Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state.
Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state.
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DOI：
10.1002/2015ef000334
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发表时间：
2016-04
期刊：
影响因子：
8.2
通讯作者：
Wigand, Cathleen
中科院分区：
文献类型：
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作者：
Morris, James T.;Barber, Donald C.;Callaway, John C.;Chambers, Randy;Hagen, Scott C.;Hopkinson, Charles S.;Johnson, Beverly J.;Megonigal, Patrick;Neubauer, Scott C.;Troxler, Tiffany;Wigand, Cathleen
一个混合模型来自第一性原理描述了作为烧失量（LOI）的函数的潮间带湿地沉积物的体积密度（BD）。该模型假设沉积物的总体积等于有机和无机组分的自堆积体积之和或BD = 1/[LOI/k1 +（1-LOI）/k2]，其中k1和k2分别是纯有机和无机组分的自堆积密度。该模型解释了78%的变异，总BD时，拟合到5075测量来自33个湿地分布在毗邻美国。k1和k2的值估计分别为0.085 ± 0.0007 g cm−3和1.99 ± 0.028 g cm−3。基于拟合的有机密度（k1）和初级生产力的约束，该模型表明，由难降解有机物的封存产生的最大稳态吸积≤ 0.3 cm/年。因此，如果没有重要的矿物沉积物来源，潮汐泥炭地不太可能无限期地生存在更高的海平面上升率下。将k2应用于东部和东部墨西哥湾沿岸河口典型的矿物沉积物负荷，得到无机沉积物的垂直加积速率为0.2 cm/yr−1。总的稳态吸积是各部分的总和，因此在模型的假设下不应大于0.5 cm yr-1。吸积率可能会偏离该值，具体取决于植物生产力、根冠比、悬浮泥沙浓度、泥沙捕获效率和事件的变化。沉积物的体积密度在很大程度上可以通过其有机物浓度来解释。体积近似于矿物和有机组分的体积之和。
A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes that the bulk volume of sediment equates to the sum of self‐packing volumes of organic and mineral components or BD = 1/[LOI/k1 + (1‐LOI)/k2], where k1 and k2 are the self‐packing densities of the pure organic and inorganic components, respectively. The model explained 78% of the variability in total BD when fitted to 5075 measurements drawn from 33 wetlands distributed around the conterminous United States. The values of k1 and k2 were estimated to be 0.085 ± 0.0007 g cm−3 and 1.99 ± 0.028 g cm−3, respectively. Based on the fitted organic density (k1) and constrained by primary production, the model suggests that the maximum steady state accretion arising from the sequestration of refractory organic matter is ≤ 0.3 cm yr−1. Thus, tidal peatlands are unlikely to indefinitely survive a higher rate of sea‐level rise in the absence of a significant source of mineral sediment. Application of k2 to a mineral sediment load typical of East and eastern Gulf Coast estuaries gives a vertical accretion rate from inorganic sediment of 0.2 cm yr−1. Total steady state accretion is the sum of the parts and therefore should not be greater than 0.5 cm yr−1 under the assumptions of the model. Accretion rates could deviate from this value depending on variation in plant productivity, root:shoot ratio, suspended sediment concentration, sediment‐capture efficiency, and episodic events. Sediment bulk density can be largely explained by its organic matter concentration Bulk volume approximates the summed volumes of the mineral and organic fractions Upper bound of steady‐state accretion defines sustainability of coastal marshes under SLR