Temporal constraints on lateral organic matter transport along a coastal mud belt
Temporal constraints on lateral organic matter transport along a coastal mud belt
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DOI：
10.1016/j.orggeochem.2019.01.007
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发表时间：
2019-02-01
影响因子：
3
通讯作者：
Eglinton, Timothy I.
中科院分区：
文献类型：
--
作者：
Bao, Rui;Zhao, Meixun;Eglinton, Timothy I.
对沉积有机碳（OC）在大陆架上横向迁移的时间尺度的限制以及对OC分布和丰度的相关影响仍然很少。不稳定的，年轻的OC在横向运输过程中的优先降解结果在明显的“成岩老化”的OC。此外，沉积物迁移也可能导致相关的有机质（OM）的“运输时间相关的老化”作为横向运输时间（LTT）的函数。在这里，我们使用一个耦合的热分解和放射性碳（C-14）的方法来约束的时间尺度的横向运输和随之而来的损失与不同的粒度级的沉积物收集从两个位置类似的分散路径上的内陆架沿着275公里。相应的热馏分之间的C-14年龄对比被用来区分这两个组成部分的沉积有机质“老化”。为了最大限度地减少水动力分选和成岩老化的OC伴随横向运输的干扰，我们评估C-14年龄差异的分解产物从最热耐火OC组件与特定的粒度级之间的位置。我们发现，LTTs不同的粒度级之间的变化，并检查LTTs和沉积OC损失之间的关系，以评估OC的分解作为横向运输的结果。我们认为，OC的分解与长期的横向运输产生了强烈的影响OC埋葬效率，具有广泛的影响，在大陆架上的碳循环。(C)2019年，任作者。由爱思唯尔有限公司发布
Constraints on timescales of lateral transport of sedimentary organic carbon (OC) over continental shelves and associated influences on the distribution and abundance of OC remain sparse. Preferential degradation of labile, young OC during lateral transport results in apparent "diagenetic aging" of OC. Additionally, sediment translocation can also result in "transport time-associated aging" of associated organic matter (OM) as a function of the lateral transport time (LTT). Here, we use a coupled thermal decomposition and radiocarbon (C-14) approach to constrain timescales of lateral transport and concomitant loss of OC associated with different grain size fractions of sediments collected from two locations similar to 275 km apart along a dispersal pathway on the inner shelf of the East China Sea. The C-14 age contrasts between corresponding thermal fractions are used to distinguish these two components of sedimentary OM "aging". To minimize interferences from hydrodynamic sorting and diagenetic aging of OC accompanying lateral transport, we assess C-14 age differences of decomposition products from the most thermally-refractory OC components associated with specific grain size fractions between locations. We show that LTTs vary among different grain size fractions, and examine relationships between LTTs and sedimentary OC loss in order to assess the decomposition of OC as a consequence of lateral transport. We suggest that the decomposition of OC associated with protracted lateral transport exerts a strong influence on OC burial efficiency, with broad implications for carbon cycling over continental shelves. (C) 2019 The Author(s). Published by Elsevier Ltd.