Determination of atmospheric iodine species using a system of specifically prepared filters and IDMS

Depletion of iodide in ageing aerosols and the role of humidity: A case study of mixed sodium iodide-malonic acid aerosol

Global sea to air iodine emissions, along with organic emissions and their oxidation products, have increased tremendously. This work presents a comprehensive analysis of the humidity mediated changes in ageing aerosols comprising iodide and water soluble dicarboxylic acid using aerosol micro-Raman spectroscopy. The studies in the model system, sodium iodide-malonic acid mixed aerosols, unveiled the depletion in iodide. Mechanistic insights gleaned through comparative studies conducted under inert (nitrogen) and oxidative (air) atmospheres reveal the iodide depletion occurs possibly via oxidation to molecular iodine. The reaction involves gaseous components, diffusion of which across the particles will be impacted by the physical state of the particles, such as viscosity, which in turn is intricately linked to ambient humidity levels. To this end, studies on the temporal evolution of the reaction at three distinct RHs covering 30-80% revealed the enhanced progression of the reaction with increasing humidity. Given that geographical locations serving as major sources for atmospheric iodine typically experience high humidity, these reactions could emerge as an additional process controlling iodine speciation in ageing aerosols.

On the Speciation of Iodine in Marine Aerosol

We have compiled and analyzed a comprehensive data set of field observations of iodine speciation in marine aerosol. The soluble iodine content of fine aerosol (PM₁) is dominated by soluble organic iodine (SOI; ∼50%) and iodide (∼30%), while the coarse fraction is dominated by iodate (∼50%), with nonnegligible amounts of iodide (∼20%). The SOI fraction shows an equatorial maximum and minima coinciding with the ocean "deserts," which suggests a link between soluble iodine speciation in aerosol and ocean productivity. Among the major aerosol ions, organic anions and non-sea-salt sulfate show positive correlations with SOI in PM₁. Alkali cations are positively correlated to iodate and negatively correlated with SOI and iodide in coarse aerosol. These relationships suggest that under acidic conditions iodate is reduced to HOI, which reacts with organic matter to form SOI, a possible source of iodide. In less acidic sea-salt or dust-rich coarse aerosols, HOI oxidation to iodate and reaction with organic matter likely compete.

Concentrations of iodine isotopes ((129)I and (127)I) and their isotopic ratios in aerosol samples from Northern Germany

New data about (129)I, (127)I concentrations and their isotopic ratios in aerosol samples from the trace survey station of the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Northern Germany, are presented and discussed in this paper. The investigated samples were collected on a weekly basis during the years 2011 to 2013. Iodine was extracted from aerosol filters using a strong basic solution and was separated from the matrix elements with chloroform and was analysed by accelerator mass spectrometry (AMS) for (129)I and by inductively coupled plasma mass spectrometry (ICP-MS) for (127)I. The concentrations of (127)I and (129)I in aerosol filters ranged from 0.31 to 3.71 ng m(-3) and from 0.06 to 0.75 fg m(-3), respectively. The results of (129)I/(127)I isotopic ratios were in the order 10(-8) to 10(-7). The (129)I originated directly from gaseous emissions and indirectly from liquid emissions (via sea spray) from the reprocessing plants in Sellafield and La Hague. In comparison with the results of (131)I after the Fukushima accident, no contribution of (129)I from this accident was detectable in Central Europe due to the high background originating from the (129)I releases of the European reprocessing plants. (129)I atmospheric activity concentrations were compared with those of an anthropogenic radionuclide ((85)Kr). We did not find any correlation between (129)I and (85)Kr, both having nuclear reprocessing plant as the main source.

Detection and Quantification of Gaseous and Particulate Fukushima Fission Products at Orangeburg, South Carolina

Large amounts of fission products were released from the Fukushima nuclear accident after a devastating earthquake and subsequent tsunami hit the northeast coast of Japan on 11 March 2011. The radioactive mass was sent high into the atmosphere by hydrogen explosions and fires in the reactor buildings at Fukushima Daiichi Nuclear Power Plant and spread all over the world. A relatively complete detection of both gaseous and particulate fission products was conducted during 15 March and 30 May 2011 at Orangeburg, South Carolina, located along the southeast coast of the United States, 11,000 km from the accident site. The histograms of gaseous and particulate radionuclides were obtained, and the major radioactivity plateaus were found between 18 March and 7 April 2011. The maximum levels of particulate and gaseous 131I were 1.0 ± 0.1 and 5.0 ± 0.4 mBq m-3, respectively. The maximum radioactivities of 134Cs and 137Cs were 10 times less than that of the particulate 131I. The average activity ratio of 134Cs to 137Cs was determined as 0.98 ± 0.26 throughout the observation. It was found that the plateaus and spikes in the histogram curves corresponded to the nuclear release events at Fukushima Daiichi. The arrival times of the particulate and gaseous nuclear fallout were determined to be 8 and 10 d, respectively. The deposition rates of gaseous and particulate iodine and the mass transfer between the two phases were discussed based on the radioactivity ratios of the fission products. By comparing with the radionuclide effluent concentrations issued in NRC 10 CFR 20, it was concluded that the Fukushima fallout presented negligible radiation risk to the public at Orangeburg as well as in the southeastern coastal region of the U.S.

