Consumption of dissolved methane in the deep ocean 1

Oceanic dissolved methane concentrations are normally in excess of atmospheric equilibrium values in surface waters but show a rapid decrease with depth. Deep North Atlantic waters have only ca. 30% of their atmospheric equilibrium values of methane and deep North Pacific waters have only ca. 10%. Methane consumption rates calculated from methane analyses and water mass ages derived from published data on 3 H/ 3 He ages, 14 C ages, and model calculations show that both methane and oxygen are rapidly consumed in “young” water but, while oxygen consumption continues at a low rate throughout the deep ocean, methane consumption virtually ceases within about 100 years of isolation from the surface ocean.