HR: 0830h
AN: B21F-0787    [PDF]
TI: Geochemical Fluxes Associated With a Long-range Dust Cloud From the Gobi Desert Region, Central Asia.
AU: * Zdanowicz, C M
EM: czdanowi@nrcan.gc.ca
AF: Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8 Canada
AU: Hall, G E
EM: ghall@nrcan.gc.ca
AF: Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8 Canada
AU: Vaive, J E
EM: jvaive@nrcan.gc.ca
AF: Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8 Canada
AB: In early April, 2001, an exceptionally intense series of dust storms originated in the Gobi desert region of southern Mongolia and northern China. The dust cloud generated during these storms was tracked by satellite over the North Pacific Ocean and was detected all across North America. Instrumented floats deployed in the subarctic western Pacific Ocean revealed a near-doubling of the carbon biomass in the mixed layer over the 2-week period following the passage of the dust cloud, illustrating the impact of the dust on biological productivity in the surface Ocean (Bishop et al. 2002, Nature vol. 298). During its passage over northwestern America ca April 13, 2001, the Gobi dust plume deposited a widespread, distinctive layer of yellowish-red dust-laden snow, up to 5-cm thick, in the icefields of the St-Elias mountains, Yukon Territory. The dust fallout was probably enhanced by snowfall scavenging associated with orographic uplift of the moist Pacific air mass over the high mountain range (max elevation 5959 m). Samples of dust-laden snow were collected from a series of sites on the Mount Logan massif (60 N, 140 W), during a glaciological research expedition. The samples, collected between elevations of 2400 and 5340 m, contained as much as 80 ppm (mass) of dust. The dust particles were analyzed in the laboratories of the Geological Survey of Canada to characterize their physical attributes (e.g., grain size distribution) as well as their bulk mineralogical and geochemical composition. The concentrations of over 60 major, minor and trace elements were determined using ICP-MS an ICP-ES, including some important nutrients and biolimiting to biointermediate elements such as P, Si, Ba and Ca. Using these measurements, we calculated first-order estimates of the depositional fluxes for various geochemical elements associated with the Gobi dust fallout. Such detailed compositional data on far-traveled dust clouds are rarely available. We hope our findings presented here will assist researchers engaged in evaluating the potential biogeochemical impact of long-range dust transport events on marine, freshwater and terrestrial ecosystems.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2003 Fall Meeting