Flushing submarine canyons
Flushing submarine canyons
复制标题
DOI：
10.1038/nature05271
复制
发表时间：
2006-11-16
期刊：
影响因子：
64.8
通讯作者：
Fabres, Joan
中科院分区：
文献类型：
--
作者：
Canals, Miquel;Puig, Pere;Fabres, Joan
大陆坡是一条陡峭狭窄的边缘地带，将沿海地带与深海分隔开来。在低潮期，滑坡和密集的含沙水流侵蚀外大陆架和大陆斜坡，形成海底峡谷，将大量沉积物和有机物从浅海地区输送到深海(1)。在高海平面期间，例如目前，这些峡谷仍然会偶尔经历沉积物重力流（2 - 5），这通常被认为是由沉积物破坏或河流洪水引发的。在这里，我们提供了对地中海西北部狮子湾边缘海底峡谷的观测结果，表明这些流动也可以由密集的陆架水级联（DSWC）触发，这是一种仅由海水密度对比驱动的电流。研究结果表明，DSWC可以输送大量的水和沉积物，重塑海底峡谷底，并迅速影响深海环境。这种级联是季节性的，是由冷却和/或蒸发形成的致密水造成的，发生在高纬度和低纬度大陆边缘（6 - 8）。因此，DSWC可能将大量沉积物和有机物输送到深海。此外，未来气候变化导致的DSWC频率和强度的变化可能对深海生态系统的有机质供应以及大陆边缘和海洋盆地的碳储量产生重大影响。
The continental slope is a steep, narrow fringe separating the coastal zone from the deep ocean. During low sea- level stands, slides and dense, sediment- laden flows erode the outer continental shelf and the continental slope, leading to the formation of submarine canyons that funnel large volumes of sediment and organic matter from shallow regions to the deep ocean (1). During high sea-level stands, such as at present, these canyons still experience occasional sediment gravity flows(2 - 5), which are usually thought to be triggered by sediment failure or river flooding. Here we present observations from a submarine canyon on the Gulf of Lions margin, in the northwest Mediterranean Sea, that demonstrate that these flows can also be triggered by dense shelf water cascading ( DSWC) - a type of current that is driven solely by seawater density contrast. Our results show that DSWC can transport large amounts of water and sediment, reshape submarine canyon floors and rapidly affect the deep- sea environment. This cascading is seasonal, resulting from the formation of dense water by cooling and/ or evaporation, and occurs on both high- and low- latitude continental margins(6 - 8). DSWC may therefore transport large amounts of sediment and organic matter to the deep ocean. Furthermore, changes in the frequency and intensity of DSWC driven by future climate change may have a significant impact on the supply of organic matter to deep- sea ecosystems and on the amount of carbon stored on continental margins and in ocean basins.