Onboard Experiments of Photochemical Production and Microbial Consumption of Carbon Monoxide and Molecular Hydrogen

Abstract

Carbon monoxide (CO) and molecular hydrogen (H2) are important trace gases that have potential for affecting the global climate. The ocean is a minor source for these gases although it covers ~70% of the earth. In the surface of the ocean, CO is produced by photochemical degradation of chromophoric dissolved organic matter (CDOM). CO emitted to the atmosphere is oxidized by active reaction with the OH radical, which is the indicator of oxidation capacity of the atmosphere. On the surface of the ocean, H2 is supersaturated with respect to the atmosphere and has maximum at surface decreasing with depth in the euphotic zone. So the ocean is one of the natural sources for H2. However, the production and removal mechanism of H2 in the ocean is not clear yet. Unlike CO which is produced wherever light and dissolved organic matter exist, H2 may not be the case.an, CO is produced by photochemical degradation of chromophoric dissolved organic matter (CDOM). CO emitted to the atmosphere is oxidized by active reaction with the OH radical, which is the indicator of oxidation capacity of the atmosphere. On the surface of the ocean, H2 is supersaturated with respect to the atmosphere and has maximum at surface decreasing with depth in the euphotic zone. So the ocean is one of the natural sources for H2. However, the production and removal mechanism of H2 in the ocean is not clear yet. Unlike CO which is produced wherever light and dissolved organic matter exist, H2 may not be the case.