Atmospheric fluxes of 210Pb to the western Mediterranean Sea and the Saharan dust influence

Abstract

Pb 210 is a well known tracer of particle dynamics in the marine environment. Geochemical models partially rely on the knowledge of its atmospheric input. Unfortunately, this is poorly known in the western Mediterranean Sea, especially regarding long‐term records. In this work we have evaluated the 210Pb annual atmospheric flux to this region from the analysis of 12 soil cores collected from coastal and island sites and total atmospheric deposition collected in Corsica during 1 year. The 210Pb fluxes ranged from 34 ± 3 to 121 ± 12 Bq m−2 yr−1, with an average of 75 Bq m−2 yr−1, and were strongly correlated (R2 = 0.95) with mean annual rainfall. This provides the possibility to determine 210Pb fluxes in a given location if the mean annual rainfall is well known, a useful outcome for both marine biogeochemical and soil erosion studies in this region. We have also estimated the mean annual atmospheric flux of 210Pb due to Saharan dust events registered in total deposition north of Barcelona during the last 17 years, yielding a value of 20 Bq m−2 yr−1. This flux represents a fraction of about 16% of the total atmospheric deposition of 210Pb in this area, but it could be up to 50% in sites with lower rainfall.