Author(s): Jianan Liu, Hainan University (First Author, Presenting Author) Ehui Tan, Hainan University Xueqing Yu, Hainan Normal University Shuh-Ji Kao, Hainan University
Seagrass beds store carbon but also release potent greenhouse gases methane (CH4) and nitrous oxide (N2O), reducing their climate benefit. We studied how submarine groundwater discharge (SGD) affects this in seagrass ecosystems. Surprisingly, while this groundwater adds CH4 (a source), strong natural biogeochemical activity removes large amounts of N2O within it, making SGD a net sink for N2O. Crucially, the climate-cooling effect from SGD removing N2O offsets about one-third of the warming caused by the CH4 it adds. This reveals SGD as a powerful, hidden natural N2O sink in seagrass beds. Protecting or restoring seagrass areas with active groundwater exchange thus offers a double climate win: storing carbon andboosting this natural N2O removal process.
