Stable lead isotope characteristics of lead ore deposits of environmental significance

Abstract

Stable Pb isotopes are increasingly used in environmental science as tracers of natural and anthropogenic Pb sources. This review provides a summary of the recent geological literature concerning Pb isotopes in global Pb ore deposits. The isotopic characteristics of 151 Pb deposits, including 78 20th-century producing mines, have been summarized using the 204Pb-based ratios common to geological science and the 206Pb- and 207Pb-based ratios (i.e., excluding 204Pb) more often employed in environmental studies. A number of current mines, including those exploiting several Australian, Scandinavian, and U.S.A. deposits, have extreme isotopic compositions that provide unique signatures. However, a majority of mines (and unproductive deposits) fall within a relatively narrow range:206Pb/207Pb of 1.15-1.22 and 208Pb/207Pb of 2.42-2.50. In some contexts, unequivocal identification of a source exhibiting one of these common signatures would be difficult, especially with the relatively low precision (ca. 0.2-0.5% RSD) of quadrupole inductively coupled plasma - mass spectrometry (ICP-MS) which has been the most common instrument for environmental Pb isotope measurements. In settings with disparate industrial and natural Pb signatures (i.e., sources withisotopic ratios differing by about 2% or more), ICP-MS precision is adequate for source discrimination. Statistical analyses suggested that while 204Pb is critical for identifying a small proportion of environmental Pb sources, about 86% of the source discrimination power is due to the 206Pb, 207Pb, and 208Pb isotopes. Thus, the requisite analytical precision, rather than a lack of 204Pb data, is the most critical issue with respect to unequivocal identification of Pb sources in most cases. Several factors, especially the increasing dominance of recycling in global Pb production and the international transportation of ore concentrate and refined Pb, may cause unpredictable changes in the isotopic signatures of industrial sources,with a long-term trend towards homogenization. More frequent,comprehensive, and high-precision isotopic characterization of possible point and non-point Pb emitters such as gasoline, smelters, and battery-recycling plants, together with increased efforts to document the origin of constituent leads in industrial sources, would help to address these concerns.Key words: lead isotopes; lead pollution; source identification; lead ore deposits.

Origin and significance of ice‐rafted detritus in the Atlantic sector of the Southern Ocean

“…Phenocrysts from the young SSI volcanic material should Leat et al [2004], and the Southern Thule Group from Leat et al [2003]. Grey fields are modern lead data from Sangster et al [2000]. Dotted line marks the two-step common lead age model of Stacey and Kramers [1975].…”

Isotopes as tracers of sources of lead and strontium in aerosols (TSP & PM2.5) in Beijing

“…206 Pb/ 204 Pb,207 Pb/ 206 Pb,87 Sr/ 86 Sr) can provide clearer evidence for anthropogenic input compared to concentrations data alone, as the different anthropogenic sources, whether point-source or of regional scale, commonly show distinct characteristic isotope compositions compared to those found in natural sediments (e.g., Hamelin et al, 1990;Monna et al, 1997). The signatures of "heavy" isotope may ultimately be related to the isotope geochemistry of the ore deposit from which the industrial element was produced (Sangster et al, 2000). In the case of Pb air pollution, impact studies were supported, since the 1980s (e.g.…”

Variation in soil chemistry related to different classes and eras of urbanisation in the London area

“…The data in this study do not indicate a concomitant rise in Fe, Mn or Ti with Pb, Ca and associated elements with data grouped over the range 0-24 m to > 200 m (Supplementary materials Table SM-4) reducing the likelihood of contamination related to brake dust from vehicles being a dominant factor. Mao et al (2014) demonstrated that London soils have a relatively narrow range of 206 Pb/ 207 Pb falling on a mixing line between geogenic (UK coal and UK Pb ore; Shepherd et al, 2016) and UK leaded petrol (1.06-1.09 Shepherd et al, 2016;Chenery et al, 2012;Sangster et al, 2000) suggesting multiple sources of Pb contamination including petrol, paint, water pipes, coal ash. Whereas Total Pb does not correlate with 206 Pb/ 207 Pb, it is the primary determinant of isotopically exchangeable Pb (Mao et al, 2014) as it is for bioaccessible Pb .…”