ISOTOPIC RECONNAISSANCE OF WATER QUALITY DEGRADATION IN THE MIDDLE EAST

Increasing demand for water resources in the Middle East has accelerated rates of water quality degradation and resulted in the exploitation (mining) of fossil groundwater. Sustainable water management under these conditions requires adequate tools for delineating the origin of typical non-point contamination sources -- in particular, the evaluation of the effect of man-made versus naturally occurring contaminants on the water quality. This paper presents results from three examples whereby multiple isotopic systems were applied to elucidate contamination sources: (1) salinization of the Mediterranean Coastal aquifer and the Gaza Strip, which is derived from seawater intrusion, lateral flow of saline groundwater from adjacent aquifers, and irrigation/recharge of treated waste water, all characterized by distinguished isotopic (boron, strontium, oxygen, hydrogen) fingerprints that enables elucidating of the preferential impacts of these sources; (2) Elevated high nitrate concentrations in the Mediterranean Coastal aquifer and the Gaza Strip (up to 400 mg/L) has distinguished nitrogen isotopic ratios, which enables discrimination between natural nitrate leached from the unsaturated zone due to historic soil cultivation and anthropogenic nitrate derived directly from sewage contamination; (3) Elevated levels of radioactivity in groundwater from the Nubian Sandstone and carbonate aquifers in Israel and Jordan. The use of the radium isotope quartet, combined with an integrated geochemical investigation, establishes that the radionuclides are naturally occurring and provides geochemical tools to delineate the mechanisms for their mobilization from the aquifer rocks. These findings could have implications for possible high radioactivity anomalies in many other aquifers, particularly for fossil groundwater from the Nubian Sandstone basins in the Middle East.