Application of chlorine-36 technique in determining the age of modern groundwater in the Al-Zulfi province, Saudi Arabia

Abstract

The present study aims to estimate the residence time of groundwater based on bomb-produced36Cl.36Cl/Cl ratios in the water samples are determined by inductively coupled plasma mass spectrometry and liquid scintillation counting.36Cl/Cl ratios in the groundwater were estimated to be 1.0–2.0 × 10−12. Estimates of residence time were obtained by comparing the measured bomb-derived36Cl concentrations in groundwater with the background reference. Dating based on a36Cl bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s. The above36Cl background concentration was deduced by determining the background-corrected Dye-3 ice core data from the frozen Arctic data, according to the estimated total36Cl resources. The residence time of 7.81 × 104 y is obtained from extrapolated groundwater flow velocity.36Cl concentration in groundwater does not reflect the input of bomb pulse36Cl, and it belongs to the era before 1950.