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Using excess 3He to estimate Southern Ocean upwelling timescales
  • William John Jenkins
William John Jenkins
Woods Hole Oceanographic Institution

Corresponding Author:wjenkins@whoi.edu

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Using a recently compiled global marine dataset of dissolved helium isotopes and helium and neon concentrations, we make an estimate of the inventory of hydrothermal He in the Southern Ocean to be 3.4 ± 0.7 x 10 moles. Under the assumption that the bulk of the hydrothermally sourced He is upwelled there, we use recent estimates of the global hydrothermal He flux to determine an e-folding residence time of 62 ± 14 years, depending on assumptions of water mass and upwelling boundaries. Our estimate is comparable to values obtained from circulation models. The time-scale is at the lower end of the estimated scavenging life-time for dissolved iron (70 to 270 years), suggesting that a significant fraction of hydrothermally-sourced dissolved iron in the deep Pacific may reach the surface ocean to influence new primary production.