STRONTIUM IN RAINWATER FROM ISRAEL - SOURCES, ISOTOPES AND CHEMISTRY

Eighteen rain samples from Israel have been analyzed for their chemical composition and Sr-87/Sr-86 ratios. The Sr-isotopic ratios lie in the range 0.7078 and 0.7092, and the Sr concentrations vary from 1 x 10(-4) to 9 x 10(-4) meq Sr/l. Soluble salts in rainwater are inherited from three major natural sources, seaspray. Recent marine minerals and mineral dust eroded from rock outcrops and soil. A mixing model is formulated to apply the chemical composition of rain (Cl- and Sr2+) and its isotopic Sr-87/Sr-86 ratio, for the identification and estimation of the Sr sources. All the samples fall within the mixing space predicted by the model for the three end members mentioned above. The data indicate that the most important non-seaspray source contributing dissolved salts to the rains in Israel comprises a mixture of Senonian to Eocene chalk (and its weathering products) and Recent marine minerals, from local and imported sources. Most of the samples (67%) contain 50% or more non-seaspray Sr (i.e., Sr dissolved from dust or Recent marine minerals), whereas 56% of the samples display Sr-87/Sr-86 ratios lower than 0.7090. The rest represent mixtures of seaspray and Recent marine minerals.