Sediment deposition and accretion in a Mid-Atlantic (U.S.A.) tidal freshwater marsh
Sediment deposition and accretion in a Mid-Atlantic (U.S.A.) tidal freshwater marsh
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大西洋中部（美国）潮汐淡水沼泽中的沉积物沉积和堆积
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
S. Kuehl
中科院分区：
文献类型：
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作者：
S. Neubauer;I. Anderson;J. Constantine;S. Kuehl
测量了弗吉尼亚潮汐淡水沼泽的沉积物沉积和吸积速率，以深入了解对于维持沼泽表面高程至关重要的过程和时间尺度。短期沉积物沉积率（每两周至每月）测量使用沉积物收集瓦片的空间和时间变量。率是最大的潮汐附近的吱吱声和下降沿着向沼泽内部延伸的横断面。当把整个沼泽综合起来时，年沉积物沉积量（以有机碳计）平均为517±353 g C m−2 y−1，足以平衡现有的相对海平面上升和沼泽呼吸速率的影响。在溪岸，最高的沉积速率在夏季测量，虽然利率相对恒定，随着时间的推移，在内部网站。类似的空间和时间模式时，沉积速率计算7Be库存（每月的时间尺度）。沉积物库存的7 Be大于支持大气，表明沉积的空间格局是不是由于沼泽内的沉积物侵蚀和再分配。从137Cs（十年尺度）和14C测年（百年至千年）计算的吸积率大大低于年沉积率，随着时间尺度的增加，吸积率下降。最近沉积的沉积物的矿化速率（测量为O2消耗）表明，沉积物代谢可能会在沉积后一个月内去除近30%的最近沉积的碳。一个不稳定的沉积物部分的新陈代谢可以解释的一部分，所观察到的增加时间尺度的吸积率下降，其余的是由于定期风暴引起的侵蚀和沉积物沉积率的历史变化。
Sediment deposition and accretion rates in a Virginia tidal freshwater marsh were measured to provide insight to the processes and time scales that are important for maintaining marsh surface elevation. Short-term sediment deposition rates (biweekly to monthly) measured using sediment collection tiles were spatially and temporally variable. Rates were greatest near a tidal creak and decreased along a transect extending toward the marsh interior. When integrated across the entire marsh, annual sediment deposition (as organic carbon) averaged 517±353 g C m−2 y−1 and was sufficient to balance the effects of existing relative sea level rise and marsh respiration rates. At the creekbank, the highest deposition rates were measured during summer although rates were relatively constant over time at the interior sites. Similar spatial and temporal patterns were obtained when deposition rates were calculated from 7Be inventories (monthly time scale). Sediment inventories of7 Be were greater than those supported atmospherically, indicating that the spatial patterns of sedimentation were not due to sediment erosion and redistribution within the marsh. Accretion rates calculated from 137Cs (decadal scale) and14 C dating (centuries to millennia) were substantially less than annual deposition rates, with a decrease in accretion rate with increasing time scale. Mineralization rates of recently deposited sediments (measured as O2 consumption) indicated that sediment metabolism could potentially remove ∼30% of recently deposited carbon within one month of deposition. The metabolism of a labile sediment fraction could explain a portion of the observed decrease in accretion rate with increasing time scale, with the remainder due to periodic storm-induced erosion and historical variability in sediment deposition rates.