Iodine soil dynamics and methods of measurement: a review.

Iodine is an essential micronutrient for human health: insufficient intake can have multiple effects on development and growth, affecting approximately 1.9 billion people worldwide. Previous reviews have focussed on iodine analysis in environmental and biological samples, however, no such review exists for the determination of iodine fractionation and speciation in soils. This article reviews the geodynamics of both stable 127I and the long-lived isotope 129I (t1/2 = 15.7 million years), alongside the analytical methods for determining iodine concentrations in soils, including consideration of sample preparation. The ability to measure total iodine concentration in soils has developed significantly from rudimentary spectrophotometric analysis methods to inductively coupled plasma mass spectrometry (ICP-MS). Analysis with ICP-MS has been reported as the best method for determining iodine concentrations in a range of environmental samples and soils due to developments in extraction procedures and sensitivity, with extremely good detection limits typically <µg L-1. The ability of ICP-MS to measure iodine and its capabilities to couple on-line separation tools has the significance to develop the understanding of iodine geodynamics. In addition, nuclear-related analysis and recent synchrotron light source analysis are discussed.

Selection and applicability of quenching agents for the analysis of polar iodinated disinfection byproducts.

Iodide is widely present in drinking water sources as well as wastewater effluents. Chlorination and chloramination are the most commonly used disinfection methods. During chlorination or chloramination of drinking water/wastewater effluents, iodide may be oxidized to hypoiodous acid, which may further react with organic matter to form iodinated disinfection byproducts (DBPs). Recently, several new polar iodinated DBPs have been identified in drinking water as well as chlorinated wastewater effluents, and they have drawn increasing concerns due to their high toxicity. In DBPs studies, the selection of an appropriate quenching agent is critical to prevent further formation or any decomposition of DBPs during the holding time between sample collection and analysis. A previous study reported the applicability of different quenching agents for the analysis of various categories of chlorinated and brominated DBPs. But the applicability of quenching agents for the analysis of polar iodinated DBPs has not been reported. In this study, four different quenching agents (sodium sulfite, sodium thiosulfate, ascorbic acid and sodium borohydride) were tested for their suitability for the analysis of polar iodinated DBPs, and ascorbic acid was selected as the suitable quenching agent. Furthermore, it was found that ascorbic acid was applicable for the analysis of polar iodinated DBPs under the quenching agent doses of 0-0.42 mmol/L (stoichiometric amounts equivalent to 0-30 mg/L Cl2), contact times within 24 h, and pHs in the range of 6-8. Therefore, ascorbic acid was a widely applicable quenching agent for the analysis of polar iodinated DBPs under various conditions.

Iodine speciation in dog foods and treats by high performance liquid chromatography with inductively coupled plasma mass spectrometry detection.

An analytical method for determination of the iodine species 3-monoiodotyrosine (MIT), iodide, 3,5-diiodotyrosine (DIT), 3,5-diiodothyronine (3, 5-T2), 3,5,3'-triiodothyronine (T3), and thyroxine (T4) in dog foods and treats is reported. Iodine speciation was carried out using a HPLC method capable of both anion-exchange and reversed-phase retention coupled with inductively coupled plasma mass spectrometry detection (LC-ICP-MS). The method was evaluated by the analysis of the iodine species concentrations in twelve dog foods and treats following enzymatic digestion. The concentrations of MIT, iodide, DIT, T3, and T4 in the samples ranged from 0.64-59.5µg/g, 0.86-4.05µg/g,

Use of Dual-Energy CT and Iodine Maps in Evaluation of Bowel Disease.

