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Pré-Publication, Document De Travail Année : 2020

Unequal anthropogenic enrichment of mercury in Earth’s northern and southern hemispheres

Jeroen Sonke
Gael Le Roux
Natalia Piotrowska
  • Fonction : Auteur
Nathalie van Der Putten
  • Fonction : Auteur
Stephen Roberts
  • Fonction : Auteur
Tim Daley
Emma Rice
  • Fonction : Auteur
Roland Gehrels
  • Fonction : Auteur
Dmitri Mauquoy
  • Fonction : Auteur
Thomas P. Roland
  • Fonction : Auteur
Francois de Vleeshouwer
  • Fonction : Auteur

Résumé

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.

Domaines

Géochimie
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Dates et versions

hal-02990211 , version 1 (10-11-2020)

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Chuxian Li, Jeroen Sonke, Gael Le Roux, Natalia Piotrowska, Nathalie van Der Putten, et al.. Unequal anthropogenic enrichment of mercury in Earth’s northern and southern hemispheres. 2020. ⟨hal-02990211⟩
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