Aerosol Selenium at Bermuda and Barbados

Daily aerosol samples collected at Bermuda and Barbados as part of the Atmospherc/Ocean Chemistry Experiment (AEROCE) wen analyzed to evaluate the sources for selenium (Se). Isentropic trajectories wen used to further evaluate the sources suggested by the chemial information. At Bermuda, the major source for Se was anthropogeniccmissions from ~ G h ~ m e r i c a . Daily Seconcentrations wen highly comlated withantimony (Sb) which originated from a wllution source. However. a~oroximatelv 6% of the Sb was associated with mineral dust from nortiern ~ f r i c a thai reached Bermudaduringtk;ummer months. The Bermuda aerosol data showed a weak correlation between Se and methane sulfonate (MSA), but the intercept of the Se versus Sb regression indicated that a marine biogenic source of Se accounted for -45% of the mean concentration at Bermuda. At Barbados the variability of Se concentrations could not be explained solely by pollution sources. Conelations between Se and Sb, nitrate (NO,'), non-sea-salt sulfate (nsJsO;), and MSA were significant. The comlations of Se with Sb, NO,'. and nssSO; suggested continental sources. The cornlation with MSA indicated there was a significant marine biogenic source. Our results indicated that a marine biogenic source of Se accounted for 60-80% of the Se at Barbados. Analyses of seasonal relationships indicated that the marine biogenic source was most important during the summer.