Stable carbon isotopes to monitor the CO2 source mix in the urban environment

Abstract:

Urban areas are said to be responsible for approximately 71% of fossil fuel CO₂ emissions while comprising only two percent of the land area [IEA, 2008]. This limited spatial expansion could facility a monitoring of anthropogenic GHGs from atmospheric observations. As major sources of emissions, cities also have a huge potential to drive emissions reductions. To effectively manage emissions, cities must however, first establish techniques to validate their reported emission statistics. A pilot study which includes continues ¹³CO₂ data from calibrated cavity ring-down spectrometers [Vogel et al. 2013] of two “sister sites” in the vicinity of Toronto, Canada is contrasted to recent observations of ¹³CO₂ observations in Paris during significant pollution events. Using Miller-Tans plots [Miller and Tans, 2003] for our multi-season observations reveals significant changes of the source signatures of night time CO₂ emissions which reflect the importance of natural gas burning in Megacities (up to 80% of fossil fuel sources) and show-case the potential of future isotope studies to determine source sectors. Especially the winter data this approach seems suitable to determine the source contribution of different fuel types (natural gas, liquid fuels and coal) which can inform the interpretation of other Greenhouse Gases and air pollution levels.