AUTHOR=Toki Tomohiro , Chibana Hideki , Shimabukuro Teppei , Yamakawa Yo TITLE=Distribution of dissolved methane in seawater from the East China Sea to the Ryukyu forearc JOURNAL=Frontiers in Earth Science VOLUME=11 YEAR=2023 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1174504 DOI=10.3389/feart.2023.1174504 ISSN=2296-6463 ABSTRACT=

Methane is a greenhouse gas, and the East China Sea acts as a source of emissions to the atmosphere. On the other hand, the distribution of methane concentration in the Ryukyu Arc shelf and forearc region has not been clarified. Therefore, we investigated the continental slope and continental shelf areas from the Okinawa Trough to the landward side and the island shelf and forearc areas to the seaward side of the East China Sea. The methane concentration in the Kuroshio Current region was very low, and the methane concentration in the seawater just above the seafloor in the area directly above the hydrothermal systems was exceptionally high. In addition, methane concentration in seawater just above the seafloor where cold seeps and mud volcanoes are known is higher than the background, and higher methane concentrations were found in continental slope area and the island shelf area. The results suggest the existence of previously unreported methane sources such as cold seeps and mud volcanoes in the continental slope region and the island shelf region.