Biomass burning signatures in the atmosphere and snow at Summit, Greenland: An event on 5 August 1994

Two recent reports have suggested that thin layers of ice in Greenland cores with anomalously high concentrations of NH4+ K+ and HCOO− represent deposition from biomass burning plumes advected over Greenland. These interpretations were based primarily on the similarity between the suite of enriched species in the ice and several recent characterizations of biomass burning plumes from various regions around the globe. In August 1994 a biomass burning plume was transported to Summit, Greenland (72°N 38°W) from the Hudson Bay lowlands region of Canada. Gas-phase, aerosol and snow samples impacted by this plume had large enhancements of HCOOH/HCOO−, CH3COOH/CH3COO−, NH3/NH4+ and K+. Several other species that have been reported to be enriched in some biomass burning plumes were also enriched in at least one of the three phases (gas, aerosol and snow) at Summit. Comparisons between the plume at Summit and biomass burning plumes sampled in 1990 over the Hudson Bay lowlands suggest that the carboxylic acids may be significantly enhanced by secondary production during the 3–4 days of transport between Canada and Greenland. It also appears that gas to particle conversion during transport may modify the partitioning of the carboxylates, nitrate, and perhaps ammonium and inorganic sulfur between the gas and aerosol phases in the plume. The relative enrichments of these species differ considerably between the atmosphere and snow, but the signal in snow was quite similar to the composition of the anomalous samples previously described in the ice cores.