Lead variability in the western North Atlantic Ocean and central Greenland ice: Implications for the search for decadal trends in anthropogenic emissions (original) (raw)
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Stable lead isotope ratios in arctic aerosols: evidence for the origin of arctic air pollution
Atmospheric Environment (1967)
The isotopic composition of aerosol lead in the polar region potentially contains information on the origin of Arctic pollution which will complement that from meteorological and trace elemental composition studies. Weekly samples of atmospheric aerosols were collected at three locations in the Canadian Arctic from mid-1983 to mid-1984. They were analyzed for elemental composition and stable lead isotope ratios (Pb 206/207). High crustal enrichment factors confirmed that the majority of samples contained lead of anthropogenic origin. Pb 206/207 ratios were very uniform over time and between sites, suggesting a common origin of lead pollution in the Canadian Arctic. The mean isotope ratios at the Alert and Mould Bay stations were 1.160~0.010 and 1.161+0.006, respectively (samples from a third site at Igloolik were eiidently contaminated by local sources). A small nun&r of samples from Spitsbergen, taken durine flow medominantlv out of the northern U.S.S.R.. were found to have a similar mean Pb 206/207 ratio .d 1 of 1.154~0.006. From published lead isotope analyses of Soviet lead-bearing ores, we would ex&t a mean isotope ratio in industrial and vehicular emissions in the U.S.S.R. of around 1.158. Contributions to Arctic lead pollution from the U.S. and western Canadian sources can probably be ruled out, as they have significantly higher Pb 206/207 ratios. Similarly, emissions from northern Canadian and Kola Peninsula smelters can be disregarded, as they appear to have low isotope ratios. Eastern Canadian automotive lead aerosol contained only marginally lower Pb 206/207 ratios than in the Arctic, but meteorological studies argue against this region being a major source area for Arctic pollution. Scant European data suggest that European Pb emissions generally have lower isotope ratios than the Arctic samples. However, more data in Eurasia are needed before apportionments of Arctic Pb between sources within the region can be made.
Lead isotopic fingerprinting of 250-years of industrial era pollution in Greenland ice
Anthropocene, 2022
Emissions from mid-latitude industrial activities (e.g., mining, smelting, coal combustion) result in long-range atmospheric transport of lead (Pb) to the Arctic. While previous measurements of elemental concentrations and Pb isotopic ratios in ice and sediments have been used to suggest potential sources of toxic heavy metal pollution in these regions, high resolution Pb isotope records are largely unavailable due to the low Pb concentrations found in Arctic ice. Here we present and interpret a high-resolution, 1759-2008 record of Pb isotopes measured in a central Greenland ice core; the first high-resolution Pb isotope record for Greenland to include the First Industrial Revolution. Records of past industrial activities coupled with Pb isotopic signatures for regional ores and coals suggest Pb pollution prior to the mid-19th century was dominated by emissions from mining and combustion of coals in England, Scotland, and Wales. Rapid 1860s increases in Pb levels and decreases in 206 Pb/ 207 Pb ratios coincided with expansion of coal consumption in Europe and North America. Significant influence of 20th century smelting of Australian Broken Hill Pb ores in Europe resulted in a less radiogenic Pb isotope signature. The phase-out of leaded gasoline and other emissions reductions following passage of airquality legislation in the United States had a pronounced effect on 206 Pb/ 207 Pb ratios, with values falling from 1.187 in 1978 to 1.154 in 1983. Increasing 208 Pb/ 207 Pb ratios through the 1990s and 2000s indicate rising influence of long-range transport from Asia countering declines in European emissions. This 250-year highresolution Pb isotope reconstruction allows attribution of Pb sources to central Greenland with unprecedented detail.
