[A-CG42] Coastal Ecosystems - 1. Water Cycle and Land-Ocean Interactions

[ACG42-P03] Carbon transport through groundwater discharge in Kesennuma Bay, Japan

*Ryo Sugimoto¹, Toshimi Nakajima¹, Isaac R Santos², Makoto Taniguchi³ (1.Faculty of Marine Biosciences, Fukui Prefectural University, 2.Southern Cross University, 3.Research Institute for Humanity and Nature)

Keywords:Submarine groundwater discharge, pCO2, 222Rn

Submarine groundwater discharge (SGD) is an important source of nutrients, trace metals, and carbon to coastal ecosystem. To quantify this processes in Kesennuma Bay, 24-hours mooring surveys for SGD tracers (Rn and Ra isotopes) and biogeochemical properties (nutrients, dissolved carbon and iron) were conducted during neap and spring tides in summer 2017. In this presentation, we will show results of simultaneous measurements of ²²²Rn and pCO₂. Although pCO₂ showed clear diurnal variation according to the photosynthesis/respiration process in both periods, excess CO₂ was supplied through significant groundwater discharge during the lowest tide in spring. These data will be used to quantify carbon flux from SGD and emission rate of CO₂ to atmosphere.