Variation of carbon contents in eelgrass (Zostera marina) sediments implied from depth profiles

Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment but global estimates are uncertain partly due to spatiotemporal heterogeneity between areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass (Zostera marina) beds spanning the distributional range of the Northern Hemisphere. Depth profiles revealed three patterns of vertical distribution where POC either increased, decreased, or showed no distinct pattern with sediment depth. These categories exhibited distinct profiles of δ13C and C:N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high ...海草床能够在其下层沉积物中储存大量有机碳，但全球有机碳储量估算仍存在不确定性，部分原因是不同区域与物种间存在时空异质性。为得到稳健可靠的储量估算结果，亟需更深入地解析有机碳储存的归宿及其背后的作用机制。本观测性研究对覆盖北半球分布范围的47处不同鳗草（Zostera marina）床的沉积物岩芯展开分析，测定了一系列生物与非生物参数。沉积物深度剖面揭示了三种垂直分布模式：颗粒有机碳（Particulate Organic Carbon, POC）含量随沉积物深度分别呈现递增、递减或无明显变化规律。这三类分布模式分别呈现出差异化的δ¹³C与碳氮比（C:N）剖面特征：高POC剖面中，鳗草来源的有机碳储存占比更高；而低POC剖面则以浮游植物与大型藻类来源的有机质为主。然而，高POC含量并不总能转化为更高的……