An Initial Assessment of the Contribution of Fresh Submarine Ground Water Discharge to the Alkalinity Budget of the Mediterranean Sea

Excess total alkalinity (TA) of Mediterranean Sea (MS) seawater relative to its Atlantic origin has been attributed to high inputs from major rivers and the Black Sea. Submarine groundwater discharge (SGD), which was recently shown to be an important source of nutrients to the MS, may also be an important source of TA to the MS. During 2015–2017, water samples were taken from a shoreline groundwater spring near Tel-Shikmona, northern Israel, and analyzed for TA, salinity, and dissolved inorganic nutrients. Spring water TA varied seasonally between a low of 3,919 and a high of 7,148 µmol kg⁻¹ in the summer and winter, respectively. Long-term records from a nearby monitoring site indicate that wintertime coastal water TA is positively correlated with annual rainfall rates. Based on the Tel-Shikmona groundwater spring measurements and other measurements from the MS region reported in the literature, we estimated that the TA flux from the fresh component of SGD (FSGD) in this region is 22%–37% and 17%–30% of the riverine and Black Sea TA fluxes to the MS, respectively.