Distributions, influencing factors and fluxes of dissolved methane in the eastern part of Liaodong Peninsula in the North Yellow Sea in spring

Distributions, influencing factors and air-sea fluxes of methane (CH₄) in the eastern part of Liaodong Peninsula in the North Yellow Sea were studied based on a field survey conducted in May 2022. Dissolved CH₄ concentrations were 3.2～11.2 nmol/L, with the saturation of 103%～364%, showing an obvious decreasing trend in surface seawater and increasing trend in bottom seawater from inshore to offshore areas. The input of Yalu River resulted in a significant increase of dissolved CH₄ in the inshore area, while dissolved CH₄ in bottom water of the offshore area increased due to the degradation of organic matters in sediments. The studied area was an important source of atmospheric CH₄ and the air-sea fluxes were 0.7～61.1 μmol/(m²·d), the inshore area is significantly higher than the offshore area. The input of Yalu River has significant effect on dissolved CH₄ in the adjacent areas even in the normal water period. Future work should mainly focus on the investigation of the estuaries and other coastal waters to scientifically assess the air-sea CH₄ fluxes in the marginal sea.