RESPONSE OF RADON IN SOIL GAS TO METEROLOGICAL FACTORS IN NORTHERN NEW JERSEY

Radon in soil gas from a glacial loamy soil in Parsippany, northern New Jersey varied by as much as 8-fold, from 80 pCi/L to 766 pCi/L, as a function of changing soil moisture and meteorological conditions over a 6-month period. The greatest variation occurred on a seasonal to annual basis in response to soil moisture conditions. Dry soil produced the lowest soil radon concentrations (80- 470 pCi/L) whereas moist to water saturated conditions produced the highest soil radon (264 -766 pCi/L). Extended rain events that lasted several days increased soil radon by as much as 318% for up to 2-3 weeks. Shorter duration meteorological events were generally less definitive and were complicated by competing factors. In some individual rain events, radon increased for periods of one to several hours by 12 - 99%. In other rain events, radon initially decreased by up to 30% but later increased by up to 26% with a lag time for increase of 7 to 36 hours. Lag time in radon response was more common when soil was moist to saturated. Radon response to other meteorological factors was even less distinct and more prone to complication by competing conditions. Radon in soil generally decreased by 12 to 50% during wind events with no lag time in response. During marked changes in barometric pressure that were not complicated by other factors, radon showed a strong correlation with barometric pressure with r = 0.8262. Not only do these results have implications for methods of radon measurement in homes, they also help clarify soil gas controls and processes in response to changes in weather.