Dry deposition velocity of iodine-129 onto grass as obtained by field measurements in the environment of a nuclear fuel reprocessing plant

The deposition velocity of gaseous organic¹²⁹I species from the exhaust air stack of the Karlsruhe reprocessing plant onto pasture grass was measured by a field experiment. By simultaneously measuring the amount of¹²⁹I deposited per unit area of pasture grass and the time integrated mean air concentration of¹²⁹I a deposition velocity of V_g=5.8×10^–1 /cm s^–1/ onto pasture grass was determined.     

Determination of Platinum in Plant Samples by Voltammetric Analysis

A voltammetric method using solid electrode of glassy carbon as a working electrode is describes for determination of platinum in grass samples taken from the vicinity of a motorway. Standard addition was used for quantitative analysis of Pt in 0.05 M H₂SO₄. The analyte concentration in plant tissues reached 19.1±1.6 ng g^?1 for leaves of samples collected from the least polluted areas, and up to 136±2 ng g^?1 for roots of sample taken from the area of heavy road‐traffic.     

Determination of 90Sr in soil, grass and cereals

⁹⁰Sr was measured in environmental samples in Upper Austria in the year 2005. After the nuclear weapon tests the average deposition of ⁹⁰Sr in Austria amounted to 3.3 kBq/m². In 1986 the average deposition was 0.9 kBq/m² [1]. To assess the actual condition in soil, grass and cereals ⁹⁰Sr was measured in these samples. For all samples oxalate precipitation was conducted and strontium specific columns (Eichrom Industries, Inc.) were used. The calcium concentration in these samples was determined to estimate the amount of resin needed for the preparation. For grass and cereal samples columns were packed with the 100–150 μm resin to gain a lower limit of detection LLD below 2 and below 0.1 Bq/kg_{dry matter} respectively. The prepacked 2 mL columns with particle size 100–150 μm were used for soil (LLD below 2 Bq/kg_{dry matter}). After digestion of soil samples, hydroxide precipitation was used as an additional separation step. The ⁹⁰Sr was measured by liquid scintillation counting. For quality control reasons, first the initial strontium concentration in the sample was determined then a strontium carrier solution was added and after the separation steps the chemical recovery was determined by ICP-MS. Thus, no radioactive tracer and just a small amount of the measuring solution were needed. The results are presented and discussed. These results will be used as reference for further ⁹⁰Sr analyses which will be conducted in a 5 year period to detect any radiological impact of the nuclear power plant Temelin on the environment of Austria.     

Correlation Between Specific Surface Area and Methyl Red Adsorbed on Silica Gel

Abstract

The amount of methyl red, adsorbed on bare silica gel, has been determined for 32 samples having a specific surface area ranging from 10 m²/g to 500 m²/g, as determined by a BET method. A linear relationship between amount of dye adsorbed and specific area exists up to about 300 m²/g. Beyond this value the amount of adsorbed dye does not increase correspondingly, which is believed to be due to the relative increase of micropores in the silica gel structure. It is proposed that the easily performed determination of the adsorbed methyl red can serve to estimate that part of the silica gel surface which is available for chromatographic interactions.     

Enzymatic degradation of large vegetation samples for the simultaneous determination of129I,actinides and strontium

A radiochemical procedure is given for the simultaneous determination of low levels of¹²⁹I, actinides (Pu, Am, Cm) and⁹⁰Sr in vegetation samples. It is shown that grass samples up to 5 kg fresh weight can be wet ashed conveniently by hydrogen peroxide under alkaline conditions, subsequent to an initial enzymatic disintegration. After purification of the iodine fraction,¹²⁹I is determined by neutron activation analysis. Using alpha spectrometry,²³⁸Pu and^239,240Pu are determined in the plutonium fraction, and²⁴¹Am,²⁴²Cm, and²⁴⁴Cm in the americium/curium fraction. The⁹⁰Sr is determined after separation by beta counting its decay product⁹⁰Y.     

Isotopic Characterization of Lead in the Scottish Upland Environment

Abstract

Experimental plots have been set up at two Research Stations in upland areas of Scotland with the intention of characterising environmental samples using lead isotopic composition which varies according to the original source of the lead. Thermal ionisation mass spectrometry (TIMS) was used to measure lead isotope ratios with high precision. The ²⁰⁶Pb/²⁰⁷Pb ratios in rainwater were in the range from 1.101 to 1.153 over a period of two years at the two sites. Low ratios were associated with the very low ratios found in Britain in petrol additives during that period whereas higher ratios indicated a larger component derived from industrial sources at the Hartwood site. The ²⁰⁶Pb/²⁰⁷Pb ratios in the surface (0–2.5 cm) soil from a roadside plot were low (1.1126 and 1.1159 in 1989 and 1990, respectively) but the ratios in surface soils in plots distant from the road were considerably higher. Whereas the lead in roadside soil had a ²⁰⁶Pb/²⁰⁷Pb ratio indicating its source to be predominantly in recent petrol lead, there were significant components from other sources in the soils away from the road. The washing of grass samples resulted in no significant change in the lead isotope ratios. The lead isotope ratios measured in grass samples reflect the isotopic character of current atmospheric inputs but those in surface soil samples are an integrated record of atmospheric deposition over a long period of time. An undisturbed plot under a tree canopy had high concentrations of lead in the surface soil and low ²⁰⁶Pb/²⁰⁷Pb ratios. The ratios in fallen leaves on this plot were slightly but significantly lower than those in the grass grown on the plot. It would appear that the tree canopy is effective at scavenging lead carried in the atmosphere.     

