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.

俄勒冈河口为评估潮汐盐沼湿地（tidal saline wetland）碳埋藏与沉积物加积的调控机制提供了重要契机——该区域沿岸的相对海平面上升（relative sea level rise, RSLR；-1.4±0.9 至 2.8±0.8 mm·a⁻¹）速率与流域悬浮泥沙负荷相对河口面积的比值（0.23 至 17×10³ t·km⁻²·a⁻¹）均存在显著空间差异。本研究提出假设：通过对7个俄勒冈河口受干扰程度最低的湿地中过剩铅210（excess ²¹⁰Pb）的测定得到的垂直加积速率，将与相对海平面上升速率或流域悬浮泥沙负荷相对河口面积的比值存在关联，且碳埋藏速率与沉积物加积速率呈显著相关。高潮滩（high marsh）加积速率的平均值范围为0.8±0.2 至4.1±0.2 mm·a⁻¹，表明俄勒冈潮汐湿地整体能够跟上20世纪的相对海平面上升速率，但中部沿岸区域的加积平衡为负值，暗示湿地正发生淹没。中部沿岸河口的相对海平面上升速率最快，其湿地状态或可预示未来海平面加速上升背景下俄勒冈其他河口湿地的演变结局。然而，将泥沙质量堆积速率与流域悬浮泥沙负荷进行对比后发现，区域泥沙捕获效率较低，因此不存在流域泥沙供给限制。由此可见，相对海平面上升与沉积物加积之间的非线性反馈或可提升湿地抵御淹没的能力。在能够跟上甚至超过相对海平面上升速率的湿地中，沉积物加积速率不受海拔高度的影响，而是由相对海平面上升速率与相对泥沙负荷共同调控，这凸显了将两类因子纳入潮汐盐沼湿地未来研究的重要性。由沉积物加积速率调控的碳埋藏速率，未来或将随海平面加速上升而升高。