Résumé/Abstract In this work, the 137 Cs dating technique with improved accuracy is shown to be a... more Résumé/Abstract In this work, the 137 Cs dating technique with improved accuracy is shown to be a powerful tool for establishing chronologies in different (lacustrine, marine) young aquatic deposits. The method has special importance when the 210 Pb method gives partial or unclear results.
The determination of the specific activities of 210Po and isotopic uranium by alpha spectrometry ... more The determination of the specific activities of 210Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and 210Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which 210Po and Isotopic Uranium were determined using liquid-liquid extraction with tributyl phosphate (TBP). Furthermore, it was made a comparison between the TBP technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for 210Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the 234U and 238U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that ch...
On-site studies have shown the radiological impact on the Tinto and Odiel rivers (SW of Spain) by... more On-site studies have shown the radiological impact on the Tinto and Odiel rivers (SW of Spain) by the phosphogypsum produced as wastes in several phosphoric-acid industries located in this area. Leaching of natural radionuclides (Ra-226, Po-210, U-234, U-238) from phosphogypsum piles formed on the bank of the Tinto river has been identified as one of the main routes of radiological impact. The aim of this work was to study the 226Ra and U-isotope leaching behaviour from phosphogypsum for a better understanding of the radiological impact caused in these aquatic systems. (c) 2005 Elsevier Ltd. All rights reserved.
Profiles of artificial fallout (such as 137Cs) and natural radioactivity radionuclides in sedimen... more Profiles of artificial fallout (such as 137Cs) and natural radioactivity radionuclides in sediment cores are useful tools to study sedimentological properties of different aquatic environments as well as to evaluate average sedimentation rates. In the Portil lagoon, a small natural reservoir located in Huelva province (southwest of Spain), and through the analysis of 210Pb, 226Ra, 137Cs, 238U and 210Po vertical profiles in sediment cores, it is shown how the accumulative or transport character of the collection zones may be inferred. In the accumulation zone of the lagoon the influence of focusing effects has been analysed and an average sedimentation rate has been determined through 210Pb in one sediment core. This 210Pb-sedimentation rate is consistent with sediment dating based on the 137Cs data.
A radiochemical sequential extraction procedure has been developed in our laboratory to determine... more A radiochemical sequential extraction procedure has been developed in our laboratory to determine 226Ra and 234,238U by alpha-particle spectrometry in environmental samples. This method has been validated for both radionuclides by comparing in selected samples the values obtained through its application with the results obtained by applying alternative procedures. Recoveries obtained, counting periods applied and background levels found in the alpha spectra give suitable detection limits to allow the Ra and U determination in operational forms defined in riverbed contaminated sediments. Results obtained in these speciation studies show that 226Ra and 234,238U contamination tend to be associated to precipitated forms of the sediments.
Résumé/Abstract In this work, the 137 Cs dating technique with improved accuracy is shown to be a... more Résumé/Abstract In this work, the 137 Cs dating technique with improved accuracy is shown to be a powerful tool for establishing chronologies in different (lacustrine, marine) young aquatic deposits. The method has special importance when the 210 Pb method gives partial or unclear results.
The determination of the specific activities of 210Po and isotopic uranium by alpha spectrometry ... more The determination of the specific activities of 210Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and 210Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which 210Po and Isotopic Uranium were determined using liquid-liquid extraction with tributyl phosphate (TBP). Furthermore, it was made a comparison between the TBP technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for 210Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the 234U and 238U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that ch...
On-site studies have shown the radiological impact on the Tinto and Odiel rivers (SW of Spain) by... more On-site studies have shown the radiological impact on the Tinto and Odiel rivers (SW of Spain) by the phosphogypsum produced as wastes in several phosphoric-acid industries located in this area. Leaching of natural radionuclides (Ra-226, Po-210, U-234, U-238) from phosphogypsum piles formed on the bank of the Tinto river has been identified as one of the main routes of radiological impact. The aim of this work was to study the 226Ra and U-isotope leaching behaviour from phosphogypsum for a better understanding of the radiological impact caused in these aquatic systems. (c) 2005 Elsevier Ltd. All rights reserved.
Profiles of artificial fallout (such as 137Cs) and natural radioactivity radionuclides in sedimen... more Profiles of artificial fallout (such as 137Cs) and natural radioactivity radionuclides in sediment cores are useful tools to study sedimentological properties of different aquatic environments as well as to evaluate average sedimentation rates. In the Portil lagoon, a small natural reservoir located in Huelva province (southwest of Spain), and through the analysis of 210Pb, 226Ra, 137Cs, 238U and 210Po vertical profiles in sediment cores, it is shown how the accumulative or transport character of the collection zones may be inferred. In the accumulation zone of the lagoon the influence of focusing effects has been analysed and an average sedimentation rate has been determined through 210Pb in one sediment core. This 210Pb-sedimentation rate is consistent with sediment dating based on the 137Cs data.
A radiochemical sequential extraction procedure has been developed in our laboratory to determine... more A radiochemical sequential extraction procedure has been developed in our laboratory to determine 226Ra and 234,238U by alpha-particle spectrometry in environmental samples. This method has been validated for both radionuclides by comparing in selected samples the values obtained through its application with the results obtained by applying alternative procedures. Recoveries obtained, counting periods applied and background levels found in the alpha spectra give suitable detection limits to allow the Ra and U determination in operational forms defined in riverbed contaminated sediments. Results obtained in these speciation studies show that 226Ra and 234,238U contamination tend to be associated to precipitated forms of the sediments.
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Papers by Rafael Garcia-tenorio