Mud‐associated organic matter and its direct and indirect role in marsh organic matter accumulation and vertical accretion
Mud‐associated organic matter and its direct and indirect role in marsh organic matter accumulation and vertical accretion
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泥伴生有机质及其在沼泽有机质积累和垂直增生中的直接和间接作用
DOI：
10.1002/lno.11475
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发表时间：
2020
影响因子：
4.5
通讯作者：
K. Valentine
中科院分区：
文献类型：
--
作者：
G. Mariotti;T. Elsey‐Quirk;G. Bruno;K. Valentine
原位植物生产通常被认为是有机质（OM）的积累和垂直加积在潮汐沼泽的主要贡献者。在这里，我们评估了路易斯安那州盐和半咸水沼泽中泥相关OM的贡献。基于14个土芯，泥部分的OM含量-即，小于64 μ m的任何物质在盐沼和半咸水沼泽中的平均含量分别为17% ± 7%和28% ± 14%。这在顶部35 cm深度上几乎保持一致，表明这种物质与泥浆同时沉积。泥浆的干容重（300-450 kg m−3）也远低于使用先前提出的双组分混合模型估计的值（1990 kg m−3）。为了调和这一差异，我们开发了一个修改后的混合模型，包括泥浆OM和区分砂作为一个单独的组成部分，其高干容重。该模型估计，泥贡献了路易斯安那州总沼泽垂直加积的约60%，远高于双组分混合模型估计的约14%。这一结果是泥质孔隙度相对较高的直接结果，突出了泥质沉积对微潮沼泽的增生至关重要。此外，该模型估计，泥OM构成~ 60%的总土壤OM，强调在原地植物生产不是唯一的，在成矿沼泽地，不是主要的贡献者OM积累。
In situ plant production is often assumed to be the major contributor to organic matter (OM) accumulation and vertical accretion in tidal marshes. Here, we evaluate the contribution of mud‐associated OM in salt and brackish marshes in Louisiana. Based on 14 soil cores, the OM content of the mud fraction—i.e., any material smaller than 64 μm—was 17% ± 7% for the salt marshes and 28% ± 14% for the brackish marshes. This remains nearly uniform over the top 35 cm depth, suggesting that this material is deposited contemporaneously with the mud. The dry bulk density of the mud (300–450 kg m−3) is also much lower than what was estimated using a previously proposed two‐constituent mixing model (1990 kg m−3). To reconcile this discrepancy, we developed a modified mixing model that includes mud OM and differentiates sand as a separate constituent with its high dry bulk density. The model estimates that mud contributes to ~ 60% of the total marsh vertical accretion in Louisiana, considerably higher than the ~ 14% estimated with the two‐constituent mixing model. The result, which is a direct consequence of the relatively high porosity of mud, highlights that mud deposition is crucial for the accretion of microtidal marshes. Further, the model estimates that the mud OM constitutes ~ 60% of the total soil OM, emphasizing that in situ plant production is not the only—and, in minerogenic marshes, not the major—contributor to OM accumulation.
影响因子：
2.8
作者：
Sapkota, Yadav;White, John R.
通讯作者：
White, John R.