Environmental radioactivity measurements in north–western Greece following the Fukushima nuclear accident

The impact of the Fukushima nuclear accident in north–western Greece was assessed through an environmental monitoring programme activated by the Nuclear Physics Laboratory of the University of Ioannina. Measurements of ¹³¹I were carried out in atmospheric particulate, ovine milk and grass samples. In daily aerosol samplings, radioiodine was first detected on March 25–26, 2011 and reached maximum levels, up to 294 μBq m^?3, between April 2 and April 4, 2011. In ovine milk samples, ¹³¹I concentrations ranged from 2.0 to 2.7 Bq L^?1 between April 2 and April 6, 2011, while an average activity of 2.7 Bq kg^?1 was measured in grass samples on April 4, 2011. The ^134,137Cs isotopes were below detection limits in all samples and could only be determined in the air, by analysis of multiple daily filters. A maximum average activity concentration of ¹³⁷Cs amounting to 24 μBq m^?3 was measured during the period from April 5 to April 9, 2011, with the ¹³⁴Cs/¹³⁷Cs activity ratio being close to unity. Activity concentrations were consistent with measurements conducted in other parts of the country and were well below those reported in May 1986 after the Chernobyl accident. The committed effective dose to the whole body and to the thyroid gland from inhalation of ¹³¹I was estimated for the adult and infant population and was found to be of no concern for the public health.     

Determination of131I,134Cs,137Cs in grass and cheese after Chernobyl accident in Austria

Various samples from Styria /grass/ and Salzburg /cheese/ were analyzed for¹³¹I,¹³⁴Cs and¹³⁷Cs concentration during April–July 1986 by -ray spectrometry. The concentrations are reported in nCi kg^–1 wet weight. The concentration values found for¹³¹I 0.2–17.2 nCi kg^–1 /grass/, 0.1–0.5 nCi kg^–1 /cheese/, for¹³⁴Cs 1.1–6.2 nCi kg^–1 /grass/, 0.2–1.3 nCi kg^–1 /cheese/, for¹³⁷Cs 1.6–15.7 nCi kg^–1 /grass/, 0.3–2.2 nCi kg^–1 /cheese/. While radioactivity of¹³¹I,¹³⁴Cs and¹³⁷Cs in cheese samples increases from May to June, it decreases in grass samples from May to July 1986.     

Strontium-90 determination in biological and environmental samples by direct milking of its daughter product, yttrium-90

A method is presented for the determination of ⁹⁰Sr in environmental samples by direct milking of ⁹⁰Y. Pyridine-2,6-dicarboxylic acid forms an anionic complex with yttrium which is retained on an anionic resin. Most of the matrix elements are washed out of the column as neutral or uncomplexed species and yttrium is eluted by increasing the ionic force of the eluent solution. This method gives yttrium recoveries between 65% to 85% for soil, grass, milk and bone samples with very high radiochemical purity (⁹⁰Y average half-life of 66±4 hours) and a detection limit of 0.3 Bq/kg of soil. The method supports a calcium content up to 3 g per sample without any decrease in yttrium yield, allowing the measurement of milk, milk-teeth and bone samples with no concentration step in one day.     

Non-destructive determination of spontaneously fissioning nuclides by neutron coincidence counting using multichannel time spectroscopy

A non-destructive method for determining the amount of actinoids has been developed. The method is based on thermal neutron coincidence counting and employs a selective detection of neutrons resulting from the spontaneous fission of actinoids. The detection system is described in detail and the measurement results of²⁴⁴Cm as an example are presented. The results show that the measured fission rate of²⁴⁴Cm is consistent with the fission rate calculated from ENDF/B-V data and that the amount of²⁴⁴Cm can be determined within about 5% accuracy even in the presence of a large amount of actinoids, for example, up to 2.6·10⁶, 3.6·10⁴, or 1.6·10³ times in the mass ratio of²³⁹Pu,²⁴¹Am, or²⁴⁰Pu to²⁴⁴Cm, respectively.     

