Mediterranean Mercury Assessment 2022: An Updated Budget, Health Consequences, and Research Perspectives

Type Article
Date 2022-04
Language English
Author(s) Cossa DanielORCID1, Knoery JoelORCID2, Bănaru Daniela3, Harmelin-Vivien Mireille3, Sonke Jeroen E.ORCID4, Hedgecock Ian M.5, Bravo Andrea G.ORCID6, Rosati Ginevra7, Canu Donata7, Horvat Milena8, Sprovieri Francesca5, Pirrone Nicola5, Heimbürger-Boavida Lars-EricORCID3
Affiliation(s) 1 : Université Grenoble Alpes, ISTerre, CS 40700, 38058 Grenoble Cedex 9, France
2 : Ifremer, Centre Atlantique de Nantes, BP 44311, 44980 Nantes, France
3 : Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France
4 : Géosciences Environnement Toulouse, CNRS/Observatoire Midi-Pyrénées (OMP)/Université de Toulouse, 31400 Toulouse, France
5 : Istituto sull’inquinamento atmosferico, CNR-IIA, 87036 Rende, Italy
6 : Institut de Ciències del Mar, 08003 Barcelona, Spain
7 : Istituto Nazionale di Oceanografia e di Geofisca Sperimentale (OGS), 34010 Trieste, Italy
8 : Institut Józef Stefan, 1000 Ljubljana, Slovenija
Source Environmental Science & Technology (0013-936X) (American Chemical Society (ACS)), 2022-04 , Vol. 56 , N. 7 , P. 3840-3862
DOI 10.1021/acs.est.1c03044
WOS© Times Cited 16
Keyword(s) Mediterranean, Mercury, Hg, MeHg, Earth System Models
Abstract

Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 ± 0.27 pmol L–1 in the upper water layer and 1.02 ± 0.12 pmol L–1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This difference appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufficiencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air–sea exchange, hydrothermal and cold seep inputs, point sources, submarine groundwater discharge, and exchanges between margins and the open sea. Future assessment of global change impacts under the Minamata Convention Hg policy requires long-term observations and dedicated high-resolution Earth System Models for the Mediterranean region.

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Cossa Daniel, Knoery Joel, Bănaru Daniela, Harmelin-Vivien Mireille, Sonke Jeroen E., Hedgecock Ian M., Bravo Andrea G., Rosati Ginevra, Canu Donata, Horvat Milena, Sprovieri Francesca, Pirrone Nicola, Heimbürger-Boavida Lars-Eric (2022). Mediterranean Mercury Assessment 2022: An Updated Budget, Health Consequences, and Research Perspectives. Environmental Science & Technology, 56(7), 3840-3862. Publisher's official version : https://doi.org/10.1021/acs.est.1c03044 , Open Access version : https://archimer.ifremer.fr/doc/00754/86597/