Deposition and fate of organic carbon in floodplains along a tropical semiarid lowland river (Tana River, Kenya)
Deposition and fate of organic carbon in floodplains along a tropical semiarid lowland river (Tana River, Kenya)
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热带半干旱低地河流（肯尼亚塔纳河）洪泛区有机碳的沉积和归宿
DOI：
10.1002/2015jg003288
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Gerard Govers
中科院分区：
文献类型：
--
作者：
F. Omengo;N. Geeraert;S. Bouillon;Gerard Govers
内陆沃茨沉积物埋藏的有机碳（OC）最近被证明是河流流域碳（C）预算的重要组成部分。然而，迄今为止，有关沉积作用OC埋藏的数据主要限于温带地区。我们调查了热带低地塔纳河（肯尼亚）洪泛区两个主要测量站（加里萨和加森）之间沉积物相关有机碳的沉积和归宿。对新鲜沉积的表层沉积物和沉积物柱样进行了采样和分析，以获得OC、总氮含量、OC的稳定同位素特征（δ 13 C）和粒度分布。此外，我们孵化沉积物芯量化CO2生产作为代理OC矿化。河漫滩沉积物中有机碳含量相对较低（1.56 ± 0.42%），而河漫滩沉积物中有机碳含量则高于3%。沉积物岩心显示OC随深度急剧下降，从（子）表面的3%至12% OC到约60 cm深度以下的不到1% OC。OC矿化率（0.14 ± 0.07 mol. CO2 kgC−1 d−1）。我们使用这些数据，使第一次评估的塔纳河漫滩的C埋藏效率。与在温带环境中观察到的情况相反，在不到世纪的时间里，顶层中超过50%的C丢失。虽然大量的有机碳被埋在塔纳河洪泛区，但沉积后损失的高速率限制了这一热带洪泛区长期碳汇的发展。
Inland waters organic carbon (OC) burial by sedimentation has recently been shown to be an important component in river catchment carbon (C) budgets. However, data on OC burial by sedimentation are hitherto largely limited to temperate zones. We investigated the deposition and fate of sediment‐associated OC in the floodplains of the tropical lowland Tana River (Kenya), between two main gaging stations (Garissa and Garsen). Freshly deposited surface sediments and sediment cores were sampled and analyzed for OC, total nitrogen content, stable isotope signatures (δ13C) of OC, and grain size distribution. In addition, we incubated sediment cores to quantify CO2 production as a proxy for OC mineralization. While the floodplain receives sediment with a relatively low OC content (1.56 ± 0.42%), sediments are enriched with OC inputs from floodplain vegetation to levels above 3%. Sediment cores show a sharp decrease of OC with depth, from 3 to 12% OC in the (sub) surface to less than 1% OC below approximately 60 cm depth. Relatively elevated OC mineralization rates (0.14 ± 0.07 mol. CO2 kgC−1 d−1) were recorded. We used these data to make a first assessment of the C burial efficiency of the Tana River floodplain. In contrast to what is observed in temperate environments, over 50% of C present in the top layers is lost in less than a century. While significant amounts of OC are buried in the Tana River floodplain, the high rates of postdepositional loss limit the development of a long‐term C sink within this tropical floodplain.
影响因子：
18.3
作者：
Borges, Alberto V.;Darchambeau, Francois;Bouillon, Steven
通讯作者：
Bouillon, Steven