Jónasdóttir Sigrún Huld, Visser André W, Richardson Katherine, Heath Michael R
National Institute for Aquatic Resources, Oceanography and Climate, Technical University of Denmark, DK-2920 Charlottenlund, Denmark;
National Institute for Aquatic Resources, Oceanography and Climate, Technical University of Denmark, DK-2920 Charlottenlund, Denmark; Center for Ocean Life, Technical University of Denmark, DK-2920 Charlottenlund, Denmark;
Proc Natl Acad Sci U S A. 2015 Sep 29;112(39):12122-6. doi: 10.1073/pnas.1512110112. Epub 2015 Sep 3.
Estimates of carbon flux to the deep oceans are essential for our understanding of global carbon budgets. Sinking of detrital material ("biological pump") is usually thought to be the main biological component of this flux. Here, we identify an additional biological mechanism, the seasonal "lipid pump," which is highly efficient at sequestering carbon into the deep ocean. It involves the vertical transport and metabolism of carbon rich lipids by overwintering zooplankton. We show that one species, the copepod Calanus finmarchicus overwintering in the North Atlantic, sequesters an amount of carbon equivalent to the sinking flux of detrital material. The efficiency of the lipid pump derives from a near-complete decoupling between nutrient and carbon cycling—a "lipid shunt," and its direct transport of carbon through the mesopelagic zone to below the permanent thermocline with very little attenuation. Inclusion of the lipid pump almost doubles the previous estimates of deep-ocean carbon sequestration by biological processes in the North Atlantic.
对深海碳通量的估算对于我们理解全球碳预算至关重要。碎屑物质的下沉（“生物泵”）通常被认为是这种通量的主要生物组成部分。在此，我们识别出一种额外的生物机制，即季节性“脂质泵”，它在将碳隔离到深海方面效率极高。它涉及越冬浮游动物对富含碳的脂质的垂直运输和代谢。我们表明，北大西洋越冬的一种桡足类动物——哲水蚤，所隔离的碳量相当于碎屑物质的下沉通量。脂质泵的效率源于营养物质和碳循环之间几乎完全解耦——一种“脂质分流”，以及它将碳直接通过中层带运输到永久性温跃层以下，且几乎没有衰减。将脂质泵纳入考量后，此前对北大西洋生物过程导致的深海碳固存的估计几乎翻倍。
