Measurement of radiocesium in Irish peatland soils

Results are presented for soils taken from twelve peatland sites in Ireland. Two depth horizons, 0–5 and 5–15 cm, were sampled on each site and sampling was carried out in summer and autumn. Deposition of Chernobyl¹³⁷Cs varied between 0.4 and 4.6 kBq m^–2, which is at the lower end of values reported by other authors for Irish agricultural soils. The data showed that the relative percentages of activity and deposition remained internally consistent in each soil horizon for Chernobyl and weapons fallout sources on both sampling occasions: this provided evidence that sampling and analytical procedures were consistent. An apparent reversal in the relative importance of weapons fallout in soils was found when deposition data were compared to the same data presented in activity format, and this same reversal was found for both soil horizons. Different conclusions may erroneously be drawn from data depending on the parameter by which we make measurements. Presentation of results should be carefully considered and depends on the purpose for which a study is intended. A statistically significant change in bulk density of the deeper soil horizon was found between summer and autumn. Changes in bulk density important to bear in mind that in addition to analytical errors, sampling methods can only provide estimations which themselves have inherent sources of error.     

Dosimetric depth distribution of Fukushima-derived 137Cs in coniferous forest soil

Journal of Radioanalytical and Nuclear Chemistry - The ambient dose rate (ADR) in a coniferous forest floor contaminated by Fukushima-derived 137Cs was calculated for small temporal scale as a...     

Experimental and modeling studies of radiocesium retention in soils

A two-compartment model was used to describe the irreversible sorption behavior of ¹³⁷Cs on frayed edge sites (FES) of finite capacity in soils in Hong Kong reservoir. The sorption rate was assumed to depend on factors like the fractional water activity concentration, the difference between the activity concentration of ¹³⁷Cs in aqueous phase and that in particulate phase, and the number of available sorption sites. By varying the exponents of the different factors, very good fitting was obtained between experimental data and theory. A relationship between the number of available frayed edge sites and the mass of soil was proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sorption of radiocesium on soils in the presence of electrolytes

The influence of background electrolytes (KCl, NH₄Cl, CTABr) in different concentrations on the sorption ability of radiocesium by measuring the distribution coefficient has been studied. Sorption isotherms of cesium for characterization of soil sorption ability were used. Sorption of cesium depends on its concentration and at least three different sorption sites are active in the sorption process. In the case of low cesium concentration, two very selective sites with high distribution coefficients are responsible for the sorption. With increasing cesium concentration in the aqueous phase, distribution coefficient is decreasing. Frayed edge sites of illite in soil and exchangeable potassium are probably responsible for nonlinear isotherms at low cesium concentrations. From sorption isotherms and determination of potassium by activation analysis, it was found that the capacity of very selective sites for different concentrations of background electrolyte was up to 7 mmol·kg^–1.     

Sorption and desorption experiments using stable cesium: considerations for radiocesium retention by fresh plant residues in Fukushima forest soils

Journal of Radioanalytical and Nuclear Chemistry - We conducted sorption experiments with stable cesium (133Cs) solution in different organic matter samples, aiming to understand the sorption of...     

Sorption of cadmium in some arable and forest soils

The sorption of cadmium labeled with ¹⁰⁹Cd in nitrate form, from aqueous solutions in different horizons of some arable and forest soils was studied under static (batch) conditions. Before sorption, a method of sequential soil treatment was applied, which consist in the consecutive removal of individual soil components by the use of appropriate reagents and procedures. Three sorption isotherms were tested. Kinetic studies showed that the sorption of cadmium is rather rapid and it can be well described by a Freundlich or a linear isotherm, whereas the closeness of Langmuir isotherm to the experimental results is lower. From the different sorption isotherms, it would also be possible to estimate the effect of individual components on the sorption of cadmium in soils. It was found that the untreated soils exhibit the highest sorption and the sorption decreases in the order of untreated > acetate treated > water treated > peroxide treated > dithionite treated soil. Sorption of cadmium increases with the depth of the studied soils disregarding their chemical treatment.This revised version was published online in November 2005 with corrections to the Cover Date.     

