Abstract：In this study, the photoproduction of CO in the seawater of Qingdao Coast Sea (QCS) and the East China Sea (ECS) was investigated. The optical characteristics of Chromophoric Dissolved Organic Matter (CDOM) and the Apparent Quantum Yield [AQY(λ)] of CO in the seawater of the two different research areas were compared. The results showed that the absorption coefficient at 355nm [α(355)] of QCS and the ECS were (0.381~0.868)m-1 and (0.083~0.427)m-1, with the averages of 0.622m-1 and 0.196m-1, respectively, indicating that the value along the coast area was higher than that in the ECS. There is a clear correlation between α(355) and Sg in the water of QCS, but the two parameters in the seawater of the ECS did not have the obvious correlation, suggesting the correlation between α(355) and Sg was undetermined. The positive correlation between α(355) and photochemical production rate of CO showed the photochemical degradation of CDOM was the important source to produce CO. Similar to the variation trend of α(355), the average AQY(λ) in QCS was higher than that in the ECS, indicating that the CDOM with the high optically active substance could yield CO more efficiently in its photodegradation reaction.