Iodine-129 and iodine-127 in European seawaters and in precipitation from Northern Germany

In order to obtain a comprehensive survey on the consequences of the marine (129)I discharges from the European reprocessing plants La Hague and Sellafield, the distribution of (129)I and (127)I in surface waters of the North Sea, the English Channel, the Irish Sea, and the Northeast Atlantic was studied using accelerator mass spectrometry for (129)I and ICP-MS for (127)I. Samples of seawater were taken in the German Bight in May, September, and November 2005 and in the entire North Sea and the English Channel in August 2005. Further samples were obtained from the Irish Sea in June and August 2006 and from Arctic waters between Spitsbergen and Southern Norway in September 2005. (129)I is a conservative tracer in seawater. The concentrations of (127)I are relatively constant with exceptions of coastal areas with high biological activity and of areas influenced by influx from rivers and the Baltic Sea. The variability of the (129)I/(127)I isotopic ratios is exclusively determined by admixture of (129)I released from the reprocessing facilities Sellafield and La Hague to the seawater. The (129)I/(127)I ratios were between 4 × 10(-9)and 3 × 10(-6): at least 3 orders of magnitude higher than the natural equilibrium isotopic ratio 1.5 × 10(-12). (129)I/(127)I ratios of a few times 10(-10) were only found in seawater from the Indian Ocean and from the Pacific at Hawaii. Comparison of the results obtained for seawater with those of a measurement of airborne iodine species and with iodine isotopes in precipitation in Northern Germany demonstrates the transfer of (129)I and (127)I from the sea into the atmosphere and the dominating role of the marine discharges for the atmospheric fallout of (129)I in Western Europe. The results are discussed with the goal to estimate the relevance of the marine discharges for the contamination of the continental areas.

Time series of 129I and 127I speciation in precipitation from Denmark

Environmental 129I mainly released from reprocessing plants at La Hague (France) and Sellafield (U.K.) provides a unique atmospheric and environmental tracer. This study deals with 129I and 127I speciation in precipitation collected in Denmarkduring 2001-2006 that indicates many newfindings. The concentrations of total 129I in precipitation vary from 0.28 to 5.63 x 10(9) atoms 129I L(-1) with an average of (2.34 +/- 1.43) x 10(9) atoms 129I L(-1), and the annual deposition flux of 129I is (1.25 +/- 0.30) x 10(12) atoms m(-2). Increased 129I levels in precipitation and 129I/ 127I ratio are attributed to the releases of 129I from the reprocessing plants at La Hague and Sellafield. Iodide is the major specie of 129I, which accounts for 50-99% of total 129I. The concentrations of total 127I vary from 0.78 to 2.70 microg iodine L(-1) with an average of 1.63 +/- 0.47 microg iodine L(-1), and annual deposition flux of 0.95 +/- 0.26 mg m(-2). Unlike 129I, iodate is the major specie of 127I, which accounts for 43-93% of total 127I. The 291I/ l27I atomic ratios for total iodine vary from 5.04 to 76.5 x 10(-8) with an average of (30.1 +/- 16.8) x 10(-8). These values are 10 times lower for iodate with an average of (2.95 +/- 3.13) x 10(-8). Seasonal variations of 129I/127 ml values and 129I concentrations are associated with highs in spring and lows in summer-autumn periods. Re-emission of 129 from the surface water of the English Channel, Irish Sea, North Sea, and Norwegian Sea, especially from the European continental coast areas, is evidently the major source of 129I in the precipitation, while stable 127I in the precipitation has multiple sources, i.e., marine, as well as terrestrial emission. This work shows that data on speciation of iodine isotopes can provide thorough indications about the sources and geochemical cycle despite the complicated atmospheric chemistry of iodine.

Uptake and distribution of iodine in rice plants

Rice (Oryza sativa L.) plants were cultivated in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, straw, and root. The contents of iodine in these components and the soil were determined by inductively coupled plasma-mass spectrometry and radiochemical neutron activation analysis, respectively. Iodine content varied by more than three orders of magnitude among the plant components. Mean concentration of iodine in the entire plants was 20 mg kg(-1) dry weight, and the concentration of iodine in the surface soil (0-20 cm depth) was 48 mg kg(-1). The highest concentration of iodine (53 mg kg(-1) dry weight) was measured in root and the lowest concentration (0.034 mg kg(-1) dry weight) in polished rice. While the edible component (polished rice) accounted for 32% of the total dry weight, it contained only 0.055% of iodine found in the entire rice plants. Atmospheric gaseous iodine (5.9 ng m(-3)) was estimated to contribute <0.2% of the total iodine content in the biomass of rice plants; therefore nearly all of the iodine in the rice plants was a result of the uptake of iodine from the soil. The content of iodine in the aboveground part of rice plants was 16 mg kg(-1) dry weight and the percentage of iodine transferred per cropping from the soil into the aboveground biomass corresponded to 0.27% (20 mg m(-2)) of the upper soil layer content.

Contribution of mass spectrometry to assess quality of milk-based products

The vast knowledge of milk chemistry has been extensively used by the dairy manufacturing industry to develop and optimize the modern technology required to produce high-quality milk products to which we are accustomed. A thorough understanding of the chemistry of milk and its numerous components is essential for designing processing equipment and conditions needed for the manufacture and distribution of high-quality dairy products. Knowledge and application of milk chemistry is also indispensable for fractionating milk into its principal components for use as functional and nutritional ingredients by the food industry. For all these reasons, powerful analytical methods are required. Because of the complexity of the milk matrix, mass spectrometry, coupled or not to separation techniques, constitutes a key tool in this area. In the present manuscript, we review the contribution and potentialities of mass spectrometry-based techniques to assess quality of milk-based products.