Influences of atmospheric transport pathways on radionuclide activities inaerosol particles from over the North Atlantic

Data for Be-7 (produced in the upper troposphere and lower stratosphere (UT /LS)) and Pb-210 (a tracer of continental emissions) activities in daily ae rosol samples from over the North Atlantic were combined with meteorologica l information to investigate how the composition of aerosol particles varie d in relation to transport pathways and precipitation scavenging. The stron gest UT/LS influences (highest Be-7/Pb-210 ratios) occurred in winter, but differences in nuclide activities among sites reflect heterogeneity over th e basin. High values for a radionuclide loading index (RLI) at Bermuda were matched to northwesterly air mass trajectories, while low RLIs, due at lea st in part to precipitation scavenging, occurred under easterly flow. The a ctivities of both nuclides and the RLI at Bermuda were lower on rainy versu s nonrainy days, but there was no evidence that a day-of-the-week cycle was imposed on radionuclide activities by precipitation scavenging.