Carbon Sequestration in Sediment as an Ecosystem Function of Seagrass Meadows
Carbon Sequestration in Sediment as an Ecosystem Function of Seagrass Meadows
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沉积物中的碳封存作为海草草甸的生态系统功能
DOI：
10.1007/978-981-13-1295-3_2
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Hamaguchi Masami
中科院分区：
文献类型：
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作者：
Miyajima Toshihiro;Hamaguchi Masami
海草草甸有潜力将大量的有机碳（OC）作为碎屑OC固定在下伏沉积物中。海草草甸的这种生态系统功能不仅取决于海草和相关藻类的高初级生产力，还取决于海草草甸的物理和水文特性，海草草甸积累了细粒矿物沉积物和外来有机物，并使沉积物稳定。有机碳在海洋沉积物中的埋藏效率主要受到以下因素的制约：（i）累积有机质的结构稳定性，（ii）通过有机-矿物相互作用增强有机碳的保存，以及（iii）沉积物反应层中氧暴露时间的长度。我们将讨论这些机制如何有助于和限制海草沉积物中的OC封存。从沉积物源-汇的角度来看，长期固碳能力可以被视为沿海植被生态系统（如海草草甸）的一种新兴特性。有机碳的封存还取决于所供应的有机碳的性质，而这在很大程度上取决于有机碳的来源。根据有机碳在早期成岩过程中的迁移和降解方式，对海草草甸沉积物中有机碳的主要来源进行了综述和分类。评估各种OC来源，包括最近开发的环境DNA技术，可用的方法也进行了严格审查。最后，汇编了关于海草草甸沉积物中有机碳浓度和埋藏速率的现有数据，并提供了海草草甸长期（约1000年）有机碳封存速率的初步全球估计值，为1.6-9.4 Tg C年-1。这低于先前对全球海草草甸有机碳埋藏率的估计。
Seagrass meadows have the potential to sequester large amounts of organic carbon (OC) in underlying sediments as detrital OC. This ecosystem function of seagrass meadows depends not only on the high primary productivity of seagrasses and associated algae, but also on the physical and hydrological properties of seagrass meadows that accumulate fine-grained mineral sediment and allochthonous organic matter and stabilize the sediment. The burial efficiency of OC in marine sediment is constrained principally by (i) structural recalcitrance of accumulated organic matter, (ii) enhancement of OC preservation through organic–mineral interactions, and (iii) the length of the oxygen exposure time in the reactive layer of sediment. We discuss how these mechanisms contribute to and constrain OC sequestration in seagrass sediments. From the sediment source–sink perspective, long-term carbon sequestration capacity can be viewed as an emergent property of coastal vegetated ecosystems such as seagrass meadows. Sequestration of OC also depends on the nature of the OC supplied, which is largely determined by the origin of the OC. The major sources of OC to seagrass meadow sediments are reviewed and classified in terms of their mode of transport and degradability in the early diagenetic process. The available methods of evaluating various OC sources, including recently developed environmental DNA techniques, are also critically reviewed. Finally, available data are compiled on the concentration and burial rate of OC in seagrass meadow sediments and a tentative global estimate of the long-term (~1000 years) OC sequestration rate in seagrass meadows as 1.6–9.4 Tg C year−1is provided. This is lower than previous estimates of the global OC burial rate in seagrass meadows.