Holocene Atmospheric Mercury Levels Reconstructed from Peat Bog Mercury Stable Isotopes.
Environ Sci Technol
; 51(11): 5899-5906, 2017 Jun 06.
Article
em En
| MEDLINE
| ID: mdl-28440654
ABSTRACT
Environmental regulations on mercury (Hg) emissions and associated ecosystem restoration are closely linked to what Hg levels we consider natural. It is widely accepted that atmospheric Hg deposition has increased by a factor 3 ± 1 since preindustrial times. However, no long-term historical records of actual atmospheric gaseous elemental Hg (GEM) concentrations exist. In this study we report Hg stable isotope signatures in Pyrenean peat records (southwestern Europe) that are used as tracers of Hg deposition pathway (Δ200Hg, wet vs dry Hg deposition) and atmospheric Hg sources and cycling (δ202Hg, Δ199Hg). By anchoring peat-derived GEM dry deposition to modern atmospheric GEM levels we are able to reconstruct the first millennial-scale atmospheric GEM concentration record. Reconstructed GEM levels from 1970 to 2010 agree with monitoring data, and maximum 20th century GEM levels of 3.9 ± 0.5 ng m-3 were 15 ± 4 times the natural Holocene background of 0.27 ± 0.11 ng m-3. We suggest that a -0.7 shift in δ202Hg during the medieval and Renaissance periods is caused by deforestation and associated biomass burning Hg emissions. Our findings suggest therefore that human impacts on the global mercury cycle are subtler and substantially larger than currently thought.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Solo
/
Áreas Alagadas
/
Isótopos de Mercúrio
Limite:
Humans
País/Região como assunto:
Europa
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article