Atmospheric depositional fluxes of trace elements, Pb-210, and Be-7 to theSargasso Sea

Atmospheric wet and bulk depositional fluxes of trace elements (Fe, Al, Mn, Zn, Pb, Cu, Cd, Ni, and Cr), Pb-210, and Be-7 (bulk only) to the Sargasso Sea were measured at Bermuda from September 1996 to September 1997. Wet dep osition was the dominant process of trace element deposition over most of t he sampling seasons, based on the measured bulk versus wet depositional flu xes. Although about half of the Mn in Bermuda precipitation was calculated to originate from noncrustal sources, its seasonal trend is similar to the Fe and Al, suggesting primary sources from continental crustal materials. O n the other hand, Cd, Zn, Pb, Cu, Ni, and Cr in Bermuda precipitation origi nate mainly from noncrustal sources (presumably anthropogenic) based on enr ichment factor analyses. The noncrustal sources were highest during the fal l-winter due to more frequent intrusion of U.S. continental air as the Berm uda High weakens. Atmospheric depositional fluxes of Pb-210 showed a good c orrelation with the Be-7 fluxes (r(2)=0.84) at Bermuda, indicating major tr ansport of Pb-210 via the upper troposphere from continents, along with oth er trace elements. Annual depositional fluxes of noncrustal elements (Cd, Z n, Pb, Cu, Ni, and Cr) at Bermuda were a factor of 2 to 3 lower than those at the mid-Atlantic Eight and were about 2-20 fold lower during the samplin g year than those during the early 1980s. This confirms the rapid evolution of trace element inputs to the upper Sargasso Sea during the last few deca des resulting from industrial emission controls in the surrounding continen ts.