The use of Pb isotope ratios determined by magnetic sector ICP-MS for tracing Pb pollution in marine sediments near Casey Station, East Antarctica

Magnetic sector inductively coupled plasma mass spectrometry (ICP-SMS) was used to measure lead concentrations and isotope ratios in marine sediments and other samples collected from near the Australian Antarctic Station Casey. Precisions obtained from the repetitive analysis of a standard Broken Hill Pb sample at a concentration of ∼40 ng g−1 in solution were <±0.2% for ratios involving 204Pb, and <±0.1% for those referenced to 206Pb or 207Pb (n = 12 replicates over 2 days, values as 1s). Ratios were accurate to within ∼±0.1% for the analysis of this standard sample. Comparative measurements between ICP-SMS and TIMS had typical differences in values of 10 ng g−1, instrumental capability was characterised by isotopic precisions ranging from 0.1-0.5% (1s) for ratios involving 204Pb, and <0.25% (1s) for ratios with 206Pb or 207Pb as the basis (typically found from triplicate analyses). For sediments of low Pb concentration (<10 ng g−1 in the sample digest), isotope ratios to 204Pb were found to be limited by instrument counting statistics when using standard ICP-SMS. To help overcome this problem, Pb isotope ratios for these samples were measured with a capacitive decoupling Pt guard electrode employed, offering considerable signal enhancement (5–10×). These natural background sediments were found to display typical Pb isotope ratios of 40.5, 15.5, 18.6 and 1.19 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb. For comparison, the most contaminated samples had Pb isotope ratios of approximately 36.2, 15.4, 16.4 and 1.06 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb, respectively. Evidence of simple two component mixing between anthropogenic and natural geogenic Pb was found near Casey Station. Runoff from the Thala Valley tip site, adjacent to the bay, was identified as a clear source of Pb pollution, with impacted sediments displaying an isotopic signature approaching that of abandoned lead batteries collected from the tip. These batteries possessed Pb isotope ratios identical to Australian Broken Hill lead. In this study, the use of Pb isotope data has proved to be a sensitive method of assessing contamination levels in the Antarctic marine environment adjacent to a waste disposal site. Lead isotope ratios have proved superior to simple elemental concentration determinations when distinguishing between impacted and non-impacted samples. ICP-SMS has been shown to offer relatively fast, accurate and cost effective Pb isotope ratios, with precisions suitable for many environmental applications.

[1]  G. Ramelow.  Environmental Contamination in Antarctica: a Challenge to Analytical Chemistry , 2002 .

[2]  C. Barbante,et al.  Ultrasensitive determination of heavy metals at the sub-picogram per gram level in ultraclean Antarctic snow samples by inductively coupled plasma sector field mass spectrometry , 2001 .

[3]  A. Banin,et al.  Distribution of natural and anthropogenic lead in Mediterranean soils , 2001 .

[4]  D. Gore,et al.  Management and remediation of contaminated sites at Casey Station, Antarctica , 2001, Polar Record.

[5]  D. Walton,et al.  Environmental contamination in Antarctica : a challenge to analytical chemistry , 2001 .

[6]  T. Prohaska,et al.  Evaluation of detector dead time calculation models for ICP-MS , 2001 .

[7]  W. Hansmann,et al.  Lead-isotopes as tracers of pollutants in soils , 2000 .

[8]  A. Townsend.  Enhanced sensitivity for Os isotope ratios by magnetic sector ICP-MS with a capacitive decoupling Pt guard electrode , 2000, Fresenius' journal of analytical chemistry.

[9]  F. Vanhaecke,et al.  Lead isotopic and elemental analysis of copper alloy statuettes by double focusing sector field ICP mass spectrometry , 2000 .

[10]  W. K. Johnson,et al.  Sub-part per trillion levels of lead and isotopic profiles in a fjord, using an ultra-clean pumping system , 1999 .

[11]  M. Arens,et al.  Identification and assessment of contaminated sites at Casey Station, Wilkes Land, Antarctica , 1999, Polar Record.

[12]  C. Barbante,et al.  A 200 Year Record of Atmospheric Cobalt, Chromium, Molybdenum, and Antimony in High Altitude Alpine Firn and Ice , 1999 .

[13]  C. Barbante,et al.  Determination of Rh, Pd, and Pt in Polar and Alpine Snow and Ice by Double-Focusing ICPMS with Microconcentric Nebulization. , 1999, Analytical chemistry.

[14]  D. Wiederin,et al.  Strategies for isotope ratio measurements with a double focusing sector field ICP-MS , 1999 .

[15]  P. Ritson,et al.  Stable lead isotopic analyses of historic and contemporary lead contamination of San Francisco Bay estuary , 1999 .

[16]  C. Barbante,et al.  Trace element determination in alpine snow and ice by double focusing inductively coupled plasma mass spectrometry with microconcentric nebulization , 1999 .

[17]  R. Thomas,et al.  Pb, Nd, and Sr Isotope Mapping of Grenville‐Age Crustal Provinces in Rodinia , 1998, The Journal of Geology.

[18]  C. Guerrot,et al.  Assessment of the precision and accuracy of lead-isotope ratios measured by TIMS for geochemical applications: example of massive sulphide deposits (Rio Tinto, Spain) , 1998 .

[19]  A. Townsend,et al.  Ultratrace analysis of Antarctic snow and ice samples using high resolution inductively coupled plasma mass spectrometry , 1998 .

[20]  P. McGoldrick,et al.  Precise lead isotope ratios in Australian galena samples by high resolution inductively coupled plasma mass spectrometry , 1998 .

[21]  H. Gäggeler,et al.  Determination of lead concentrations and isotope ratios in recent snow samples from high alpine sites with a double focusing ICP-MS , 1997 .

[22]  C. Anagnostou,et al.  Source Apportionment of Pb Pollution in the Coastal Waters of Elefsis Bay, Greece , 1997 .

[23]  S. Jay,et al.  Direct Determination of Heavy Metals at Picogram per Gram Levels in Greenland and Antarctic Snow by Double Focusing Inductively Coupled Plasma Mass Spectrometry , 1997 .

[24]  M. Sturm,et al.  Recent changes in stable lead isotope ratios in sediments of lake Zug, Switzerland , 1996 .

[25]  F. Vanhaecke,et al.  Precise Measurement of Isotope Ratios with a Double-Focusing Magnetic Sector ICP Mass Spectrometer. , 1996, Analytical chemistry.

[26]  M. McCulloch,et al.  Routine lead isotope determinations using a lead-207–lead-204 double spike: a long-term assessment of analytical precision and accuracy , 1995 .

[27]  G. Faure.  Principles of isotope geology , 1977 .