Groundwater pollution in Israel mainly occurs in the populated urban areas. Yet, in the 90's a major salinization was identified in a deep well in the northeastern part of the Negev desert, and a trend of increasing salinity was recognized in an adjacent spring. Since then the salinity of the spring is on the rise reaching a rate of 21 mgCl/L per month. New geochemical data allows the identification of the source, composition and volume of the contaminant, as well as its dispersion in the aquifer. The source of the contamination is attributed to highly saline (~40,000 mgCl/L), acidic and trace elements-rich industrial wastewater that leaked from evaporation ponds and also drained through karstic sinkhole to the subsurface over a period of decades. The contamination is reflected by a sharp increase in the concentrations of most major elements and by a moderate increase in a few trace elements. The total waste water volume that leaked is assessed to be 75 MCM. The study reveals that most of the contaminated water is still far upstream of the natural outlet. Due to the specific geological configuration the highly contaminated groundwater is channeled into a narrow corridor of an elongated syncline. Unlike other similar contamination cases around the world, pumping along this syncline can reduce the flow of the contaminated water further downstream towards a region where it disperses. The study provides the decision makers with tools that can reduce the environmental hazard and enable development of water production in this arid region. The current research emphasizes the importance of a combined geological, hydrological and geochemical study of a contaminated aquifer to fully understand the flow regime and contamination process. Such studies are a crucial step before an optimal mitigation action can be undertaken to rehabilitate a contaminated aquifer.
Keywords: Channeled flow; Judea Group; Mixing ratio; Salinization; Trace elements; Waste water.
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