(Table 3) Interannual variability of total mass flux at the deep sediment trap site CBmeso between 1988 and 2006@en

This article will review major features of the 'giant' Cape Blanc filament off Mauritania with regard to the transport of chlorophyll and organic carbon from the shelf to the open ocean. Within the filament, chlorophyll is transported about 400 km offshore. Modelled particle distributions along a zonal transect at 21°N showed that particles with a sinking velocity of 5 m d**-1 are advected offshore by up to 600 km in subsurface particle clouds generally located between 400 m and 800 m water depth, forming an Intermediate Nepheloid Layer (INL). It corresponds to the depth of the oxygen minimum zone. Heavier particles with a sinking velocity of 30 m d**-1 are transported from the shelf within the Bottom Layer (BL) of more than 1000 m thickness, largely following the topography of the bottom slope. The particles advected within the BL contribute to the enhanced winter-spring mass fluxes collected at the open-ocean mesotrophic sediment trap site CB-13 (200 nm offshore), due to a long distance advection in deeper waters. The lateral contribution to the deep sediment trap in winter-spring is estimated to be 63% and 72% for organic carbon and total mass, respectively, whereas the lateral input for both components on an annual basis is estimated to be in the order of 15%. Biogenic opal increases almost fivefold from the upper to the lower mesotrophic CB-13 trap, also pointing to an additional source for biogenic silica from eutrophic coastal waters. Blooms obviously sink in smaller, probably mesoscale-sized patches with variable settling rates, depending on the type of aggregated particles and their ballast content. Generally, particle sinking rates are exceptionally high off NW Africa. Very high chlorophyll values and a large size of the Cape Blanc filament in 1998-1999 are also documented in enhanced total mass and organic carbon fluxes. An increasing trend in satellite chlorophyll concentrations and the size of the Cape Blanc filament between 1997 and 2008 as observed for other coastal upwelling areas is not documented.本文将围绕叶绿素与有机碳从陆架向开阔大洋的输运过程，评述毛里塔尼亚外海巨型布兰科角丝状体（Cape Blanc filament）的核心特征。在该丝状体内部，叶绿素可被平流输送至离岸约400 km的海域。通过21°N纬向断面的模拟粒子分布结果显示，沉降速率为5 m·d⁻¹的粒子会在通常分布于400 m至800 m水深的次表层粒子云中，被平流输送至最远离岸600 km的区域，进而形成中间雾状层（Intermediate Nepheloid Layer，INL），该层的深度与氧最低带（oxygen minimum zone）一致。沉降速率为30 m·d⁻¹的较重粒子则在厚度超过1000 m的底层（Bottom Layer，BL）中从陆架向外输运，整体遵循底坡地形分布。由于在深层水体中经历长距离平流输送，底层输运的粒子会使得离岸200海里的开阔大洋中营养沉积陷阱站位CB-13所收集到的冬春季增强质量通量显著提升。冬春季该站位深层沉积陷阱的侧向输运贡献分别约为有机碳的63%与总质量的72%；而上述两种组分的年度侧向输入贡献则约为15%。生物蛋白石含量从中营养CB-13沉积陷阱的上层至下层几乎增长五倍，这也表明富营养化近岸水域可为生物硅提供额外来源。水华显然会以较小的、大概率为中尺度大小的斑块形式沉降，其沉降速率会因聚合粒子的类型及其球团含量的差异而有所不同。总体而言，西北非外海的粒子沉降速率异常偏高。1998—1999年布兰科角丝状体的极高叶绿素含量与庞大规模，也在总质量与有机碳通量的增强数据中得到了印证。现有研究并未记录到1997—2008年间卫星叶绿素浓度与布兰科角丝状体规模存在上升趋势，而这一趋势在其他沿岸上升流区均有观测记录。