Enhanced mercury reduction in the South Atlantic Ocean during carbon remineralization

Igor Živković; Matthew P Humphreys; Eric P Achterberg; Cynthia Dumousseaud; E Malcolm S Woodward; Natalia Bojanić; Mladen Šolić; Arne Bratkič; Jože Kotnik; Mitja Vahčič; Kristina Obu Vazner; Ermira Begu; Vesna Fajon; Yaroslav Shlyapnikov; Milena Horvat

doi:10.1016/j.marpolbul.2022.113644

Enhanced mercury reduction in the South Atlantic Ocean during carbon remineralization

Mar Pollut Bull. 2022 May:178:113644. doi: 10.1016/j.marpolbul.2022.113644. Epub 2022 Apr 9.

Authors

Affiliations

¹ Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia. Electronic address: igor.zivkovic@ijs.si.
² NIOZ Royal Netherlands Institute for Sea Research, Department of Ocean Systems (OCS), P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands.
³ GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1-3, 24148 Kiel, Germany.
⁴ Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH, United Kingdom.
⁵ Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3DH, United Kingdom.
⁶ Laboratory of Plankton and Shellfish Toxicity, Institute of Oceanography and Fisheries, Šetalište I. Meštrovića 63, 21000 Split, Croatia.
⁷ Laboratory of Marine Microbiology, Institute of Oceanography and Fisheries, Šetalište I. Meštrovića 63, 21000 Split, Croatia.
⁸ Chemistry Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium.
⁹ Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia.
¹⁰ Joint Research Centre, European Commission, Retieseweg 111, 2440 Geel, Belgium.
¹¹ Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia; Ecological Engineering Institute, Ljubljanska ulica 9, 2000 Maribor, Slovenia.
¹² Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.

PMID: 35413504
DOI: 10.1016/j.marpolbul.2022.113644

Abstract

Mercury (Hg) in seawater is subject to interconversions via (photo)chemical and (micro)biological processes that determine the extent of dissolved gaseous mercury (DGM) (re)emission and the production of monomethylmercury. We investigated Hg speciation in the South Atlantic Ocean on a GEOTRACES cruise along a 40°S section between December 2011 and January 2012 (354 samples collected at 24 stations from surface to 5250 m maximum depth). Using statistical analysis, concentrations of methylated mercury (MeHg, geometric mean 35.4 fmol L^-1) were related to seawater temperature, salinity, and fluorescence. DGM concentrations (geometric mean 0.17 pmol L^-1) were related to water column depth, concentrations of macronutrients and dissolved inorganic carbon (DIC). The first-ever observed linear correlation between DGM and DIC obtained from high-resolution data indicates possible DGM production by organic matter remineralization via biological or dark abiotic reactions. DGM concentrations projected from literature DIC data using the newly discovered DGM-DIC relationship agreed with published DGM observations.

Keywords: Dissolved gaseous mercury; Dissolved inorganic carbon; Mercury; Organic matter remineralization; South Atlantic Ocean.

MeSH terms

Atlantic Ocean
Carbon / analysis
Environmental Monitoring
Gases
Mercury* / analysis
Water Pollutants, Chemical* / analysis

Substances

Gases
Water Pollutants, Chemical
Carbon
Mercury