SWI Flux of CH4 in the Gunsan Basin of the South-Eastern Yellow Sea, Off the Coast of Western Korea

Abstract

The sediment&#8211 water interface (SWI) flux of methane (CH4) was investigated using Fick’s first law of diffusion in box cores from eight stations in the Gunsan Basin, the south-eastern part of the Yellow Sea, in 2015 [1]. The dissolved CH4 concentrations in the samples were measured using a gas chromatograph&#8211 semiconductor detector (EG Analyzer, model GS-23 Sensortec, Inc., Shiga, Japan) by injecting an aliquot of headspace gas [2]. The CH4 flux of the SWI in the Gunsan Basin ranges from 0.002 to 0.029 (average 0.012) mM·m-2·day-1. The average CH4 emission flux over the total area of the Gunsan Basin (60,000 km2 [3]) is 11.8 ton·year-1. This value is lower compared with those in other parts of the world. The range of CH4 flux is higher than the 0.007&#8211 0.01 mM·m-2·day-1 observed in Tomales Bay, New York, USA, but much lower than those in intertidal zones, estuaries, and lakes [4]. To clearly predict the SWI flux of CH4, budget or modelling is recommended, together with more measurements of CH4 emission rates during field monitoring approaches in the Gunsan Basin of the South-Eastern Yellow Sea are required.

[1] Martin et al. (2005) J. Control Release 102, 123-133. [2] Lee et al. (2018) J. Environ. Sci. Heal. A. 53, 457-466. [3] Wang et al. (2014) Geology of the China Seas 6, 392-393. [4] Sansone et al. (1998) Estuaries 21, 66-77.ellow Sea, in 2015 [1]. The dissolved CH4 concentrations in the samples were measured using a gas chromatograph&#8211 semiconductor detector (EG Analyzer, model GS-23 Sensortec, Inc., Shiga, Japan) by injecting an aliquot of headspace gas [2].

Discussion of Results The CH4 flux of the SWI in the Gunsan Basin ranges from 0.002 to 0.029 (average 0.012) mM·m-2·day-1. The average CH4 emission flux over the total area of the Gunsan Basin (60,000 km2 [3]) is 11.8 ton·year-1. This value is lower compared with those in other parts of the world. The range of CH4 flux is higher than the 0.007&#8211 0.01 mM·m-2·day-1 observed in Tomales Bay, New York, USA, but much lower than those in intertidal zones, estuaries, and lakes [4]. To clearly predict the SWI flux of CH4, budget or modelling is recommended, together with more measurements of CH4 emission rates during field monitoring approaches in the Gunsan Basin of the South-Eastern Yellow Sea are required.