Determination of partition coefficients of metals in the Sava River environment

Site specific data and partition coefficients of stable elements in the Sava River environment have been measured. Distribution of metals in periphyton was similar to those found in sediments from the same locations. The concentration ratios of periphyton over sediments for Zn, As, Cd and Pb exceeded one. Thus the content of these metals in periphyton provides more information about anthropogenic pollution than either sediment or water samples collected at the periphyton site. In addition, the enrichment factors of the most abundant metals in the sediment samples have been calculated.     

Long lived radionuclides in the ecosystem of the Sava river

Summary The radioactivity of water and sediments from the Sava river in the course through Serbia during 2001-2003 has been examined by alpha- and gamma-ray spectrometry. Except for cesium originating from Chernobyl, the radioactivity level of water and sediment coincide with the content of natural radionuclides in the environment of the river basin. Distribution coefficients as well as the runoff coefficient were determined for ¹³⁷Cs.     

Factors influencing the determination of analyte ion surface partitioning coefficients in electrosprayed droplets

The observed response in mass spectrometry utilizing electrospray as a sample introduction technique can be affected by a number of factors. In this study a series of two-electrolyte systems was investigated and the mass spectrometric responses were modeled by the use of droplet surface partitioning coefficients and instrumental response factors according to a recently reported method (Sjöberg et al., Anal. Chem. 2001, 73, 23–28). The partitioning coefficient and the instrumental response factor were found to be affected by the chosen experimental conditions. Experimental parameters that were investigated include spray position relative to the orifice, spray potential, nebulizer and curtain gas flow rates, ionic strength, and organic content of the sprayed solution. The time history of the generated droplets turned out to be of importance to both the partitioning coefficients and the instrumental response factor. For example, a general increase in the surface partitioning coefficients for the tetrapentylammonium ion was initially observed when the spray was aiming closer to the sampling orifice. Furthermore, it was shown with a small amount of deuterium labeled electrolyte that the total ionic strength and not just the electrolyte concentration influence the instrumental response factor.     

Determination of gamma-emitting radionuclides in the Sava river deposits

The concentrations of radionuclides in deposits from the Sava River were determined by gamma-ray spectrometry. Thirteen nuclear reactor radionuclides and eight naturally occurring radionuclides were determined. The site specific activity levels of the Sava River deposits were assessed. The results of measurements show that the radioactivity of the Sava River deposits is due to naturally occurring radionuclides and an elevated concentration of artificial radionuclides such as radiocesium and radioruthenium.     

Determination of Henry''s law coefficients by combination of the equilibrium partitioning in closed systems and solid-phase microextraction techniques

This paper describes the determination of Henry's law coefficients by means of the EPICS (equilibrium partitioning in closed systems) technique in combination with SPME (solid-phase microextraction). The use of solid-phase microextraction-sampling allowed us to extend the possibilities of the equilibrium partitioning in closed systems technique with respect to the range of Henry's law coefficients which can be measured. Whereas the equilibrium partitioning in closed systems technique is limited to determine air–water equilibrium partitioning of volatile compounds with Henry's law coefficients of at least 0.06 (dimensionless), the current method allowed to measure coefficients between 0.0023 and 13.5. In this way Henry's law coefficients of 20 compounds, being in a range covering five orders of magnitude, were measured with relative standard deviations between 1.0 and 19.8% (mean standard deviation: 5.7%; median of standard deviations: 4.8%, n=99). Several types of compounds were examined i.e. aliphatic hydrocarbons, monocyclic and polycyclic aromatic hydrocarbons, chlorinated and fluorinated compounds, ethers and esters, biphenyl and N-containing compounds, including compounds for which availability of experimental Henry's law coefficients is limited. Measurement of the equilibrium partitioning in the 2 to 25°C range allowed to establish relations of Henry's law coefficient as a function of temperature.     

Radionuclide variations in the air over Monaco

Radionuclides in aerosols and precipitation have been analyzed by IAEA-MEL in Monaco since 1987 and 1999, respectively, to identify their behavior in the atmosphere and delivery into the northwestern Mediterranean Sea. While the concentration of ⁷Be in aerosols has been affected by the stratospheric-tropospheric mixing and precipitation, the concentration of ¹³⁷Cs in aerosols has been influenced by a combination of local meteorological conditions and re-suspension of ¹³⁷Cs from soil. Higher concentrations of ⁷Be, ¹³⁷Cs, ^239,240Pu and ²⁴¹Am in precipitation occurred during spring and summer. The highest deposition rates of these radionuclides were observed in spring and autumn during periods of high precipitation. A good correlation was found between the amount of precipitation and depositional flux for ⁷Be, but not for ¹³⁷Cs, ^239,240Pu and ²⁴¹Am. This indicates that the wet process as well as the dry process seem to be important factors in determining the annual deposition for transuranic radionuclides and ¹³⁷Cs.     