Determination of concentration of iodine in grass and cow milk by NAA methods using reactor neutrons

Instrumental and preconcentration methods of neutron activation analysis (NAA) have been standardized for the determination of concentration of iodine in grass and cow milk samples, respectively. To study the transfer of iodine from grass to milk, known quantity of grass spiked with potassium iodide solution was fed to a cow. The spiked grass samples and milk samples, obtained from the cow after the ingestion of spiked grass, were collected. Iodine was separated from the milk samples chemically using Dowex 1X8 anion exchange resin. Spiked grass and ion exchange resin samples were neutron irradiated and radioactive assay was carried out using a 45?% relative efficiency HPGe detector coupled to an 8k channel analyzer. Iodine concentrations in spiked grass samples were found to be in the range of 1,487?C2,002?mg?kg^?1. Concentration of iodine in milk after 12?h of feeding the cow with spiked grass was 871?±?56???g?L^?1 which was reduced to 334?±?32???g?L^?1 after 48?h.     

Preparation and analysis of14C-lignin grass lignocellulose and DHP

(¹⁴C-lignin) grass lignocellulose was prepared from wheat seedlings injected with (¹⁴C-uniform) phenylalanine. Seedlings were injected 2 wk after germination and grown for 3–4 wk in a diurnal light cycle before harvesting. The plant material was ground in liquid N₂, extracted with hot water, benzene-ethanol, and ethanol, and treated with protease. Treatment of the lignocellulose with acid, alkali, and cellulase solubilized¹⁴C, which was analyzed by HPLC and TLC. Reverse-phase HPLC demonstrated that¹⁴C-ferulic and coumaric acid were bound primarily to carbohydrate and lignin, respectively. Gel permeation chromatography by HPLC of¹⁴C solubilized by treatment with 1M NaOH confirmed that the majority of the¹⁴C was incorporated into high molecular weight material. No¹⁴C was detected in either hexoses or pentoses obtained from the lignocellulose and only a minor amount was present as¹⁴C-phenylalanine. These studies show that (¹⁴C-lignin) grass lignocelluloses must be carefully characterized before being used as defined substrates for biodegradation studies. Coniferyl alcohol was synthesized by a route derived from those of Nakamura et al. (1974) and Nakamura and Higuchi (1976). DHP was then prepared by a modification of the method of Brunow and Wallin (1981) in which solutions of coniferyl alcohol and hydrogen peroxide were added alternately by a computer controlled HPLC system so that the coniferyl alcohol concentration was maintained below 1 mM throughout the synthesis. The DHP obtained was characterized by HPLC gel permeation chromatography and by NMR. The results of these analyses will be discussed.     

Effective Utilisation of Halophyte Biomass from Saline Soils for Biorefinering Processes

The salinity of European soil is increasing every year, causing severe economic damage (estimated 1–3 million hectares in the enlarged EU). This study uses the biomass of halophytes—tall fescue (grass) and hemp of the Białobrzeskie variety from saline soils—for bioenergy, second generation biofuels and designing new materials—fillers for polymer composites. In the bioethanol obtaining process, in the first stage, the grass and hemp biomass were pretreated with 1.5% NaOH. Before and after the treatment, the chemical composition was determined and the FTIR spectra and SEM pictures were taken. Then, the process of simultaneous saccharification and fermentation (SSF) was carried out. The concentration of ethanol for both the grass and hemp biomass was approx. 7 g·L⁻¹ (14 g·100 g⁻¹ of raw material). In addition, trials of obtaining green composites with halophyte biomass using polymers (PP) and biopolymers (PLA) as a matrix were performed. The mechanical properties of the composites (tensile and flexural tests) were determined. It was found that the addition of a compatibilizer improved the adhesion at the interface of PP composites with a hemp filler. In conclusion, the grass and hemp biomass were found to be an interesting and promising source to be used for bioethanol and biocomposites production. The use of annually renewable plant biomass from saline soils for biorefinering processes opens up opportunities for the development of a new value chains and new approaches to sustainable agriculture.     

Development of a method for the estimation of low amount of plutonium in 200 L waste drums in presence of high amount of β γ activity due to 137Cs and 60Co

The waste drum monitoring system based on HPGe detector was used to study its performance for the estimation of low amounts of plutonium in presence of high activity of ¹³⁷Cs and ⁶⁰Co. The counting was carried out by keeping amount of plutonium constant at 100 mg level and varying the count rate for the γ rays of ¹³⁷Cs and ⁶⁰Co. Present study has shown that the estimation of low amount of ²³⁹Pu in a waste drum can be carried out using 129 keV γ ray in the presence of ¹³⁷Cs up to an activity level of 16 mCi and in the presence of ⁶⁰Co up to an activity level of 8 mCi.     

