Vincent Perrrot

Research interest and project summary

My research is generally motivated by the study of the (bio)geochemical cycles of trace elements, and mostly focusing on mercury (Hg) fate at global, regional and local scales. I am especially interested in Hg chemical speciation in aquatic environments (such as its inorganic form and methylmercury) and the transformation pathways of these Hg compounds associated with bio-physico-chemical parameters.

Hg is very toxic depending on its speciation, has both natural and anthropogenic sources and is very reactive towards environmental conditions. This element has high rates of bioaccumulation and biomagnification which threaten food web top predators such as humans, but occurs naturally in the environment at ultra-trace levels (ng/L in natural water and ng/m3 in the atmosphere) where its bioavailability regulates its entering into food webs. This leads the complex challenges of the accurate measurement of Hg speciation and, hence, the deciphering of Hg sources and transformations in the environment. To achieve these goals as an environmental chemist, I use different sampling techniques on the field (for water, sediment, organisms, air) together with specific sample preparation in the laboratory (such as mineralisation, filtration, isotope dilution, ethylation, …) and associated with analytical equipment allowing ultra-trace level measurements (such as ICP-MS, AMA-254, CV-AFS). During my PhD and following post-docs, I have been studying Hg cycle in lacustrine (lake Baikal, Russia) and marine (Gulf of Mexico) environments using stable Hg isotope ratio measurements (performed with multi-collector ICP-MS) as a technique to identify specific sources and processes (e.g. methylation, (photo)reduction) affecting Hg speciation and bioaccumulation.

My project here at VUB in the AMGC Team is to use the diffusive gradient in thin films (DGT) technique to investigate Hg cycle in estuarine and marine environments. The advantages of this technique are the preconcentration of the analytes, their time-integrated concentration determination in waters, and the ability to sample only bioavailable species of these analytes through diffusion processes. This project is in association with the Joseph Stefan Institute (Slovenia) with the aim to combine DGT techniques with Hg stable isotope ratios analysis in order to identify the main sources and transformations affecting bioavailable Hg compounds in the marine environment. The main areas investigated in this project are the North Sea, the Scheldt Estuary and the Adriatic Sea. The use of the SeaExplorer automated submersible for DGT deployment in the Adriatic Sea is also planned.

Keywords

Mercury, methylmercury, aquatic environment, speciation, bioavailability,