Observational and modeling constraints on global anthropogenic enrichment of mercury.
Centuries of anthropogenic releases have resulted in a global legacy of mercury (Hg) contamination. Here we use a global model to quantify the impact of uncertainty in Hg atmospheric emissions and cycling on anthropogenic enrichment and discuss implications for future Hg levels. The plausibility of sensitivity simulations is evaluated against multiple independent lines of observation, including natural archives and direct measurements of present-day environmental Hg concentrations. It has been previously reported that pre-industrial enrichment recorded in sediment and peat disagree by more than a factor of 10. We find this difference is largely erroneous and caused by comparing peat and sediment against different reference time periods. After correcting this inconsistency, median enrichment in Hg accumulation since pre-industrial 1760 to 1880 is a factor of 4.3 for peat and 3.0 for sediment. Pre-industrial accumulation in peat and sediment is a factor of ∼ 5 greater than the precolonial era (3000 BC to 1550 AD). Model scenarios that omit atmospheric emissions of Hg from early mining are inconsistent with observational constraints on the present-day atmospheric, oceanic, and soil Hg reservoirs, as well as the magnitude of enrichment in archives. Future reductions in anthropogenic emissions will initiate a decline in atmospheric concentrations within 1 year, but stabilization of subsurface and deep ocean Hg levels requires aggressive controls. These findings are robust to the ranges of uncertainty in past emissions and Hg cycling.
†Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts 02115, United States.
Helen M
HM
Amos
‡Laboratoire Géosciences Environnement Toulouse, Observatoire Midi-Pyrénées, CNRS-IRD-Université Paul Sabatier, 31062 Toulouse, France.
Jeroen E
JE
Sonke
§Desert Research Institute, Reno, Nevada 89512, United States.
Daniel
D
Obrist
∥Department of History, North Carolina State University, Raleigh, North Carolina 27695, United States.
Nicholas
N
Robins
⊥Environmental Health Council, Durham, North Carolina 27701, United States.
Nicole
N
Hagan
#Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
Hannah M
HM
Horowitz
∇Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States.
Robert P
RP
Mason
○Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, United Kingdom.
Melanie
M
Witt
◆Rende Division, CNR-Institute of Atmospheric Pollution Research, 87036 Rende, Italy.
Ian M
IM
Hedgecock
#Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
Elizabeth S
ES
Corbitt
†Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts 02115, United States.|¶School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
Elsie M
EM
Sunderland
D004785:Environmental Pollutants / Q000266:history*; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D007221:Industry / Q000266:history*; D008628:Mercury / Q000266:history*; D008906:Mining / Q000266:history; D008962:Models, Theoretical; D012987:Soil / Q000737:chemistry
D004785:Environmental Pollutants; D012987:Soil; D008628:Mercury