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

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Title Geochemical and microbiological fingerprinting of airborne dust that fell in Canberra, Australia, in October 2002
Author Deckker, Patrick De; Abed, Raeid M. M.; Beer, Dirk de; Hinrichs, Kai-Uwe; O'Loingsigh, Tadhg; Schefuß, Enno; Stuut, Jan-Berend W.; Tapper, Nigel J.; Kaars, Sander van der
Journal Name G3: Geochemistry, Geophysics, Geosystems
Year Published 2008
Place of publication United States
Publisher American Geophysical Union
Abstract 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.
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1029/2008GC002091
Volume 9
Issue Number 12
Page from 1
Page to 22
ISSN 1525-2027
Date Accessioned 2011-06-15
Date Available 2011-08-30T06:22:25Z
Language en_AU
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Natural Hazards; Physical Geography and Environmental Geoscience
URI http://hdl.handle.net/10072/40496
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1x

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