Dual-energy computed tomography (CT) relies on material-dependent x-ray absorption behavior from concurrently acquired high- and low-kilovolt peak data and has a range of imaging applications. This article focuses on use of dual-energy CT in assessment of bowel disease. After a summary of relevant dual-energy CT image acquisition and postprocessing principles, the authors describe dual-energy techniques of greatest utility in evaluation of benign and malignant pathologic conditions in the bowel, including neoplastic, vascular, infectious, and inflammatory disorders, as well as in assessment of abdominopelvic trauma. The dual-energy postprocessing techniques of iodine-selective imaging and virtual monochromatic imaging have the broadest applicability in bowel imaging. They may be used for improved visualization of subtle differences in bowel wall enhancement or for quantitative assessment of altered enhancement for evaluation of a neoplasm or bowel ischemia. Iodine images and virtual monochromatic low-kiloelectron volt images are particularly helpful for assessment of a neoplasm, ischemia, infection, or inflammation, while iodine maps paired with virtual nonenhanced images are most helpful to differentiate iodine from other dense materials, as in gastrointestinal bleeding or trauma. In most applications, radiation doses at dual-energy CT are comparable to those at traditional CT. However, dual-energy CT may allow reduction in radiation dose by using virtual nonenhanced images that obviate an additional nonenhanced CT acquisition. Limitations of dual-energy CT are discussed, including potential challenges in acquisition, postprocessing, and interpretation.

Dual-Energy CT-Based Differentiation of Benign Posttreatment Changes From Primary or Recurrent Malignancy of the Head and Neck: Comparison of Spectral Hounsfield Units at 40 and 70 keV and Iodine Concentration.

OBJECTIVE: The goals of our study were to evaluate dual-energy CT (DECT) differences between benign posttreatment changes and primary or recurrent head and neck malignancies in terms of spectral Hounsfield units for virtual monochromatic series at 40 keV and iodine concentration and compare their utility with that of spectral Hounsfield units at 70 keV. MATERIALS AND METHODS: A retrospective review of patients with a history of head and neck malignancy evaluated with DECT of the neck from November 2012 through December 2014 revealed 16 patients with benign posttreatment changes and 24 with malignancies (17 primary tumors and seven recurrent tumors). One reader placed ROIs within benign posttreatment changes or malignant tumors in each patient to generate spectral Hounsfield units at 40 keV, iodine concentration, and spectral Hounsfield units at 70 keV, and the Wilcoxon rank sum test was used to evaluate the differences between the two cohorts. ROC curves were also generated, and AUC and partial AUC were calculated at the three following specificities: 75%, 80%, and 90%. RESULTS: Malignant tissues were significantly different from benign posttreatment changes in spectral Hounsfield units at 40 keV (p < 0.0001), iodine concentration (p < 0.0001), and spectral Hounsfield units at 70 keV (p = 0.0001). The AUCs were 0.949, 0.943, and 0.858 for spectral Hounsfield units at 40 keV, iodine concentration, and spectral Hounsfield units at 70 keV, respectively. Both spectral Hounsfield units at 40 keV and iodine concentration had statistically higher partial AUCs than spectral Hounsfield units at 70 keV at 90% specificity (p = 0.0133 and 0.0063, respectively) but were not significantly different from each other. CONCLUSION: DECT-derived spectral Hounsfield units at 40 keV and iodine concentration may be superior to spectral Hounsfield units at 70 keV, which is similar to MDCT, in differentiating benign posttreatment changes from primary or recurrent head and neck malignancies.

Identification, toxicity and control of iodinated disinfection byproducts in cooking with simulated chlor(am)inated tap water and iodized table salt.

