231Pa/230Th ratios in sediments as a proxy for past changes in Southern Ocean productivity
231Pa/230Th ratios in sediments as a proxy for past changes in Southern Ocean productivity
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DOI：
10.1038/362045a0
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发表时间：
1993-03
期刊：
影响因子：
64.8
通讯作者：
Naresh Kumar;R. Gwiazda;Robert F. Anderson;P. Froelich
中科院分区：
文献类型：
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作者：
Naresh Kumar;R. Gwiazda;Robert F. Anderson;P. Froelich
海洋的生物生产力对气候变化很敏感，气候变化会影响营养和光照等基本因素。反过来，海洋生产力可能通过调节海洋和大气之间的二氧化碳（一种温室气体）分配来影响气候。调查人员试图将记录在冰芯中的大气CO2含量的变化与南大洋的生产力联系起来3 -6，但缺乏一种明确的方法来评估过去海洋生产力的变化。在这里，我们利用已建立的关系between 231 Pa/230 Th比值和颗粒通量7 - 12推断，从过时的沉积物岩心分析，通过时间的变化，从地表沃茨输出的颗粒生物物质通量。南大洋大西洋部分的两个岩心记录表明，在冰川期，南极极锋以南的海洋生产力低于目前的水平，这支持了早先的结论，即最大生产力区在冰川期向北迁移。虽然需要在其他地点进一步开展工作，以评估南极总生产力的变化，但我们的技术有可能提供这一信息，同时避免其他生产力代理的一些限制。
THE biological productivity of the oceans is sensitive to changes in climate, which can affect essential factors such as nutrient and light availability. In turn, ocean productivity may influence climate by regulating the partitioning of carbon dioxide, a greenhouse gas, between the ocean and the atmosphere. Investigators have attempted to link variations in atmospheric CO2content, recorded in ice cores1,2, to the productivity of the Southern Ocean3–6, but an unambiguous means of assessing past changes in ocean productivity has been lacking. Here we exploit established relationships between231Pa/230Th ratios and particle flux7–12to infer, from the analysis of dated sediment cores, variability through time of fluxes of particulate biogenic material exported from surface waters. Records from two cores in the Atlantic sector of the Southern Ocean indicate that ocean productivity during glacial periods was lower than at present south of the Antarctic polar front, and support earlier conclusions13–16that the zone of maximum productivity migrated northwards during glacial conditions. Although further work at other sites is needed for an assessment of changes in total Antarctic productivity, our technique has the potential to provide this information while avoiding some of the limitations of other productivity proxies.