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An environmental record of lead isotopes over four centuries at Law Dome, Antarctica Entry ID: ASAC_1092 |
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Summary
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Abstract:
Antarctic ice provides an archive of Earths atmospheric composition over time. It therefore records evidence of human impact on the atmosphere. Lead is a toxic element, whose isotopic fingerprint can also be used as a tracer. This project will investigate a 400 year Pb pollution record in ice from Law Dome. From the abstracts of the referenced papers: Techniques for Pb measurements have reached the stage where Antarctic ice with sub-picogram per gram concentrations can be reliably analysed for isotopic composition. Here, particular attention has been given to measuring the quantity of Pb added during the decontamination and sample storage stages of the sample preparation process because of their impact on accuracy at low concentrations. These stages, including the use of a stainless steel chisel for the decontamination, contributed ~5.2pg to the total sample analysed, amounting to a concentration increase of ~13fg per gram, which is significantly less than expected. Consequently the corrections to the isotopic ratios and concentration were also smaller. Other contributions to the blank, such as Pb fallout onto critical working areas in the HEPA-filtered laboratories, were also relatively small as was the amount of Pb leached from preconditioned perfluoroalkoxy (PFA) beakers during sample processing. The ion source contributed typically 89plus or minus 19 fg to the blank. Although this was relatively large, its influence depended upon the amount of Pb available for analysis and it had the greatest impact when small volumes of samples with a very low concentration were analysed. A 15 months investigation of the leaching characteristics of Pb from a low-density polyethylene (LDPE) sample storage bottle showed 11 fg per cm per cm per day was released immediately following the initial 2 months cleaning process, but this decreased to immeasurable values after a further 3 months of cleaning. Lead isotopic compositions and Pb and Ba concentrations have been measured in ice cores from Law Dome, East Antarctica, covering the past 6500 years. 'Natural' background concentrations of Pb (~0.4 pg/g) and Ba (~1.3 pg/g) are observed until 1884 AD, after which increased Pb concentrations and lowered 206Pb/207Pb ratios indicate the influence of anthropogenic Pb. The isotopic composition of 'natural' Pb varies within the range 206Pb/207Pb=1.20-1.25 and 208Pb/207Pb=2.46-2.50, with an average rock and soil dust Pb contribution of 8-12%. A major pollution event is observed at Law Dome between 1884 and 1908 AD, elevating the Pb concentration four-fold and changing 206Pb/207Pb ratios in the ice to ~1.12. Based on Pb isotopic systematics and Pb emission statistics, this is attributed to Pb mined at Broken Hill and smelted at Broken Hill and Port Pirie, Australia. Anthropogenic Pb inputs are at their greatest from ~1900 to ~1910 and from ~1960 to ~1980. During the 20th Century, Ba concentrations are consistently higher than 'natural' levels and are attributed to increased dust production, suggesting the influence of climate change and/or changes in land coverage with vegetation. The fields in this dataset are: Sample Date 206Pb/207Pb 208Pb/207Pb 206Pb/204Pb Pb concentration Ba concentration |
Related URL
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Link:
GET DATA
Description: Download point for the data Link: VIEW PROJECT HOME PAGE Description: Public information for ASAC project 1092 Link: VIEW RELATED INFORMATION Description: Citation reference for this metadata record and dataset |
Geographic Coverage
| N: -66.0 | S: -66.0 | E: 110.0 | W: 110.0 |
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Temporal Coverage
| Start Date: 1998-09-30 |
| Stop Date: 2001-03-31 |
Paleo_Temporal_Coverage
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Paleo Start Date:
7500 YBP
Paleo Stop Date: 0 YBP Chrono Unit: |
Location Keywords
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CONTINENT
> ANTARCTICA
GEOGRAPHIC REGION > POLAR |
Science Keywords
| CRYOSPHERE >GLACIERS/ICE SHEETS >ICE SHEETS [Definition] |
| HUMAN DIMENSIONS >ENVIRONMENTAL IMPACTS >CONTAMINANT LEVELS/SPILLS [Definition] |
| HUMAN DIMENSIONS >ENVIRONMENTAL IMPACTS >HEAVY METALS CONCENTRATION [Definition] |
| PALEOCLIMATE >ICE CORE RECORDS >ISOTOPES [Definition] |
ISO Topic Category
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CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
GEOSCIENTIFIC INFORMATION INLAND WATERS |
Instrument
| MASS SPECTROMETERS [Information] |
Quality
| Values provided in temporal coverage are approximate only. |
Access Constraints
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The data are available for download from the url given below. PDF copies of the referenced papers are also included in the download file. |
Use Constraints
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This data set conforms to the PICCCBY Attribution License (http://creativecommons.org/licenses/by/3.0/). |
Keywords
| ANALYTICAL BLANK |
| ANTARCTICA |
| BARIUM |
| ICE |
| ICE CORES |
| LAW DOME |
| LEAD |
| LEAD ISOTOPES |
| MASS SPECTROMETRY |
| POLLUTION |
| THERMAL IONISATION MASS SPECTROMETRY |
Data Set Progress
| COMPLETE |
Data Center
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Australian Antarctic Data Centre, Australia
[Information]
Data Center URL: http://data.aad.gov.au
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Distribution
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Distribution_Media:
HTTP
Distribution_Size: 5865 kb Distribution_Format: excel, pdf, word Fees: free |
Personnel
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KEVIN
ROSMAN Role: INVESTIGATOR Role: TECHNICAL CONTACT Role: DIF AUTHOR Phone: +61 8 9266 7542 Fax: +61 8 9266 2377 Email: k.rosman at curtin.edu.au Contact Address: Department of Applied Physics GPO Box U 1987 Curtin University City: Perth Province or State: Western Australia Postal Code: 6845 Country: Australia |
Publications/References
Vallelonga, P., Van de Velde, K., Candelone, J.P., Ly, C., Rosman, K.J.R., Boutron, C.F., Morgan, V.I., and Mackey, D.J. (2002), Recent advances in measurement of Pb isotopes in polar ice and snow at sub-picogram per gram concentrations using thermal ionisation mass spectrometry., Analytica Chimica Acta, 453, 1-12
Vallelonga, P., Van de Velde, K., Candelone, J.P., Morgan, V.I., Boutron, C.F. and Rosman, K.J.R. (2002), The lead pollution history of Law Dome, Antarctica, from isotopic measurements on ice cores: 1500 AD to 1989 AD., Earth Planet. Sci. Lett, 204, 291-306
Vallelonga, P., Van de Velde, K., Candelone, J.P., Morgan, V.I., Boutron, C.F. and Rosman, K.J.R. (2002), The lead pollution history of Law Dome, Antarctica, from isotopic measurements on ice cores: 1500 AD to 1989 AD., Earth Planet. Sci. Lett, 204, 291-306
Creation and Review Dates
DIF Creation Date:
2000-08-09
Last DIF Revision Date:
2011-05-10
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