Hydrothermalism: a major contributor to the oceanic inventory of dissolved zinc

29 August 2016

High-quality dataset of dissolved zinc (Zn) from the US GEOTRACES EPZT cruise (GP16 section) allows Roshan and co-workers (2016, see reference below) to revisit the oceanic budget of dissolved Zn. These investigators have observed a basin-scale transport of mantle-derived dissolved Zn from the hydrothermal vents of the East Pacific Rise to the farfield regions (>4000 km away) across the South Pacific at depths 2300–2800 m (see Figure). The strong correlation (R² = 0.9) between hydrothermal-controlled component of dissolved Zn (i.e. Excess Zn) and hydrothermal activity tracer, ³He leads to a global hydrothermal zinc flux of 1.75 ± 0.35 G mol yr^{− 1} that is many-fold higher than the input fluxes estimated by other studies. These results suggest that mantle-derived dissolved Zn dominates the oceanic Zn inventory and that dissolved Zn residence time is much shorter (3000 ± 600 years) than previous input-based estimates (11,000 and 50,000 years) and more consistent with previous removal-based estimate (3000–6000 years)…

16 Roshan l — **Figure:** The top panel shows the dispersion of hydrothermal-controlled component of dissolved Zn (Excess Zn) from the East Pacific Rise (elevated topography at the east of the transect and shown in the bottom left panel) to the west of the transect (>4000 km). Excess Zn shows a strong correlation with hydrothermal tracer, 3He which allows for the accurate estimation of hydrothermal dissolved Zn input rate of 1.75 G mole/year.

Reference:

Roshan, S., Wu, J., & Jenkins, W. J. (2016). Long-range transport of hydrothermal dissolved Zn in the tropical South Pacific. Marine Chemistry, 183, 25–32. doi:10.1016/j.marchem.2016.05.005

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