Mercury fluxes from hydrothermal venting at mid-ocean ridges constrained by measurements
- 1Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO), Marseille, France (lars-eric.heimburger@mio.osupytheas.fr)
- 2Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
- 3GEOMAR-Helmholtz Centre for Ocean Research, Kiel, Germany
- 4Fundación Canaria Parque Científico Tecnológico de la Universidad de las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
- 5Géosciences Environment Toulouse GET CNRS UMR5563, IRD/UPS/CNES, Université de Toulouse, Toulouse, France
- 6CNRS, IRD, Ifremer, LEMAR, University of Brest, Plouzané, France
- 7Jozef Stefan Institute, Department of Environmental Sciences, Ljubljana, Slovenia
- 8Université de Pau et des Pays de l’Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l’Environment et les Matériaux, Pau, France
- 9UMR6538 Geo-Ocean, IFREMER CNRS UBO UBS, Plouzané, France
- 10School of Marine Science and Policy, University of Delaware, Lewes, DE, USA
The UNEP Minamata Convention on Mercury aims to reduce human exposure to toxic mercury through the reduction of anthropogenic emissions. We are primarily exposed via the consumption of fish that bioaccumulate mercury from the ocean. The current paradigm is that anthropogenic mercury emissions (present-day 3,100 tons per year) have increased the global oceanic mercury reservoir by 21%. This estimate is flawed because we do not know how much natural mercury resided in the ocean before anthropogenic emissions started. We are similarly unable to quantify how anthropogenic emissions have affected fish mercury levels. Hydrothermal venting is the only direct source of natural mercury to the ocean. Previous studies, based on vent fluid measurements alone, suggested that hydrothermal mercury inputs could range from 20 and 2,000 tons per year. We use observations of vent fluids, plume, sea water and rock cores from the Trans-Atlantic Geotraverse (TAG) hydrothermal vent at the Mid-Atlantic ridge aquired during three dedicated oceanographic cruises. The combined observations suggest that the majority (67–95%) of the mercury enriched in the vent fluids (4,966 ± 497 picomoles per litre) is diluted into sea water to reach background seawater levels (0.80 picomoles per litre) and a small fraction is scavenged locally (2.6–10%). An extrapolation of our results suggests that the global hydrothermal mercury flux from mid ocean ridges is small (1.5 - 65 tons per year) compared to anthropogenic mercury missions. While this suggests that most of the mercury present in the ocean is of anthropogenic origin, it also gives hope that the strict implementation emission reductions in the framework of the Minamata Convention could effectively reduce fish mercury levels and human exposure.
Torres-Rodriguez, N., Yuan, J., Petersen, S., Dufour, A., González-Santana, D., Chavagnac, V., Planquette, H., Horvat, M., Amouroux, D., Cathalot, C., Pelleter, E., Sun, R., Sonke, J. E., Luther, G. W., and Heimbürger-Boavida, L.E.: Mercury fluxes from hydrothermal venting at mid-ocean ridges constrained by measurements, Nat. Geosci., 1–7, https://doi.org/10.1038/s41561-023-01341-w, 2023.
How to cite: Heimbürger-Boavida, L.-E., Torres-Rodriguez, N., Yuan, J., Petersen, S., Dufour, A., Gonzalez-Santana, D., Chavagnac, V., Planquette, H., Horvat, M., Amouroux, D., Cathalot, C., Pelleter, E., Sun, R., Sonke, J., and Luther, G.: Mercury fluxes from hydrothermal venting at mid-ocean ridges constrained by measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10653, https://doi.org/10.5194/egusphere-egu24-10653, 2024.
