Significant role of physical transport in the marine carbon monoxide (CO) cycle: observations in the East Sea (Sea of Japan), the western North Pacific, and the Bering Sea in summer

The carbon monoxide (CO) in the marine boundary layer and in the surface waters and water column were measured along the western limb of the North Pacific from the Korean Peninsula to Alaska, USA, in summer 2012. The observation allows us to estimate the CO budgets in the surface mixed layer of the three distinct regimes: the East Sea (Sea of Japan) (ES), the Northwest Pacific (NP), and the Bering Sea (BS). CO photochemical production rates were 56( +/- 15) mu mol m - 2 d - 1 , 27( +/- 3) mu mol m - 2 d - 1 , and 26( +/- 2) mu mol m - 2 d - 1 , while microbial consumption rates were 30( +/- 8) mu mol m - 2 d - 1 , 24( +/- 5) mu mol m - 2 d - 1 , and 63( +/- 19) mu mol m - 2 d - 1 in the ES, NP, and BS, respectively, both of which are the dominant components of the CO budget in the ocean. The other two known components, air-sea gas exchange and downward mixing, remained negligible (less than 3 mu mol m - 2 d - 1 ) in all regimes. While the CO budget in the surface mixed layer of the NP was in balance, the CO production surpassed the consumption in the ES, and vice versa in the BS. The significant imbalances in the CO budget in the ES (25 +/- 17 mu mol m - 2 d - 1 ) and the BS (40 +/- 19 mu mol m - 2 d - 1 ) are suggested to be compensated by external physical transport such as lateral advection, subduction, or ventilation. Notably, the increase in the CO column burden correlated with the imbalance in the CO budget, highlighting the significant role of the physical transport in the marine CO cycles. Our observation, for the first time, underscores the potential importance of physical transport in driving CO dynamics in the marine environment.