Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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4. Conclusions and recommendations (perspectives) The principal findings of this thesis are summarized as follows: • A routine on-line HPLC-ICP-MS procedure for analysis of 127 I as iodide, iodate and other iodine species in fresh and seawater samples and leachate from soil/sediment and seaweed has been developed. The iodate (1-tret = 0.66 min) and iodide (2-tret = 4.80 min) were qualitatively and quantitatively measured and no sample pretreatment is required. The reproducibility and accuracy of the procedure were evaluated through standard solutions. The method is rapid and very suitable for the in situ separation on board of research vessels. • The first documentation of 129 I and 127 I (as iodide and iodate) profiles from the Baltic Proper, Skagerrak and Kattegat covering two different seasons (summer 2006 and spring 2007) is presented. Reduction of iodate and oxidation of iodide in Skagerrak and Kattegat may be a slow process since insignificant change in 129 I and 127 I speciation was found along the water of those areas. Reduction of iodate to iodide seems to be a relatively fast process in surface water of the southern Baltic Sea since iodide is the predominant chemical specie along the surface and deep water profiles of the Baltic Sea. Furthermore in spite of suboxic or anoxic condition encountered in some of the Baltic Sea deep waters, the concentration of 129 IO3 - increases with water depth indicating that the reduction of iodate in the anoxic bottom water of Baltic Sea as a slow process. • Chemical speciation analysis of 129 I and 127 I (as iodide, iodate and organic iodine) in fresh water samples collected from Denmark and Sweden in 2007 was carried out. 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. The 129 I concentration in the studied lakes may be dominated by the continuous supply to the marine environment from the nuclear fuel reprocessing plants (La Hague (France) and Sellafield (U.K.)) and subsequent redistribution through volatilization from seawater followed by precipitation. Except for the Skærsø Lake, were the organic iodine – 127 accounts for 50% of the total iodine, the iodide (both 129 I and 127 I) is the predominant species form in surface water of the studied lakes. 52
• Adsorption of iodine species on activated charcoal and or/DEAE 32 cellulose was investigated as a possibility for quantification of its total concentration (as inorganic and organic iodine) in fresh and seawater samples. The results shown that the adsorption of iodide was high over the concentration range studied (1-30ppb) as long as the concentration of iodate was low. The presence of iodate, a relatively large ion with low effective charge, seems to block adsorption of iodide even at iodate levels as low as 5ppb. 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 9% of the total iodine in seawater can be adsorbed onto those materials. The large amounts of competitive ions that are present in the seawater may be the reasons for the low fraction of iodine absorbed onto activated charcoal and DEAE 32 cellulose. This method cannot be applied for determination of total concentration of iodine in fresh and seawater samples. • Oxidation of organic iodine by K2S2O8 followed by reduction to iodide and precipitation as silver iodide were studied. The results show that the iodine was quantitatively removed from studied sample, even when the concentration of iodine organic compounds extracted from soils and seaweed and added to studied fresh water increase significantly. Due to this, oxidation of iodine organic matter by using K2S2O8 followed by reduction of iodine species and precipitation with silver nitrate can be a potential method for determination of total iodine in fresh water samples. • Iodine-129 associated with humic and fulvic acid respectively and with humin in soil and sediments samples is reported for the first time. New findings on the partition of iodine in the organic fractions were presented. The iodine distribution among organic fractions seemed to be controlled by pH conditions, where pH value below 5.0-5.5 promoted occurrence of 127 I and 129 I in the humic acid while at pH > 6 the partitioning was towards fulvic acid. Another important finding of this study is that the anoxic conditions seem to increase the mobility and availability of iodine (larger fraction of extractable iodine in the water soluble and exchangeable fractions) compared to oxic, while suboxic conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. 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. 53
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Chemical Speciation Analysis and En
Page 3 and 4: Thesis for the Degree of Doctor of
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
Page 53: 129 I TBq 2,00E+00 1,80E+00 1,60E+0
Page 57 and 58: Reference Aldahan A, Kekli A, Possn
Page 59 and 60: Fuge R& Johnson C. 1986. The geoche
Page 61 and 62: Lo´pez-Gutie´rrez JM, Garcı ´a-
Page 63 and 64: Shinohara K. 2004. Measurement and
Page 65 and 66: http://www.irsn.fr/EN/news/Document
Page 67 and 68: Review Analytica Chimica Acta 632 (
Page 69 and 70: Table 1 Nuclear properties and prod
Page 71 and 72: Fig. 2. Liquid discharges of 129 I
Page 73 and 74: Fig. 5. Schematic diagram and pictu
Page 75 and 76: 129 I in iodide and iodate is then
Page 77 and 78: Fig. 8. Diagram of air sampler for
Page 79 and 80: Fig. 10. Iodine L3-edge (a) and K-e
Page 81 and 82: analysis of 129 I in water sample a
Page 83 and 84: Yi P, Aldahan A, Hansen V, Possnert
Page 85 and 86: FIGURE 1. Sampling sites (the red s
Page 87 and 88: FIGURE 3. Horizontal distribution o
Page 89 and 90: FIGURE 5. Time series data of 129 I
Page 91 and 92: Environmental Science & Technology
Page 93 and 94: prepared using KI and KIO3. No diff
Page 95 and 96: of their contribution to the Baltic
Page 97 and 98: Fig. S-1 Sampling sites (the red so
Page 99 and 100: Fig. S-3 Vertical distribution of I
Page 101 and 102: Fig. S-5 Marine discharges function
Page 103 and 104: Fig.S-7 Relationship between I-129
Page 105 and 106:
Table S-1 Results of I-129 and I-12
Page 107 and 108:
S17
Page 109 and 110:
Paper III Hansen,V., Yi, P., Hou, X
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conversion process between iodide a
Page 113 and 114:
Table 1 Analytical results of 129 I
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August April I-129 iodide ( 10 8 at
Page 117 and 118:
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
Page 129 and 130:
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
Page 145 and 146:
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
Page 157 and 158:
References Aldahan A, Kekli A, Poss
Page 160 and 161:
Risø-PhD-81(EN)
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Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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