Triple Isotopic Ratios to Characterize Atmospheric N Compounds in Alberta – Work in Progress

Is it possible to recognize source types of emissions using isotopic ratios in reactive-nitrogen (Nr)-bearing air species collected several kilometers downwind from their sources? The δ15N values present the potential for fingerprinting sources of atmospheric Nr, whereas the δ18O and δ17O results may bring insights on transformation processes. Here we have sampled NH4+, NOx and HNO3, NO3− in areas downwind from six sources in Alberta, Canada: coal-fired power plants, beef/pork feedlots, an oil upgrader/refinery complex, chemical industries, gas compressors and city traffic. The samples were prepared using chemical conversion and thermal protocol to produce N2O, later analyzed to simultaneously obtain δ15N, δ18O and δ17O values using a gold-furnace pre-concentrator online with an IRMS. Integrating the data obtained so far will help evaluate the possibility of fingerprinting these Albertan sources and of inferring reactions affecting N-species along their transport trajectories.