Analysis of Po, Bi, and Pb in atmospheric and oceanic samples by simultaneously auto-plating Po and Bi onto a nickel disc.

Po and Pb are commonly measured to study particle cycling and particulate organic carbon export (POC) flux from the upper ocean. Bi is a potential oceanographic tracer. However, no convenient and rapid analytical method for Bi has been developed in the marine environment due to its short half-life (5 days). The aims are to study factors influencing the simultaneous auto-plating of Po and Bi onto nickel disc and to develop an effective ship-board procedure for the rapid measurement of Po, Bi, and Pb at sea. The results suggest that the optimal conditions for auto-deposition of Po and Bi were achieved by using a 25 mm diameter nickel disc in 60 mL acidic solution (pH = 0.5) for 16 h at 25 ± 1 °C. By adding Po and Bi as yield tracers to the sediments, recoveries of Po and Bi were >90%. If Po or Bi were in equilibrium with Pb, Po and Bi could also be potential proxies for Pb in sedimentary chronology. The overall recoveries of Po and Bi were >70% for rainwaters and >60% for seawater samples, respectively, which indicates this analytical procedure is also applicable to marine and atmospheric environments. This method allows the rapid measurement of Bi on a ship and help to obtain its vertical profile or spatial distribution in the marine environment within 1-2 days.