Development of Lead-210 Measurement in Peat Using Polonium Extraction. A Procedural Comparison

Abstract

Abstract:Two chemical treatments for lead-210 measurement were compared on the sub-surface samples of a core from an ombrotrophic bog from East Belgium. The classical procedure involves a concentrated acid extraction of polonium. However, this treatment represents substantial health risks together with unknowns regarding both the degree of cleanliness and the Po extraction rate, and most importantly, is rather time consuming. We developed here an improved procedure involving an ashing step prior to acid extraction. This allows substantial improvements such as: 1/ the use of a relatively small amount of acid compared to the classical procedure and 2/ the substantial reduction of a total sample digestion time. Measurements of 210 Pb concentrations were conducted by alpha spectrometry. Results show a good agreement of unsupported 210 Pb activity obtained for both procedures, although some unknowns remain concerning the adsorption of 210 Po on the plastic test tube, the volatilization of a small amount of ash, or the absorption of alpha particle at the alpha source surface. This however should not affect the 210 Pb measurement as all the samples are spiked prior to ashing (i.e. the recoveries are fully monitored). Through this study, we are suggesting researchers to follow this new procedure in order to increase safety, cleanliness, better recovery and substantial time gain.

Seagrass Restoration Enhances “Blue Carbon” Sequestration in Coastal Waters

“…A 209 Po spike was added to each sample and digested in a microwave with concentrated nitric acid. Then, hydrogen peroxide and heat were used to digest the solution and extract the tracer from organic compounds [29]. Polonium was spontaneously electroplated onto stainless steel planchets and 209 Po/ 210 Po activities were measured via alpha spectrometry using silicon surface barrier detectors linked to a multi-channel analyzer [30].…”

Responses of the Roanoke Bayhead Delta to variations in sea level rise and sediment supply during the Holocene and Anthropocene

“…The bulk sediment was freeze dried and dry mass recorded. 210 Pb activities were determined via isotope-dilution alpha spectrometry for 210 Po, granddaughter isotope of 210 Pb, acknowledging that 210 Po and 210 Pb are in secular equilibrium with each other (Flynn, 1968;El-Daoushy et al, 1991;Matthews et al, 2007;de Vleeschouwer et al, 2010). To calculate excess 210 Pb, the supported ( 226 Ra) activity was subtracted from the total 210 Pb value (Appleby and Oldfield, 1992).…”

Recent acceleration of carbon accumulation in a boreal peatland, south central Alaska

“…Postmodern 14 C dates were calibrated using CALIBomb and a concatenation of the Levin's Vermunt and Schauinsland calibration data sets [ Levin and Kromer, 2004]. 210 Pb measurements were performed on an alpha spectrometer at GEOTOP of Université du Québec, Montréal, using an acid extraction of Polonium [Flynn, 1968;De Vleeschouwer et al, 2010]. The analytical error in 210 Pb measurements ranged from 1.6 to 3.8% and the constant rate of supply model [Appleby and Oldfield, 1978] was used to reconstruct recent peat chronologies since it is believed to constitute the best model for peatlands [Turetsky et al, 2004;Ali et al, 2008].…”