EVALUATING THE EFFECT OF DIFFERENT TYPES OF IRRIGATION WATER ON LEVEL OF HEAVY METALS IN SOIL IN AL- HASSA OASIS, SAUDI ARABIA

The present study is conducted to investigate the effect of irrigation water quality on heavy metals content in soil of Al- Hassa Oasis. The investigated irrigation water included groundwater (GW), mixture of groundwater and drainage water (GW+DW), mixture of groundwater and tertiary treated wastewater (GW+TTWW) and mixture of groundwater, drainage water and tertiary treated wastewater (GW+DW+TTWW). The results of this study indicate that the water types used in the present study may cause one problem or another according to the water type. By applying the criteria used for interpreting water quality for irrigation, the most domain problems are salinity hazard, potential salinity and soluble sodium percentage. Therefore, it is expected that continuous irrigation without good water management (leaching requirements) can led to severe problems from the salinity point of view. (GW+DW +TTWW) have the highest effect on elemental composition of soil followed by (GW+TTWW), (GW+DW) and then (GW). Generally, a significant difference in the heavy metals concentrations for both treated soil was found. The contents of the heavy metals in soil samples are compared with the worldwide standards. Based on these comparisons some recommendations are raised.