Temporal variability of Cd, Pb, and Pb isotope deposition in central Greenland snow
Geochemistry, Geophysics, Geosystems, 2000
We present a decade-long (1981-1990) high-resolution (subseasonal) record of Pb and Cd concentrations and Pb isotopic composition in a series of 119 snow samples from a 6-m snow pit at Summit, Greenland. Both metals show order of magnitude seasonal variability, with maxima in spring of every year, coinciding with sulfate peaks. These short-term features complicate attempts to quantify secular decadal-scale trends associated with anthropogenic source changes (e.g., phasing out of leaded gasoline). A small (<50%) decrease during the decade is estimated for Pb, but no significant trend is observed for Cd. Mean concentrations for the snow pit (Pb = 216, Cd = 11 pmol kg À1) are indistinguishable from mean values for nearly continuous samples of the 1-6 m section of a firn core drilled 1 km away, suggesting freedom from contamination artifact. An evaluation of potential sources confirms that Pb and Cd are dominated by anthropogenic inputs. Isotopic ratios (206 Pb/ 207 Pb and 208 Pb/ 207 Pb) determined on a subset of snow pit samples of varying ages within the decade indicate that springtime Pb concentration maxima are consistent with a mixture of eastern European, former Soviet Union, and western European sources, while seasonal Pb minima, especially from the early portion of the decade, plot along a different mixing line, suggesting a mixture of U.S. and European sources. The combination of Pb concentration and isotopic composition are consistent with an estimated decrease in U.S. Pb contributions of about twofold over the decade, which predicts a decadal concentration decrease in the snow of $30%. However, the secular trends in both concentration and isotopes are barely detectable against seasonal and interannual variability. The evidence for seasonally distinct source regions may be useful for interpretation of high-resolution records of other chemical species in Greenland snow and ice. Analyses of two deep core sections dated at 1699-1700 and 1780-1788, compared to the snow pit data, indicate that both Pb and Cd deposition in central Greenland roughly doubled during the eighteenth century, then doubled again by the 1980s.
Geophysical Research Letters, 2005
1] Atmospheric Pb contamination was studied using snow and ice from the Canadian arctic. Forty-five samples representing the past ten years of snow accumulation on Devon Island contain an average of 45.2 pg/g of Pb but only 0.43 pg/g of Sc. The average ratio of Pb to Sc (105) is far greater than that of soil-derived dust particles (in the range 1 to 5) which indicates that ca. 95 to 99% of recent Pb is anthropogenic. Isotopic analyses ( 206 Pb, 207 Pb, 208 Pb) confirm that anthropogenic sources continue to dominate atmospheric Pb inputs. Unlike snow from Greenland which receives Pb predominantly from the U.S. ( 206 Pb/ 207 Pb % 1.2), snow from Devon Island is less radiogenic ( 206 Pb/ 207 Pb % 1.15). There are pronounced seasonal variations, and the snow samples containing the greatest Pb enrichments are from winter when the Arctic is dominated by air masses originating in Eurasia. While the elimination of gasoline lead additives in Europe, North America and Japan has helped to reduce Pb emissions during the past two to three decades, aerosols in the Arctic today are still highly contaminated by industrial Pb.
Isotopic composition of lead in moss and soil of the European Arctic
Geochimica et Cosmochimica Acta, 2004
Moss, O and C horizons of podzols, mainly forming complementary sample triplets, as well as filter residues of molten snow from northern Norway, northern Finland and NW Russia have been analyzed by TIMS for their Pb isotopic composition in order to study the impacts of local geogenic/anthropogenic sources and long range atmospheric transport on the Pb balance in the European Arctic. Samples were taken along two N-S transects covering an area of ϳ188.000 km 2 , including both pristine environments in the W and certain regions towards the E severely contaminated by heavy metal emissions originating from large nickel smelters and processing plants in NW Russia. The lead in moss and O horizon samples clearly reflects atmospheric deposition, as it displays overall uniform isotope ratios and is decoupled from the geogenic background, i.e. the underlying mineral soils in the C horizon. Moss and O horizon samples from the eastern N-S transect are isotopically indistinguishable from those taken along the western transect but their Pb concentrations tend to be ϳ2 times higher. This points to considerable contamination originating from the nearby Russian industrial and urban centers. However, isotopic signals of emissions from individual industrial point sources cannot be unambiguously identified because they lack characteristic isotope signatures. Pb derived from gasoline additives is swamped by Pb from other sources and can also be excluded as a major contributor to the environmental Pb in the European Arctic. Overall, the Pb isotopic signatures of moss and O horizon overlap values recorded in atmospheric lead all over central and southern Europe, more than 2000 km south of the study area. This may be taken as indicating continent-wide mixing of Pb derived from similar sources in the atmosphere or as reflecting economic globalization, or both. O horizon samples, which accumulate lead over 20-30 yr, conform to a distinct Pb isotope reference line in 207 Pb/ 206 Pb vs. 208 Pb/ 206 Pb space ("European Standard Pollution," ESP) defined by atmospheric Pb considered to be representative for the technical civilization in Europe. Conversely, the Arctic moss samples with a lifetime of Ͻ3 yr display a deviating linear trend reflecting a recent change of atmospheric input towards significantly more radiogenic Pb derived from Mississippi Valley-type ores in the U.S., fully compatible with signatures found in epiphytic lichens from Canada, but also in Pb from urban waste incinerators in central Europe. Considering the elevated Pb concentrations in moss collected along the eastern N-S transect, this congruence indicates that the Pb in moss of the European Arctic most probably originates from the nearby Russian centers of urbanization and not from transatlantic transport. We therefore suspect imported industrial goods and their subsequent attrition to be a more plausible explanation for the appearance of MVT lead in Europe.
