地区的生物生产力不受冰川期铁，硅和氮的可用性限制。我们假设在冰川海的低纬度地区更常见的情况是充满活力的生物二氧化碳泵可能仅受磷的限制。

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  • 来源
    《Nature》 |2009年第25期|1114-1117|共4页
  • 作者

    L. E. Pichevin; B. C. Reynolds; R. S. Ganeshram; I. Cacho; L. Pena; K. Keefe; R. M. Ellam;

  • 作者单位

    School of Geosciences, Grant Institute, University of Edinburgh, West Main Road, EH1O 3JW, Edinburgh, UK.;

    IGMR, ETH Zurich, Clausiusstrasse 25, CH-8092 Zurich, Switzerland.;

    School of Geosciences, Grant Institute, University of Edinburgh, West Main Road, EH1O 3JW, Edinburgh, UK.;

    GRC Geociencies Marines, Facultat de Geologia, Universitat de Barcelona C/ Marti Franques s 08028 Barcelona, Spain.;

    GRC Geociencies Marines, Facultat de Geologia, Universitat de Barcelona C/ Marti Franques s 08028 Barcelona, Spain.;

    Scottish Universities Environment Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, G75 OQF, UK.;

    Scottish Universities Environment Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, G75 OQF, UK.;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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