Distribution, flux, and photoproduction of carbon monoxide in the East China Sea and Yellow Sea in spring

Abstract

[1] The distribution, photoproduction, and sea-to-air flux of carbon monoxide (CO) were investigated in the East China Sea (ECS) and the Yellow Sea (YS) during April–May 2009. The concentrations of CO in the surface seawater ranged from 0.12 to 6.99 nmol L−1, with a mean of 2.24 nmol L−1. Concentrations of CO showed pronounced diurnal variations within the euphotic zone with early afternoon or noon maxima 5–40 fold that of the predawn minima. The sea-to-air flux of CO was significantly correlated with the supersaturation factor of CO and wind speeds. The sea surface was a net source of atmospheric CO, and the supersaturation factors of CO varied from 1.1–50.4 with an average of 16.0. On the basis of the concentration of CO in the atmosphere and sea surface, wind speeds, and gas exchange, the calculated mean flux of CO from the ECS and the YS to the atmosphere was 6.67 ± 4.61 μmol m−2 d−1. Using Simple Model of the Atmospheric Radiative Transfer of Sunshine spectral irradiance and chromophoric dissolved organic matter (CDOM) based apparent quantum yield of CO (AQYCO) spectrum, the estimate of CO production from CDOM of the ECS and the YS was 64.5 Gg CO-C in spring. The total photomineralization dissolved organic carbon in the ECS and the YS was estimated to be 5.4–10.5 Tg C yr−1, representing 2.9–5.7% of the primary production in the two seas. Our results indicate that CO cycling in coastal areas was significant to the global carbon cycle.