Seagrass contributes substantially to the sedimentary lignin pool in an estuarine seagrass meadow
Seagrass contributes substantially to the sedimentary lignin pool in an estuarine seagrass meadow
复制标题
海草对河口海草草甸的沉积木质素库有重大贡献
DOI：
10.1016/j.scitotenv.2021.148488
复制
发表时间：
2021
影响因子：
9.8
通讯作者：
Yamamoto Shuichi
中科院分区：
文献类型：
--
作者：
Nakakuni Masatoshi;Watanabe Kenta;Kaminaka Khoki;Mizuno Yukiko;Takehara Keiko;Kuwae Tomohiro;Yamamoto Shuichi
浅海生态系统是碳的储存库，这些碳来自微藻和大型植物产生的外来有机物和本地有机物。海岸带植被生态系统碳储量作为碳汇的重要组成部分受到广泛关注。确定沉积物中碳的来源对于定量评价浅海生态系统的固碳功能至关重要。在这项研究中，我们调查了有机质的来源，使用有机生物标志物（木质素酚，脂肪酸，角质酸，二元酸，ω-羟基酸）在表层沉积物中的海草为主的泻湖（Furen泻湖，日本）。来自异地维管植物的生物标志物，如长链脂肪酸，在河口附近浓度较高。此外，生物标志物信号表明，沉积有机碳来源于大部分来自退化的异地维管植物，包括根。贝叶斯混合模型使用的比率，香叶基酚香草基酚和肉桂基酚香草基酚表明，高达约65%的木质素在沉积物中来自海草。这一结果表明，在河口海草草甸的沉积木质素池海草的重大贡献。然而，海草的百分比贡献的木质素池变化，具有较高的值附近的潮汐入口和河口附近的相对较低的值。有机生物标志物的垂直分布随有机物降解性的不同而变化。具体而言，长链脂肪酸随着深度的增加而减少，比其他化合物更多，这表明它们更容易降解。相反，我们观察到的倾向，木质素酚被选择性地保存在垂直沉积物剖面。我们的研究结果表明，沉积物有机生物标志物可以提供多样的信息，如有机碳的组成和来源，海草衍生木质素的贡献，以及不同程度的分解。这种方法应该为未来蓝碳研究中的碳估计带来新的见解。
Shallow coastal ecosystems are reservoirs of carbon derived from allochthonous organic matter and autochthonous organic matter produced by microalgae and macrophytes. Carbon stored in vegetated coastal ecosystems has attracted broad attention as an important component of carbon sinks. Characterizing the source of carbon in sediments is essential for quantifying the carbon-sequestration function of shallow coastal ecosystems. In this study, we investigated the origins of organic matter using organic biomarkers (lignin phenols, fatty acids, cutin acids, diacids, and ω-hydroxy acids) in surface sediments in a seagrass-dominated lagoon (Furen Lagoon, Japan). Biomarkers derived from allochthonous vascular plants, such as long-chain fatty acids, showed higher concentrations near river mouths. Furthermore, biomarker signals indicated that sedimentary organic carbon originated in large part from degraded allochthonous vascular plants including roots. A Bayesian mixing model using the ratios of syringyl phenols to vanillyl phenols and cinnamyl phenols to vanillyl phenols indicated that up to about 65% of lignin in the sediments was derived from seagrass. This result indicates a substantial contribution of seagrass to the sedimentary lignin pool in an estuarine seagrass meadow. However, the percent contribution of seagrass to the lignin pool varied, with higher values near a tidal inlet and relatively low values near river mouths. Vertical profiles of organic biomarkers varied with the differences in degradability of organic compounds. Specifically, long-chain fatty acids decreased with increasing depth more than the other compounds, suggesting that they degraded more easily. Conversely, we observed a tendency for lignin phenols to be selectively preserved in the vertical sediment profiles. Our results show that sediment organic biomarkers can provide diverse information such as the composition and origins of organic carbon, the contribution of seagrass derived lignin, and the varying degrees of decomposition. This approach should bring new insights to the estimation of carbon in future blue carbon studies.