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. 2019 Jul 23;116(30):14910-14915.
doi: 10.1073/pnas.1904515116. Epub 2019 Jul 8.

Pervasive Arctic lead pollution suggests substantial growth in medieval silver production modulated by plague, climate, and conflict

Joseph R McConnell  1 , Nathan J Chellman  2 , Andrew I Wilson  3   4 , Andreas Stohl  5 , Monica M Arienzo  2 , Sabine Eckhardt  5 , Diedrich Fritzsche  6 , Sepp Kipfstuhl  7 , Thomas Opel  6 , Philip F Place  8 , Jørgen Peder Steffensen  9
Affiliations

Pervasive Arctic lead pollution suggests substantial growth in medieval silver production modulated by plague, climate, and conflict

Joseph R McConnell et al. Proc Natl Acad Sci U S A. .

Abstract

Lead pollution in Arctic ice reflects large-scale historical changes in midlatitude industrial activities such as ancient lead/silver production and recent fossil fuel burning. Here we used measurements in a broad array of 13 accurately dated ice cores from Greenland and Severnaya Zemlya to document spatial and temporal changes in Arctic lead pollution from 200 BCE to 2010 CE, with interpretation focused on 500 to 2010 CE. Atmospheric transport modeling indicates that Arctic lead pollution was primarily from European emissions before the 19th-century Industrial Revolution. Temporal variability was surprisingly similar across the large swath of the Arctic represented by the array, with 250- to 300-fold increases in lead pollution observed from the Early Middle Ages to the 1970s industrial peak. Superimposed on these exponential changes were pronounced, multiannual to multidecadal variations, marked by increases coincident with exploitation of new mining regions, improved technologies, and periods of economic prosperity; and decreases coincident with climate disruptions, famines, major wars, and plagues. Results suggest substantial overall growth in lead/silver mining and smelting emissions-and so silver production-from the Early through High Middle Ages, particularly in northern Europe, with lower growth during the Late Middle Ages into the Early Modern Period. Near the end of the second plague pandemic (1348 to ∼1700 CE), lead pollution increased sharply through the Industrial Revolution. North American and European pollution abatement policies have reduced Arctic lead pollution by >80% since the 1970s, but recent levels remain ∼60-fold higher than at the start of the Middle Ages.

Keywords: Arctic; Middle Ages; ice core; lead pollution; plague.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Annual lead pollution deposition during the past 2,200 y documented in an array of ice cores spanning nearly half the Arctic, including 12 ice cores from Greenland and 1 from Severnaya Zemlya in the Russian Arctic (SI Appendix, Fig. S1). (A) Median filtered (11-y) AN record from Severnaya Zemlya and Greenland regional composite records (records and colors same as in B–G) on the same logarithmic scale. (B–F) Individual Greenland regional composites (annual and 11-y median filtered values shown with thin and thick lines, respectively). (G) AN record from Severnaya Zemlya. The individual Greenland ice core records (SI Appendix, Fig. S1 and Table S1) were grouped by location and regional records of annual concentration (SI Appendix, Fig. S2), flux, and enrichment (SI Appendix, Fig. S3) were computed as the geometric mean of the individual ice core records. The ACT2 (4) and the 200 BCE to 800 CE part of the NGRIP2 (2) record have been published previously (SI Appendix, Table S1). Measurements in the few previously reported Arctic lead measurements (–5), all confined to the central region of the Greenland ice sheet, are consistent with the records presented here (SI Appendix, Fig. S2). Because accurate dating of ice core records is critical for meaningful historical interpretation, all cores were volcanically synchronized to an accurately dated Arctic reference record (Materials and Methods). Uncertainties in the individual core chronologies were estimated to be <2 y (2) for the Greenland records and <5 y for the AN core (Materials and Methods). Widespread pollution increased more than 250-fold from the Early Middle Ages to 1970s, with sharp, often sustained increases coincident with periods of political stability (e.g., early Carolingian Empire) and exploitation of new mining regions, and decreases coincident with plagues (e.g., Black Death, second plague pandemic from 1348 to ∼1700 CE; second cholera pandemic from 1829 to 1837 CE; third cholera pandemic from 1846 to 1860 CE), climate (e.g., Little Ice Age), major wars, and other externalities. Similar variability throughout the Arctic array indicates large-scale, common changes in lead emissions.
Fig. 2.
Fig. 2.
Arctic lead pollution (11-y median filter) with fitted average growth rates (Materials and Methods) during specific historical periods in the NG (green) and AN (red) records (SI Appendix, Table S2).
Fig. 3.
Fig. 3.
FLEXPART (18, 19) simulation-based sensitivity of the (A) AN and (B) NG ice core records to lead emissions and (C) their ratio. The ∼8-fold higher lead deposition observed in the AN record compared with the NG composite (Fig. 1) is consistent with the 2- to 12-times higher sensitivity to European emissions in the AN/NG ratio, indicating that lead pollution in the Arctic array was dominated by European emissions before the Industrial Revolution.
Fig. 4.
Fig. 4.
Arctic lead pollution compared with indicators of plague, economic conditions, and climate from 500 to 1800 CE: (A) number of plague outbreaks per year (29), (B) average European grain prices (11), (C) tree fellings per decade from historical construction timbers (12), (D) relative lead pollution flux in NG (blue) and AN (black) calculated by subtracting a 600-y spline fit from the log-transformed deposition records, (E and F) reconstructed north central European (E) temperature anomaly (41) and (F) precipitation (23), (G) SG/NG and AN/NG lead flux ratios, and (H) approximate locations and periods of known medieval and Early Modern mining activity.
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References

    1. Hong S., Candelone J. P., Patterson C. C., Boutron C. F., Greenland ice evidence of hemispheric lead pollution two millennia ago by Greek and Roman civilizations. Science 265, 1841–1843 (1994). - PubMed
    1. McConnell J. R., et al. , Lead pollution recorded in Greenland ice indicates European emissions tracked plagues, wars, and imperial expansion during antiquity. Proc. Natl. Acad. Sci. U.S.A. 115, 5726–5731 (2018). - PMC - PubMed
    1. McConnell J. R., Lamorey G. W., Hutterli M. A., A 250-year high-resolution record of Pb flux and crustal enrichment in central Greenland. Geophys. Res. Lett. 29, 2130–2132 (2002).
    1. McConnell J. R., Edwards R., Coal burning leaves toxic heavy metal legacy in the Arctic. Proc. Natl. Acad. Sci. U.S.A. 105, 12140–12144 (2008). - PMC - PubMed
    1. Candelone J. P., Hong S. M., Pellone C., Boutron C. F., Post-industrial revolution changes in large-scale atmospheric pollution of the Northern Hemisphere by heavy metals as documented in central Greenland snow and ice. J. Geophys. Res. 100, 16605–16616 (1995).

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