a method study of radon measurements in soil gas
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A METHOD STUDY OF RADON MEASUREMENTS IN SOIL GAS
AKE HESSELBOM
Geological Survey of Sweden, Box 670, S-75128 Uppsala (Sweden)
Radon as an environmental hazard has become a new field of work for geophysicists and geologists in Sweden. Experience gained from uranium exploration has proved to be useful in the search of buildings with increased radon concentrations in the indoor atmosphere.
The source for the radon can be either building materials containing higher than normal amounts of radioactive elements, or bedrock and/or drift cover with relatively high concentrations of uranium.
The techniques for measuring radon concentrations in the ground or radon- emanation from the ground are still not fully developed. The same applies to the theory of transport of radon in the ground and into the buildings.
This paper will summarize the results of a study of different commercially available techniques for measuring the radon soil-gas concentration and radon- emanation from the ground.
INTERPRETATION OF VECTOR MAGNETIC DATA FROM BOREHOLES
SVEN-ERIK HJELT, AIM0 HATTULA and PERTTI TURUNEN
University of Oulu, Department of Geophysics, SF-90570 Oulu 57 (Finland) Rautaruukki Oy, Exploration, PL 217 SF-901 01 Oulu 10 (Finland) Geological Survey of Finland, P.O. Box 77, SF-961 01 Rovaniemi 10 (Finland)
An interactive routine interpretation system is described, where the measure- ments consist of three-component magnetometer data. Interaction is provided through the use of a graphic screen in combination with a HP 9845 desk-top computer system. The present version uses combinations of two-dimensional plates, the field of which is computed using Joseph’s demagnetization correc- tion. Interpretation is performed by trial and error together with visual com- parison of vector fields.
The effect of known magnetized bodies is easily subtracted from the measured anomalous field, Visual examination of the residual fields enables the interpreter to detect new, hidden magnetized objects. All systematic errors are detected more easily this way.
The example describing the use of the interpretation system includes data from the Otanmaki mine.