Burial of organic carbon in marine sediments is a long-term sink of atmospheric CO2, and submarine turbidity currents are volumetrically the most important sediment transport process on Earth. Yet the processes, amounts, and efficiency of organic carbon transfer by turbidity currents through submarine canyons to the deep sea are poorly documented and understood. We present an organic carbon budget for the submarine Congo Canyon, offshore West Africa, constrained with time-lapse bathymetry, sediment cores, and flow monitoring, including the effects of two >1000-km-runout canyon-flushing turbidity currents. In one year, flows eroded an estimated 6.09 ± 2.70 Mt of previously buried terrestrial organic carbon in the canyon, primarily from fine-grained and vegetation-rich muddy sand facies with high organic carbon contents (as high as 11%). The age and composition of organic carbon in the Congo Canyon is comparable to those in the Congo River, indicating that transfer is efficient. Over the whole canyon-channel system, we extrapolate that 43 ± 15 Mt of organic carbon was eroded and transported to the deep (>5 km) sea, equivalent to 22% of the annual global particulate organic carbon export from rivers to oceans and 54%–108% of the predicted annual terrestrial organic carbon burial in the oceans. Canyon-flushing turbidity currents carried a globally significant mass of terrestrial organic carbon down just one submarine canyon in a single year, indicating their importance for redistribution and delivery of organic carbon to the deep sea.

中文翻译：

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全球范围内大量陆地有机碳通过峡谷冲刷浊流有效输送


海洋沉积物中有机碳的埋藏是大气二氧化碳的长期汇，海底浊流是地球上最重要的沉积物输送过程。然而，有机碳通过海底峡谷通过海底峡谷转移到深海的过程、数量和效率却鲜有记录和了解。我们提出了西非近海刚果峡谷海底的有机碳预算，该预算受到延时测深、沉积物岩心和流量监测的约束，包括两个> 1000公里径流的峡谷冲刷浊流的影响。一年内，水流侵蚀了峡谷中先前埋藏的约 6.09 ± 2.70 公吨陆地有机碳，主要来自有机碳含量高（高达 11%）的细粒且植被丰富的泥砂相。刚果峡谷中有机碳的年龄和成分与刚果河中的有机碳相当，表明转移是有效的。在整个峡谷-水道系统中，我们推断有 43 ± 15 公吨的有机碳被侵蚀并输送到深海（>5 公里），相当于全球每年从河流到海洋的颗粒有机碳出口的 22%，以及 54预测每年陆地有机碳埋藏在海洋中的%–108%。冲刷峡谷的浊流在一年内仅将全球范围内大量的陆地有机碳带入海底峡谷，这表明它们对于有机碳重新分配和输送到深海的重要性。