Chlorine/chloramine residuals are maintained in drinking water distribution systems to prevent microbial contamination and microorganism regrowth. During household cooking processes (e.g., soup making), the residual chlorine/chloramines in tap water may react with the iodide in iodized table salt to form hypoiodous acid, which could react with remaining natural organic matter in tap water and organic matter in food to generate iodinated disinfection byproducts (I-DBPs). However, I-DBPs formed during cooking with chloraminated/chlorinated tap water are almost completely new to researchers. In this work, by adopting precursor ion scan of m/z 127 using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, many new polar I-DBPs formed during cooking with chloraminated/chlorinated tap water were detected and proposed with structures, of which 3-iodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzoic acid, 3-iodo-4-hydroxy-5-methylbenzoic acid, diiodoacetic acid, 3,5-diiodo-4-hydroxybenzaldehyde, 3,5-diiodo-4-hydroxybenzoic acid, 2,6-diiodo-4-nitrophenol, 2,4-diiodo-6-nitrophenol, and 2,4,6-triiodophenol were confirmed with standard compounds. With the aid of ultra fast liquid chromatography/ion trap-time of flight-mass spectrometry, molecular formula identification of five new I-DBPs (C8H5O4I, C7H4NO4I, C8H5O5I, C7H4NO5I, and C8H6O3I2) was achieved. A developmental toxicity with a recently developed sensitive bioassay was conducted for the newly identified I-DBPs, suggesting that phenolic I-DBPs (except for iodinated carboxyphenols) were about 50-200 times more developmentally toxic than aliphatic I-DBPs. The major I-DBPs in a baseline simulated cooking water sample were determined to be from 0.72 to 7.63 µg/L. Polar I-DBPs formed under various disinfection and cooking conditions were compared, and suggestions for controlling their formation were provided.

Major Factors Affecting Incidence of Childhood Thyroid Cancer in Belarus after the Chernobyl Accident: Do Nitrates in Drinking Water Play a Role?

One of the major health consequences of the Chernobyl Nuclear Power Plant accident in 1986 was a dramatic increase in incidence of thyroid cancer among those who were aged less than 18 years at the time of the accident. This increase has been directly linked in several analytic epidemiological studies to iodine-131 (131I) thyroid doses received from the accident. However, there remains limited understanding of factors that modify the 131I-related risk. Focusing on post-Chernobyl pediatric thyroid cancer in Belarus, we reviewed evidence of the effects of radiation, thyroid screening, and iodine deficiency on regional differences in incidence rates of thyroid cancer. We also reviewed current evidence on content of nitrate in groundwater and thyroid cancer risk drawing attention to high levels of nitrates in open well water in several contaminated regions of Belarus, i.e. Gomel and Brest, related to the usage of nitrogen fertilizers. In this hypothesis generating study, based on ecological data and biological plausibility, we suggest that nitrate pollution may modify the radiation-related risk of thyroid cancer contributing to regional differences in rates of pediatric thyroid cancer in Belarus. Analytic epidemiological studies designed to evaluate joint effect of nitrate content in groundwater and radiation present a promising avenue of research and may provide useful insights into etiology of thyroid cancer.

Pharmaceuticals and iodinated contrast media in a hospital wastewater: A case study to analyse their presence and characterise their environmental risk and hazard.

This work analyses the presence of twenty-five pharmaceutical compounds belonging to seven different therapeutic groups and one iodinated contrast media (ICM) in a Spanish medium-size hospital located in the Valencia Region. Analysis of the target compounds in the hospital wastewater was performed by means of solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry analysis (HPLC-MS/MS). A screening level risk assessment combining the measured environmental concentrations (MECs) with dose-response data based on Predicted No Effect Concentration (PNEC) was also applied to estimate Hazard Quotients (HQs) for the compounds investigated. Additionally, the environmental hazard associated to the various compounds measured was assessed through the calculation of the Persistence, Bioaccumulation and Toxicity (PBT) Index, which categorizes compounds according to their environmentally damaging characteristics. The results of the study showed the presence of twenty-four out of the twenty-six compounds analysed at individual concentrations ranging from 5 ng L(-1) to 2 mg L(-1). The highest concentrations corresponded to the ICM iomeprol, found at levels between 424 and 2093 µg L(-1), the analgesic acetaminophen (15-44 µg L(-1)), the diuretic (DIU) furosemide (6-15 µg L(-1)), and the antibiotics (ABIs) ofloxacin and trimethoprim (2-5 µg L(-1)). The lowest levels corresponded to the anti-inflammatory propyphenazone, found at concentrations between 5 and 44 ng L(-1). Differences in terms of concentrations of the analysed compounds have been observed in all the therapeutic groups when comparing the results obtained in this and other recent studies carried out in hospitals with different characteristics from different geographical areas and in different seasons. The screening level risk assessment performed in raw water from the hospital effluent showed that the analgesics and anti-inflammatories (AAFs) acetaminophen, diclofenac, ibuprofen and naproxen, the antibiotics (ABIs) clarithromycin, ofloxacin and trimethoprim, and the ß-blocker (BBL) propranolol were present at concentrations leading to HQ values higher than 10, thus indicating high risk. When applying a factor to take into account potential dilution and degradation processes, only the compound ibuprofen showed a HQ higher than 1. Likewise, the cumulative HQ or Toxic Units (TUs) calculated in the raw water for each of the therapeutic groups studied showed that these three classes of drugs were at concentrations high enough to potentially generate high risk to aquatic organisms while taking into account possible dilution and degradation processes only one of them, the AAFs can be considered to represent high risk. Finally, the environmental hazard assessment performed showed that the AAFs diclofenac and ibuprofen and the ABI clarithromycin have the highest, maximum value of 9 of PBT Index due to their inherent environmentally damaging characteristics of persistence, bioaccumulation and toxicity. The methodology followed in the present case study can be taken as a novel approach to classify and categorize pharmaceuticals on the basis of their occurrence in hospital effluents, their derived environmental risks, and their associated environmental hazard. This classification becomes important because it can be used as a model or orientation for hospitals in the process of developing environmentally sustainable policies and as an argument to justify the adoption of advanced, specific treatments for hospital effluents before being discharged into the public sewage system.

