The study investigated the spatial distribution, production, and removal pathways of seawater carbon monoxide(CO) in the Yellow Sea (YS) and the East China Sea (ECS) in spring 2021. Measurements revealed that photochemical processes in the UV bands (UVB, UVA) dominate CO production, with UVA contributing 50%. Nearshore waters exhibited higher CO photo-production rates compared to offshore waters, with microlayer seawater displaying more efficient CO photoproduction due to a higher concentration of chromophoric dissolved organic matter (CDOM). The study identified nitrate and silicate as significant promoters of CO production, and highlighted the correlation between CDOM characteristics (e.g., a_CDOM[350], S_275-295) and CO production rates. Microbial consumption rates (k_CO) were measured across various stations, revealing a turnover time of 1.45 ± 0.48 days for microbial CO consumption. Additionally, the sea-to-air CO fluxes were estimated, with the ECS exhibiting higher release rates than the YS. Overall, the study suggests that CO production in the mixed layer exceeds its removal, implying the potential release of excess CO via vertical diffusion.
 

carbon monoxide, microlayer, mixed layer