Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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129 I/ 127 I in all the samples investigated here are four – five orders of magnitude higher than the reported natural isotopic ratio of 129 I/ 127 I (10 -12 , Fehn et al., 2007). The ratios of 129 I/ 127 I in Fucus from Rømø were found to be in order of 10 -7 and 10 -8 in Fucus from Bornholm. Those variations may be related to different factors as for example: i) Fucus from different locations have integrated the iodine signal over different periods of time meaning that the seaweed cannot be used as a monitor of water concentration, ii) short – term variations in the discharge of radioiodine from nuclear reprocessing plants, iii) variations in transfer factors from the two reprocessing plants in this case La Hague and Sellafield. Even if fluctuating biological functions in seaweed may be compensated for by using the 129 I/ 127 I ratio the question still remains to what level the seaweed is reflecting an average seawater ratio. This question is particularly interesting if the uptake of iodine depends on what species it occurs in. Previous investigation (Hou et al., 2007; Hansen et al., 2011) have shown that the two isotopes does not distribute among the two species, iodate and iodide, in a similar way. This is an effect of the very slow kinetic exchange between iodide and iodate in seawater. Iodine-129 in the form of iodide may thus remain as iodide even when the coastal water from the English Channel mixes with more open ocean water where the main fraction of stable iodine, I-127, exist in the form of iodate. If steady state conditions occur and the iodine uptake in seaweed would be the same irrespectively of species the concentration factor defined as ratio of 129 I/ 127 I (seaweed) relative 129 I/ 127 I (seawater) should be one. Using existing 129 I/ 127 I data in seawater from North Sea, Kattegat and Baltic Sea (Hou et al., 2007, Hansen et al. 2011) and combining it with the 129 I/ 127 I data at corresponding years presented here yields ratios of 0.5 for North Sea (2005), 0.7 (2006) for Southern Kattegat and ~1 (2007) for Bornholm. Thus, the 129 I/ 127 I ratios in collected Fucus samples, closely match with corresponding data from water. The somewhat larger difference at Rømø may be an effect of this location being closer to the source and the relatively short residence time of water in the 8
North Sea. 129 I/ 127 I ratios in water at this location may be expected to have a larger short term variance than sites further away such as Kattegat and the south Baltic Sea. The 129 I/ 127 I ratios in water at Rømø may thus deviate more from the average concentration which is reflected in the Fucus data. The time period over which Fucus is integrating water iodine is not known. The seawater salinity at the three locations may also be the reason for the large difference in concentration factors. The salinity at the three locations is roughly 35 ‰ (Romø), 18‰ (Klint) and 7‰ (Bornholm) respectively. Variation in concentration factors (Fucus to seawater ratios) between Fucus samples collected on the Swedish west and east coast were reported by Carlsson and Erlandsson (1991) for radiocesium where they observed higher concentration factors at lower salinity. Furthermore studies conducted with the aim of understanding the mechanism of iodine uptake in brown seaweed have pointed out that oxidation of seawater iodide to more lipophilic species such as HIO and I2 which finally are taken up by marine algae (Shaw 1959; Kupper et al., 1998). In seawater iodine exists mainly as iodide (-1), iodate (+5) and to a lesser extent as organic iodine (Wong and Zhang, 2003; Wong, 1991). Earlier publication by Hou et al., (2007) on the speciation pattern of 127 I in surface water of the North Sea (high salinity) near Rømø, indicate similar concentrations of iodide (0.126 µM) and iodate (0.121µM). Results of Hansen et al., (2011) shows relatively high concentrations of 127 I-iodide in surface water of Kattegat basin near Klint and Baltic Sea, Bornholm. Using the speciation pattern of iodine ( 129 I and 127 I) in seawater in all three surveys and combining it with the values of 129 I/ 127 I (seaweed) relative 129 I/ 127 I (seawater) we conclude that the iodide is more efficient to accumulate than iodate in Fucus. The high enrichment of iodine in Fucus may however be explained not only by preferential uptake of iodide since a significant increase of 127 I in Fucus occur mostly in autumn – winter even different speciation of 127 I in all three investigated studies occur. Several factors such as various physical parts of the plant, salinity, temperature, 9
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Chemical Speciation Analysis and En
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Thesis for the Degree of Doctor of
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Abstract This thesis deals with che
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environment since they reflect the
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organiske jodformer. Adsorption af
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None of this would have been possib
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Abbreviations and acronyms b+ - pos
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3.1 Analytical Development………
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Table 1 Some properties of iodine P
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In soils/sediments iodine occurs as
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Table 2 Nuclear properties of iodin
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Liquid scintillation counting (LSC)
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The bioavailability of radioactive
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data (Englund et al., 2010; Hou et
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2. Analytical procedures used in th
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2.3 Quantification of total iodine
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Fig. 5 Quantification of total iodi
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iodate were measured by counting 12
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Fig. 6 Sequential extraction proced
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a Fig. 8 Calibration curve for (a)
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experiment was subjected to combust
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Table 7 Adsorption of iodine specie
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numbers 11-14), which is about the
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marine environment from nuclear fue
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127 I - (ppb) 127 IO3 - (ppb) a b 1
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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
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
Page 111 and 112: 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
Page 119 and 120: Partition of iodine ( 129 I and 127
Page 121 and 122: Norway (Table 1). CTD-casts with ox
Page 123 and 124: 5. Discussion 5.1. Separation of hu
Page 125 and 126: 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
Page 133 and 134: espectively. The iodine was leached
Page 135: salinities in the same area. Apart
Page 139 and 140: Table 2 Analytical results of 129-I
Page 141 and 142: 129 I/ 127 I 1,40E-07 1,20E-07 1,00
Page 143 and 144: References Aldahan A, Englund E, Po
Page 145 and 146: O’Dowd, C.; Jimenez, J. L.; Bahre
Page 147 and 148: Iodine ( 129 I and 127 I) speciatio
Page 149 and 150: water in winter by molecular oxygen
Page 151 and 152: 0.2 M KNO3. The effluent and the wa
Page 153 and 154: maximum values is at 0.03-0.06×10
Page 155 and 156: 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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