Characterizing nitrogen dynamics in a groundwater-dependent wetland in South Korea using field and novel laboratory methods

Wetlands are affected by and also have a significant influence on climate change because of their ability to regulate atmospheric concentrations of the greenhouse gases such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). This study aimed to characterize nitrogen dynamics in a groundwater-dependent wetland in South Korea. Soil textures and compositions, surface and groundwater constituents, groundwater levels, and air temperatures were determined in the field and laboratory in summer, 2021. Production rates and isotopic signatures of N₂O gases were measured using static chamber and novel kinetic cell methods. Production rates of N₂O gas were were up to 78.8 g N₂O N/ha/d, N₂O production was most active at 20-32 cm depths, and the source of N₂O production was identified as denitrification of nitrate in groundwater. Statistical analyses indicated N₂O flux generally increased with increased groundwater level and air temperature. Quantitative analyses via in situ N₂O gas isotopic transport modeling will provide novel approach for rapidly characterizing the sources and dynamics of nitrogen and other greenhouse gases in groundwater-dependent wetlands around the world.