Beach-cast seagrass wrack contributes substantially to global greenhouse gas emissions
Beach-cast seagrass wrack contributes substantially to global greenhouse gas emissions
复制标题
海滩上的海草残骸对全球温室气体排放有重大贡献
DOI：
10.1016/j.jenvman.2018.10.047
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发表时间：
2019-02-01
影响因子：
8.7
通讯作者：
Macreadie, Peter I.
中科院分区：
文献类型：
--
作者：
Liu, Songlin;Trevathan-Tackett, Stacey M.;Macreadie, Peter I.
海草生态系统最近因其捕获和储存碳的能力而受到极大关注，从而有助于减缓气候变化。然而，如果出口的植物材料-占总叶产量的90%-经历微生物分解并作为温室气体排放到大气中，它们的碳汇能力可能会有所抵消。在这里，我们测量了出口海草植物材料分解的排放量（CO2和CH 4），重点是海滩铸造的“wrack”。我们测试了两个海草物种;大叶藻nigricaulis和Amphibolis anapartica，这具有对比的形态和化学。我们发现，这两个物种的残骸是大量的CO2来源，但不是CH 4，在分解过程中。在30天的试验中，生物量的损失和CO2的排放都是同步的，CO2的排放模式符合双指数模型（R-2 > 0.92）。最初的通量率相对较高，很可能是由于不稳定化合物的快速浸出，然后在2-9天内大幅下降，并在剩余的分解期内稳定在< 3 μ mol g（-1）d（-1）。此外，海草残骸投高的海滩上，仍然干燥有72%的排放量低于残骸，受到反复润湿的潮间带。这意味着，沿海资源管理者重新安置海草残骸（例如从水边到干燥的沙丘地区）可能有助于减少大气中的二氧化碳排放量。按比例放大，我们估计全球海草藻的年CO2-C通量在1.31和19.04 Tg C yr（-1）之间，相当于63 - 919万中国公民的年排放量。随着气候变化和沿海开发的增加，预计将加速海滩上的沉船积累速度，这项研究为制定沿海碳预算提供了及时的信息。
Seagrass ecosystems have received a great deal of attention recently for their ability to capture and store carbon, thereby helping to mitigate climate change. However, their carbon-sink capacity could be offset somewhat if exported plant material - which accounts for similar to 90% of total leaf production - undergoes microbial breakdown and is emitted into the atmosphere as a greenhouse gas. Here we measured emissions (CO2 and CH4) from the breakdown of exported seagrass plant material, focusing on beach-cast 'wrack'. We tested two seagrass species; Zostera nigricaulis and Amphibolis antarctica, which have contrasting morphologies and chemistries. We found that both species of wrack were substantial sources of CO2, but not CH4, during the decomposition process. Biomass loss and the coinciding CO2 emissions occurred over the 30-day experiment, and the pattern of CO2 emissions over this time followed a double exponential model (R-2 > 0.92). The initial flux rate was relatively high, most likely due to rapid leaching of labile compounds, then decreased substantially within the 2-9 days, and stabilizing at < 3 mu mol g(-1) d(-1) during the remaining decomposition period. Additionally, seagrass wrack cast high up on beaches that remained dry had 72% lower emissions than wrack that was subjected to repeated wetting in the intertidal zone. This implies that relocation of seagrass wrack by coastal resource managers (e.g. from water's edge to drier dune areas) could help to reduce atmospheric CO2 emissions. Scaling up, we estimate the annual CO2-C flux from seagrass wrack globally is between 1.31 and 19.04 Tg C yr(-1), which is equivalent to annual emissions of 0.63-9.19 million Chinese citizens. With climate change and increasing coastal development expected to accelerate the rate of wrack accumulation on beaches, this study provides timely information for developing coastal carbon budgets.