Degradation of medium-chain-length polyhydroxyalkanoates in tropical forest and mangrove soils

Bacterial polyhydroxyalkanoates (PHAs) are perceived to be a suitable alternative to petrochemical plastics because they have similar material properties, are environmentally degradable, and are produced from renewable resources. In this study, the in situ degradation of medium-chain-length PHA (PHA_MCL) films in tropical forest and mangrove soils was assessed. The PHA_MCL was produced by Pseudomonas putida PGA1 using saponified palm kernel oil (SPKO) as the carbon source. After 112 d of burial, there was 16.7% reduction in gross weight of the films buried in acidic forest soil (FS), 3.0% in the ones buried in alkaline forest soil by the side of a stream (FSst) and 4.5% in those buried in mangrove soil (MS). There was a slight decrease in molecular weight for the films buried in FS but not for the films buried in FSst and in MS. However, no changes were observed for the melting temperature, glass transition temperature, monomer compositions, structure, and functional group analyses of the films from any of the burial sites during the test period. This means that the integral properties of the films were maintained during that period and degradation was by surface erosion. Scanning electron microscopy of the films from the three sites revealed holes on the film surfaces which could be attributed to attack by microorganisms and bigger organisms such as detritivores. For comparison purposes, films of polyhydroxybutyrate (PHB), a short-chain-length PHA, and polyethylene (PE) were buried together with the PHA_MCL films in all three sites. The PHB films disintegrated completely in MS and lost 73.5% of their initial weight in FSst, but only 4.6% in FS suggesting that water movement played a major role in breaking up the brittle PHB films. The PE films did not register any weight loss in any of the test sites.     

Determination of organic acids in aerosol particles from a coniferous forest by liquid chromatography-mass spectrometry

LC-MS methods with use of ion-trap and time-of-flight mass spectrometers were developed for the determination of organic acids in aerosol samples collected by a high-volume sampler in a Finnish coniferous forest. Comparison was made of the composition of samples collected during atmospheric formation of new aerosol particles and on days when this formation did not occur. A dynamic sonication-assisted solvent extraction system was developed for fast and quantitative extraction of the filter samples. Several organic acids, including pinonic acid, pinic acid, and homologous series of n-alkanoic acids, n-alkenoic acids, and aliphatic dicarboxylic acids, were identified. In samples collected between 08:00 and 16:00 hours the concentration of pinonic acid ranged from 0.5 ng m(-3) to 3.7 ng m(-3) and that of pinic acid from 0.2 ng m(-3) to 1.5 ng m(-3). For most of the compounds identified, the trends in concentration could be explained by the differences in temperature during collection. However, concentrations of short-chain n-alkanoic acids were clearly higher on the days when new aerosol particle formation occurred.     

On peculiarities of vertical distribution of 239,240Pu, 238Pu and 137Cs activity concentrations and their ratios in lake sediments and soils

Distributions of ^239,240Pu, ²³⁸Pu and ¹³⁷Cs activity concentrations in the cores of sediments in the shallow lake, flooded and upland forest soils taken in the vicinity of Vilnius city were analyzed. The radiochemical, α-spectrometric and mass spectrometric methods were used for the plutonium evaluation and γ-spectrometry was used for the radiocesium evaluation. The only peak of enhanced radionuclide activity concentrations was determined for the lake bottom sediments, whereas vertical profiles of the radionuclide activity concentrations in flooded and upland forest soil cores were distinguished by two peaks. The obtained values of the activity concentration ratio ²³⁸Pu/^239,240Pu and the isotopic ratio ²⁴⁰Pu/²³⁹Pu indicated that the global fallout was a source of plutonium in the investigated environment. Chernobyl-derived radiocesium was detected solely in the surface layers (2–11 cm) of the studied sample cores. The contribution of the Chernobyl deposits amounted to about 2.26, 6.11 and 20.9 % of the total radiocesium inventory in the bottom sediments, the upland soil and flooded soil, respectively.     

The vertical distribution of halocarbons in the stratosphere

Summary By means of cryogenic sampling and subsequent gas-chromatographic analysis vertical profiles of CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl and CH₃CCl₃ were derived for stratospheric heights up to 35 km. Vertical profiles of halocarbons computed by means of one-dimensional and two-dimensional models fall off less rapidly in the stratosphere than the measured profiles, this systematic discrepancy being due to deficiencies in the radiation and transport schemes of present models. It is shown that measured profiles of fully halogenated hydrocarbons provide a tool for systematically studying these deficiencies and thus improving the models. Sources and sinks of halocarbons are discussed, and an assessment of past and future sources of organically bound chlorine in the atmosphere is made.

---

Die vertikale Verteilung halogenierter Kohlenwasserstoffe in der stratosphäre

Zusammenfassung Die vertikalen Profile von CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl und CH₃CCl₃ wurden für stratosphärische Höhen bis zu 35 km mit Hilfe kryogener Probenahme und anschließender gas-chromatographischer Analyse bestimmt. Die mit Hilfe von ein- und zweidimensionalen Modellen berechneten Profile fallen in der Stratosphäre weniger schnell ab als die gemessenen. Dieser systematische Unterschied ist auf Mängel in den Strahlungs- und Transportmechanismen der gegenwärtigen Modelle zurückzuführen. Es wird gezeigt, daß die gemessenen Profile der vollhalogenisierten Kohlenwasserstoffe dazu dienen können, diese Mängel zu untersuchen und die Modelle zu verbessern. Ursprung und Verbleib der halogenierten Kohlenwasserstoffe werden beschrieben und vergangene und zukünftige Quellen organisch gebundenen Chlors in der Atmosphäre diskutiert.

