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  • Author or Editor: D. Desideri x
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Abstract  

In various samples of marine organisms from the central Adriatic Sea 210Po was determined by alpha spectrometry and thirteen heavy metals (Mn, Fe, Co, Cr, V, Ni, Cu, Zn, Cd, As, Sn, Hg and Pb) by energy dispersive, polarised X ray fluorescence spectrometry (EDPXRF). 210Po activity concentration ranged between 0.3 and 44.6 Bq kg−1 fresh weight. The data obtained depend upon the type of the marine organism; among the pelagic species, anchovy displayed the highest polonium concentration. Typical concentration
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ranges were as follows: Mn: <1.32–1.73; Fe: 4.11–94.27; Co < 0.13–0.23; Ni: <0.13–0.52; Cu: 0.37–145.31; Zn: 0.46–16.46; Cd: <0.10–0.25; As: 0.36–60.52; Hg: <0.13–0.70; Pb: <0.13–0.35, Sn: <0.20–12.67; V and Cr were always <1.32. The data obtained are also compared with those obtained by other authors for the same organism coming from other Italian seas.
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Summary  

The dispersion of radioactive substances in the environment following nuclear weapon tests in atmosphere since 1954 and accidents to nuclear plants, like that in Chernobyl in 1986, have allowed us to study the migration processes of some radionuclides in complex ecosystems such as lakes are. In the present paper the behavior of 137Cs and 90Sr in different compartments of the Monterosi Lake (central Italy) was assessed. The 137Cs concentration was measured in lake water as well as sediment, stream water, aquatic plant and fish samples. 90Sr concentration in water and sediments was also determined. A total inventory of 4206±76 Bq . m-2 and 958±79 Bq . m-2 (on 27/6/01) has been found for 137Cs and 90Sr, respectively. The experimental data presented here allow to calibrate theoretical models predicting the temporal trend of radionuclide concentration in similar ecosystems. Moreover, information on cesium and strontium migration processes can be extended to other pollutants having similar environmental behavior.

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Abstract  

The paper describes the radiochemical and chemical analyses of industrial graphite scraps showing high radioactivity levels. The uranium concentration in some graphite scraps was very high (up to l kBq/g, 7.7%w/w) and its distribution greatly heterogeneus. Some uranium solubility tests carried out on the graphite scraps showed that 60–70% of the element could be dissolved with a buffer solution at pH 4 and that complete dissolution could be obtained by leaching with conc. HNO3 . By taking into account these results it can be concluded that the radioactive contaminant consists of uranium chemically purified and isotopically treated.

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Summary  

It is well known that the interest in radon concentration indoor as a pollutant emerged during the energy crisis of seventies which led to reduce ventilation in dwellings. Recently the Euratom Recommendation 2001/928 suggested the necessity of performing frequent 222Rn checks on tap waters. As a consequence of this Recommendation, Urbino and Perugia Universities carried out a preliminary 222Rn determination on tap waters of the Pesaro-Urbino province. Samplings were carried out in twenty-eight sites and radon concentration was determined by liquid scintillation counting and gamma-spectrometry. The results obtained by the two techniques were comparable (the deviation from the mean is lower than 10% for 54.5% of the samples). The resulted 222Rn concentration was very low (5 Bq . l-1 for 43% of the samples) and, therefore, radon in waters cannot be considered as a direct radiological risk for the local population.

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Abstract  

A simple, sensitive and selective method is described for the simultaneous determination of plutonium and americium in lichen and moss samples which can be used as the atmospheric radioactivity bioindicators. Plutonium is separated from a HCl leaching solution by a Microthene-TNOA column; americium is separated by a KL-HDEHP column and purified by PMBP-TOPO extraction. A special attention has been paid to the decontamination of plutonium and americium from210Po. Ten lichen and 12 moss samples from tree trunks have been analyzed: starting from 2 g sample, the average yields and the detection limits were 70.2±12.5% and 28 mBq/kg for plutonium and 70.0±15.1% and 34 mBq/kg for americium. The concentrations (mBq/kg) ranged from 28 to 4960 for239,240Pu, from 28 to 171 for238Pu and from 34 to 1930 for241Am, respectively.

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Abstract  

During the last 14 years the Radioecology Laboratory of Parma University and the General Chemistry Institute of Urbino University collaborated on a radioecological programme having the aim to observe the evolution of antropogenic radioactivity in Antarctica in the period 1987-2001. The artificial radionuclides considered were 90Sr, 137Cs, 239+240Pu,238Pu and 241Am. The contamination seems to be higher in the continental environment rather than in the marine one. Mosses, algae and lichens showed the highest values for all radionuclides analyzed. The results prove that the Antarctic continent is interested by radioactive pollution. As far as 137Cs is concerned, a progressive decrease was observed.

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Abstract  

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, 40K) and antropogenic (Pu, 241Am, 137Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. 137Cs and 40K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.

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Abstract  

A selective method is described for the determination of210Pb in sediments, based on the separation of the daughter210Bi by extraction chromatography with Microthene 710-tri-n-octylphosphine oxide (TOPO) and on a final source counting with a low background -counter. The average chemical yield is 92.0%. The detection limit for 2 g samples is 19 Bq kg–1. An IAEA reference sediment sample was analyzed to check the reliability of the method.

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Abstract  

Suitable separation techniques were prepared for actinide,90Sr and226Ra determinations in environmental and industrial samples. Extraction chromatography with tri-n-octylphosphine oxide (TOPO) and di(2-ethylhexyl) phosphoric acid (HDEHP) solutions was used. IN some cases, a powder of Microthene (Microporous polyethylene) supporting solid TOPO was prepared thus obtaining a material showing better storing and column preparation features.Uranium and226Ra were determined in phosphorites, phosphoric acid and phosphogypsum.Uranium, thorium and226Ra were also measured in the low specific activity scales of hydrocarbon production equipment:226Ra was found to concentrate in some parts of the plant so causing a radiation protection problem.Plutonium and90Sr were measured either in some Mediterranean Sea samples or in environmental samples collected in Antarctica. Some interesting sea sediment profiles were also obtained.All the chemical methods were verified by: a) adding some yield tracers (232U,228Th,242Pu); b) analyzing some certified samples supplied by IAEA and NIST; c) participating in some international intercomparison runs; d) using, when possible, both an analytical and a radiometric method and e) following the radioactivity decay or growth (90Y and226Ra).

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