Geochemical characterization (REE, Nd and Pb isotopes) of atmospheric mineral dust deposited in two maritime peat bogs from the St. Lawrence North Shore (eastern Canada)

Dust deposited on two ombrotrophic peat bogs (Baie and IDH bogs) of the St. Lawrence Gulf and Estuary north shore (Quebec) was geochemically characterized using rare earth element (REE) concentrations, Nd and Pb isotopes along with particle grain size. Both cores display similar Nd values, which suggests either a common source or sources with similar signatures in both regions. Combining Nd isotope data with REE patterns and particle size allowed for better insights into the source of deposited dust and the inference of past environmental and climatic conditions in both regions. REEs, Nd and grain-size distribution suggest that, over the last 2000 years, the Baie bog received more local dust due to increased local storminess in response to greater regional hydroclimatic variability. The same phenomenon occurred in the IDH bog since 620 cal a BP, i.e. during the Little Ice Age, where hydroclimatic and paleoecological changes have been previously documented. While the dust reconstructions and regional climatic records agree relatively well, the discrepancies between paleodust records highlight the complex and variable structure of late Holocene changes in paleoclimate and more particularly past dust deposition in eastern Canada.