Groundwater Contamination of Wadi Haliy Area, Southwestern Arabian Shield, Saudi Arabia

Abstract

Contamination of surface water, groundwater, sediment, and atmosphere by heavy metals and radionuclide is among the most significant issues facing the Kingdom. Wadi Haliy is considered as important source of water to the Red Sea coastal plain. Copper, zinc and other base-metals mineralization occur in the Precambrian Arabian shield rocks that dominate the water catchments area of this wadi. The water samples were analyzed for major, trace elements and heavy metals using collaborative techniques. The groundwaters in Wadi Haliy are of Cl–SO–Na–Ca type. The variation in water type indicates variation in natural processes such as evaporation, differences in rock units and mineralization, water rock interactions and water residence time. The data analyses showed some samples are of high heavy metals and uranium contents. Pollution by heavy metals and uranium arises mainly from neighboring rocks and also from emissions from mining activities. Generally, the uranium and heavy metal contents are higher in samples collected from the upstream area of the wadi where the crystalline rocks are exposed and in direct contact with the runoff. The Elevated heavy metal and uranium contents suggests that these mining areas are considered as potential sources for these natural pollutants and likely affecting the water quality in these wadis. The attenuation of heavy metals and uranium is reported in this study along the flow path, from the mining area to downstream. The processes governing the evolution of the leachates plume and its heavy metals budget are modeled in two steps: (1) Neutralization of acidic mine drainage water; (2) Heavy metal attenuation by adsorption, evaporation and co-precipitation with Fe oxides.