Abstract ID: 136

Weather effects on CO2 outgassing at the Curuá River (Caxiuanã, PA, Brazil)

Recent research has highlighted the importance of riverine CO 2 outgassing to regional and global carbon budgets. However, the processes controlling fluxes in these aquatic systems are still poorly understood. In this study we performed a series of measurements of CO 2 fluxes (using a floating chamber), air and water temperatures, wind velocity, dissolved O 2 and pCO 2 in the water column, during three days (10-12/Nov/2006), at the Curuá river. This small tidal river, located in Caxiuanã (PA) has low current velocities due to flat topography. At the first day we observed a stratification of the water column, with water temperature and O 2 decreasing approximately 2 oC and 6 mg L-1, respectively, from the surface to the bottom (9 meters) and pCO 2 increasing from 1700 to 7200 µatm. Mean CO2 flux was 1,0 ± 0,6 µmol CO 2 m -2 s-1 (n=16). In the second day, weather conditions changed drastically, with the occurrence of rain, air temperature drop and fast wind velocity, which mixed the water column, bringing deep water with higher pCO 2 to the surface, increasing surface pCO 2 to 4600 ± 500 µatm. These changes resulted in higher fluxes with a mean of 3,0 ± 1,0 µmol CO 2 m-2 s-1 (n=26). Our results demonstrate that stochastic weather phenomena can drastically change CO 2 outgassing magnitudes in these aquatic systems and hence extrapolations based on short term data should be carefully evaluated.

Session:  Carbon - The role of seasonality in carbon and water balance.

Presentation Type:  Poster