Application of cosmogenic radionuclides in ozone tracer studies

Downward flux of stratospheric ozone contributes to the near ground level ozone concentrations. The intensity, amount of vertical ozone flow can be evaluated by the ratio of two cosmogenic radionuclides (³³P/³²P, ⁷Be/³²P). Some examples presented in this paper are demonstrating the possibilities of this method. The application of tracer method makes evident the seasonal variations (with maxima during the spring — summer months and minima during winter) of the amount of stratospheric ozone in the ground air. Average monthly contribution from stratospheric ozone in the lower level of the atmosphere ranged from 0 to 18% in 1998–99. During short term intervals (2–3 days) the amount of the stratospheric ozone can increase up to ∼90%.     

Radioactivity of cattle fodder and milk after the Chernobyl accident

The radioactivities of⁹⁰Sr,¹³⁷Cs and¹³⁴Cs have been measured in soil, fodder and milk from the south-western region of Slovenia, Yugoslavia after the Chernobyl accident. Maximal concentrations of Sr-isotopes in samples and the rate of their decrease in a period up to two years after the accident are given. The transfer of radionuclides from soil to grass and from fodder to milk is discussed.     

Photoinduced Graft Copolymerization. V. Graft Copolymerization of Methyl Methacrylate onto Cellulose in the Presence of N-Bromosuccinimide as Initiator

Abstract

The photoinduced graft copolymerization of methyl methacrylate onto cellulose was studied using N-bromosuccinimide as the photoinitiator. The formation of graft copolymer increases with an increasing amount of cellulose. The graft copolymerization increases with increasing initiator concentration up to 1,25 × 10^?2 M and thereafter it decreases. The percentage of graft increases with increasing monomer concentration up to 46.9 × 10^?2 M and thereafter it decreases. The percentage graft-on increases with increasing temperature. The overall activation energy was computed to be 8.40 kcal/mol. The percentage graft was investigated using different water-miscible organic solvents. The graft copolymerization was also investigated using differently modified cellulose. A possible mechanism for the photo-graft copolymerization onto cellulose is suggested.     

Long term radioactive uptake by two pasture plants in a field contaminated by the Chernobyl fallout

The radioactive content of alfalfa and rye grass was measured in five consecutive harvests covering a period of one and a half years after the contamination of a field caused by the Chernobyl fallout. The measured long-lived isotopes were¹⁰⁶Ru,¹³⁴Cs and¹³⁷Cs. In the first four harvests alfalfa contained significantly less radioactivity than rye grass, while in the last harvest both plants contained comparable levels of radioactivity. The results from the first harvest, demonstrating the radioactivity obtained in the direct fallout, indicate that the fraction of total initial deposition retained on rye grass is by 55% and 70% greater than alfalfa for Cs and Ru isotopes, respectively. The second, third and fourth harvests demonstrate values of plant to soil concentration ratios /CR/ considerably larger than those observed in the fifth harvest. Only the CR values obtained in the last harvest overlap with commensurate values previously reported in the literature.     

Synthesis,characterization, and ethylene (Co)polymerization behavior of trichlorotitanium 2‐(1‐(arylimino)propyl)quinolin‐8‐olates

A series of trichlorotitanium complexes containing 2‐(1‐(arylimino)propyl)quinolin‐8‐olates was synthesized by stoichiometric reaction of titanium tetrachloride with the corresponding potassium 2‐(1‐(arylimino)propyl)quinolin‐8‐olates and was fully characterized by elemental analysis, nuclear magnetic resonance spectroscopy, and by single‐crystal X‐ray diffraction study of representative complexes. All titanium complexes, when activated with methylaluminoxane, exhibited high catalytic activity toward ethylene polymerization [up to 1.15 × 10⁶ g mol^?1(Ti) h^?1] and ethylene/α‐olefin copolymerization [up to 1.54 × 10⁶ g mol^?1 (Ti) h^?1]. The incorporation of comonomer was confirmed to amount up to 2.82 mol % of 1‐hexene or 1.94 mol % of 1‐octene, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

RADIATION INDUCED ACRYLAMIDE/CITRIC ACID HYDROGELS AND THEIR SWELLING BEHAVIORS

Citric acid (CAc) moieties containing acrylamide (AAm) hydrogels were prepared by gamma irradiation of their aqueous solutions. A possible polymerization and crosslinking mechanism for acrylamide/citric acid (AAm/CAc) hydrogels is proposed. The effects of irradiation dose and citric acid content on swelling behavior were investigated. Swelling took place in water at 25°C and was followed gravimetrically. Incorporation of a relatively low amount of citric acid to acrylamide hydrogel increased its swelling up to 950% from 700%. The diffusion of water into AAm/CAc hydrogels was found to be a non-Fickian type. Diffusion coefficients of AAm/CAc hydrogels found as 5 × 10^?7? 10 × 10^?7 cm² sec^?1. It has also been found that the number average molar mass between crosslinks is increased with the CAc content and decreased with irradiation dose.