Dissolved gases in the equatorial and south Pacific Ocean

Abstract

The nitrogen, oxygen, and argon in Pacific samples from two expeditions have been measured by gas chromatography, and the neon and helium by mass spectrometry. Nitrogen is systematically about 2% supersaturated and argon about 1.5% undersaturated, relative to the solubility data of Douglas for a moisture saturated atmosphere at 1013-mb total pressure. N2/Ar ratios are in precise agreement with the solubility ratios of Benson and Parker. The range and covariance of N2 and Ar variations are consistent with atmospheric pressure variations over the sea. Oxygen values are systematically higher than the ‘classical’ Winkler values by 3.7%. No evidence was found for the large supersaturation of argon reported by Bieri, Koide, and Goldberg in 1966 and the Ar-T-S relationships are inconsistent with their vertical mixing model. Small increases in a saturation anomaly are core properties of water types formed by subsurface mixing and are associated with T-S slope changes; these effects were found in Antarctic and North Pacific Intermediate water. An upper limit of 8.7% excess helium was found at a depth of 1000 meters at 33°S latitude.