Impact of wildfires on nickel contamination at ultramafic drinking water catchment sites : A model study in New Caledonia

Wildfires represent a growing environmental forcing on continental ecosystems. An underestimated impact is trace metals dispersion toward freshwater systems after soil heating. In New Caledonia where Ni-rich ultramafic soils are widespread, such a dispersion is suspected to be partly responsible for the significant nickel impregnation of the inhabitants through consumption of impacted freshwater. The aim of this proposal is to address this issue by assessing nickel speciation at a model site representative of the most fire-sensitive drinking water catchment sites of this French overseas Territory. Ni K-edge XAS information will be coupled with data on nickel leachability to understand how wildfires can impact drinking water quality through nickel dispersion from ultramafic soils/sediments. Beyond the single case of New Caledonia, this work will serve as a model study for Ni-rich mafic and ultramafic tropical continental settings, which are increasingly exposed to wildfires.