Industrial-era lead and mercury contamination in southern Greenland implicates North American sources

Marta Pérez-Rodríguez; Noemí Silva-Sánchez; Malin E Kylander; Richard Bindler; Tim M Mighall; J Edward Schofield; Kevin J Edwards; Antonio Martínez Cortizas

doi:10.1016/j.scitotenv.2017.09.041

Industrial-era lead and mercury contamination in southern Greenland implicates North American sources

Sci Total Environ. 2018 Feb 1:613-614:919-930. doi: 10.1016/j.scitotenv.2017.09.041. Epub 2017 Sep 21.

Authors

Marta Pérez-Rodríguez¹, Noemí Silva-Sánchez², Malin E Kylander³, Richard Bindler⁴, Tim M Mighall⁵, J Edward Schofield⁵, Kevin J Edwards⁶, Antonio Martínez Cortizas²

Affiliations

¹ Departamento de Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, Campus Sur, Santiago de Compostela 15782, Spain; Institut für Geoökologie, AG Umweltgeochemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany. Electronic address: m.perez-rodriguez@tu-bs.de.
² Departamento de Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, Campus Sur, Santiago de Compostela 15782, Spain.
³ Department of Geological Sciences, Stockholm University, SE-10691 Stockholm, Sweden; The Bolin Centre for Climate Research, Stockholm University, SE-10691 Stockholm, Sweden.
⁴ Department of Ecology and Environmental Sciences, Umeå University, SE-901 87 Umeå, Sweden.
⁵ Department of Geography and Environment, School of Geosciences, University of Aberdeen, Elphinstone Road, Aberdeen AB24 3UF, UK.
⁶ Department of Geography and Environment, School of Geosciences, University of Aberdeen, Elphinstone Road, Aberdeen AB24 3UF, UK; Department of Archaeology, School of Geosciences, University of Aberdeen, Elphinstone Road, Aberdeen AB24 3UF, UK; Clare Hall, University of Cambridge, Herschel Road, Cambridge CB3 9AL, UK.

PMID: 28946380
DOI: 10.1016/j.scitotenv.2017.09.041

Abstract

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 ~700cal.yr (~1300-2000CE) 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 19th century, with maximum values of 9.3μgm^-2yr^-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 ²⁰⁶Pb/²⁰⁷Pb 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 19th 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.

Keywords: Atmospheric deposition; Hg; Isotopic residuals; Metal pollution; Pb isotopes; Peat.