The in situ pH of hydrothermal fluids at mid-ocean ridges Academic Article uri icon


  • Here we report the first in situ pH of hydrothermal vent fluids at mid-ocean ridges. Measurements were made during dives with DSV Alvin to the Main Endeavour Field (Juan de Fuca Ridge) and the East Pacific Rise at 21 degrees N, and 9 degrees-10 degrees N using solid-state electrochemical sensors. Vent fluid temperature and pressure ranged from 180 to 384 degrees C and 220 to 250 bar, respectively. pH((in situ)) of the highest temperature vent fluid is only slightly acidic (5.1-5.4), although sharply lower values occur at the seawater/vent-fluid interface. Knowledge of pH((in situ)) is essential for unravelling the complex geochemical and biogeochemical processes controlling the evolution of seafloor hydrothermal systems. (c) 2005 Elsevier B.V. All rights reserved.

publication date

  • August 2005