Conservative Elements in Seawater
de Villiers, S. and Nelson, B.K. (1997)
from Low-temperature hydrothermal flux controls on seawater chemistry: evidence from nonconservative behavior of "conservative" elements: Science, v. 285, p.721-723
Geochemical fluxes into and out of the ocean control its chemical
composition. Measurements of the magnesium (Mg) content of seawater, an
assumed "conservative" element in the ocean, reveal mid-depth Mg
depletions in the vicinity of the East Pacific Rise. The magnitude of the
anomalies suggests that fluxes associated with the low-temperature
circulation of seawater through axial mid-ocean ridge systems are much
larger than the high-temperature axial component. A higher total axial
hydrothermal flux provides a mechanism that simultaneously satisfies the
mass balance requirement of several major seawater constituents.
Magnesium concentration profiles at three sample stations between 16 and 17 degrees south near the East Pacific Rise. Data were obtained by isotope-dilution TIMS and normalized to salinity of 35. The error bars on profile J represent 2 sigma precision of 0.1%