Resumen de Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean
Joseph A. Resing, Peter N. Sedwick, Christopher R. German, William J. Jenkins, James W. Moffett, Bettina M. Sohst, Alessandro Tagliabue
Hydrothermal venting along mid-ocean ridges exerts an important control on the chemical composition of sea water by serving as a major source or sink for a number of trace elements in the ocean1,2,3. Of these, iron has received considerable attention because of its role as an essential and often limiting nutrient for primary production in regions of the ocean that are of critical importance for the global carbon cycle4. It has been thought that most of the dissolved iron discharged by hydrothermal vents is lost from solution close to ridge-axis sources2,5 and is thus of limited importance for ocean biogeochemistry6. This long-standing view is challenged by recent studies which suggest that stabilization of hydrothermal dissolved iron may facilitate its long-range oceanic transport7,8,9,10. Such transport has been subsequently inferred from spatially limited oceanographic observations11,12,13. Here we report data from the US GEOTRACES Eastern Pacific Zonal Transect (EPZT) that demonstrate lateral transport of hydrothermal dissolved iron, manganese, and aluminium from the southern East Pacific Rise (SEPR) several thousand kilometres westward across the South Pacific Ocean. Dissolved iron exhibits nearly conservative (that is, no loss from solution during transport and mixing) behaviour in this hydrothermal plume, implying a greater longevity in the deep ocean than previously assumed6,14. Based on our observations, we estimate a global hydrothermal dissolved iron input of three to four gigamoles per year to the ocean interior, which is more than fourfold higher than previous estimates7,11,14. Complementary simulations with a global-scale ocean biogeochemical model suggest that the observed transport of hydrothermal dissolved iron requires some means of physicochemical stabilization and indicate that hydrothermally derived iron sustains a large fraction of Southern Ocean export production.
