Deconstructing Methane Emissions from a Small Northern European River: Hydrodynamics and Temperature as Key Drivers.
Deconstructing Methane Emissions from a Small Northern European River: Hydrodynamics and Temperature as Key Drivers.
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DOI：
10.1021/acs.est.6b03268
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发表时间：
2016-10
影响因子：
11.4
通讯作者：
D. McGinnis;N. Bilsley;M. Schmidt;P. Fietzek;P. Bodmer;K. Premke;A. Lorke;S. Flury
中科院分区：
文献类型：
--
作者：
D. McGinnis;N. Bilsley;M. Schmidt;P. Fietzek;P. Bodmer;K. Premke;A. Lorke;S. Flury
目前，小河溪流的甲烷（CH4）排放，特别是通过沸腾的方式，在文献中没有得到充分的描述。在这里，我们量化了一条北欧小河的甲烷流出量和驱动因素。甲烷通量与热带水生系统相当，平均排放量为320毫克CH4 m-2 d-1。在研究系统中，确定了甲烷通量变化的两个重要驱动因素：1)温度驱动的沉积物甲烷沸腾和2)流量依赖的贡献，怀疑是与邻近湿地和小型侧湾的水力交换。对于小于4 m3 s-1的流量，这种依赖于流量的对河流甲烷负荷的贡献可以忽略不计，而当流量超过7 m3 s-1时，这种贡献大于50%。虽然温度-沸腾关系与其他系统相当，但流量依赖关系尚未得到证实。总的来说，我们发现大约80%的总排放量是由甲烷气泡造成的。对目前尚未考虑的河流系统的全球估计应用沸腾率，可能会大大增加从湖泊或湿地范围内的排放率。这项工作表明，小河可以释放大量的甲烷，并强调需要进一步研究水动力学和相连湿地之间的联系。
Methane (CH4) emissions from small rivers and streams, particularly via ebullition, are currently under-represented in the literature. Here, we quantify the methane effluxes and drivers in a small, Northern European river. Methane fluxes are comparable to those from tropical aquatic systems, with average emissions of 320 mg CH4 m-2 d-1. Two important drivers of methane flux variations were identified in the studied system: 1) temperature-driven sediment methane ebullition and 2) flow-dependent contribution suspected to be hydraulic exchange with adjacent wetlands and small side-bays. This flow-dependent contribution to river methane loading is shown to be negligible for flows less than 4 m3 s-1 and greater than 50% as flows exceed 7 m3 s-1. While the temperature-ebullition relationship is comparable to other systems, the flow rate dependency has not been previously demonstrated. In general, we found that about 80% of the total emissions were due to methane bubbles. Applying ebullition rates to global estimates for fluvial systems, which currently are not considered, could dramatically increase emission rates to ranges from lakes or wetlands. This work illustrates that small rivers can emit significant methane and highlights the need for further studies on the link between hydrodynamics and connected wetlands.