The development and deployment of a ground-based, laser-induced fluorescence instrument for the in situ detection of iodine monoxide radicals.

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based instrument that measures IO at mixing ratios less than one part in 10(12). The IO radical is measured by detecting laser-induced fluorescence at wavelengths longer that 500 nm. Tunable visible light is used to pump the A(2)Π3/2 (v(') = 2) ← X(2)Π3/2 (v(″) = 0) transition of IO near 445 nm. The laser light is produced by a solid-state, Nd:YAG-pumped Ti:Sapphire laser at 5 kHz repetition rate. The laser-induced fluorescence instrument performs reliably with very high signal-to-noise ratios (>10) achieved in short integration times (<1 min). The observations from a validation deployment to the Shoals Marine Lab on Appledore Island, ME are presented and are broadly consistent with in situ observations from European Coastal Sites. Mixing ratios ranged from the instrumental detection limit (<1 pptv) to 10 pptv. These data represent the first in situ point measurements of IO in North America.

Development of a colorimetric method for the dosage of OI- anions and I2 in aqueous media.

Lactoperoxidase catalyzes the oxidation of thiocyanate (SCN-) and iodide (I-) in presence of hydrogen peroxide in hypothiocyanite (OSCN-) ions and, depending on the pH, in hypoiodite (OI-) ions or in iode (I2). Oxidized SCN- and I- are part of the lactoperoxidase system, which is a natural biological protection in cow milk, and are described as having inhibitory properties against pathogenic human bacteria, fungi and viruses. We have developed an aqueous solution containing only OSCN- and OI- ions (without the enzyme) and we tested it successfully against plant pathogens. In order to characterize this new soft chemical control against plant pathogens we had to determine the concentration of OSCN- and OI- ions. The dosage of OSCN- consists in a well referenced colorimetric method but no procedure is described for the determination of OI- ions. We have thus developed an easy method, based on the oxidation of the amine moiety of 3,3',5,5'- tetramethylbenzidine (TMB) by OI- or I2 in a strongly absorbing blue product for the detection and dosage of both molecules. Interestingly the OSCN- ions are not able to oxidize TMB and render this method specific to enzymatic oxidized iodide. We have calculated its sensitivity, repeatability and linearity. This method could also be used for the determination of OCI- and OBr- ions produced during the enzymatic oxidation of chloride and bromide by mammalian's peroxidases.

Use of eXIA 160 XL for contrast studies in micro-computed tomography: experimental observations.

