| Popis: |
Publisher Summary The collection of soil-gas samples in low permeability soils is often complicated due to a high resistance that must be overcome. An enlargement of the cavity, from that the samples are taken, is then required, but this action may affect the measurement result. A relationship between the measured soil-gas radon concentration and the changing sampling geometry was studied in four reference areas characterized by low permeable soils and/or by a high soil moisture. The results of the survey indicate that measured soil-gas radon concentrations do not depend on the changing sampling geometry if the vertical profile of the uppermost soil layers is homogeneous. A decrease of soil-gas radon concentration with increasing dimensions of the cavity was observed when the soil permeability was higher at shallow depths. Due to a lower resistance, the soil-gas sample is collected mostly from the upper part of the active area. A good knowledge of the vertical soil profile is thus very important for correct interpretation of measured soil-gas radon concentrations. A perfect sealing of all parts of the equipment is required when soil-gas samples are collected in low permeability soils. |
