Biological and climatic consequences of a cold, stratified, high latitude ocean
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- 作者：James D. Hays ; Douglas G. Martinson ; Joseph J. Morley
- 关键词：Biological pump ; Radiolaria ; North Pacific ; Deep sea cores ; Ocean carbon sequestration ; Flux ; Glacial ocean ; Stratification ; Pleistocene ; Holocene ; Sea of Okhotsk
- 刊名：Quaternary Science Reviews
- 出版年：15 December, 2013
- 年：2013
- 卷：82
- 期：Complete
- 页码：78-92
- 全文大小：2356 K
文摘
The flux from deep- and shallow-living radiolarian assemblages provides evidence of a glacial, high latitude, cold ocean stratification that increased biological pump efficiency and promoted ocean carbon sequestration. Greater deep (>200聽m) than shallow-living (<200聽m) radiolarian assemblage flux characterizes glacial North Pacific (>45掳 N) sediments with the deep-living Cycladophora davisiana dominant (>24%). By contrast modern radiolarian flux consists primarily of shallow-living species (C.聽davisiana <10%). Clues to the cause of this unusual glacial radiolarian flux come from the presently, strongly stratified Sea of Okhotsk. Here beneath a thin nutrient depleted mixed layer radiolarian and zooplankton faunas conform to the sea's physical stratification with lower concentrations of both in a Cold (鈭?.5 to 1聽掳C) Intermediate Layer (CIL) (20-125聽m) and higher concentrations in waters between 200 and 500聽m (). This biological stratification generates a radiolarian flux echoing that of the glacial northwest Pacific with C.聽davisiana 26% of total flux. Widespread C.聽davisiana percentages (>20%) in high latitude (>45掳) glacial sediments of both hemispheres is evidence that these oceans were capped with an Okhotsk-Like Stratification (O-LS). O-LS provides mechanisms to (1) strip nutrients from surface waters depriving the deep-ocean of preformed nutrients, increasing biological pump efficiency and (2) deepen carbon re-mineralization increasing deep-ocean alkalinity. Both may have contributed to lower glacial atmospheric CO2 concentrations. O-LS would also have amplified glacial climatic cycles by promoting the spread of high latitude sea ice in winter as occurs in the Sea of Okhotsk today, and reducing gas exchange between ocean and atmosphere in summer.