Hydrogen-bonding abilities for phenols assessed by quantitative analyses of their partition coefficients derived from different partitioning systems

We recently proposed a new hydrogen-accepting scale, S(HA), on the basis of the heat of formation calculated by the conductor-like screening model (COSMO) method. In this work, the same approach was applied to a series of compounds with a common hydrogen-donor group. Thus the S(HA) values for monosubstituted phenols were calculated and used for correlating their log P(oct) values (P(oct): 1-octanol/water partition coefficient) with log P(CL) (P(CL): chloroform/water partition coefficient) and log P(E) (P(E): butyl ether/water partition coefficient). It was demonstrated that the S(HA) parameter works effectively, providing excellent correlations whose physicochemical meanings are well rationalized in terms of hydrogen-bonding characteristics of the substituents.     

Spatial and temporal distribution of inorganic species in water and sediments of the Tronto River ecosystem

Analytical results are reported for the determination of inorganic species in water and sediments sampled in the Tronto river ecosystem. The species determined are Cd, Co, Cr, Cu, Fe, Mn, Ni, Zn, Hg, F, NO3-, SO4-, Na, K, Ca, Mg, NH4+ in integrated water, and Cd, Co, Cr, Cu, Fe, Mn, Ni, Zn, Hg in sediments. For all the elements, in addition to detection limits, precision and accuracy are given: the former, expressed as relative standard deviation (Sr), and the latter, expressed as relative error (e), were good, being in all cases lower than 5%.     

Radionuclide Separations in Radioactive Waste Disposal

Radionuclide separation processes that have been used successfully in the past as well as recent developments in separati on techniques are discussed with emphasis on their applications in the treatment of radioactive wastes. Both aqueous and nonaqueous processes are evaluated. Separation procedures proposed for use in systems involving transmutation of nuclear waste products are also discussed.     

Radionuclide Identification in Liquid Scintillation Alpha-Spectroscopy

Emission peak position on the apparent energy scale is a function of the number of photons created in the radioactive decay process. The sample, which is the detector in liquid scintillation (LS) spectroscopy, may contain quenching substances. These inhibit creation of photons and, consequently, radionuclide emission peak shifts towards lower channels. Identification of the radionuclide by its peak position is therefore not straightforward under variable quench in LS spectroscopy. The end point of the Compton spectrum (or external standard quench parameter SQP(E)) gives a direct measure of the sample quench. It is normally used in LS spectroscopy for the measurement of counting efficiency. Because SQP(E) does not depend on the sample emission energy, it can be used in verification of the peak energy together with the peak position. Two known energy calibration lines are required as a function of quench to verify the peak energy.     

Determination of the distribution coefficients for134Cs,60Co and234Th in the Pinheiros River sediment-water

We have investigated the possibility of determining the relative concentrations of two radon isotopes (²²²Rn and²²⁰Rn) in the air, using solid state nuclear track detectors (CR-39) as alpha spectrometers. The detectors were exposed to²²²Rn and its daughters and²²⁰Rn and its daughters in the air. Analyzing only roundish tracks, it was observed that the performance of CR-39 as alpha spectrometer varies with etching time, improving markedly for long etching times.     

Development of negligible depletion hollow fiber membrane-protected liquid-phase microextraction for simultaneous determination of partitioning coefficients and acid dissociation constants

A new method based on negligible depletion hollow fiber-protected liquid-phase microextraction coupled with high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of partitioning coefficients (K_OW) and acid dissociation constants (pK_a), by using phenol, 4-chlorophenol and 2,4-dichlorophenol as model compounds. A 37-mm length polypropylene hollow fiber membranes (600 μm inner diameter, 200 μm wall-thickness, 0.2 μm pore size, ∼70% porosity) with two-end sealed were filled with 1-octanol by ultrasonic agitation to prepare the extraction device. The extraction device was deployed in sample solutions, prepared by spiking target analytes in 1-octanol saturated aqueous solutions (500 mL), for negligible depletion extraction. After equilibrium was reached (∼5 h), the 1-octanol in the lumen of the hollow fiber membrane was collected for HPLC determination of the target analytes. As the depletion of the analytes in aqueous samples was negligible, the distribution coefficient (D_OW) could be calculated based on the measured equilibrium concentration in 1-octanol (C_O) and the initial concentration (C_W) in the aqueous sample of the target analyte (D_OW = C_O/C_W). The D_OW values measured at various pH values were nonlinearly regressed with pH to obtain the K_OW and pK_a values of a compound. Results showed that the measured values of the K_OW and pK_a of these model compounds agreed well with literature data.     

