Abstract
ABSTRACTThe stable oxygen isotope composition, major ions and isotopic compositions of strontium (Sr), neodymium (Nd) and lead (Pb) in insoluble dust from recent surface snow samples along the transect from the Zhongshan and Progress stations (located on the Amery Ice Shelf, East Antarctica) to Dome A (Summit, Antarctica) were analysed. No previous isotopic fingerprinting studies have been conducted for this transect. These data were used to document the dust provenances in Antarctica along the transect up to the highest site, Dome A, for the first time. The insoluble dust in snow samples along the coast displays an overall crust-line isotopic signature that is characterised by highly radiogenic 87Sr/86Sr values and less radiogenic 143Nd/144Nd values. These signatures are comparable with those of samples collected near the ice-free areas of the Zhongshan and Progress stations. Spatial differences are statistically significant along the transect, and the Sr, Nd and Pb isotope components in insoluble dust from two continuous snow samples at Dome A exhibit marked differences, indicating that additional dust reaches the East Antarctic Plateau. The isotopic characteristics of insoluble dust from this transect indicate that the long-distance natural dust and anthropogenic pollutants in these samples primarily originate from Australia.
Highlights
Mineral dust plays an important role in the climate system by altering the radiative balance of the atmosphere both directly by scattering and absorbing solar and terrestrial radiation and indirectly by affecting cloud microphysical properties (Choobari and others, 2014; Mahowald and others, 2014)
The results show that 36% of the dust at Dome A (0–4 cm snow layer) and 36–90% of the insoluble dust in the transect snow samples (
(206Pb/207Pb)Ant was set to 1.134 based on the average of the results from Australia, including aerosol and wildfire sources (1.139 for aerosols and 1.129 for wildfires; Kristensen and others, 2017). These results indicate that the anthropogenic contributions from Australian pollutants account for ∼11.3–60.9%, assuming the natural dust is from the local coast and 20.4–65.0%, assuming the natural dust is from Australia mineral dust, of the insoluble dust in this transect
Summary
Mineral dust (aerosols) plays an important role in the climate system by altering the radiative balance of the atmosphere both directly by scattering and absorbing solar and terrestrial radiation and indirectly by affecting cloud microphysical properties (Choobari and others, 2014; Mahowald and others, 2014). Insoluble dust can be extracted from snow/ice on high-altitude mountains and Antarctica and Greenland at high latitudes Such sites provide the most valuable clues regarding the atmospheric circulation patterns of previous glacial-interglacial climate cycles (Mayewski and others, 1997; Thompson and others, 2000; Lambert and others, 2012). Previous studies primarily focused on the chemical compositions in snow/ice at fixed sites; it is difficult to determine the mineral dust concentrations over large spatial scales To overcome this limitation, surface snow sampling can be conducted over a large surface area and is best suited for material-demanding Sr, Nd and Pb isotopic analyses.
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