Dataset: Controls on sediment accretion and blue carbon burial in tidal saline wetlands: Insights from the Oregon coast, U.S.A.

Oregon estuaries provide important opportunities to assess controls on tidal saline wetland carbon burial and sediment accretion as both rates of relative sea level rise (RSLR; -1.4 ± 0.9 to 2.8 ± 0.8 mm y-1) and fluvial suspended sediment load relative to estuary area (0.23 to 17 x 103 t km-2 y-1) vary along the coast. We hypothesized that vertical accretion, measured using excess 210Pb in least-disturbed wetlands within seven Oregon estuaries, would vary with either RSLR or sediment load relative to estuary area, and carbon burial would correlate strongly to sediment accretion. Mean rates of high marsh accretion (0.8 ± 0.2 to 4.1 ± 0.2 mm y-1) indicate that Oregon tidal wetlands have kept pace with 20th century RSLR though accretionary balance in the central-coast is negative, suggesting drowning. Experiencing the fastest rates of RSLR, central-coast estuaries may foreshadow the fates of other Oregon estuaries under future accelerated sea level rise. Comparison of mass accumulation rates with sediment loads, however, indicates low trapping efficiency and therefore no fluvial sediment limitation. Thus, non-linear feedbacks between RSLR and sediment accretion may enhance wetland resistance to drowning. Amongst wetlands keeping pace with or exceeding RSLR, sediment accretion is not influenced by elevation but rather appears controlled by both the rate of RSLR and relative sediment load, highlighting the importance of incorporating both factors into future studies of tidal saline wetlands. Carbon burial rates, controlled by sediment accretion, will likely increase with future accelerated sea level rise.