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(Lanci et al.
2008
) and lithium solubility (Siggaard-Andersen et al.
2007
)also
indicate a change in the composition, and hence sources, of Antarctic dust from
glacial to interglacial conditions.
18.4.2
Greenland
As for Antarctica, Greenland ice core dust has been characterized by a number
of different provenance tracers, such as isotopes of Sr, Nd, and Pb, mineralogy
(determined by X-ray Fluorescence), REEs and other trace elements (Biscaye et al.
1997
). The ice core dust is compared to samples from PSAs that for Greenland are
mainly North America, Eastern Asia, Northern Africa and the Middle East, exposed
continental shelf areas as well as local Greenland sources. It is important to evaluate
PSA sample size fractions that are comparable to those of Greenland dust because
the characteristics of some tracers, such as Sr isotopes and trace elements, do vary
with particle size (Chen et al.
2007
;Fengetal.
2011
).
During the second half of last glacial period, where dust concentrations of the
ice are generally high, the Greenland dust has a very homogeneous composition in
all tracers (Svensson et al.
2000
). The dust appears to originate almost entirely from
deserts and dry areas in eastern Asia, such as the Gobi and Taklimakan Deserts
(Biscaye et al.
1997
), although the number of samples from potential sources is
rather limited (Muhs
2013
). In milder climatic periods during the last glacial there
may be a contribution originating from glacial sediments adjacent to Greenland
(Burton et al.
2007
).
During recent times, Asia is also a major dust source for Greenland (Bory et al.
2002
) but in addition there is evidence for a significant Saharan contribution (Lupker
et al.
2010
;VanCurenetal.
2012
). In general, more studies of both ice core samples
and potential source area samples are needed in order to improve the understanding
of Greenland dust provenance throughout time. Besides dust of terrestrial origin,
the contributions of volcanic tephra (Abbott et al.
2012
) and extraterrestrial dust
(Maurette et al.
1987
; Gabrielli et al.
2004
; Lanci et al.
2012
) have been intensively
studied in Greenland ice cores (Fig.
18.7
).
18.5
Dust Size Distributions
18.5.1
Antarctica
The first evaluation of dust size distributions in Antarctic ice was conducted by Petit
et al. (
1981
) in Dome C ice. Petit and coworkers observed that dust particle size
modes were consistently between 1 and 2 m, with a tendency toward larger modes
in LGM samples. The absence of large particles (>10 m diameter) was interpreted
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