FastFind »   Lastname: doi:10.1029/ Year: Advanced Search  

G-Cubed: Geochemistry, Geophysics, Geosystems; an electronic journal of the Earth sciences

 

Keywords

  • aeolian dust
  • biogeochemistry
  • polymerase chain reaction
  • 16SrRNA cloning
  • trace element geochemistry

Index Terms

  • Geochemistry: Composition of aerosols and dust particles
  • Geochemistry: Major and trace element geochemistry
  • Geochemistry: Organic and biogenic geochemistry
  • Biogeosciences: Sulfur cycling
  • Atmospheric Processes: Land/atmosphere interactions
Abstract
Cited By (0)
 

Abstract

Geochemical and microbiological fingerprinting of airborne dust that fell in Canberra, Australia, in October 2002

Patrick De Deckker

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

Raeid M. M. Abed

Max Planck Institute for Marine Microbiology, Celsiusstraße 1, D-28359 Bremen, Germany

Biology Department, College of Science, Sultan Qaboos University, P.O. Box 36, Postcode 123, Al Khoud, Sultanate of Oman

Dirk de Beer

Max Planck Institute for Marine Microbiology, Celsiusstraße 1, D-28359 Bremen, Germany

Kai-Uwe Hinrichs

Department of Geosciences and Center for Marine Environmental Sciences, University of Bremen, D-28334 Bremen, Germany

Tadhg O'Loingsigh

School of Geography and Environmental Science, Monash University, Clayton, Victoria 3800, Australia

Enno Schefuß

Center for Marine Environmental Sciences, University of Bremen, D-28334 Bremen, Germany

Jan-Berend W. Stuut

Center for Marine Environmental Sciences, University of Bremen, D-28334 Bremen, Germany

Nigel J. Tapper

School of Geography and Environmental Science, Monash University, Clayton, Victoria 3800, Australia

Sander van der Kaars

Department of Palynology and Climate Dynamics, Albrecht von Haller Institute for Plant Sciences, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany

During the night of 22–23 October 2002, a large amount of airborne dust fell with rain over Canberra, located some 200 km from Australia's east coast, and at an average altitude of 650 m. It is estimated that during that night about 6 g m−2 of aeolian dust fell. We have conducted a vast number of analyses to “fingerprint” some of the dust and used the following techniques: grain size analysis; scanning electron microscope imagery; major, trace, and rare earth elemental, plus Sr and Nd isotopic analyses; organic compound analyses with respective compound-specific isotope analyses; pollen extraction to identify the vegetation sources; and molecular cloning of 16S rRNA genes in order to identify dust bacterial composition. DNA analyses show that most obtained 16S rRNA sequences belong mainly to three groups: Proteobacteria (25%), Bacteriodetes (23%), and gram-positive bacteria (23%). In addition, we investigated the meteorological conditions that led to the dust mobilization and transport using model and satellite data. Grain sizes of the mineral dust show a bimodal distribution typical of proximal dust, rather than what is found over oceans, and the bimodal aspect of size distribution confirms wet deposition by rain droplets. The inorganic geochemistry points to a source along/near the Darling River in NW New South Wales, a region that is characteristically semiarid, and both the organic chemistry and palynoflora of the dust confirm the location of this source area. Meteorological reconstructions of the event again clearly identify the area near Bourke-Cobar as being the source of the dust. This study paves the way for determining the export of Australian airborne dust both in the oceans and other continents.

Received 10 May 2008; accepted 30 October 2008; published 24 December 2008.

Citation: De Deckker, P., R. M. M. Abed, D. de Beer, K.-U. Hinrichs, T. O'Loingsigh, E. Schefuß, J.-B. W. Stuut, N. J. Tapper, and S. van der Kaars (2008), Geochemical and microbiological fingerprinting of airborne dust that fell in Canberra, Australia, in October 2002, Geochem. Geophys. Geosyst., 9, Q12Q10, doi:10.1029/2008GC002091.

Cited By

Please wait one moment ...