Using lead-210, bismuth-210, and polonium-210 to estimate particulate organic carbon flux to the benthos of Lake Michigan

Abstract

210Bi is a short-lived (t1/2: 5.01 days) naturally occurring radionuclide and a potential tracer of particle dynamics in high flux aquatic environments such as lakes, coastal oceans, and continental shelves. While its parent, 210Pb, and daughter, 210Po, have been used to estimate particle removal rates from the ocean, few studies have investigated the behavior of 210Bi in aquatic systems or its use as a tracer of particle export fluxes. In this study, a time series experiment was conducted where 210Pb, 210Bi, and 210Po activities were measured in rainwater and in the water column on the slope of southwestern Lake Michigan. Particulate matter was filtered from the lake water samples to separate radionuclide activities into operationally defined particle-bound and dissolved (1. 2) 210Bi was observed to be in disequilibrium with its parent 210Pb. 3) 210Bi-derived POC export flux estimates were in agreement with concurrent 210Po-derived flux estimates.