Fate of reduced organic sulfur

Arctic suffers of the global warming and as a consequence ground- and surface waters are more and more mixed, increasing microbial activities.

Because roS are present in all living organisms as amino acids (i.e. cysteine and methionine), increasing microbial activities induce increasing production of reduced organic sulfur (roS) and organic matter (OM). Some metals and metalloids (Me) have a large affinity for roS (i.e. Pt2+, Pd2+, Hg2+, Cd2+, As(OH)3, Sb(OH)3), leading to the formation of ros-Me complexes.

The presence of roS modifies thus the fate, speciation (i.e. all chemical and physical forms), bioaccumulation and toxicity of Me.

Rate of roS and rate of Me are interconnected: aquatic living organisms produce roS in response to Me stress, in order to modify the speciation of Me, which in turn modifies the bioaccumulation and toxicity of Me.

Despite the interconnections of Me and S biogeochemical cycles, such roS-Me forms are neither quantified (i) in the environment (i.e. water), (ii) nor in laboratory ecotoxicological studies, (iii) or in ecotoxicological modelling, and (iv) only partly in laboratory geochemical experiments (i.e. only the model I developed in 2015 consider As association to reduced S of OM).

In Fate roS, we will elucidate roS-Me associations through analytical developments dedicated to natural waters, which will be able to quantify roS speciation in boreal waters (including high Arctic).

Thanks to a coupling of original experimental and spectroscopic results, a toxicogeochemical model will then be developed to predict the toxicity of Me and Me-roS.

A successful scientific and training project is expected due to a cleverly thought 3-way-transfer of complementary skills in between me, my supervisors of the host institution (HI) and the partner institution (PI) such as: Me geochemistry knowledge (me), S biogeochemical cycle and fate in arctic context (PI) and finally Me toxicity (HI).