Meteorological influences upon the radon‐content of soil‐gas

This paper is a continuation of one given at the Twenty-Fifth Annual Meeting of the American Geophysical Union, in June, 1944, on “A study of the radoncontent of soil-gas” [see 1 of “References” at end of paper]. The present paper covers the period from May 17, 1944, to March 25, 1945. Its main purpose is to consider the meteorological influences upon the radon-content, such as barometricpressure changes, wind-velocity effects, and temperature-variations. Four depths, 25, 75, 150, and 200 cm, were investigated. In the course of 177 days of actual investigation during this period, covering 642 Individual readings, the radon-content of the soil-gas was measured. Ionization-chambers connected with a Wulf bifilar-electrometer were used, and the amount of radon was calculated in (curie/cc) X 10−14 , after calibrating the apparatus by means of a standard solution of radium. From the results obtained the following conclusions can be drawn: (1) Dry ground produces constant values of the radon-content at each depth and shows an increase of the content with depth. (2) A long period of snow-and-ice-coverage of the ground causes all pipes to approach the same value. Frozen ground gives the highest values for the year. (3) Barometric pressure causes, at least to a depth of 200 cm, a variation such that an increasing pressure tends to decrease the radon-content, while a decreasing pressure produces an increase in radon-content. This effect is most pronounced at the 25- and 75-cm levels. (4) A high wind-velocity over a number of hours will noticeably reduce the radon-content in the top layers of the ground. (5) Ground-temperature changes have apparently no great effect upon the radoncontent of soil-gas.