HR: 09:45h
AN: PP31C-08    [Abstracts]
TI: Sub-annual Ice-Core Record of Major Ion and Heavy Metal Variability and Sources in the North Pacific Free Troposphere, Mt. Logan, Yukon, Canada
AU: * Osterberg, E C
EM: erich_osterberg@hotmail.com
AF: Climate Change Institute, University of Maine, Sawyer Environmental Research Building, Orono, ME 04469 United States
AU: Kurbatov, A V
EM: akurbatov@maine.edu
AF: Climate Change Institute, University of Maine, Sawyer Environmental Research Building, Orono, ME 04469 United States
AU: Mayewski, P A
EM: paul.mayewski@maine.edu
AF: Climate Change Institute, University of Maine, Sawyer Environmental Research Building, Orono, ME 04469 United States
AU: Kreutz, K J
EM: karl.kreutz@umit.maine.edu
AF: Climate Change Institute, University of Maine, Sawyer Environmental Research Building, Orono, ME 04469 United States
AU: Fisher, D
EM: david.fisher@NRCan.gc.ca
AF: National Glaciology Programme, Geological Survey of Canada, 601 Booth Stret, Ottawa, ON K1A 0E8 Canada
AB: The Mt. Logan, Yukon, Canada summit plateau (PR Col; 5300 m.a.s.l.) ice core has been continuously sampled at high resolution (2-3 cm/sample) by a novel ice core melting system with discrete sampling, and analyzed for 8 major ions and 35 trace elements. Co-registered, sub-annual timeseries covering the past 500 years reveal seasonal aerosol fluctuations dominated by dust, with sea-salt contributing less than 5% of sulfate and calcium concentrations. Dating of the top 500 years of the record is by annual layer counting. Concentration spikes of sulfate greater than three times the standard deviation (60 ppb) above the mean (75 ppb) correspond in time with historical explosive volcanic eruptions. Sulfate spikes corresponding in time with large (VEI>4) historical Alaskan eruptions, including Katmai (1912) and St. Augustine (1986), are commonly associated with concentration and crustal enrichment factor spikes in lead, cadmium, antimony, copper, zinc, bismuth and thallium an order of magnitude above background (non-volcanic event) values. Sulfate spikes corresponding in time to large eruptions from distant volcanoes, including Agung (1963), do not show a corresponding rise in heavy metal concentrations. Apart from the periodic spikes in concentration, heavy metal timeseries largely mirror those of the major dust species (Al, Fe), but maintain significantly elevated crustal enrichment factors, probably due primarily to quiescent degassing of volcanoes. Such datasets are necessary to understand the cycling of heavy metals in the free troposphere, including the relative source strength of explosive eruptions vs. quiescent volcanic degassing, and the relative strength of natural vs. anthropogenic sources.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0322 Constituent sources and sinks
DE: 0700 CRYOSPHERE (4540)
DE: 8428 Explosive volcanism
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005