Cl/Br ratios of Lake Kinneret, pore water and associated springs

The Cl/Br ratio (wt/wt) of pore water in a lake, having diverse saline inputs, was used to distinguish among the influx of different water sources and estimate their relative contributions. Pore water concentration profiles obtained by a passive multi-layer sampler from bottom sediments of Lake Kinneret, Israel, depict Cl/Br ratios that vary between 70 and 156 and are similar to ratios in nearby onshore springs - Hamei Tiberias and Fulya, respectively. The Cl/Br ratio of the lake (135) is strongly influenced by the Cl/Br fingerprint of Fulya-type water. However, the discharge of the known Fulya springs can not provide the required Br^- mass (about 648 tons/y) to maintain the Cl/Br ratio in the lake. Therefore, diffusive and advective fluxes of pore water are additional important mechanisms by which Br^- is added to lake water. Moreover, it is demonstrated that a combination of Fulya and Hamei Tiberias-type waters (90 and 10%, respectively) can explain the Cl/Br ratio of the lake. The areal distribution of the Cl/Br ratio in pore water may be the result of dilution of an ancient evaporated solution (Cl/Br ≃ 70) with fresh water from adjacent aquifers (Cl/Br ≃ 150), followed by mixing with a saline solution having a high Cl/Br ratio (Cl/Br ≃ 300). The results of this work suggest that the Cl/Br ratio is a sensitive tool for the study of other similar environments.