IDIOSYNCRATIC PHENOLOGY OF GREENHOUSE GAS EMISSIONS IN A MEDITERRANEAN RESERVOIR

Extreme hydrological and thermal regimes characterize the Mediterranean biome and can significantly impact the phenology of greenhouse gas (GHG) emissions in reservoirs. Our study examined the seasonal changes in GHG emissions of a shallow, eutrophic, hardwater reservoir in Spain. We observed distinctive seasonal patterns for each gas. CH₄ emissions substantially increased during stratification, reaching more than 1200 mg C m^-2 day^-1 predominantly by ebullition. This dynamic was influenced predominantly by the rise of water temperature, gross primary production, and the drop-in reservoir mean depth. N₂O emissions mirrored CH₄'s seasonal trend, significantly correlating to water temperature, wind speed, and net primary production with maximum values of 671 µg N m^-2 day^-1. The CO₂ emissions ranged from 12 to 567 mg C m^-2 day^-1 and decreased during stratification. These emissions displayed a quadratic, rather than a linear relationship with water temperature -an unexpected deviation from CH₄ and N₂O emission patterns- not reported previously and likely associated with the coupling between intracellular calcite formation and photosynthesis. We found the maximum climatic forcing during the summer due to the CH₄ and N₂O emissions. This investigation highlights the need to integrate these idiosyncratic patterns of Mediterranean hardwater reservoirs into GHG emissions models, enhancing the prediction of global GHG emissions in the global change era.

Primary Presenter: Isabel Reche, Universidad de Granada (ireche@ugr.es)

Authors:

Eva Rodríguez-Velasco, Universidad de Granada, Spain  (erodvel@ugr.es)

Ignacio Peralta-Maraver, Universidad de Granada, Spain  (peraltamaraver@ugr.es)

Andrés Martínez-García, Universidad de Granada, Spain  (andmargar@ugr.es)

Miriam García-Alguacil, Universidad de Granada, Spain  (mga00043@ugr.es)

Félix Picazo, Universidad de Granada, Spain  (fpicazo@ugr.es)

Rodrigo Gonçalves, Universidad de Granada, Spain  (rogo@ugr.es)

Cintia Ramón, Universidad de Granada, Spain  (crcasanas@ugr.es)

Rafael Morales-Baquero, Universidad de Granada, Spain  (rmorales@ugr.es)

Francisco Rueda, Universidad de Granada, Spain  (fjrueda@ugr.es)

Isabel Reche, Universidad de Granada, Spain  (ireche@ugr.es)