Coastal and deltaic sediment balances are crucial for a region's sustainability. However, such balances remain difficult to quantify accurately, particularly for large regions. We calculate organic and mineral sediment mass and volume balances using field measurements from 273 Coastwide Reference Monitoring System sites across the Louisiana Coast between 2006 and 2015. The rapid relative sea level rise rate (average 13.4 mm/year) is offset by the small dry bulk densities observed (average 0.3 g/cm³) to produce a 16.2 ± 41.1% mass deficit and 24.1 ± 14.0% volume deficit, significantly smaller than recent predictions for 2000–2100 (73–79% mass deficit). Geostatisical estimates show that this deficit is primarily located in areas not directly nourished by major rivers, yet these regions still accumulate ~24 MT/year of mineral sediment. A fluvial sediment discharge of 113.8 MT/year suggests a coast‐wide trapping efficiency of 31.5 ± 15.8% of the riverine sediment, excluding subaqueous deposition. Organic accumulation accounts for 25% of all mass accumulation during our study period, and total organic mass accumulation per unit area is relatively constant in both directly and indirectly nourished regions. Sediment characteristics in the modern coastal wetlands differ from the Holocene deposit, suggesting secular changes within the system that will likely continue to influence coastal dynamics over the coming decades. Our results suggest that the gap between accommodation and accumulation (mass or volume) during this decade was not as large as the previously predicted century average.

中文翻译：

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基于田野的路易斯安那州沿海地区泥沙淤积估算

沿海和三角洲的沉积物平衡对于该地区的可持续性至关重要。但是，这种余额仍然难以准确量化，尤其是对于大区域。我们使用2006年至2015年间在路易斯安那州沿海的273个沿海参考监测系统站点进行的野外测量，计算了有机和矿物沉积物的质量和体积平衡。相对快速的海平面上升速度（平均每年13.4毫米）被少量的干散货抵消了观察到的密度（平均0.3 g / cm ³）产生16.2±41.1％的质量亏缺和24.1±14.0％的体积亏缺，大大小于最近对2000–2100的预测（73–79％的质量亏缺）。地统计估计表明，这一赤字主要位于主要河流未直接营养的地区，但这些地区每年仍积累约24 MT的矿物沉积物。每年113.8 MT的河流沉积物排放量表明，不包括水下沉积物，全海岸的捕集效率为河流沉积物的31.5±15.8％。在我们的研究期间，有机质累积占所有质量累积的25％，在直接和间接营养的地区，每单位面积的有机质累积总量相对恒定。现代沿海湿地的沉积特征不同于全新世沉积，这表明系统内的长期变化可能会在未来几十年继续影响沿海动力。我们的结果表明，在这十年中，住宿和蓄积（质量或体积）之间的差距没有以前预测的世纪平均值大。