Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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3.2 Analytical Development and Environmental Studies. 3.2.1 Speciation analysis as iodide, iodate and total iodine in fresh water samples by alkaline oxidation with NaOH - NaClO of organic iodine for total iodine quantification and anion exchange chromatography for separation of iodide and iodate (in paper VI). The chemical behavior of iodine and the extent with which it is able to be trapped by soils, sediments and plants or released into the atmosphere from lakes are mainly determined by its physico-chemical forms, i.e. speciation, and lesser extent by their gross concentrations. Iodine speciation analysis in lakes (as iodide, iodate and organic iodine) has not been so numerous. This report deals with laboratory studies conducted to provide needed input for determination of organic iodine as well as inorganic iodine in freshwater samples. Conventional, organic matter destruction can be performed by hydrolysis, reduction, wet oxidation and thermal methods (Stevenson, 1994). Oxidation methods include oxidizing agents, such as potassium permanganate (KMnO4), disodium peroxodisulphate (Na2S2O8), or sodium hypochlorite (NaOCl). In order to be able to include iodine-129 in the total iodine budget in the lake water it is not sufficient to summarize the iodate and iodide fractions resulting from inorganic speciation analysis using standard anion exchange. Since the iodine (both 127 I and 129 I) to a large extent may be associated to organic matter it is important to destroy this fraction or at least liberate the iodine from the organic matter so that it can be included in the budget. In this study the iodine organic matter was destroyed by using NaClO in alkaline medium at 150 0 C for 3h and then iodine was separated from the matrix as total iodine (inorganic and organic) by extraction and back-extraction with CHCl3 and KHSO4 solution. The inorganic iodine ( 129 I and 127 I) as iodide and iodate were investigated by using anion exchange chromatography coupled with accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICP-MS) respectively. 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) (Fåresø lake), near the North Sea. The concentration of stable iodine varies from 2.6 to 35.6 µg L -1 in Danish lakes and 4.8 to 7.6 µg L -1 in Swedish lakes. Except for a few locations in Denmark were organic iodine-127 accounts for around 50% of the total iodine-127 and the precipitation sample collected form Råsbäck, Sweden the iodine (both isotopes) associated to organic matter (calculated by subtracting inorganic iodine (iodide + iodate) from total iodine (see paper VI)) were not detected. Those results may be partly attributed to decomposition of NaClO which occurred while increasing the temperature (in this study 150 0 C for 3h). Due to this a part of iodine organic matter in those samples may not destroyed and consequently not measured. The results further indicate that iodide (both isotopes) is the predominate speciation form in surface water of the studied lakes. The higher concentrations of 129 I in lakes collected form Engsø, Fåresø and Skærsø, located near North Sea, southwest Jutland, comparing with those collected from southern Baltic Sea and Sweden (in Paper VI) may indicate that the 129 I concentrations in the studied lakes may be dominated by the continuous supply to the 44
marine environment from nuclear fuel reprocessing plants and subsequent redistribution through volatilization and precipitation. 3.2.2 Partitioning of Iodine ( 129 I and 127 I) Isotopes in Soil and Marine Sediments (in Paper IV). The mobility of iodine in soil and sediments seems to be strongly dependent on the content and type of organic matter (Aldahan et al., 2007; Lo´pez-Gutie´rrez et al., 2004; Gallagher et al., 2005, Muramatsu et al., 1996). Here we present a speciation analysis method for 129 I and 127 I in soil and sediment, to identify different iodine fractions such as water soluble, exchangeable, carbonate, oxide, as well as iodine associated to humic acid, fulvic acid, humin and unaffected mineral forms. The specific association of 129 I to humic acid, fulvic acid, and humin has not been reported earlier. For extraction of iodine bound to organic fractions (humic and fulvic acid), two different extractants as well as optimal leaching time of this fraction were investigated (in Paper IV). The analytical results point out that a large part of 127 I (30-50%) and 129 I (40-60%) in soil and marine sediments associate with soluble humic and fulvic acids. The isotope distribution among organic fractions seemed to be controlled by pH conditions, where a pH value below 5.0-5.5 promoted occurrence of 127 I and 129 I in the humic acid fraction while at pH > 6 the partitioning was towards the fulvic acid fraction. The large part (30-60%) of total iodine ( 127 I and 129 I) bound to the organic matter fraction as well as the primary association of both iodine isotopes with humic acid at a soil/sediment pH below 6 and with fulvic acid at a sediment pH above 6 may indicate that the mechanism by which iodine is bound to organic matter is similar for both isotopes. Another important finding of this study is that 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. 3.3 Environmental Studies. 3.3.1 Speciation analysis of iodine as iodide, iodate and total inorganic iodine in seawater profiles samples collected from the Baltic Proper, Skagerrak and Kattegat (in Papers II, III and unpublished results). Long physical half life, long residence time in the marine environment and continuous releases from nuclear fuel reprocessing plants make 129 I a suitable transient tracer for studies of the marine biogeochemical cycle of stable iodine, using its chemical speciation. Here we applied a modified version of 45
Page 1 and 2: 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: numbers 11-14), which is about the
Page 49 and 50: 127 I - (ppb) 127 IO3 - (ppb) a b 1
Page 51 and 52: Although the oxygen concentration d
Page 53 and 54: 129 I TBq 2,00E+00 1,80E+00 1,60E+0
Page 55 and 56: • Adsorption of iodine species on
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
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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
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
Page 115 and 116:
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
Page 127 and 128:
Hutta, M., Gora, R., 2003. Novel st
Page 129 and 130:
Analysis of 129 I and 127 I in arch
Page 131 and 132:
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
Page 137 and 138:
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
Page 143 and 144:
References Aldahan A, Englund E, Po
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O’Dowd, C.; Jimenez, J. L.; Bahre
Page 147 and 148:
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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