Toward an Assessment of the Global Inventory of Present-Day Mercury Releases to Freshwater Environments.
Aquatic ecosystems are an essential component of the biogeochemical cycle of mercury (Hg), as inorganic Hg can be converted to toxic methylmercury (MeHg) in these environments and reemissions of elemental Hg rival anthropogenic Hg releases on a global scale. Quantification of effluent Hg releases to aquatic systems globally has focused on discharges to the global oceans, rather than contributions to freshwater systems that affect local exposures and risks associated with MeHg. Here we produce a first-estimate of sector-specific, spatially resolved global aquatic Hg discharges to freshwater systems. We compare our release estimates to atmospheric sources that have been quantified elsewhere. By analyzing available quantitative and qualitative information, we estimate that present-day global Hg releases to freshwater environments (rivers and lakes) associated with anthropogenic activities have a lower bound of ~1000 Mg· a-1. Artisanal and small-scale gold mining (ASGM) represents the single largest source, followed by disposal of mercury-containing products and domestic waste water, metal production, and releases from industrial installations such as chlor-alkali plants and oil refineries. In addition to these direct anthropogenic inputs, diffuse inputs from land management activities and remobilization of Hg previously accumulated in terrestrial ecosystems are likely comparable in magnitude. Aquatic discharges of Hg are greatly understudied and further constraining associated data gaps is crucial for reducing the uncertainties in the global biogeochemical Hg budget.
Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana 1000, Slovenia. david.kocman@ijs.si.
David
D
Kocman
Arctic Monitoring and Assessment Programme (AMAP) Secretariat, Oslo N-0349, Norway. s.wilson@inter.nl.net.
Simon J
SJ
Wilson
Department of Environmental Health, Harvard School of Public Health, Boston, MA 02215, USA. helen.amos@gmail.com.|Harvard School of Engineering and Applied Sciences, Cambridge, MA 02138, USA. helen.amos@gmail.com.
Helen M
HM
Amos
Artisanal Gold Council, Victoria, BC V8W 1B9, Canada. ktelmer@artisanalgold.org.|School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada. ktelmer@artisanalgold.org.
Kevin H
KH
Telmer
Arctic Centre, University of Groningen, Groningen 9718CW, The Netherlands. f.steenhuisen@rug.nl.
Frits
F
Steenhuisen
Department of Environmental Health, Harvard School of Public Health, Boston, MA 02215, USA. ems@seas.harvard.edu.|Harvard School of Engineering and Applied Sciences, Cambridge, MA 02138, USA. ems@seas.harvard.edu.
Elsie M
EM
Sunderland
Department of Marine Sciences, University of Connecticut, CT 06340, USA. robert.mason@uconn.edu.
Robert P
RP
Mason
Geological Survey of Canada, Natural Resources Canada, Ottawa, ON K1A 0E8, Canada. peter.outridge@canada.ca.
Peter
P
Outridge
Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana 1000, Slovenia. milena.horvat@ijs.si.
Milena
M
Horvat
D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D008906:Mining / Q000379:methods; D045483:Rivers / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
D014874:Water Pollutants, Chemical; D008628:Mercury
mercury, freshwater systems, releases, inventory, global cycling