Carbon monoxide distribution and microbial consumption in the Southern Yellow Sea

Two cruises were conducted in the Southern Yellow Sea (SYS) in late July and early August 2008 to study marine carbon monoxide (CO) distribution, sea-to-air flux, and microbial consumption. Surface water dissolved CO showed an apparently higher average concentration (31.9% higher) during the second cruise than during the first cruise. Surface water CO concentrations were found to follow an apparent diurnal variation, during which CO concentrations varied by a factor of 8–14. Atmospheric CO mixing ratios ranged from 194 to 596 ppbv with an average of 390 ppbv for the first cruise, and from 53 to 238 ppbv with an average of 124 ppbv for the second one. Average sea-to-air CO fluxes (W92) were estimated to be 4.58 μmol m−2 d−1 and 0.08 μmol m−2 d−1 for the first and second cruise, respectively. Incubation experiments were conducted at 12 stations during the second cruise; results showed that surface-water microbial CO consumption rate constants (Kco) ranged from 0.07 to 0.83 h−1, with an average of 0.33 h−1. Microbial CO uptake typically followed first-order reaction kinetics at most of the studied stations.