| Popis: |
Deciphering the origin, age, and composition of deep marine organic carbon remains a challenge in understanding the dynamics of the marine carbon cycle. In particular, the composition of aged organic carbon and what allows its persistence in the deep ocean and in sediment is unresolved. Here, we observe that both high and low temperature hydrothermal vents at the 9 degrees 50' N; 104 degrees 17.5 W East Pacific Rise (EPR) vent field are a source for (sub) micron-sized graphite particles. We demonstrate that commonly applied analytical techniques for quantification of organic carbon detect graphite. These analyses thereby classify graphite as either dissolved or particulate organic carbon, depending on the particle size and filtration method, and overlook its relevance as a carbon source to the deep ocean. Settling velocity calculations indicate the potential for these (sub)micron particles to become entrained in the buoyant plume and distributed far from the vent fields. Thus, our observations provide direct evidence for hydrothermal vents acting as a source of old carbon to the deep ocean. NSF OCE Marine Geology and Geophysics grant [1558712]; NSFNational Science Foundation (NSF) [ECCS 1542100] This work was supported by NSF OCE Marine Geology and Geophysics grant 1558712 awarded to George W. Luther. We thank the Captain and crew of the R/V Atlantis as well as the Expedition Leader, pilots, and crew of the HOV Alvin for their knowledge and facilitation of sample collection. We thank the science party of AT37-11 for additional assistance in handling the titanium Major Samplers. Sunita Shah-Walter read and provided valuable feedback on drafts of the manuscript. This work used shared facilities at the Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), supported by NSF (ECCS 1542100). |
