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Tools to assess keys parameters affecting Hg biogeochemical cycle in the environment

Thursday 5 November, 4 PM CET

Dr. Vincent Perrot

ABSTRACT: Various anthropogenic and natural emissions of mercury (Hg), combined with its high reactivity towards environmental factors and high residence time (0.5-2years) in the atmosphere, makes studying the cycle of this toxic heavy metal within the environment very challenging. Specifically, aquatic systems are compartments where Hg behavior has to be carefully investigated because they control its bioavailability to primary organisms and are privileged sites for methyl-Hg (the most toxic Hg species) production via biological processes and further bioaccumulation in food webs, which ultimately threatens humans via fishery products consumption. However, the measurement of Hg speciation in natural/remote environments requires working with ultra-clean techniques and specific instruments, due to nano- to femto-molar levels in waters in such environments and high risk of contamination from laboratory and/or field handling.

Since the early 2000s, the development of analytical tools in mass spectrometry has enabled highly precise and accurate measurements of Hg stable isotopes signatures in environmental samples, which has allowed new ways to explore Hg sources and transformations in the environment. DGTs are also a relatively new and underexplored method consisting in a Hg preconcentration, time averaged and low-cost sampling technique, and also enabling the estimation of Hg bioavailability to organisms via passive diffusion in natural waters. First I briefly present several examples of my previous studies (2010-2019) where we combined Hg speciation measurements (inorganic forms, methyl-Hg) with stable Hg isotope ratios measurements in different types of samples (biological, sediments, soils, atmosphere) and environments (marine, lake, industrial/mine impacted), and how this helps having better insights into Hg transformations due to different bio/physico/chemical parameters, as well as making Hg sources apportionments. Then I will present my work in the AMGC group at VUB, which combines analytical and field work to monitor Hg species levels and use the DGT technique for bioavailable Hg fractions assessment in marine waters. This will be illustrated by some data from lab experiments and last Belgica (2020) field campaign in the Scheldt Estuary/North Sea.

BIOMy research is motivated by the study of elements’ biogeochemical cycles and specifically interactions between environmental parameters and trace metal pollutants. I am mostly focusing on mercury (Hg) fate at global, regional and local scales. For that purpose, I work on the use (and potential combination) of different analytical and sampling techniques to assess levels and transformations of Hg compounds (molecular, size-fractionated, isotopic, bioavailable Hg species) in natural environments.