Abstract
Remote Northern Hemisphere (NH) and Southern Hemisphere (SH) lake sediment and peat records of mercury (Hg) deposition have shown a ×3 to ×5 Hg enrichment since pre-industrial times (<1880 AD), leading to the perception that global atmospheric Hg enrichment is moderate and uniform across the hemispheres. Anthropogenic Hg emissions in the NH are, however, approximately 4 times higher than those in the SH. Here, we reconstruct atmospheric Hg deposition in four remote SH peatlands and review sediment and peat Hg records from both hemispheres. We observe a ×4 all-time enrichment in SH Hg deposition from pre-anthropogenic (<1450 AD) to the late 20th-century periods, which is lower than the large ×16 all-time enrichment in NH Hg deposition. We attribute this difference to lower anthropogenic Hg emissions in the SH, and higher natural atmospheric SH Hg concentrations, supported by ×2 higher natural background Hg accumulation in SH peat records. We suggest that the higher SH natural atmospheric Hg deposition reflects the SH land-ocean distribution, and is driven by important SH marine Hg emissions. Our findings indicate that atmospheric Hg background levels and anthropogenic enrichment in both hemispheres are different and should be taken into account in international Hg assessments and environmental policy.
Original language | English |
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Pages (from-to) | 2073-2081 |
Number of pages | 9 |
Journal | ACS Earth and Space Chemistry |
Volume | 4 |
Issue number | 11 |
Early online date | 30 Oct 2020 |
DOIs | |
Publication status | Published - 19 Nov 2020 |
Funding
Field work was funded by the French Polar Institute (IPEV, Brest, France) through the IPEV Programmes 1066 “PARAD” (to F.D.V.) and 1065 PALATIO (to N.V.P. and E. Michel). J.E.S. acknowledges funding from the H2020 ERA-PLANET (689443) iGOSP and iCUPE programs. The authors thank the South Atlantic Environmental Research Institute (SAERI) for providing laboratory facilities in the Falkland Islands and E. Brook (Falkland Islands Government Training Centre) for logistical support. They are grateful to N. Marchand (IPEV) for the logistical support, C. Marteau for making the sampling possible in very restricted areas of the TAAF Nature Reserve, and N. Roberts for help processing the San Carlos core and scientific discussions. They thank A. Coronato, R. López, and V. Pancotto from CADIC-CONICET (Ushuaia) for the field campaigns in Andorra and Harberton. Radiocarbon ages were obtained as part of the Idex Peat3 project of the University of Toulouse and through the national service support: Artemis-INSU-CNRS (to G.L.R.). C.L.’s PhD is supported by a scholarship from the China Scholarship Council. The authors thank 12 anonymous reviewers for their constructive comments on the various versions of this paper, and editor J. D. Blum for handling the final version.
Funders | Funder number |
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Horizon 2020 Framework Programme | 689443 |
Institut Polaire Français Paul Emile Victor |
Keywords
- archive
- deposition
- enrichment
- hemisphere
- mercury
- peat
- sediment