Carbon monoxide cycling in the marginal sea: A case of the yellow sea and the east China sea

Gao-Bin Xu; Shi-Bo Yan; Jian Wang; Feng Xu; Xuan Ji; Jie Ni; Zhi-Wen Liu; Gui-Peng Yang

doi:10.1016/j.marenvres.2025.107328

Carbon monoxide cycling in the marginal sea: A case of the yellow sea and the east China sea

Mar Environ Res. 2025 Jun 25:210:107328. doi: 10.1016/j.marenvres.2025.107328. Online ahead of print.

Authors

Gao-Bin Xu¹, Shi-Bo Yan¹, Jian Wang¹, Feng Xu¹, Xuan Ji¹, Jie Ni¹, Zhi-Wen Liu², Gui-Peng Yang³

Affiliations

¹ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China; Institute of Marine Chemistry, Ocean University of China, Qingdao, 266100, China.
² Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
³ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Institute of Marine Chemistry, Ocean University of China, Qingdao, 266100, China. Electronic address: gpyang@mail.ouc.edu.cn.

PMID: 40602211
DOI: 10.1016/j.marenvres.2025.107328

Abstract

This study investigated carbon monoxide (CO) dynamics in the Yellow Sea (YS) and the East China Sea (ECS) during spring, revealing significant spatial variability in surface CO concentrations (0.23-3.02 nmol L^-1, mean 1.29 ± 0.73 nmol L^-1). Photochemical production dominated CO generation, with UV radiation contributing ∼80 % of total production, while the sea surface microlayer (SML) exhibited 2.2-fold higher rates due to chromophoric dissolved organic matter (CDOM) enrichment. Microbial consumption (mean k_CO = 0.69 ± 0.19 d^-1) accounted for 81 % of CO removal, yet total production exceeded sinks, suggesting unaccounted pathways such as algal release or vertical diffusion. The YS and the ECS were strong CO sources, with sea-to-air fluxes (4.75 ± 4.23 μmol m^-2 d^-1) surpassing global oceanic averages, contributing ∼0.6 % of total oceanic CO emissions. Key factors driving the CO dynamics in these regions included terrestrial inputs, phytoplankton activity, and anthropogenic influences. This study underscores the crucial role that marginal seas, like the YS and the ECS, play in the global CO cycling process.

Keywords: CO budget; Carbon monoxide (CO); Marginal sea; Mixed layer; Sea surface microlayer (SML).