Air-water CO2 evasion from U.S. East Coast estuaries
Other literature type
Laruelle, Goulven Gildas
Cai, Wei - Jun
(issn: 1726-4189, eissn: 1726-4189)
This study presents the first regional-sca–45° N). The focus is on 43 tidal estuaries, which together drain a catchment of 697 10<sup>3</sup> km<sup>2</sup> or 76 % of the total area within this latitudinal band. The approach is based on the Carbon – Generic Estuarine Model (C-GEM) that allows simulating hydrodynamics, transport and biogeochemistry for a wide range of estuarine systems using readily available geometric parameters and global databases of seasonal climatic, hydraulic, and riverine biogeochemical information. Together, US East coast estuaries emit 1.9 TgC yr<sup>−1</sup>, which correspond to about 40 % of the carbon inputs from rivers, marshes and mangroves. Carbon removal within estuaries results from a combination of physical (outgassing of supersaturated riverine waters) and biogeochemical processes (net heterotrophy and nitrification). The CO<sub>2</sub> evasion and its underlying drivers show important variations across individual systems, but reveal a clear latitudinal pattern characterized by a decrease in the relative importance of physical over biogeochemical processes along a North-South gradient. Finally, results reveal that the ratio of estuarine surface area to the river discharge, S/Q (which has a scale of per meter discharged water per year), could be used as a predictor of the estuarine carbon processing in future regional and global scale assessments.