Response of lead cycling in the surface Sargasso Sea to changes in tropospheric input

Lead and its stable isotopes have been analyzed in surface water samples (0-600 m) and trapped particles collected at the Bermuda Atlantic Time Series Station in April and November 1989. These results are compared with wet atmospheric lead deposition as determined from precipitation continuously collected in Bermuda since August 1988. Despite an expected seasonal variability, lead concentrations in surface waters have clearly decreased by 30 to 40% since 1979 in response to a corresponding decline by a factor of 5 to 8 of the tropospheric deposition. The actual ²⁰⁶Pb/²⁰⁷Pb average ratio in surface waters of the Sargasso Sea is estimated to be 1.188 (±0.004). -from Authors