Radionuclide technique in mechanical engineering in Germany

A subject of increasing application of cyclotron machines is the RadionuclideTechnique inMechanical Engineering (RTM), a measuring system that enables wear and corrosion diagnostics of components of operating machines, apparatus or processing plants. The three components of the RTM-system, the thin layer-activation at the cyclotron, the measuring methods and the measuring instruments for application in industry, have been developed systematically at KfK over more than 15 years and are being used increasigly by industry in Germany, Japan and the United States. The present development of RTM to modern problems in engineering and material research as well as the successful application in new industrial areas will be reported.     

Natural Radionuclide Contents in Human Whole-Body Ashes

Whole-body ashes from nine cremated adult humans were acquired from local mortuaries in Ft. Collins, Colorado (USA) with the consent of next of kin. Ashes of each individual corpse were ground, homogenized and sealed in a steel can for 30 days before gamma-spectroscopy measurements were made to determine the ²²⁸Ra, ²²⁸Th, ²³⁸U, ²²⁶Ra and ⁴⁰K contents. The median values of radionuclide contents in our study subjects were generally higher than literature values in which only a selected set of organs had been analyzed. Direct estimates of natural or man-made radionuclides in whole-body human ashes should be more accurate than estimates based on analysis of small bone or tissue samples that require extrapolation to the entire body.     

Radionuclide levels and temporal variation in phosphogypsum

Summary Three samples of phosphogypsum of different ages were analyzed for natural radioelements using high-resolution gamma-ray spectrometry. The phosphogypsum samples were taken from the filter of a 10-year old pile, and a 50 year old pile. The distribution of ²²⁶Ra remains relatively constant as a function of storage time (up to 50 years) which confirms the immobility of ²²⁶Ra in the phosphogypsum matrix. However, the concentration of ²³⁸U and ²³² Th have shown a decreasing tendency going from the most recent sample to the oldest. For radionuclides belonging to the ²³² Th series, we noticed an enrichment factor of 1.5 for ²²⁸Ac in the most recent phosphogypsum, whereas the right proportions exist for the other two samples. This is due to the fact that most of the thorium fractionates to the phosphoric acid during the production process and the equilibrium between ²³² Th and its descendants is not yet reached for fresh phosphogypsum.     

Radionuclide migration experiments in the laboratory: Some radioanalytical aspects

Radionuclide transport studies in consolidated and unconsolidated geological media are being performed in the laboratory as part of the Canadian Nuclear Fuel Waste Management Program. These studies present an interesting challenge to radiochemists because many of the radionuclides are either not eluted or only partially eluted from fractures or from columns. Therefore, non-invasive radiometric analyses have been applied to determine the location of radionuclides along a flow path during a migration experiment, and invasive analyses have been developed to determine the transport behaviour of these radionuclides at the termination of a migration experiment. Linear gamma scanning has been used in migration experiments with^95mTc and¹³¹I through columns of crushed fracture-infilling material to follow their movement through the columns. Two-dimensional gamma scanning has been used to determine the distribution of¹⁴⁴Ce on fracture surfaces at the termination of migration experiments through natural fractures in granite. In addition, information on the interaction of radionuclides with specific minerals can often be obtained by separating minerals on the basis of density, or by a combination of density and magnetic properties, followed by radiometric assay of the separated fractions.     

Radionuclide fractionation in a forest soil profile

Two alternative approaches, a sequential extraction scheme and the calculation of the variation of the distribution coefficient of radiocaesum in different K–Ca–NH₄ scenarios, were used to study the behaviour and fractionation of this radionuclide in a forest soil profile. The first approach was applied to samples originating from an experiment in which the original L (litter) layer was replaced by an L layer contaminated with a radioactive aerosol, allowing a downward migration of radiocaesium. The samples belonged to different stages after the contamination. The second approach was applied to samples contaminated with soluble radiocaseium. The results indicate that radiocaesium behaviour is quite similar in the Hand A layers, and that the mineral matter seems to govern the behaviour of radiocaesium in case of direct condensed deposition or when radiocaesium is released from structural components of the organic matter phase.