Science of The Total Environment, 2018
To study the long-range transport of atmospheric pollutants from lower latitude industrial areas to the Arctic, we analysed a peat core spanning the last ~700 cal. yr (~AD 1300-2000) from southern Greenland, an area sensitive to atmospheric pollution from North American and Eurasian sources. A previous investigation conducted in the same location recorded atmospheric lead (Pb) pollution after ~1845, with peak values recorded in the 1970s, and concluded that a North American source was most likely. To confirm the origin of the lead, we present new Pb isotope data from Sandhavn, together with a high-resolution record for mercury (Hg) deposition. Results demonstrate that the mercury accumulation rate has steadily increased since the beginning of the 19 th century, with maximum values of 9.3 μg m-2 yr-1 recorded ∼1940. Lead isotopic ratios show two mixing lines: one which represents inputs from local and regional geogenic sources, and another that comprises regional geogenic and pollution sources. Detrending the Pb isotopic ratio record (thereby extracting the effect of the geogenic mixing) has enabled us to reconstruct a detailed chronology of metal pollution. The first sustained decrease in Pb isotope signals is recorded as beginning ~1740-1780 with the lowest values (indicating the highest pollution signature) dated to ~1960-1970. The 206 Pb/ 207 Pb ratio of excess Pb (measuring 1.222, and reflecting pollution-generated Pb), when compared with the Pb isotopic composition of the Sandhavn peat record since the 19 th century and the timing of Pb enrichments, clearly points to the dominance of pollution sources from North America, although it did not prove possible to further differentiate the emissions sources geographically.
Pb isotope ratios of lake sediments in West Greenland: inferences on pollution sources
2001
Lead (Pb), like many other pollutants, is carried into the Arctic by long-range atmospheric transport from industrial centers at lower latitudes. Unlike other pollutants, Pb can be used to assess emission source regions through the use of stable Pb isotope analyses. Using sediment cores from 17 lakes (three profiles and 14 top/bottom sample pairs) in the Sndre Strmfjord (Kangerlussuaq) region, West Greenland (678N), this study assesses the extent and origin of Pb pollution along a 150 km transect between the Inland Ice and Davis Strait. Like ice core analyses from the interior of Greenland, the isotope analyses suggest pre-industrial contamination, although significant concentration changes in the lake sediments do not occur until the 18th/19th centuries, with the maximum concentrations occurring about 1970. Compared to the background, the Pb concentrations in recent sediments have increased about 2.5-fold, with slightly higher enrichments towards the coast, where annual precipitation is highest. For all of the lakes, there is a major decline in the 206 Pb/ 207 Pb ratio in the recent sediments (mean 1.218 AE 0.030) as compared to deeper sediments (mean 1.365 AE 0.084). Using a Pb isotope mixing model, we calculated an excess Pb isotope ratio, i.e. the isotope ratio necessary to produce the observed declines in recent sediments. While studies of atmospheric aerosols in the high Arctic ( 206 Pb/ 207 Pb ratio 1.16)haveindicatedthatRussianemissions(206Pb/207Pbratio1.16) have indicated that Russian emissions ( 206 Pb/ 207 Pb ratio 1.16)haveindicatedthatRussianemissions(206Pb/207Pbratio1.15-1.16) are a dominant source of arctic pollution, the excess Pb ratios of the lake sediments in the Sndre Strmfjord region ( 206 Pb/ 207 Pb ratio 1.14−1.15),inthelowArctic,suggestthatWEurope(206Pb/207Pbratio1.14-1.15), in the low Arctic, suggest that W Europe ( 206 Pb/ 207 Pb ratio 1.14−1.15),inthelowArctic,suggestthatWEurope(206Pb/207Pbratio1.14) is also a major emission source for this region. #