CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS); Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, China.
Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
Environ Sci Technol. 2021 May 4;55(9):6495-6504. doi: 10.1021/acs.est.1c00636. Epub 2021 Apr 22.
Vegetated coastal habitats (VCHs) rank among the most intense carbon sinks in natural ecosystems, playing an important role in the global carbon cycle. A significant part of the organic carbon (OC) they store may be allochthonous OC that has been sequestered elsewhere. Yet, the compositions of allochthonous OC are largely unknown. Here, we present concentrations and carbon isotopic (C and C) compositions and accumulation rates of carbon in the VCHs from major temperate-subtropical deltas of China: Yellow, Yangtze, and Pearl river deltas. We find that black carbon (BC) amounts to 9-25% of OC across sites. Temperate VCHs exhibit lower BC contents but higher BC contributions than subtropical VCHs. This seemingly counterintuitive result can be explained by increased accumulation of long-term, stable, allochthonous OC in temperate VCHs. BC in temperate VCHs contains 1.5-2 times more fossil BC than that in subtropical VCHs in the 1 m depth soil, which is likely influenced by atmospheric input and the aging effect. We estimate an accumulation rate of BC in China's VCHs of 33.1 ± 14.5 g m year, acting as a hotspot for BC burial. These results point to a substantial and hitherto unquantified contribution of BC components to blue carbon storage, as well as the VCHs to global BC storage. Preservation of this old-aged, stable OC implies an important ecosystem service of the VCHs for climate change mitigation.
植被覆盖的沿海生境 (VCHs) 是自然生态系统中最强烈的碳汇之一，在全球碳循环中发挥着重要作用。它们储存的有机碳 (OC) 中有很大一部分可能是来自其他地方的异源 OC。然而，异源 OC 的组成在很大程度上是未知的。在这里，我们介绍了来自中国主要温带-亚热带三角洲的 VCHs 中的 OC 浓度和碳同位素 (C 和 C) 组成和积累速率：黄河、长江和珠江三角洲。我们发现，黑碳 (BC) 在 OC 中的含量占 9-25%。温带 VCHs 的 BC 含量较低，但 BC 贡献高于亚热带 VCHs。这一看似违反直觉的结果可以通过温带 VCHs 中稳定的、长期的异源 OC 的积累来解释。温带 VCHs 中 1 米深土壤中的 BC 含有 1.5-2 倍的化石 BC，这可能受到大气输入和老化效应的影响。我们估计中国 VCHs 中 BC 的积累速率为 33.1±14.5 g m year，是 BC 埋藏的热点。这些结果表明，BC 成分对蓝碳储存的贡献以及 VCHs 对全球 BC 储存的贡献相当大，但迄今为止尚未量化。这种古老而稳定的 OC 的保存意味着 VCHs 为气候变化缓解提供了一项重要的生态系统服务。
