Bouchet , S. ., IPREM-ECABIE, PAU, France, Sylvain.Bouchet@etud.univ-pau.fr
Bridou , R. ., IPREM-ECABIE, PAU, France,
Rodriguez-Gonzalez, P. ., IPREM-ECABIE, PAU, France,
Tessier , E. ., IPREM-ECABIE, PAU, France,
Monperrus , M. ., IPREM-ECABIE, PAU, France,
Amouroux , D. ., IPREM-ECABIE, PAU, France,

COMBINING MICROCOSM EXPERIMENT AND ISOTOPIC TRACERS TO STUDY MERCURY TRANSFORMATIONS UNDER REDOX OSCILLATIONS IN COASTAL SEDIMENTS

Major questions are still associated with the fate of Hg species in coastal sediments: first, the methylmercury (MMHg) formation extent of the fresh pool of Hg (exogenous Hg) and the legacy pool of Hg (endogenous Hg) and secondly, the transformations and partitioning of the Hg species under redox oscillating regimes in surface sediments. In this work, a time course experiment was developed using a microcosm to investigate the surface sediment reactivity of Hg species under controlled redox oscillations. Isotopic enriched species of inorganic Hg and MMHg were added at the beginning of the experiment. Sampling was done in the solid, aqueous and gaseous phase along the redox oscillations allowing the simultaneous measurement of transformation and partition extents of endogenous and exogenous Hg species. It was found that methylation yields and desorption of inorganic and organic Hg species were enhanced during the redox transitions periods. Phase partitioning and methylation extent between each Hg pools reach equilibrium at different timescale. Equilibration of labile exogenous Hg can be achieved after 24h considering phase partitioning and more than 2 weeks considering methylation extent.

Oral presentation

Presentation is given by student: Yes
Session #:187
Date: 03-07-2008
Time: 09:00