Environmental isotopic and hydrochemical study of water in the karst aquifer and submarine springs of the Syrian coast

The groundwater of major karst systems and submarine springs in the coastal limestone aquifer of Syria has been investigated using chemical and isotopic techniques. The d delta O-18 values of groundwater range from -6.8 to -5.05%, while those for submarine springs vary from -6.34 to +1.08 parts per thousand (eastern Mediterranean seawater samples have a mean of +1.7 parts per thousand). Groundwater originates from the direct infiltration of atmospheric water. Stable isotopes show that the elevation of the recharge zones feeding the Banyas area (400-600 m a.s.l.) is higher than that feeding the Amrit area (100-300 m a.s.l.). The O-18(extracted) (O-18 content of the seawater contribution) for the major submarine springs suggests a mean recharge area elevation of 600-700 m a.s.l., and lower than 400 m a.s.l. for the spring close to Amrit. Based on the measured velocity and the percentage of fresh water at the submarine springs outlet, the estimated discharge rate is 350 million m(3)/year. The tritium concentrations in groundwater (1.6-5.9 TU) are low and very close to the current rainfall values (2.9-5.6 TU). Adopting a model with exponential time distribution, the mean turnover time of groundwater in the Al-sen spring was evaluated to be 60 years. A value of about 3.7 billion m(3) was obtained for the maximum groundwater reservoir size.