Toward understanding the contribution of waterbodies to the methane emissions of a permafrost landscape on a regional scale—A case study from the Mackenzie Delta, Canada
Toward understanding the contribution of waterbodies to the methane emissions of a permafrost landscape on a regional scale—A case study from the Mackenzie Delta, Canada
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DOI：
10.1111/gcb.14289
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发表时间：
2018-09
影响因子：
11.6
通讯作者：
K. Kohnert;B. Juhls;Sina Muster;S. Antonova;A. Serafimovich;S. Metzger;J. Hartmann;T. Sachs
中科院分区：
文献类型：
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作者：
K. Kohnert;B. Juhls;Sina Muster;S. Antonova;A. Serafimovich;S. Metzger;J. Hartmann;T. Sachs
除了北极湿地的CH4排放外，北极永久冻土带的水体被认为是温室气体甲烷（CH4）的主要来源。然而，水体CH4通量的时空变异性使单个水体CH4测量值的空间外推变得复杂。因此，它们对北极永久冻土带CH4收支的贡献尚未得到很好的了解。以加拿大麦肯齐三角洲两个1,000 km²的研究区域为例，我们(i)通过分析景观尺度上众多水体与CH4通量之间的相关性，（ii）通过分析CH4通量数据的空间分辨率对探测到的关系的影响来解决这个问题。利用2012年和2013年夏季两次飞机涡动相关运动获得了分辨率为100 m的CH4通量图。我们将CH4通量图与来自多年冻土区池塘和湖泊数据库的高空间分辨率（2.5 m）水体图结合起来，并基于Sentinel‐1 SAR后向散射数据对水体深度进行了分类。随后，我们降低了CH4通量图的分辨率，分析不同空间分辨率的CH4通量数据是否影响水体覆盖、数量、深度或大小与CH4通量之间关系的可探测性。在不同分辨率下，两个研究区水体特征与CH4通量之间没有一致的相关性。我们的研究结果表明，多年冻土景观中的水体，即使它们在个别基础上似乎是排放热点或包含高于平均排放量的区域，目前也不一定转化为区域尺度上显著的CH4排放热点，但它们的作用可能在气候变暖时发生变化。
Waterbodies in the arctic permafrost zone are considered a major source of the greenhouse gas methane (CH4) in addition to CH4 emissions from arctic wetlands. However, the spatio‐temporal variability of CH4 fluxes from waterbodies complicates spatial extrapolation of CH4 measurements from single waterbodies. Therefore, their contribution to the CH4 budget of the arctic permafrost zone is not yet well understood. Using the example of two study areas of 1,000 km² each in the Mackenzie Delta, Canada, we approach this issue (i) by analyzing correlations on the landscape scale between numerous waterbodies and CH4 fluxes and (ii) by analyzing the influence of the spatial resolution of CH4 flux data on the detected relationships. A CH4 flux map with a resolution of 100 m was derived from two aircraft eddy‐covariance campaigns in the summers of 2012 and 2013. We combined the CH4 flux map with high spatial resolution (2.5 m) waterbody maps from the Permafrost Region Pond and Lake Database and classified the waterbody depth based on Sentinel‐1 SAR backscatter data. Subsequently, we reduced the resolution of the CH4 flux map to analyze if different spatial resolutions of CH4 flux data affected the detectability of relationships between waterbody coverage, number, depth, or size and the CH4 flux. We did not find consistent correlations between waterbody characteristics and the CH4 flux in the two study areas across the different resolutions. Our results indicate that waterbodies in permafrost landscapes, even if they seem to be emission hot spots on an individual basis or contain zones of above average emissions, do currently not necessarily translate into significant CH4 emission hot spots on a regional scale, but their role might change in a warmer climate.