Cordilleran ice-sheet growth fueled primary productivity in the Gulf of Alaska, northeast Pacific Ocean
Cordilleran ice-sheet growth fueled primary productivity in the Gulf of Alaska, northeast Pacific Ocean
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DOI：
10.1130/g39904.1
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发表时间：
2018-04
期刊：
影响因子：
5.8
通讯作者：
J. Müller;O. Romero;E. Cowan;E. McClymont;M. Forwick;H. Asahi;C. März;C. Moy;I. Suto;A. Mix;J. Stoner
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文献类型：
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作者：
J. Müller;O. Romero;E. Cowan;E. McClymont;M. Forwick;H. Asahi;C. März;C. Moy;I. Suto;A. Mix;J. Stoner
风沙和冰山对海洋的施肥是提高初级生产力的有效机制。特别是，在浮游植物生长严重受铁限制的高营养、低叶绿素（HNLC）地区，如亚北极太平洋和南大洋，建议通过提高浮游植物生产力和向海底输出碳来应对生物可利用铁供应的增加。虽然人们普遍认为来自沙尘的铁肥可以解释南大洋冰期较高的出口产量，但支持生产力与北太平洋风沙和/或冰山之间联系的古海洋学记录很少。通过结合来自单一海洋沉积记录（Integrated ocean Drilling Program [IODP] Site U1417）的独立指示冰盖动力学和海洋生产力的代用指标，我们获得了包括中更新世过渡期在内的亚北极东北太平洋1.5 ~ 0.5 Ma浮游植物对不同施肥机制响应的综合数据集。重要的是，施肥事件的时间更多地受当地冰盖范围的控制，而不是受冰期-间冰期气候变率的控制。我们的研究结果表明，冰川碎屑的施肥导致了与冰盖相邻的HNLC地区的生产力事件，这一机制可能是浮游植物生长的一个重要但很少被考虑的驱动因素。
Fertilization of the ocean by eolian dust and icebergs is an effective mechanism to enhance primary productivity. In particular, high-nutrient, low-chlorophyll (HNLC) areas where phytoplankton growth is critically iron-limited, such as the subarctic Pacific Ocean and the Southern Ocean, are proposed to respond to increases in bioavailable Fe supply with enhanced phytoplankton productivity and carbon export to the seafloor. While Fe-fertilization from dust is widely acknowledged to explain a higher export production during glacial periods in the Southern Ocean, paleoceanographic records supporting links between productivity and eolian dust and/or icebergs in the North Pacific are scarce. By combining independent proxies indicative of ice-sheet dynamics and ocean productivity from a single marine sedimentary record (Integrated Ocean Drilling Program [IODP] Site U1417), we present a comprehensive data set of phytoplankton response to different fertilization mechanisms in the subarctic northeast Pacific between 1.5 and 0.5 Ma, including the Mid Pleistocene Transition. Importantly, the timing of the fertilization events is more strongly controlled by local ice-sheet extent than by glacial-interglacial climate variability. Our findings indicate that fertilization by glacigenic debris results in productivity events in HNLC areas adjacent to ice sheets, and that this mechanism may represent an important, yet rarely considered, driver of phytoplankton growth.