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.
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.
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.
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.
Ombrotrophic peat bogs, which are quite common in temperate regions, receive chemical compounds only from the atmosphere. These bogs are therefore well suited to study temporal and spatial trends of air pollutants such as heavy metals, provided that the substances concerned are sufficiently strongly retained in the peat. In this paper, the use of instrumental and radiochemical neutron activation analysis to study trace elements in ombrotrophic peat is described. This work has provided very useful information with respect to the impact of long range atmospheric transport of pollutants to different parts of Norway, and has also been shown to be a useful tool in the study of natural trace element cycling processes. Elements discussed in particular are Zn, Se, Sb, and Br.