Venturing into the "Twilight Zone": where does all carbon go?

据估计，覆盖地球表面70%的海洋吸收了1800年以来人类排放的近一半的二氧化碳，因此在调节全球气候方面发挥着关键作用。二氧化碳在海洋中的命运在很大程度上取决于水柱中的生物过程。深度在100米至1000米之间的中上层，在几十年的时间里，通过将从海面输出的大约90%的有机物质转化回二氧化碳、重要的营养物质和微量元素，从而促进地表初级生产力，为地球提供了重要的服务。尽管它很重要，但中远洋领域是海洋中研究最少的区域之一，对控制有机物分解或其区域变化的过程知之甚少。随着越来越多的建议将海洋施肥计划作为减少大气二氧化碳浓度的手段，提高我们对中上层区域过程的理解的重要性变得越来越紧迫。

The oceans, covering 70% of the Earth surface, are estimated to absorb nearly half of the human carbon dioxide emissions produced since 1800 playing therefore a key role in regulating global climate. The fate of carbon dioxide in the ocean is largely determined by biological processes in the water column. The mesopelagic layer, depth between 100 and 1000 m, is providing a vital planetary service by converting > 90% of organic matter exported from the sea surface back into carbon dioxide, vital nutrients, and microelements returning it to the surface over the decades thus fuelling surface primary productivity. Despite its importance, the mesopelagic realm is one of the least studied regions of the ocean and little is known about the processes that control the decomposition of organic matter or its regional variation. The importance of improving our understanding of the processes in the mesopelagic zone is becoming increasingly pressing with the proliferation of proposals for ocean fertilization programs as means reducing atmospheric carbon dioxide concentrations.