|
Interannual variation in summer N2O concentration in the hypoxic region of the northern Gulf of Mexico, 1985–2007Abstract: We present evidence of temporal variation in nitrous oxide (N2O) concentrations in the bottom waters of the northern Gulf of Mexico (nGOM) hypoxic zone. The analysis is based on a conceptual model simulating N2O biogeochemical processes in conjunction with water-column O2 levels, derived from summer Texas–Louisiana shelf-wide hydrographic data for twenty Julys between 1985 and 2007. The mean modeled nGOM N2O concentration was 7.7 ± 6.7 nmol L 1, and was significantly correlated with the areal extent of hypoxia. Our modeling analysis indicates that the nGOM is a persistent summer source of N2O, and nitrification is a primary factor leading to its production in this region. Based on the ongoing increase in the areal extent of hypoxia in the nGOM, we conclude that N2O emission from this environmentally stressed region will continue to increase into the future contributing to the global increase in greenhouse gases.
|