Emission of dissolved organic carbon from submarine mud volcanoes off Kikaijima Island, Tanegashima Island and Hyuga-nada, Japan.

Abstract

Submarine mud volcanoes (SMVs) are mounds formed when high pore pressure sediments at deep subsurface ascend as mud diapirs and erupt onto the seafloor. They emit deep subsurface materials into the ocean including methane. Recent studies suggest that dissolved organic carbon (DOC) is produced as a byproduct associated with anoxic methane oxidation in the surface sediments at methane seeps, thereby contributing to the ocean carbon cycle. Since SMVs are methane seeps, they may also release DOC to the ocean. However, there have been few reports on DOC release from SMVs to the ocean. Thus, the release amounts and origins of DOC from SMVs remain unclear. In this study, we investigated the release amounts and origins of DOC from SMVs by analyzing DOC concentrations in water samples taken above SMVs. Additionally, we explored the correlation between DOC and dissolved CH₄ released from SMVs by analyzing dissolved CH₄ concentrations in the same water samples.