Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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Author: Violeta Hansen Title: Chemical Speciation Analysis and Environmental Behaviour of 127 I and 129 I Division: Radiation Research This thesis is submitted in fulfilment of requirements for the Ph. D. degree at Risø National Laboratory for Sustainable Energy, Technical University of Denmark. Abstract: This thesis deals with chemical speciation analysis and behaviour of the anthropogenic radioisotope 129 I as well as stable iodine 127 I in environmental samples such as freshwater, seawater, soils, sediments and seaweed. The behaviour and chemical speciation of iodine ( 127 I and 129 I) in environmental samples are very complex and strongly dependent on several factors, such as water/soil/sediment chemistry, seaweed type, different pH, Eh, quantity and quality of organic matter, microbiological activity as well as differences in contaminant origin. The 129 I isotope, where the main inventory has been present in the biosphere for a relatively short time, may not show the same behaviour as the stable 127 I isotope. The present study illustrates this. Chemical speciation analysis of 129 I and 127 I as iodide, iodate and total inorganic iodine in seawater samples from the Baltic Proper, Skagerrak and Kattegat has been carried out. The general trend in variability of the iodide and iodate speciation of the two iodine isotopes is, to a large extent, linked to environmental conditions. The important findings of this study are that the reduction of iodate and oxidation of iodide in Skagerrak and Kattegat may be a slow process while along the Baltic Sea surface water reduction of iodate is a relatively fast process. Although suboxic or anoxic condition are encountered in some of the Baltic Sea deep basins, the concentration of 129 IO 3 - increases with water depth indicating that the reduction of iodate in the oxygen deficient bottom water of the Baltic Sea is a slow process. Iodine chemical speciation analysis (as iodide, iodate and total iodine including inorganic and organic iodine species) in lake water samples collected from Denmark and southern Sweden has been carried out. Destruction of organic iodine was performed by alkaline oxidation using NaOH – NaClO at 100 0 C and anion exchange chromatography was used for separation of iodide and iodate. Iodine-129 concentrations in the lakes ranged from 1.3 – 12.8 ×10 9 at/L and show elevated concentrations in lakes located in southwest Jutland (Denmark), near the North Sea. Except the Skærsø Lake, were the organic iodine – 127 accounts for 50% of the total iodine, iodide (both 129 I and 127 I) is the predominant species form in surface water of the studied lakes. 129 127 An investigation was conducted in order to quantify the total aquatic iodine ( I and I as inorganic and organic iodine) from fresh water and seawater samples by adsorption onto activated charcoal and DEAE 32 cellulose followed by alkaline digestion or combustion. The results show that iodide from freshwater samples can easily be adsorbed onto activated charcoal. The sorption was not affected by the pH. The absorption capacity of iodate is low and reduces quickly when its concentration increases. Compared with activated charcoal, DEAE 32 cellulose showed a lower adsorption capacity of inorganic and organic iodine species. Adsorption of iodine species onto activated charcoal and DEAE 32 cellulose from seawater samples shows that only about 10% of the total iodine in seawater can be adsorbed onto those materials. Adsorption of iodine species from water samples onto activated charcoal/DEAE is not a suitable method for quantifying the total iodine in freshwater and seawater. An investigation was conducted in order to decompose organic iodine using K2S2O8 in water samples for developing a method 129 127 for quantification of aquatic organic iodine ( I and I). The results show that iodine was quantitatively removed even when the concentration of organic iodine compounds in the studied sample was very high. Due to this, oxidation of iodine organic matter by using K2S2O8 followed by reduction of iodine species and precipitation with silver can be a potential method for determination of total iodine in fresh water samples. An improvement was made of the method for 129 I and 127 I speciation analysis in soil and sediment samples involving the extraction and fractionation of organic matter. The improved method was further used for the partitioning of 127 I and 129 I in marine sediments and soils. Sequential extraction results point out that partitioning of 127 I and 129 I within the organic fraction in soil and marine sediments is controlled by pH conditions where pH values below 5.0-5.5 promote occurrence of 127 I and 129 I in the humic acid, while at pH > 6 the partitioning was in the fulvic acid fraction. Anoxic conditions seemed to increase the mobility and availability of iodine compared to oxic, while suboxic conditions (soils) reduced the availability of the water soluble fraction compared to the subaqueous (marine) one. The distribution of 129 I/ 127 I values differed significantly between phases and samples, indicating that equilibrium with stable iodine have not yet been reached for a large fraction of the released 129 I. This means that geochemical models based on stable iodine behavior may not necessarily be able to predict the present behavior of I-129. Concentrations of 129 I and 127 I in archived Fucus Vesiculosus samples collected between 2002 – 2010 at Romø (German Bight), Klint (Kattegat) and Bornholm were analysed. Since previous investigations have shown that iodine speciation differ between the sites a comparison between 129 I/ 127 I ratios in seaweed relative to water at the three sites were done in order to evaluate if uptake was independent on speciation. The 129 I/ 127 I (seaweed) relative 129 I/ 127 I (seawater) were found to be 0.5 for the North Sea (2005), 0.7 (2006) for Southern Kattegat and 0.97 (2007) for Bornholm. In spite of the very different iodine speciation at the three sites the concentration ratio seaweed to water is more or less the same indicating that Fucus Vesiculosus can be used as a bio-indicator for iodine-129 in the marine environment. The results shows however that iodide is somewhat more efficient accumulate than iodate in Fucus. 127 A rapid on-line HPLC-ICP-MS method for direct speciation analysis of I (as iodide and iodate) in water samples was developed. The method was further used for the speciation analysis of 127 I in freshwater and seawater (following dilution). The results demonstrate that the on-line HPLC – ICP - MS method developed in this study is reliable and efficient for accurate assay for speciation analysis of stable iodine in water samples. Due to the low concentrations of 129 I in the environment the HPLC-ICP- MS method cannot be applied for speciation analysis of this isotope in environmental samples but can be applied for water samples highly contaminated with 129 I. Risø-PhD-81(EN) October 2011 ISBN 978-87-550-3889-9 Pages:175 Tables:10 References:106 Information Service Department Risø National Laboratory for Sustainable Energy Technical University of Denmark P.O.Box 49 DK-4000 Roskilde Denmark Telephone +45 46774005 bibl@risoe.dtu.dk
