Establishing the range of background for radon variations in groundwater along the Serghaya fault in southwestern Syria

Abstract

Long-term groundwater radon measurements were carried out in two selected karstic springs emerging from the Serghaya fault zone in southwestern Syria. The work is aimed at determining the range of radon background along the concerned fault, which represents a prominent branch segment of the Dead Sea Fault System in the region. The obtained data was statistically analyzed and the mean radon values have been standardized in terms of probability of magnitude in order to enable the separation between normal radon variations from other anomalous or geotectonic related values. The results revealed a general background range of radon concentration varying between 5000 and 13000 Bqm-3, and thus all radon values lying outside this range were considered anomalous. However, remarkable clusters of high radon concentrations with peak values more than twice times the background level, were observed in both monitoring springs through the period (1992-1994). These abnormal radon values were positively correlated with simultaneous time of high precipitations, while no significant earthquake activities were recorded in the region during that period. Therefore, such radon signals do not seem to be a reflection of regional changes in crustal strain, but rather they mostly indicate evidences of radon response to the groundwater table fluctuations due to high precipitations. These consequences may confirm the usefulness of radon application as an important natural tracer in hydrogeological investigations.