A methods assessment and recommendations for improving calculations and reducing uncertainties in the determination of 210Po and 210Pb activities in seawater. (25th October 2013)

• Record Type: Journal Article
• Authors: Rigaud, S.; Puigcorbé, V.; Cámara‐Mor, P.; Casacuberta, N.; Roca‐Martí, M.; Garcia‐Orellana, J.; Benitez‐Nelson, C. R.; Masqué, P.; Church, T.
• Is Part Of: Limnology and oceanography, methods. Volume 11:Number 10(2013:Oct.)
• Page Start: 561
• Page End: 571
• Publication Date: 2013-10-25
• Subjects: Limnology -- Methodology -- Periodicals; Oceanography -- Methodology -- Periodicals; 551.48
• DOI: 10.4319/lom.2013.11.561
• Languages: English
• ISSNs: 1541-5856

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>In marine systems, <sup>210</sup>Po and <sup>210</sup>Pb disequilibria are being increasingly used to examine oceanic particle formation and export. Here, an updated assessment of current methods for determining <sup>210</sup>Po and <sup>210</sup>Pb activity in marine samples is provided and includes a complete description of the vast number of calculations and uncertainties associated with Po and Pb loss, decay, and ingrowth during sample processing. First, we summarize the current methods for the determination of <sup>210</sup>Po and <sup>210</sup>Pb activities in dissolved and particulate seawater samples and recommend areas for improvement. Next, we detail the calculations and associated uncertainties using principles of error propagation, while also accounting for radionuclide ingrowth, decay, and recovery. A spreadsheet reporting these calculations is included as a downloadable Web Appendix. Our analysis provides insight into the contributions of the relative uncertainty for each parameter considered in the calculation of final <sup>210</sup>Po and <sup>210</sup>Pb activities and gives recommendations on how to obtain the most precise final values. For typical experimental conditions in open seawater, we show that our method allows calculating <sup>210</sup>Pb activity with a relative uncertainty of about 7%. However for <sup>210</sup>Po activities, the final relative uncertainty is more variable and depends on the <sup>210</sup>Po/<sup>210</sup>Pb activity ratio in the initial sample and the time elapsed between sampling and sample processing. The lowest relative uncertainties on <sup>210</sup>Po that can be obtained by this method is 6% and can only be obtained for samples with high <sup>210</sup>Po/<sup>210</sup>Pb activity ratios (>1) that were rapidly processed.</p> </abstract>