Thesis for the Degree of Doctor of Philosophy Radiation Research Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark Chemical Speciation Analysis and Environmental Behaviour of 127 I and 129 I Violeta Hansen To be presented with the permission of the Radiation Research Division for public criticism in Risø-DTU, Roskilde, Denmark on 28 th November, 2011 1
Page 1: Chemical Speciation Analysis and En
Page 5 and 6: Abstract This thesis deals with che
Page 7 and 8: environment since they reflect the
Page 9 and 10: organiske jodformer. Adsorption af
Page 11 and 12: None of this would have been possib
Page 13 and 14: Abbreviations and acronyms b+ - pos
Page 15 and 16: 3.1 Analytical Development………
Page 17 and 18: Table 1 Some properties of iodine P
Page 19 and 20: In soils/sediments iodine occurs as
Page 21 and 22: Table 2 Nuclear properties of iodin
Page 23 and 24: Liquid scintillation counting (LSC)
Page 25 and 26: The bioavailability of radioactive
Page 27 and 28: data (Englund et al., 2010; Hou et
Page 29 and 30: 2. Analytical procedures used in th
Page 31 and 32: 2.3 Quantification of total iodine
Page 33 and 34: Fig. 5 Quantification of total iodi
Page 35 and 36: iodate were measured by counting 12
Page 37 and 38: Fig. 6 Sequential extraction proced
Page 39 and 40: a Fig. 8 Calibration curve for (a)
Page 41 and 42: experiment was subjected to combust
Page 43 and 44: Table 7 Adsorption of iodine specie
Page 45 and 46: numbers 11-14), which is about the
Page 47 and 48: marine environment from nuclear fue
Page 49 and 50: 127 I - (ppb) 127 IO3 - (ppb) a b 1
Page 51 and 52: Although the oxygen concentration d
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129 I TBq 2,00E+00 1,80E+00 1,60E+0
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• Adsorption of iodine species on
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Reference Aldahan A, Kekli A, Possn
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Fuge R& Johnson C. 1986. The geoche
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Lo´pez-Gutie´rrez JM, Garcı ´a-
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Shinohara K. 2004. Measurement and
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http://www.irsn.fr/EN/news/Document
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Review Analytica Chimica Acta 632 (
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Table 1 Nuclear properties and prod
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Fig. 2. Liquid discharges of 129 I
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Fig. 5. Schematic diagram and pictu
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129 I in iodide and iodate is then
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Fig. 8. Diagram of air sampler for
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Fig. 10. Iodine L3-edge (a) and K-e
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analysis of 129 I in water sample a
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Yi P, Aldahan A, Hansen V, Possnert
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FIGURE 1. Sampling sites (the red s
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FIGURE 3. Horizontal distribution o
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FIGURE 5. Time series data of 129 I
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Environmental Science & Technology
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prepared using KI and KIO3. No diff
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of their contribution to the Baltic
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Fig. S-1 Sampling sites (the red so
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Fig. S-3 Vertical distribution of I
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Fig. S-5 Marine discharges function
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Fig.S-7 Relationship between I-129
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Table S-1 Results of I-129 and I-12
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S17
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Paper III Hansen,V., Yi, P., Hou, X
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conversion process between iodide a
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Table 1 Analytical results of 129 I
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August April I-129 iodide ( 10 8 at
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References Aldahan A, Kekli A, Poss
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Partition of iodine ( 129 I and 127
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Norway (Table 1). CTD-casts with ox
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5. Discussion 5.1. Separation of hu
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In the present study 40e60% of 129
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Hutta, M., Gora, R., 2003. Novel st
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Analysis of 129 I and 127 I in arch
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et al., 2002). Due to the fact that
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espectively. The iodine was leached
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salinities in the same area. Apart
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North Sea. 129 I/ 127 I ratios in w
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Table 2 Analytical results of 129-I
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129 I/ 127 I 1,40E-07 1,20E-07 1,00
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References Aldahan A, Englund E, Po
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O’Dowd, C.; Jimenez, J. L.; Bahre
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Iodine ( 129 I and 127 I) speciatio
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water in winter by molecular oxygen
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0.2 M KNO3. The effluent and the wa
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maximum values is at 0.03-0.06×10
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into the English Channel from the L
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References Aldahan A, Kekli A, Poss
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Risø-PhD-81(EN)
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Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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