³⁶Cl in chloride-rich rainwater, Israel

Eleven rainwater samples from Israel have been analyzed for their isotopic ³⁶Cl/Cl ratios and their soluble salt content. The rains display a range of ³⁶Cl/Cl ratios between 1.8 × 10^-15 and 50 × 10^-15, and chloride ion concentrations of between 0.3 and 4.2 meq Cl^- l. The ratios between the concentrations of Na⁺, Mg²⁺ and Cl^- in the samples demonstrate a clear marine origin for these ions in the rainwater. Although the stable ³⁵Cl isotope in rainwater is marine in origin, while the accompanying ³⁶Cl radioisotope is non-marine, both are linearly and positively correlated in chloride-rich ( > 1 meq Cl/l) rains. The ³⁶ClCl seawater solute relationship may be explained as result of a mixing process between two chloride-bearing sources: (a) sea-spray laden air with a low ³⁶Cl/Cl ratio, and (b) a Cl-rich mineral dust reservoir, with a high ³⁶Cl Cl ratio. Both are introduced and admixed into the atmosphere during storms. The possibility of a high ³⁶Cl/Cl ratio stratospheric end-member is rejected in view of the non-marine nature of the chlorine therein.