Controlling factors and impacts of river-borne neodymium isotope signatures and rare earth element concentrations supplied to the Canadian Arctic Archipelago

Determining the factors controlling neodymium (Nd) isotopic compositions (expressed as ?Nd) and rare earth element (REE) concentrations of rivers is imperative to improve our understanding distribution these water mass tracers in ocean. Here we present first measurements <0.45 ?m-filtrate REE (i.e., concentration truly dissolved, nano-particulate colloidal REEs passing through a 0.45 ?m filter, hereafter referred dissolved) ?Nd draining into Canadian Arctic Archipelago (CAA). Results show large variation both (Nd=[8;37,260] pmol/kg) ([?32.1;?15.1]) thirteen sampled. Dissolved increase with increasing fractions metamorphic rocks ice cover rivers' watersheds, while PAAS-normalized patterns are inherited from watershed's bedrock lithology. The four watersheds composed Precambrian exhibit highest concentrations, least radiogenic ?Nd, shale-normalized enriched light REEs. remaining nine drain mainly or exclusively sedimentary have lower more generally heavy enrichment, variable negative cerium (Ce) anomalies. presence sheets drainage area, ionic strength, pH, dissolved organic carbon river main determining riverine by formation stabilization colloids. We estimate flow Nd transported discharging CAA equivalent flux seawater entering CAA. Depending on percentage removal during mixing seawater, impact exiting could be modest (if 90% removal) significant ?90% removal). This contribution potentially impart climate-sensitive signature reaching Baffin Bay, possible implications for use paleoceanographic reconstructions distribution.