My research is essentially based on the internal dynamics of volatile elements (C, N, H, S) and to elucidate the processes that control their long-term distribution in the different terrestrial reservoirs (oceans, oceanic and continental crust, upper and lower mantle). Their study provides a better understanding of their initial state, i.e. 4.5 billion years ago, and thus understand the origin and chronology of their contribution, for example understanding what type of meteorites contributed to the presence of water on Earth and when they were brought in (after or before the impact that generated the Moon?).

During the first fifteen years of my career, with my colleagues and students, we concentrated on the study of the nitrogen cycle - in particular through the study of diamonds for which nitrogen is the major impurity, with in parallel several works on rocks in subduction zones, mid ocean-ridge basalts and hot spots. Amongst other results, we highlighted the 'massive recycling' of nitrogen in the mantle and have shown that, contrary to popular belief, that most so-called 'ecologic' diamonds are not formed from surface carbon recycling.

Since 2008, after having set up methods for analysing the three isotope ratios of sulphur, I extended my investigations to the sulphur cycle. Among our main results, we were able to demonstrate that sulphur isotopes are very good tracers of chemical geodynamics (i.e. recycling of surface material) and that the mantle retains the signature of sulphur sequestration in the earth's core. Our current work is interested in better establishing the fate and flux of sulphur recycled in the mantle.

My research, using the three isotopic ratios of sulphur and oxygen, falls more generally speaking on the frame of better understanding and applying 'mass-independent isotope fractionation' (MIF), with several recent works in the field of atmospheric chemistry, focusing on the formation of sulphate aerosols, where we provided some original constraints on their formation. Our on-going work concerns more fundamental aspects of mechanisms for generating MIF, particularly during evaporation processes and heterogeneous gas/solid chemical reactions.

In parallel, through several collaborations, I am collaborating with several cool colleagues on the study of ancient paleo-environmental conditions (> 2.3 billion years, ~ 630 million years, 8 million years) for which sulphur isotopes allow us to deduce e.g. the presence/absence/appearance of atmospheric oxygen, and the types of organisms present.