Ecohydrology of Greenhouse Gas Fluxes in a Temperate Estuary

Abstract:

Estuaries are among the world’s most biologically rich and economically important ecosystems, and are vulnerable as they are threatened by the front lines of natural and human-induced change. It is unclear which are the biophysical processes that control carbon dynamics (including CO₂ and CH₄) in estuaries, and whether these ecosystems are net sources or sinks of carbon to the atmosphere. Most efforts have been placed to study CO₂ dynamics, but the complex biogeochemical reactions within the sediments that play a role of in situ GHG production cannot be forgotten, especially for CH₄ dynamics in wetlands. We present results of ecosystem-scale CO₂, CH₄ and H₂O fluxes using the eddy covariance technique in a brackish temperate estuary near the Delaware Bay, USA. We also present a synthesis effort to bring together concepts and measurements form hydrology and biogeochemistry to explain the temporal patterns and magnitudes of the GHG fluxes measured by the eddy covariance technique. We conclude that an ecohydrological approach and a deeper understanding of biogeochemical characteristics and reactions within the sediments is needed to better understand GHG fluxes in estuaries.