How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?
How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?
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DOI：
10.1111/gcb.12924
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发表时间：
2015-07
影响因子：
11.6
通讯作者：
Kuwae T
中科院分区：
文献类型：
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作者：
Watanabe K;Kuwae T
海洋生物捕获的碳有助于封存大气中的二氧化碳，特别是在浅海沿海生态系统中，这些生态系统的初级生产率和来自多种来源的有机碳 (OC) 的埋藏率很高。然而，人们对多种来源的有机碳动态与碳封存之间的联系知之甚少。我们利用日本风莲泻湖的元素、同位素和光学特征，研究了水体中颗粒 OC (POC) 和溶解 OC (DOC) 以及沉积物 OC 的来源（陆地、底栖植物和浮游植物）。基于这些数据分析，我们探讨了多种来源的有机碳如何通过沉积物中的储存、水柱封存和海气二氧化碳交换来促进封存，并分析了这些贡献如何随浅海草甸中的盐度变化。水体中陆地 POC 的相对贡献随着盐度的增加而降低，而本土 POC 在盐度范围 10-30 内增加。在此盐度范围内，浮游植物来源的 POC 在水体 POC 中占主导地位 (65-95%)；然而，沉积物中的含量很少（3-29%）。相比之下，陆地和底栖植物来源的 POC 在水体中的贡献相对较小，但在沉积物中却是主要贡献者（分别为 49-78% 和 19-36%），这表明陆地和底栖植物来源的 POC 选择性地储存在沉积物中。在盐度范围为 15-30 的水体 DOC 池中，本地 DOC 占总水体 DOC 库的 25% 以上，其中部分可有助于水体中的长期碳封存。原生有机碳的产生降低了水体中溶解的无机碳的浓度，从而促进了大气中二氧化碳的吸收，低盐区除外。我们的研究结果表明，浅海沿海生态系统不仅充当陆地和海洋之间的过渡区，而且还充当碳封存过滤器。它们在不同的时间尺度上发挥作用，具体取决于盐度和 OC 来源。
Carbon captured by marine organisms helps sequester atmospheric CO2, especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air–sea CO2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10–30. Phytoplankton-derived POC dominated the water column POC (65–95%) within this salinity range; however, it was minor in the sediments (3–29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49–78% and 19–36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15–30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They function at different timescales, depending on the salinity, and OC sources.