The origin and age of groundwater in the Nubian Sandstone aquifer in the Negev, Israel

摘要

Future prospects of utilization of the Lower Cretaceous Nubian Sandstone aquifer in many basins in the Middle East are overshadowed by the lack of modern replenishment and groundwater salinity. Here we examined the chemical and isotopic (~(87)Sr/~(86)Sr, δ~(11)B, δ~(18)O, δ~2H, ~(14)C, ~(36)Cl) compositions of brackish to saline groundwater from the Nubian Sandstone aquifer in the Negev, Israel. The data reveal two major recharge sources, one with low D-excess (～10), originated from recharge of southern wet air masses in southern Sinai and a second with high D-Excess (～16) derived from local and dry Mediterranean air masses recharged in the Negev. Groundwater salinity is derived from both flushing of residual entrapped brines and dissolution of gypsum and halite. Groundwater from both sources have a low ~(36)Cl/Cl (5-20 x 10~(-15)) signal, but measurable ~(14)C values (0.9-3.9 pmc) suggest dissolution of old ( > 1 Ma) salts by Late Pleistocene (23 to 35 ka) meteoric water.