The purpose of this study was to evaluate the time course of contrast enhancement of spleen, liver, and blood using eXIA 160 XL in healthy mice. eXIA 160 XL was intravenously injected in C57bl/6 mice (n  =  12) at a dose of 0.1 mL/20 g (16 mg iodine [I]/20 g) (n  =  6) or 0.2 mL/20 g (32 mg I/20 g) (n  =  6). The distribution was analyzed by repeated micro-computed tomographic scans up to 48 hours after contrast administration. Images were analyzed using Amide software. Regions of interest were drawn in the spleen, liver, and left ventricle. Contrast enhancement was measured and expressed as a function of time. Peak contrast enhancement of the spleen was reached at 30 minutes, and peak contrast enhancement of the liver occurred 45 minutes after 16 mg I/20 g. Given that this contrast was found to be rather low in the spleen in comparison with former eXIA 160 products, experiments were done at a higher dose. However, the 32 mg I/20 g dose was lethal for mice. Enhancement inside the heart lasts for 1 hour. Administration of eXIA 160 XL results in long-lasting blood pool contrast with higher contrast enhancement in heart and liver in comparison with eXIA 160; however, the administered dose should be limited to 16 mg I/20 g.

Frequency comb based spectrometer for in situ and real time measurements of IO, BrO, NO2, and H2CO at pptv and ppqv levels.

We report an instrument designed for trace gas measurement of highly reactive halogenated radicals, such as bromine oxide and iodine oxide, as well as for nitrogen dioxide and formaldehyde. This compact and robust spectrometer relies on an alternated injection of a frequency-doubled femtosecond radiation at 338 and 436 nm into two parallel high-finesse cavities, for measuring BrO + H(2)CO, and IO + NO(2), respectively. The transmission of the broadband radiation through the cavity is analyzed with a high resolution, compact spectrograph consisting of an echelle grating and a high sensitivity CCD camera. The transportable instrument fits on a breadboard 120 × 60 cm size and is suitable for in situ and real time measurements of these species. A field campaign at the Marine Boundary Layer in Roscoff (in the northwest of France, 48.7°N, 4.0°W) during June 2011 illustrates the outstanding performance of the instrument, which reaches a bandwidth normalized minimum absorption coefficient of 1.3 × 10(-11) cm(-1) Hz(-1/2) per spectral element, and provides detection levels as low as 20 parts per quadrillion of IO in 5 min of acquisition.

Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.

The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.

Measurement of hypoiodous acid concentration by a novel type iodide selective electrode and a new method to prepare HOI. Monitoring HOI levels in the Briggs-Rauscher oscillatory reaction.

A new type of iodide selective electrode prepared by dipping a silver wire into molten silver iodide is reported. The electrode was calibrated for silver and iodide ions and the measured electromotive force for various Ag(+) and I(-) concentrations was close to the theoretical within a few millivolts. Besides Ag(+) and I(-) ions, however, the electrode also responds to hypoiodous acid. Thus, the electrode was calibrated for HOI as well, and for that purpose a new method of hypoiodous acid preparation was developed. To explain the close to Nernstian electrode response for HOI and also the effect of hydrogen ion and iodine concentration on that response, the corrosion potential theory suggested earlier by Noszticzius et al. was modified and developed further. Following oscillations in the Briggs-Rauscher reaction with the new electrode the potential crosses the "solubility limit potential" (SLP) of silver iodide. Potentials below SLP are controlled by the concentration of I(-), but potentials above SLP are corrosion potentials determined by the concentration of HOI. Finally, the measured HOI oscillations are compared with calculated ones simulated by a model by Furrow et al.

Commemorating two centuries of iodine research: an interdisciplinary overview of current research.

