title: Improved Method for the Quantification of Methane Concentrations in Unconsolidated Lake Sediments.
abstract: 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.
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Lina
authors.initials: L
authors.lastname: Tyroller
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.|Atmosphere and Ocean Research Institute, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8564, Japan.
authors.forename: Yama
authors.initials: Y
authors.lastname: Tomonaga
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Matthias S
authors.initials: MS
authors.lastname: Brennwald
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Cyprien
authors.initials: C
authors.lastname: Ndayisaba
authors.affiliation: Eawag, Department of Surface Waters Research and Management, Swiss Federal Institute of Aquatic Science and Technology , CH-6047 Kastanienbaum, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Naeher
authors.affiliation: Eawag, Department of Surface Waters Research and Management, Swiss Federal Institute of Aquatic Science and Technology , CH-6047 Kastanienbaum, Switzerland.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schubert
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: North
authors.affiliation: Eawag, Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Kipfer
mesh_terms: D001272:Atmosphere; D005740:Gases; D060106:Lakes; D008697:Methane
chemical_list: D005740:Gases; D008697:Methane