title: A global ocean inventory of anthropogenic mercury based on water column measurements.
abstract: Mercury is a toxic, bioaccumulating trace metal whose emissions to the environment have increased significantly as a result of anthropogenic activities such as mining and fossil fuel combustion. Several recent models have estimated that these emissions have increased the oceanic mercury inventory by 36-1,313 million moles since the 1500s. Such predictions have remained largely untested owing to a lack of appropriate historical data and natural archives. Here we report oceanographic measurements of total dissolved mercury and related parameters from several recent expeditions to the Atlantic, Pacific, Southern and Arctic oceans. We find that deep North Atlantic waters and most intermediate waters are anomalously enriched in mercury relative to the deep waters of the South Atlantic, Southern and Pacific oceans, probably as a result of the incorporation of anthropogenic mercury. We estimate the total amount of anthropogenic mercury present in the global ocean to be 290 ± 80 million moles, with almost two-thirds residing in water shallower than a thousand metres. Our findings suggest that anthropogenic perturbations to the global mercury cycle have led to an approximately 150 per cent increase in the amount of mercury in thermocline waters and have tripled the mercury content of surface waters compared to pre-anthropogenic conditions. This information may aid our understanding of the processes and the depths at which inorganic mercury species are converted into toxic methyl mercury and subsequently bioaccumulated in marine food webs.
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Carl H
authors.initials: CH
authors.lastname: Lamborg
authors.affiliation: Department of Earth and Environmental Sciences, Wright State University, Dayton, Ohio 45435, USA.
authors.forename: Chad R
authors.initials: CR
authors.lastname: Hammerschmidt
authors.affiliation: Department of Earth and Environmental Sciences, Wright State University, Dayton, Ohio 45435, USA.
authors.forename: Katlin L
authors.initials: KL
authors.lastname: Bowman
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Gretchen J
authors.initials: GJ
authors.lastname: Swarr
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Munson
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Ohnemus
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Phoebe J
authors.initials: PJ
authors.lastname: Lam
authors.affiliation: Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul-Sabatier, 14, avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Lars-Eric
authors.initials: LE
authors.lastname: Heimbürger
authors.affiliation: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, 1790 AB, The Netherlands.
authors.forename: Micha J A
authors.initials: MJ
authors.lastname: Rijkenberg
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Mak A
authors.initials: MA
authors.lastname: Saito
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005101:Expeditions; D020387:Food Chain; D006802:Human Activities; D008628:Mercury / Q000032:analysis*; D009791:Oceanography; D009792:Oceans and Seas; D010100:Oxygen / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide; D008628:Mercury; D010100:Oxygen
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