From bedrock to burial: the evolution of particulate organic carbon across coupled watershed-continental margin systems
From bedrock to burial: the evolution of particulate organic carbon across coupled watershed-continental margin systems
复制标题
DOI：
10.1016/j.marchem.2004.06.023
复制
发表时间：
2004-12
期刊：
影响因子：
3
通讯作者：
N. Blair;E. Leithold;R. Aller
中科院分区：
文献类型：
--
作者：
N. Blair;E. Leithold;R. Aller
三角洲封存了埋藏在海洋环境中的近一半的有机碳（OC）。埋藏的有机物的组成反映了流域和海底的过程。提出了一个概念模型，描述了颗粒有机碳（POC）的演变，因为它从陆地来源，它在海上埋藏。POC的变化主要发生在生物活性储层中，例如土壤和海底的表面混合层，在那里可以添加新的有机物质，并降解旧的物质。通过水库的快速通过是一个关键参数，因为它避免了变化。北方加州的鳗鱼河和亚马逊河系统说明了水库过境时间和储存量在确定输送到大陆边缘的POC特征方面的重要性。电鳗会使一个旁路系统变得更简单。土地上的质量浪费过程提供未改变的基岩沿着与OC来自现存的植被直接到河道中没有显着的存储在土壤中。由于洪水事件，大陆架上的快速掩埋发生。因此，埋藏的物质似乎是一个简单的混合物的碳来源于干酪根（基岩C），现代陆地和海洋来源。据预测，这是许多类似的活跃边缘的短河流的一个特征，这些河流为世界海洋提供了超过40%的河流沉积物。有机碳在低地土壤中的大量储存和加工是亚马逊流域的一个特点。高地POC组合物被叠印或被低地来源替代。在运送到大陆架时，超过一半的河流POC由于停留在沉积层中而损失，这些沉积层在几天到几个月的时间尺度上定期重新工作。此外，新鲜的活性海洋有机碳，暴露于氧气，再悬浮事件期间的金属氧化剂的再生燃料的河流有机物的氧化。流域-陆架过程的性质可能产生一种复杂的有机物混合物，具有连续的年龄和反应性。该模型说明了需要开发工具来测量颗粒在各个储层中的停留时间，以便可以在POC移动通过沉积系统时校准POC的行为。最终目标是能够使用土壤和沉积物的有机地球化学定量推断的过程，确定在不同的沉积环境中存在的POC的组成和数量的历史。
Deltas sequester nearly half of the organic carbon (OC) buried in the marine environment. The composition of the buried organic matter reflects both watershed and seabed processes. A conceptual model is presented that describes the evolution of particulate organic carbon (POC) as it travels from its terrestrial source to its burial at sea. Alterations to the POC occur primarily in bioactive reservoirs, such as soils and the surface mixed layer (SML) of the seabed, where new organic matter can be added and older material degraded. Bypassing or rapid passage through the reservoirs is a key parameter because it avoids change. The Eel River of northern California and the Amazon River systems illustrate the importance of reservoir transit time and storage in determining the character of POC delivered to the continental margin. The Eel exemplifies a bypass system. Mass-wasting processes on land deliver unaltered bedrock along with OC derived from extant vegetation directly to the river channel without significant storage in soils. Rapid burial on the shelf occurs as a result of flood events. As a consequence, the buried material appears to be a simple mixture of carbon derived from kerogen (bedrock C), and modern terrestrial and marine sources. This is predicted to be a characteristic of the many similar short rivers on active margins that supply >40% of the fluvial sediment to the world's ocean. Extensive storage and processing of OC in lowland soils is a characteristic of the large Amazon watershed. Upland POC compositions are either overprinted or replaced by lowland sources. Upon delivery to the shelf, over half of the riverine POC is lost as a result of residence in sediment layers that are periodically reworked over time scales of days to months. The addition of fresh reactive marine OC, exposure to oxygen, and the regeneration of metal oxidants during resuspension events fuel the oxidation of the riverine organic matter. The nature of the watershed-shelf processes likely produce a complex mixture of organics possessing a continuum of ages and reactivities. The model illustrates the need to develop tools to measure residence times of particles in the various reservoirs so that the behavior of POC can be calibrated as it moves through a sedimentary system. The ultimate goal is to be able to use the organic geochemistry of soils and sediments to quantitatively infer the history of processes that determine both the composition and amount of POC present in different depositional environments.