Origin of shallow gas using TVOCs and stable carbon isotopes from sediments of the South Gunsan Basin, central Yellow Sea, off the southwest of Korea

Abstract

In the Gunsan Basin, southern central Yellow Sea, shallow gases, dome structure, pockmark, and gas seepage in the upper sedimentary layer are found in some areas, that are very important indicators of marine resources, environmental changes, and geohazards. Total Volatile Organic Compounds (TVOCs) and stable carbon isotope ratio were determined in 17 surface and 2 core sediments (2013EEZ-PC-U-B and 2013EEZ-PC-V-B) in order to understand the origin of shallow gas in the South Gunsan Basin collected on board of R/V Eardo in November 22 to December 5, 2013. TVOCs values range in 5.1 to 385.7 ㎍/m³ (average, 93.0 ㎍/m³) and δ¹³C_CH4,&#8211 70.2 to &#8211 49.0 ‰_VPDB). (average, δ¹³C_CH4,&#8211 55.0 ‰_VPDB). The two compounds are positively related (R2=0.67). These geochemical characteristics of organic compounds reveal that the methane in the uppermost sediments of the South Gunsan Basin is a mixture of biogenic and thermogenic origins., and geohazards. Total Volatile Organic Compounds (TVOCs) and stable carbon isotope ratio were determined in 17 surface and 2 core sediments (2013EEZ-PC-U-B and 2013EEZ-PC-V-B) in order to understand the origin of shallow gas in the South Gunsan Basin collected on board of R/V Eardo in November 22 to December 5, 2013. TVOCs values range in 5.1 to 385.7 ㎍/m³ (average, 93.0 ㎍/m³) and δ¹³C_CH4,&#8211 70.2 to &#8211 49.0 ‰_VPDB). (average, δ¹³C_CH4,&#8211 55.0 ‰_VPDB). The two compounds are positively related (R2=0.67). These geochemical characteristics of organic compounds reveal that the methane in the uppermost sediments of the South Gunsan Basin is a mixture of biogenic and thermogenic origins.