A high-resolution time-series analyses of particle fluxes in the Northern Benguela coastal upwelling system: carbonate record of changes in biogenic production and particle transfer processes
A high-resolution time-series analyses of particle fluxes in the Northern Benguela coastal upwelling system: carbonate record of changes in biogenic production and particle transfer processes
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DOI：
10.1016/s0967-0645(00)00014-x
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发表时间：
2000-01-01
影响因子：
3
通讯作者：
Pujol, C
中科院分区：
文献类型：
--
作者：
Giraudeau, J;Bailey, GW;Pujol, C
利用时间序列沉积物捕集器研究了纳米比亚沃尔维斯湾陆架边缘生物源颗粒的通量，以评估生物源生产对上升流过程动态快速变化的响应，以及颗粒转移过程对纳米比亚边缘高速积累的沉积物性质的重要性。从实验开始到结束，总质量通量呈现出一个平滑的下降趋势，尽管从海温和风记录中可以看出上升流动力学的变化模式。在整个圈闭期间，各种生物成因组分（碳酸盐、蛋白石、有机质）对总质量通量的贡献相对恒定，表明上升流动力学的变化对圈闭位置的生物成因颗粒沉积性质没有明显影响。对碳酸盐组分的详细检查表明，在来源和向深度转移的机制方面，它的各种贡献者（球石藻和浮游有孔虫）是划分的。这些数据表明，沉积在斜坡上的大部分生物颗粒是来自外大陆架的再悬浮物质，相反，来自地表水的直接输入对深度颗粒Aux的贡献并不大。提出了一个高度分割的三维流场来解释观察到的颗粒通量模式以及影响生物成分的建议传递过程。(C) 2000 Elsevier Science Ltd.版权所有。
Fluxes of biogenic particles at the shelf edge off Walvis Bay, Namibia, are investigated from a time-series sediment trap in order to evaluate the response of biogenic production to rapid changes in the dynamics of the upwelling process, as well as the importance of particle transfer processes on the nature of sediments accumulating at a high rate on the Namibian margin. Total mass flux displays a smooth trend of lowered values from the start to the end of the experiment despite evidence, from the SST and wind records, of a variable pattern of upwelling dynamics. Contributions of the various biogenic components (carbonates, opal, organic matter) to the total mass flux were relatively constant throughout the period of trapping, suggesting that changes in upwelling dynamics have no obvious implications on the nature of biogenic particles sedimenting at the trap location. A detailed examination of the carbonate fraction indicates a partitioning of its various contributors (coccolithophores and planktonic foraminifera) in terms of sources and mechanisms of transfer to depth. From these data, it is suggested that the bulk of the biogenic particles sedimenting on the slope is resuspended material from the outer shelf, and conversely that direct input from surface waters does not contribute to a high extent to the particle Aux at depth. A highly partitioned, three-dimensional flow field is proposed to explain the observed pattern of particle flux as well as the suggested transfer processes affecting the biogenic components. (C) 2000 Elsevier Science Ltd. All rights reserved.