Determination of soil depth profiles for 137Cs and 210Pb using gamma-ray spectrometry with Compton suppression
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137Cs and to a lesser extent, 210Pb have been widely used for soil erosion and sedimentation studies. The accuracy of their quantification is greatly dependent on the proper handling of the sources of error that may affect the results. These include ambient background variation, attenuation for the 210Pb 45 keV gamma-photons in the sample, efficiency calibration and large statistical errors due to low levels of radioactivities and small sample quantities combined with Compton scattering of high energy photons during acquisition. In this study, we investigated the distribution of both 210Pb and 137Cs in three soil cores from Konza and Fort Riley, Kansas. Special attention was given to the analytical treatment of the spectra and the uncertainty budget. We show here that the ambient background is a major factor in the results. If it is not well monitored, errors of as high as 25% can result. We investigated the advantages of using Compton suppression with gamma-ray spectrometry for 137Cs and 210Pb quantification. Natural matrix certified reference materials (CRM) were used for efficiency calibration and quality assurance.
Keywords210Pb Normal Mode Uncertainty Budget Certified Reference Material Efficiency Calibration
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