A 28‐ka history of sea surface temperature, primary productivity and planktonic community variability in the western Arabian Sea
A 28‐ka history of sea surface temperature, primary productivity and planktonic community variability in the western Arabian Sea
复制标题
阿拉伯海西部海面温度、初级生产力和浮游生物群落变化的 28ka 历史
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Elizabeth J. Waterson
中科院分区：
文献类型：
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作者：
A. Pourmand;F. Marcantonio;T. Bianchi;E. Canuel;Elizabeth J. Waterson
在过去28ka的阿拉伯海西部沉积物中测量了铀系列放射性核素和有机生物标志物，它们代表了浮游生物的主要类群。研究了西南和东北季风过去强度的变化及其对初级生产力、海温和浮游生物群落结构的影响。末次冰期的平均烯酮海温比全新世的测量值低~ 3°C。在去冰期之前，最低的海温与最高测量的有机生物标记物通量一致，这些生物标记物主要代表硅藻、球石藻、鞭毛藻和浮游动物等浮游生物。末次冰期冬季东北季风的增强导致了深层对流混合、海温变冷和初级生产力的增强。相反，在生物标志物通量高的时期，冰期后（<17 ka）海温变暖。与这一转变相关的是浮游生物群落结构的变化，在去冰期和全新世，硅藻生物标志物的平均累积通量与球石藻生物标志物的平均累积通量之比是末次冰期平均比率的两倍。我们认为，这种时间转变代表了从冬季以东北季风为主（17 ka前）到夏季以西南季风为主（17 ka后）的风系统转变。
[1] Uranium series radionuclides and organic biomarkers, which represent major groups of planktonic organisms, were measured in western Arabian Sea sediments that span the past 28 ka. Variability in the past strength of the southwest and northeast monsoons and its influence on primary productivity, sea surface temperature (SST), and planktonic community structure were investigated. The average alkenone-derived SST for the last glacial period was ∼3°C lower than that measured for the Holocene. Prior to the deglacial, the lowest SSTs coincide with the highest measured fluxes of organic biomarkers, which represent primarily a planktonic suite of diatoms, coccolithophorids, dinoflagellates, and zooplankton. We propose that intensification of winter northeast monsoon winds during the last glacial period resulted in deep convective mixing, cold SSTs and enhanced primary productivity. In contrast, postdeglacial (<17 ka) SSTs are warmer during times in which biomarker fluxes are high. Associated with this transition is a planktonic community structure change, in which the ratio of the average cumulative flux of diatom biomarkers to the cumulative flux of coccolithophorid biomarkers is twice as high during the deglacial and Holocene than the average ratio during the last glacial period. We suggest that this temporal transition represents a shift from a winter northeast monsoon-dominated (pre-17 ka) to a summer southwest monsoon-dominated (post-17 ka) wind system.