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Source partitioning of atmospheric methane using stable carbon isotope measurements in the Reuss Valley, Switzerland

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Stieger Jacqueline, Bamberger Ines, Siegwolf Rolf T. W., Buchmann Nina, Eugster Werner,
Project CarboCount CH: Quantifying greenhouse gas fluxes and their sensitivity to climate variations: A case study in Central Europe and Switzerland
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Original article (peer-reviewed)

Journal Isotopes in Environmental and Health Studies
Volume (Issue) 55(1)
Page(s) 1 - 24
Title of proceedings Isotopes in Environmental and Health Studies
DOI 10.1080/10256016.2018.1561448

Abstract

Measurements of methane (CH4) mole fractions and d13C−CH4 that resolve the diel cycle in the agriculturally dominated Reuss Valley, Switzerland, were used to quantify the contributions of different CH4 sources to the atmospheric CH4 source mix. Both a nocturnal (NBL) and a diurnal convective boundary layer (CBL) Approach were employed. A diel course of CH4 mole fractions was Found with a daytime minimum (background around 1900 ppb) and a nocturnal maximum (up to 3500 ppb). The d13C value in CH4 only showed small variations during the day (9–21 hours CET, −45.0+0.2‰ mean+SE) when the atmosphere was well mixed, but decreased by −4.8+0.1‰ during the night. Biogenic emissions dominated in both approaches (ranging from 60 to 94%), but non-biogenic sources were rather important (42.2% and 46.0% with CBL, 5.8% and 40% with NBL approach in2011 and 2012, respectively, of total emissions). The CH4 sink, dominated by tropospheric OH oxidation and only to a minor extend by soil surface uptake, was quantified at roughly 4% of local emissions.
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