Iodine was discovered as a novel element in 1811 during the Napoleonic Wars. To celebrate the bicentennial anniversary of this event we reflect on the history and highlight the many facets of iodine research that have evolved since its discovery. Iodine has an impact on many aspects of life on Earth as well as on human civilization. It is accumulated in high concentrations by marine algae, which are the origin of strong iodine fluxes into the coastal atmosphere which influence climatic processes, and dissolved iodine is considered a biophilic element in marine sediments. Iodine is central to thyroid function in vertebrates, with paramount implications for human health. Iodine can exist in a wide range of oxidation states and it features a diverse supramolecular chemistry. Iodine is amenable to several analytical techniques, and iodine compounds have found widespread use in organic synthesis. Elemental iodine is produced on an industrial scale and has found a wide range of applications in innovative materials, including semiconductors--in particular, in solar cells.

Low-level bromate analysis in drinking water by ion chromatography with optimized suppressed conductivity cell current followed by a post-column reaction and UV/Vis detection.

In the present work, a high capacity anion exchange column was used to efficiently and simultaneously separate traces of oxyhalide disinfection byproducts (DBP) anions and bromide by an ion chromatography system followed by a post-column reaction (PCR). The PCR generates in situ hydroiodic (HI) acid from the excess of potassium iodate that combines with bromate from the column effluent to form the triiodide anion detectable by UV/Vis absorbance at 352 nm. The suppressed conductivity cell current was optimized at 70 mA, with a flow rate of 1.0 mL/min and a 9 mM carbonate eluent. Its performance was investigated on a trace-level determination of bromate in ozonated municipal and bottled drinking water. Based on ozonated municipal drinking water matrix, the method detection limit of 0.27 µg BrO(-)(3)/L was evaluated with the Method Quantification Limit (MQL) of 0.89 µg BrO(-)(3)/L. However, in ultrapure water, a MDL of 0.015 µg BrO(-)(3)/L and a MRL of 0.052 µg BrO(-)(3)/L were achieved. The recovery for spiked municipal samples was in the range of 90%-115%.

Presence and partitioning behavior of polyfluorinated iodine alkanes in environmental matrices around a fluorochemical manufacturing plant: another possible source for perfluorinated carboxylic acids?

The indistinct origins of some ubiquitous perfluorinated alkyl acids have attracted great attention in recent decades. In this present work, even-chained polyfluorinated iodides (PFIs), a group of volatile perfluorinated compounds (PFCs), including four perfluorinated iodine alkanes (FIAs) and three polyfluorinated telomer iodides (FTIs) were confirmed to be present in the environment. A wide concentration range was found for FIAs at 1.41 to 3.08x10(4) pg/L, and for FTIs at 1.39 to 1.32x10(3) pg/L in the ambient air collected around a fluorochemical manufacturing plant in Shandong province, northern China. Whereas for surface soils, most of these PFIs were below detection limits and only small amounts of analytes with higher carbon chain (such as perfluorododecyl iodide and 1H,1H,2H,2H-perfluorodecyl iodide, 16.6-499 pg/g) could be sporadically detected. The presence of the PFIs in different environmental matrices in the investigated area and calculated vapor pressures (0.095-20.4 Torr) verify that they can be considered as volatile organic chemicals and easily be released into the atmosphere. Together with reported degradation ability and long-range transport potential, the identification of these PFIs indicates that unintentional release during the telomer reaction process might also be another route for the formation and distribution of certain polyfluorinated alcohols, aldehydes, and carboxylic acid derivatives under oxidative conditions in the environment.

A picture of polar iodinated disinfection byproducts in drinking water by (UPLC/)ESI-tqMS.

