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  • Author or Editor: E. Steinnes x
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Abstract  

The development over time in applications of nuclear activation techniques in environmental studies is critically reviewed. A vast majority of the work has been based on activation analysis using thermal and sometimes epithermal neutrons from nuclear reactors (NAA). Whereas radiochemical methods were frequently used until about 1975, the work reported more recently has mainly been multi-element studies based on instrumental NAA. The by far most successful application has been the analysis of aerosol samples, but considerable work has also been done in other areas such as precipitation and surface waters, soils, vascular plants, moss and lichen biomonitors, and fossil fuels with by-products. Some interesting examples of speciation analysis, based on pre-irradiation separations, have also been reported. Rapid development in alternative multi-element techniques such as ICP-MS has shown these techniques to be superior in a number of cases where NAA earlier was the technique of choice. Areas where efforts should be concentrated in future NAA work are indicated.

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Abstract  

Nuclear data relevant to the determination of elements in geological materials by instrumental neutron activation analysis using a combination of epithermal neutron activation and Compton suppression counting are presented. The feasibility of this combination is discussed considering data for desired as well as interfering nuclides. Among elements determined after short irradiation, the conditions for Sr, Zr, I, Cs, Eu and U should be improved. After long epithermal irradiation and appropriate decay, Compton suppression should lead to improvement in determination of As, Rb, Sr, Mo, Sn, Sb, Ba, Gd, Ho, Tm, W, Au, Th, and U. In the case of Ga, Se, Ag, In, Cs, Tb, Yb, Hf, Ta, and W, the use of Compton suppression in connection with epithermal activation is not recommended because the radionuclides concerned decay with coincident γ-rays. In general, the use of Compton suppression should improve the determination of trace elements in geological materials by epithermal neutron activation analysis, but more work is needed to better quantify these improvements.

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Abstract  

In a study of the atmospheric deposition of trace elements in different parts of Norway, samples of the mossHylocomium Splendens were analyzed with respect to 28 elements. The determination of Cu, Zn, Cd, and Pb was carried out by atomic absorption spectrophotometry, while 24 additional elements were determined by instrumental neutron activation analysis. In samples from southernmost Norway, a substantially higher concentration was found for elements such as Pb, Sb, V, Cr, Cu, Zn, As, Se, Mo, Ag, and Cd than in samples from places located in the more northerly parts of the country. The results indicate that sources which are to the south and south-west of Scandinavia, contribute significantly to heavy metal deposition in Norway.

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Abstract  

A neutron activation method is devised for the simultaneous determination of Rb, Cs, Cr and P in silicate rocks. After alkaline fusion and removal of the insoluble hydroxides, the filtrate is assayed for Rb, Cs and Cr by Ge(Li) γ-spectrometry and for P by β-counting. An additional hydroxide scavenging step permits the γ-spectrometric measurements to be performed by means of a sodium iodide detector. Results obtained on some standard rocks are in good agreement with previous neutron activation data obtained by methods based on more complicated radiochemical procedures.

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Abstract  

INAA is known to be a powerful technique for the simultaneous determination of chlorine, bromine and iodine. In this paper INAA using epithermal neutrons is shown to be particularly useful to elucidate marine gradients of these elements. Examples are from a transect study in northern Norway where samples of the feather moss Hylocomium splendens were collected at distances of 0-300 km from the coastline. All three elements decrease exponentially as a function of distance from the ocean in the moss samples, strongly indicating that the atmospheric supply from the marine environment is the predominant source of these elements to the terrestrial ecosystem. It is suggested that environmental studies of halogens in general and iodine in particular is a promising future area of application for INAA, when employing epithermal neutrons.

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Abstract  

Epithermal neutron activation analysis is shown to be a powerful technique for the simultaneous determination of chlorine, bromine and iodine in organic-rich soils. Examples are shown from a transect study in northern Norway where samples of surface soil were collected at distances of 0–300 km from the coastline. All three elements decreased exponentially as a function of distance from the ocean, strongly indicating that atmospheric supply from the marine environment is the predominant source of these elements in the soil. The Cl/Br and Br/I ratios also showed a regular change with distance from the ocean, and hypotheses for this behavior are offered.

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