Improved Method for the Quantification of Methane Concentrations in Unconsolidated Lake Sediments

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• 作者：Lina Tyroller ; Yama Tomonaga ; Matthias S. Brennwald ; Cyprien Ndayisaba ; Sebastian Naeher ; Carsten Schubert ; Ryan P. North ; Rolf Kipfer
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：July 5, 2016
• 年：2016
• 卷：50
• 期：13
• 页码：7047-7055
• 全文大小：380K
• 年卷期：0
• ISSN：1520-5851

文摘

There is conclusive evidence that the methods most commonly used to sample methane (CH₄) dissolved in the pore water of lake sediments produce results that are likely to be affected by gas loss or gas exchange with the atmosphere. To determine the in situ amount of CH₄ per unit mass of pore water in sediments, we developed and validated a new method that combines techniques developed for noble-gas analysis in pore waters with a standard headspace technique to quantify the CH₄ present in the pore space in dissolved and gaseous form. The method was tested at two sites: Lake Lungern, where CH₄ concentrations were close to saturation; and Lake Rotsee, where CH₄ concentrations are known to exceed saturation and where CH₄ bubble formation and gas ebullition are commonly observed. We demonstrate that the new method, in contrast to the available methods, more reliably captures the total amount of CH₄ per unit mass of pore water consisting of both dissolved and free CH₄ (i.e., gas bubbles) in the pore space of the sediment.