Iodinated disinfection byproducts (DBPs) are generally more toxic than their chlorinated and brominated analogues. Up to date, only a few iodinated DBPs in drinking water have been identified by gas chromatography/mass spectrometry. In this work, a method for fast selective detection of polar iodinated DBPs was developed using an electrospray ionization-triple quadrupole mass spectrometer (ESI-tqMS) by conducting precursor ion scan of iodide at m/z 126.9. With such a method, pictures of polar iodinated DBPs in chlorinated, chloraminated, and chlorine-ammonia treated water samples were achieved. By coupling state-of-the-art ultra performance liquid chromatography (UPLC) to the ESI-tqMS, structures of 17 iodinated DBPs were tentatively proposed. The results fully demonstrate that, with respect to the DBP number/levels among the three disinfection processes, chloramination generally generated the most/highest iodinated DBPs, chlorination generally produced the fewest/lowest iodinated DBPs, and chlorine-ammonia sequential treatment formed iodinated DBPs lying in between; the numbers of iodinated DBPs in chloraminated Suwannee River Fulvic Acid (SRFA) and Humic Acid (SRHA) were nearly the same, but the levels of aliphatic iodinated DBPs were higher in the chloraminated SRFA while the levels of aromatic iodinated DBPs were higher in the chloraminated SRHA; a couple of nitrogenous iodinated DBPs were found in chloramination and chlorine-ammonia treatment. The ratio of total organic iodine levels in chlorine-ammonia sequential treatment and chloramination could be expressed as a function of the lag time of ammonia addition.

Development of a coupled diffusion denuder system combined with gas chromatography/mass spectrometry for the separation and quantification of molecular iodine and the activated iodine compounds iodine monochloride and hypoiodous acid in the marine atmosphere.

This study concerns the development of a coupled diffusion denuder system capable of separating and quantifying gaseous molecular iodine (I(2)) and two other highly reactive iodine species, ICl and HOI, which are collectively named activated iodine compounds (AIC). Both I(2) and AIC are key species in the atmospheric chemistry of iodine. 1,3,5-Trimethoxybenzene (1,3,5-TMB)- and alpha-cyclodextrin/(129)I(-) (alpha-CD/(129)I(-))-coated denuders proved to be suitable for the collection of gaseous AIC and I(2), respectively. The experimental collection efficiencies for AIC (tested as ICl) and I(2) agreed well with the theoretical values for gas flow rates in the range between 300 and 1800 mL min(-1). The coupled denuder system (1,3,5-TMB-coated denuder as front-denuder coupled upstream of an alpha-CD/(129)I(-)-coated denuder) was applied successfully to separate test gas mixtures of ICl and I(2) at various mixing ratios in the laboratory. The operation of both denuder systems was demonstrated to be independent of relative humidity (0-100%) and storage period (at least 2 weeks prior to and after sampling). Detection limits were achieved at sub-parts-per-trillion-by-volume (sub-pptv) level. The presented method provides a reliable and practical approach for the speciation of gaseous iodine compounds. In addition, we report for the first time ambient air measurements of AIC mixing ratios, carried out at the atmospheric research station in Mace Head, Ireland. A maximum concentration of AIC of 30.2 pptv was observed for nighttime measurements and 6.0 pptv for daytime measurements. A similar diurnal pattern was found for I(2) with an average concentration level of 23.2 pptv during daytime and 85.1 pptv during nighttime, indicating a strong correlation with AIC.

Superiority of K-edge XANES over LIII-edge XANES in the speciation of iodine in natural soils.

Environmental behavior of iodine is of great importance especially related to the release of radioiodine from the processing of nuclear fuel, nuclear accidents, etc. To understand the fate of radioactive iodine in soil-water systems, it is necessary to establish a speciation method of iodine in soil. XANES is one of the most important candidates and we compared the performance of L(III)-edge and K-edge XANES for this purpose. In particular, fluorescence XANES with a multi-element semiconductor detector is essential for the measurement of XANES spectra for trace amounts of iodine in natural soil samples. When comparing L(III)- and K-edges, L(III)-edge XANES can be useful for the speciation due to its ability to distinguish various iodine species in their XANES spectra. However, at L(III)-edge measuring iodine L(alpha) emission, the proximity of its energy to those of Ca K(alpha) and K(beta1) causes a large contribution of background X-rays in the XANES spectra, since Ca is a major element in soil. Thus, it was concluded that K-edge XANES is more useful than L(III)-edge for the speciation of iodine in natural soils owing to its lower detection limit. The K-edge XANES was successfully applied to the speciation of natural iodine in a soil sample (iodine concentration: 55.8 mg/kg), showing that iodine is present in the sample as organo-iodine species incorporated in humic substances.