Ground gamma-ray survey of the Solforata gas discharge area, Alban Hills-Italy: a comparison between field and laboratory measurements.

Measurements of environmental radioactivity by HPGe gamma-spectrometry were carried out with the aim of investigating the distribution of natural radionuclides in a volcanic area and to compare two different methodologies – an in situ gamma-survey of the area and high accuracy laboratory measurements of soil samples. Results demonstrate good performance of the in situ technique, also confirmed by a correlation analysis between the results obtained by the two methodologies. A volcanic gas discharge area was chosen as the test site for the presence of natural long-lived radionuclides such as 40K and 238U, 235U and 232Th, and their decay chain members. Clear evidence of 222Rn degassing in the area was confirmed by 226Ra values measured by the in situ technique. Higher 40K values measured by the in situ technique may be attributed to the presence of vegetation in the study area.