Measuring bismuth-210, its parent, and daughter in aquatic systems

Bi-210 (t(1/2): 5.01 d)-the daughter of Pb-210 and parent of Po-210-has rarely been measured in aquatic systems, and its behavior in the water column is poorly understood. In this article, I present a method for quickly measuring Pb-210, Bi-210, and Po-210 in aquatic samples, where (1) Bi-210 and Po-210 are scavenged onto an anion solid-phase extraction disk within 15 min of pretreating the sample; (2) beta decay of Bi-210 is counted on the disk immediately thereafter; (3) Po-210 is subsequently removed from the disk and redeposited on a copper plate for alpha-spectroscopy; and (4) Pb-210 is determined via the ingrowth of Bi-210. I present decay-corrected calculations for total, dissolved, and particle-bound fractions of each nuclide and conclude with an analysis of Pb-210, Bi-210, and Po-210 activities in rain, dreissenid (quagga) mussels, and water samples from the Milwaukee Inner Harbor in Lake Michigan. Results show that the loss of lead on the anion solid-phase extraction disks was negligible (0.2% +/- 2.1%; +/- 1 SD, n = 4), and the sorption of bismuth was complete (99% +/- 2%; +/- 1 SD, n = 16). Relative mean absolute deviations of duplicate sample analyses of lake water were 2.4% +/- 1.9% for Pb-210 (geometric mean of total sample activity: 3.0 disintegrations per minute [dpm], n = 6), 7.7% +/- 5.8% for Bi-210 (geometric mean of total sample activity: 2.6 dpm, n = 8), and 2.7% +/- 1.7% for Po-210 (geometric mean of total sample activity: 1.4 dpm, n = 8).