Comparison of 15N₂ flux and acetylene inhibition denitriflcation methods in Atchafalaya River basin sediments.

摘要

Flooded swamps in the Atchafalaya River basin, Louisiana, USA, are thought to be a major mechanism for removing excess riverine nitrate that may be causing hypoxia in coastal Louisiana. Two denitrification methods, the 15N₂ flux and acetylene inhibition technique, were compared and evaluated. Sediment samples were collected from three baldcypress swamp sites located within the Atchafalaya River basin. Highly 15N-labeled (61.7 at. %) and unlabeled nitrate (100 mg NO₃-NL-1) were applied to the floodwater of separate sets of sediment cores. Denitrification potential was measured 2, 6, 10, and 16 days after nitrate addition. Two days after nitrate addition, no significant differences in denitrification rates were observed between methods. On days 6, 10, and 16, denitrification measured by the 15N₂ method was higher compared to the acetylene inhibition procedure. When significance was observed, 15N₂ denitrification was approximately 5.3 times greater.