[A-CG38] 沿岸海洋生態系－2．サンゴ礁・藻場・マングローブ

[ACG38-P03] マングローブ・海草藻場・塩性湿地からの堆積物間隙水由来DIC流出

*渡辺 謙太¹、杉本 亮²、久保 篤史³、中島 壽視⁴、桑江 朝比呂¹ (1.港湾空港技術研究所、2.福井県立大学、3.静岡大学、4.東京大学)

キーワード：ブルーカーボン生態系、炭素動態、炭酸系、間隙水、ラジウム

Blue carbon ecosystems such as mangrove forests, seagrass beds, and tidal marshes, have the function of taking up atmospheric CO₂ and storing organic carbon (OC). The creation, conservation, and restoration of these habitats are attracting attention as sinks for atmospheric CO₂. OC assimilated by the photosynthesis is decomposed via biotic and abiotic remineralization processes, a part of them being buried in the sediments over long timescale. Almost all of the decomposed carbon has been recognized to be returned to the atmosphere as CO₂. However, the decomposed carbon would be stored in water column as inorganic carbon ions depending on the carbonate chemistry in chemical reactions of remineralization processes. In this study, we investigated the outwelling of dissolved inorganic carbon (DIC) and total alkalinity (TAlk) from the sediments of mangrove, seagrass, and tidal marsh habitats. We measured a Ra radioisotope with DIC and TAlk as a chemical tracer of the porewater from the sediments. Field surveys were conducted in Fukido River estuary (Ishigaki Island) and Komuke Lagoon (Hokkaido). Our results show that substantial amount of DIC is outwelled as ions from these habitats.