Isobars Separation (¹³⁷Cs-^137mBa-¹³⁷Ba) from Marine Sediments, in Order to Evaluate Directly Their Radioactive Contamination by Mass Spectrometry

Abstract

Marine sediments contamination by fission product 137 Cs- 137m Ba is a fact since the period 1945-65, when plus than two thousand atomic explosion tests were performed mainly in the southern seas, earth region with minor population density. However, marine flows have produced dissemination of this radioactive pair through the sea bottom all over the world, at different levels, because the sea movement and natural decaying of radioactive pair: parent 137 Cs ( t 1/2 = 30.17 years) and daughter 137m Ba ( t 1/2 = 2.55 minutes). Radioactive detection of these contaminants, compared as percentage with that of natural 40 K ( t 1/2 = 1.28 × 10 9 years, 0.0118% of elementary K) leads to radiation contamination factor (RCF), as one possible unit to measure the radioactive contamination intensity in different regions, as well to determine if there is some other possible source of this contaminant, for example water cooling from power nuclear reactors when it is discharged at sea. However, radioactive detection always implies an unavoidable statistical variation, which makes more difficult to appreciate the changes as function of time and region. But at beginning of this century, mass spectrometry has got impressive advances, which makes it much more precise and sensible than radioactive detection [1]. This paper attempts to measure with other units the radioactive contamination: 137 Cs atoms number per gram of sample, instead radioactivity, which could be more direct and with minor standard deviation that radioactive detection, solving at same time the isobars separation: 137 Cs versus 137m Ba plus elementary 137 Ba (11.23% of Ba element).