J. Phys. IV France 107 (2003) 953
DOI: 10.1051/jp4:20030456

Influence of sulphur cycle on mercury methylation in estuarine sediment (Seine estuary, France)

S. Niessen¹, D. Foucher¹, O. Clarisse¹, J. C. Fischer¹, N. Mikac², Z. Kwokal², V. Fajon³ and M. Horvat<sup>3

1</sup>  ELICO, UMR 8013 du CNRS, Laboratory for Marine and Analytical Chemistry, University of Lille, 59655 Villeneuve-d'Ascq cedex, France
²  Center for Marine and Environmental Research, Rudjer Boskovic Institute, Zagreb, Croatia
³  Environmental Sciences Department, Josef Stefan Institute, Ljubljana, Slovenia

Abstract
In order to investigate interaction between mercury speciation and reduced sulfur, speciation of mercury and sulfur were determined in sediment cores sampled in saline and freshwater wetlands of the Seine estuary, France. Solid phase was analyzed for total (HgT) and monome- thyl mercury (MMHg), total sulfur, acid volatile sulfides (AVS), chro- mium reducible sulfur (CRS) and organic carbon. In porewater, in addition to total and methyl mercury, ion, manganèse and sulfates were aiso determined. Levels of the HgT (0. 5 - 2.0 mgkg ^-1 d.w.) in sediment of the Seine estuary were relatively high and typical for sedirnents in industrial area. The sediment contained 0.5 - 1. 5  gkg ^-1 d.w. of MMHg, which made an average 0. 1% of the HgT in sediment. Concentration of MMHg was found to be dependant more on the chemical conditions in sediment than on the level of HgT. Depth profiles of MMHg in the solid phase and HgT in porewater at two sites studied could be related to the production of AVS in sediment as well as to the redox conditions of porewater (defined by Eh and dissolved iron and manganese).

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