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Journal Articles

Speciation of iodine isotopes inside and outside of a contaminant plume at the Savannah River Site

Schwehr, K. A.*; Otosaka, Shigeyoshi; Merchel, S.*; Kaplan, D. I.*; Zhang, S.*; Xu, C.*; Li, H.-P.*; Ho, Y.-F.*; Yeager, C. M.*; Santschi, P. H.*; et al.

Science of the Total Environment, 497-498, p.671 - 678, 2014/11

 Times Cited Count:14 Percentile:38.73(Environmental Sciences)

A new, accurate and simple pH-dependent solvent extraction method combined with accelerator mass spectrometry (AMS) measurement for $$^{129}$$I/$$^{127}$$I isotopes and iodine speciation (iodide, iodate, and organo-I) quantification in liquids of any ionic strength has been developed. We then validated the AMS method for activity concentration measurements with a recently developed gas chromatography mass spectrometry method for $$^{129}$$I concentrations of 1 Bq/L or higher. This technique was applied to $$^{129}$$I-contaminated groundwater from the Savannah River Site, USA, and demonstrated changes of $$^{129}$$I and $$^{127}$$I concentrations and speciation along a pH, redox potential, and organic carbon gradient. The data suggest that $$^{129}$$I/$$^{127}$$I and species distribution is strongly pH dependent. The new method can now be applied to a wide range of chemically-diverse aquatic systems, including uncontaminated environments.

Oral presentation

Analysis of $$^{90}$$Sr in environmental samples at the attogram-level by accelerator mass spectrometry

Martschini, M.*; Honda, Maki; Merchel, S.*; Winkler, S.*; Golser, R.*

no journal, , 

The quantitative analysis of $$^{90}$$Sr is cumbersome and time-consuming because it is a pure $$beta$$-ray emitter. The detection limit of $$^{90}$$Sr by conventional accelerator mass spectrometry (AMS) methods is comparable to the typical detection limit of 3 mBq for $$beta$$-ray detection methods, mainly due to the interference of the isobaric $$^{90}$$Zr. The worldwide unique Ion Laser Interaction Mass Spectrometry (ILIAMS), performed at the University of Vienna, effectively removes $$^{90}$$Zr with a laser and reaction gases. Therefore, the detection limits of $$^{90}$$Sr is superior ($$<$$0.1 mBq) to conventional AMS systems not equipped with such an ion-laser interaction isobaric removal system. In this study, $$^{90}$$Sr analysis in coral samples etc., an environmental sample under extreme conditions (e.g. low concentrations of $$mu$$Bq/g and limited sample volumes of grams), was tried. To lower the detection limit $$<$$0.1 mBq, Sr was purified (Sr carrier) from old age coral with almost no $$^{90}$$Sr contamination from atmospheric nuclear tests, chemical separation of environmental samples were conducted, and $$^{90}$$Sr was measured by AMS. The results showed that the detection limit of $$^{90}$$Sr achieved in the analysis was $$<$$0.03 mBq ($$^{90}$$Sr/Sr $$<$$5$$times$$10$$^{-16}$$, 1/100 of the $$beta$$-ray detection methods). The detection limit achieved in this study corresponds to 2 ag of $$^{90}$$Sr in 1 mg of Sr target. The latest results of highly sensitive $$^{90}$$Sr analysis in small amounts of general environmental samples (coral, seawater, etc.) are mainly presented.

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