科研之友
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摘要
In marine systems, Po-210 and Pb-210 disequilibria are being increasingly used to examine oceanic particle formation and export. Here, an updated assessment of current methods for determining Po-210 and Pb-210 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 Po-210 and Pb-210 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 Po-210 and Pb-210 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 Pb-210 activity with a relative uncertainty of about 7%. However for Po-210 activities, the final relative uncertainty is more variable and depends on the Po-210/Pb-210 activity ratio in the initial sample and the time elapsed between sampling and sample processing. The lowest relative uncertainties on Po-210 that can be obtained by this method is 6% and can only be obtained for samples with high Po-210/Pb-210 activity ratios (%26gt;1) that were rapidly processed.
- 出版日期2013-10
