Trace Elements in Total Atmospheric Deposition Directly Measured Over the Caribbean Region: Natural Versus Anthropogenic Sources and Geographic Origin

Abstract

Dust, sea salt, and anthropogenic and biogenic particles in total atmospheric deposition are sources of essential elements that can significantly impact biogeochemical cycles in the Atlantic Ocean and in islands of the Caribbean region. This unique 41‐month data set records direct sampling of total atmospheric deposition from March 2015 to August 2018 in Guadeloupe (North Tropical Atlantic Ocean). It quantifies the total atmospheric deposition fluxes of 33 trace elements. Results on deposition samples for Sr and Nd isotopic signatures are consistent with previous studies conducted in the Caribbean region based on aerosol samples, confirming that trans‐Atlantic Saharan dust originated predominantly in the Libya‐Algeria‐Mali region of North Africa. The REE composition is stable for the majority of samples, though some slight inter‐annual variation was observed. Samples collected in 2016 present slightly different REE patterns compared to those collected in 2015, 2017, and 2018. A large fraction of some trace elements (Se, Sb, Cu, Mo, As, and Pb) may come from biogenic sources or from atmospheric pollution occurring at the global level. Lead isotope ratios reveal a mixture of transatlantic dust from the Libya‐Algeria‐Mali region, and anthropogenic sources with no clearly defined region of origin. This result highlights the need for updated reviews of aerosol lead isotopic signatures worldwide. Backward trajectory analysis suggests that atmospheric pollution from North America and Europe may be a significant source of Sb, whereas biogenic gas from the Sargasso Sea may contribute to high levels of Se.