Mercury speciation and bioavailability to green algae
Mercury (Hg) is a global pollutant present in all environmental compartments, even in the most remote areas of the planet. Anthropogenic inputs of Hg into the environment, which mostly come from coal-fired power plants and gold production, are widely spread around the globe by atmospheric circulation. Its concentration in natural waters is very low (~ 5-100 pM). However, elevated amounts of Hg can be measured in top consumers due to the biomagnification of its methylated species along aquatic food chains. Phytoplankton is thus an important component of the Hg problematic in aquatic ecosytems as they are the main entrance of Hg into the food web and can accumulate Hg up to 106 times the ambient Hg concentrations.
The aim of the present project is to better understand which process controls Hg uptake by the unicellular green algae Chlamydomonas reinhardtii exposed to environmentally relevant Hg concentrations. To that end, stable enriched isotopic tracers (199IHg and 201MeHg) will be used. These labeled Hg species allows us to separate the added Hg to exposure media from the one already present as background in the exposure media. Thus, studied Hg concentrations are lower than the ones used with natural isotopes and transformations of the studied element are easier to trace.
This project is performed in collaboration with the LCABIE group of the “Université de Pau et des Pays de l’Adour” (France).