Re-evaluation of the composition of sediments from the Murray Darling Basin of Australia as a Potential Source Area for airborne dust to EPICA Dome C in Antarctica. Reply to Comment on "Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170,000 years" by P. De Deckker, M. Norman, I.D. Goodwin, A. Wain and F.X. Gingele

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: De Deckker, Patrick, Norman, Marc
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier
• Subjects: Keywords: Anthropogenic Pb; Contamination; Dust; Grain size; Pb isotopes; Pb/Ga; Pb/Ta; Goodwin; Antarc*; Antarctica; EPICA; ice core
• Online Access: http://hdl.handle.net/1885/51211; https://doi.org/10.1016/j.palaeo.2010.10.023; https://openresearch-repository.anu.edu.au/bitstream/1885/51211/5/De_Deckker_Norman_reply_Re-evaluation_of_the_composition_2010.pdf.jpg; https://openresearch-repository.anu.edu.au/bitstream/1885/51211/7/01_De+Deckker_Re-evaluation_of_the_2010.pdf.jpg

We re-examined the data presented by De Deckker et al. (2010; Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170, 000. years. Palaeogeography, Palaeoclimatology, Palaeoecology 285, 205-223), which argued for some parts of the Murray Darling Basin (MDB) in south-eastern Australia to have been potential source areas (PSA) for dust in the EPICA Dome C ice core. This was done in light of the comments tabled by Kamber et al. (Comment on "Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170,000. years" by P. De Deckker, M. Norman, I.D. Goodwin, A. Wain and F.X. Gingele [Palaeogeography, Palaeoclimatology, Palaeoecology 285 (2010) 205-223], 2010-this issue) suggesting that the MDB samples are variably contaminated by anthropogenically-produced Pb that originated from the Broken Hill mine, from smelters, and from agricultural practices and coal burning. We argue, first of all, that the MDB samples are not as comprehensively contaminated with Pb as claimed by Kamber et al., and the Pb isotope data presented by De Deckker et al. (2010) do provide useful information about potential dust source. Following the approach of Kamber and colleagues (Marx et al., 2010), we compare the Pb isotopic compositions of MDB sediments against their Pb content and diagnostic elemental ratios such as Pb/Ta, and Pb/Ga to evaluate possible anthropogenic contamination. We find that 3 of these MDB samples have notably high Pb concentrations, anomalously high Pb/Ta and Pb/Ga ratios, and Pb isotopic compositions that are consistent with anthropogenic contamination from a Broken Hill-type Pb source. The remaining 20 samples show a wide range of isotopic compositions and no correlation with either Pb content or element ratios, consistent with natural signatures. The 3 contaminated samples are located in heavily used agricultural areas in the Murray sub-basin but, importantly, none of these 3 samples were considered by De Deckker et al. (2010) to ...