     

Sorption capacity of cesium on different forest and agricultural soils

Journal of Radioanalytical and Nuclear Chemistry - To investigate the sorption capacity of cesium on different forest and agricultural soils, batch sorption experiment was conducted. The Freundlich...     

Migration of radiocesium in a zeolite-solution system

Some properties of natural zeolite from Zaloka gorica, Slovenia, Yugoslavia were investigated to establish its applicability in solidification and for storage purposes of radioactive waste. It was found that this material is a rather good sorber for cesium, with a capacity of about 0.6 meq g^–1. The migration rate of Cs⁺ in a system ion exchanger-aqueous solution was investigated and correlated with the sorption behaviour of cesium in a system. The leaching rate of cesium from concrete containing zeolite was measured.     

Fractionated combustion analysis of carbon in forest soils — new possibilities for the analysis and characterization of different soils

The fractionated combustion analysis of carbon allows the sequential analysis of the total organic carbon (TOC), total inorganic carbon (TIC) and total carbon (TC) fractions in forest soils. Magnesium carbonate and calcium carbonate of the inorganic carbon fraction can also be detected separately. Soils from various forest stands cause different combustion characteristics of the organic carbon fraction, also depending on the soil profile depth. This automatic combustion technique is suitable to characterize the organic carbon fraction of different soil types.     

Artificial neural network modeling of diuron and irgarol-based HPLC data and their levels from the seawaters in Izmir,Turkey

The LC determination of two well-known antifouling booster biocides, diuron and irgarol, was investigated from the seawaters in ?zmir, Turkey. The biocide levels were pre-concentrated through C18 solid-phase extraction cartridges and they were analyzed by the LC-UV method. An artificial neural network (ANN) was used to model the data obtained from LC optimization. Column temperature, percentage of acetonitrile, flow rate, wavelength, pH, and concentration of biocides were used as input parameters. The retention time was selected as output parameter. The best back-propagation algorithm in ANN modeling for diuron and irgarol was found to be the Levenberg–Marquardt algorithm. The limits of detection for diuron and irgarol were calculated as 25.38 and 39.49 ng L^?1, respectively. The inter-day and intra-day precisions were obtained less than 13.5% for each biocide. The recovery rate for diuron was 96.9% and for irgarol it was 84.6%. The maximum diuron and irgarol levels were measured as 1779 ng L^?1 and 908 ng L^?1, respectively. In conclusion, ANN is a robust modeling method to predict the retention time in LC studies. Since diuron and irgarol have been detected in Turkish waters, it is therefore suggested that booster biocides with less impact on the environment should be used in antifouling paint formulas.     

Behavior of radiocesium in atmospheric arerosol and fallout in Prague

Radiocesium in ground layer atmospheric aerosol and fallout in Prague has been examined. After a decline in 1986–1988, controlled by a sum of two negative exponentials,¹³⁷Cs aerosol concentration reached a constant level based on an equilibrium between its deposition and resuspension. Deposition velocity was compared to that of⁷Be and²²⁶Ra. It confirmed the supposed source of¹³⁷Cs as resuspension from the ground. Resuspension factor of the order of magnitude of 10^–9 was determined, reminding similar values found earlier in Prague as well as those found in Munich. It also agrees well with the USAEC resuspension model. Solubility of¹³⁷Cs was measured in combined wet and dry fallout. The average undissolved fraction of¹³⁷Cs was found to be about 70% which can be explained by the conditions of the¹³⁷Cs aerosol formation in Chernobyl.     

Geographic distribution of K-40 in soils in Canada

Background levels of K-40 on non-cultivated soils in Quebec and in several northern sites elsewhere in Canada are presented. The activity of K-40 was measured at 34 sites. The specific activity levels ranged from 59 to 801 Bq kg^–1 with an overall mean of 396±195 Bq kg^–1. This activity generates the annual dose equivalent of 0.1 mSv. In most cases (24 out of 34), the concentration of K-40 slightly decreases with the increasing depth. The activities were found to be approximately normally distributed. There is a regional difference between the concentrations of K-40 in soils in northern and southern Quebec.     

Trace elements distribution in the Amazon floodplain soils

Neutron activation analysis was performed on aluvial soil samples from several sites on the floodplains of the Amazon River and its major tributaries for trace elements determination. The spatial and temporal variations of chemical composition of floodland sediments in the Amazon basin are discussed. No significant difference was found in trace elemental distribution in the floodland soils along the Amazon main channel, even after the source material has been progressively diluted with that from lowland draining tributaires. It was also seen that the average chemical composition of floodplain soils compares well with that of the suspended sediments.