[A-HW22] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW22-01] Carbon Sequestration in Coastal Wetlands - The Lateral Carbon Flux

★Invited Papers

*Adina Paytan¹, Ariane Arias Ortiz⁴, Dennis Baldocchi², Lisamarie Windham-Myers³, Brian Bergamaschi³, Aliya Khan¹, Patty Oikawa⁵ (1.University of California Santa Cruz, 2.University of California Berkeley, 3.United State Geological Survey, 4.Universitat Autònoma de Barcelona, 5.California State University East Bay)

Keywords:Wetlands, Carbon Budget, Latteral Flux, Nature-Based Solutions

Coastal wetlands are among the most productive habitats on Earth and sequester globally significant amounts of atmospheric carbon (C). High rates of soil C accumulation are widely assumed to reflect efficient C storage and along with estimates of C emissions to the atmosphere used to assess net ecosystem C budgets (NECB). However, the C storage potential of tidal wetlands based on these estimates may not be accurate as most studies do not account for lateral export of C to the coastal ocean. High temporal resolution monitoring of gas emissions and lateral transport simultaneously, along with assessment of soil burial is needed for NECB calculation and this is not routinely done. We used several methods for estimating the lateral flux of C from tidal wetlands in California where eddy covariance towers are installed, and soil C burial was estimated. The contribution of lateral C transport to the C budget of these systems ranged from 30% to 60% of net ecosystem exchange. Most of the C transported laterally was in the form of dissolved inorganic C while dissolved organic C and particulate C contributions were smaller. Considering the large fraction of C exported laterally it is necessary to better monitor this flux and to determine the fate of this C once in the coastal ocean. These estimates are particularly important with the increasing interest of restoring wetlands for blue carbon sequestration as a nature-based climate mitigation solution.