Evaluation of Groundwater Quality in Shallow Aquifers Under Cultivated Lands at Al Oha Area, United Arab Emirates

To assess the impact of application of chemical fertilizers in agriculture on the Quaternary aquifer at AI Oha area, United Arab Emirates, 76 groundwater samples were collected during February 1995 - March 1996. Samples were analyzed for major, minor and trace chemical constituents in the Food Control Laboratory, Abu Dhabi. The Total Dissolved Solids (TDS) of collected samples varied between 500 milligrams per liter (mg/l) in the east and 3,500 mg/l in the west. Except for bicarbonate ion (HC03-), concentration of major cations (Ca2+, Mg2+, Na+ and K+) and anions (CO32-, SO42- and Cl-) shows a general increase from east to west. The increase of salinity and concentration of all ions from east to west occurs in the direction of groundwater flow, where ion-depleted water from recharge area in the east becomes progressively loaded with more ions towards discharge areas in the west. Concentration of nitrate ion (NO3- in groundwater within the study area during February 1995 - March 1996 remained below the limits recommended by the World Health Organization (WHO) for drinking water (45 mg/l as NO3- or 10 mg/l as NO3--N). Phosphate ion (PO4-) shows trace concentrations in groundwater within the study area, averaging 0.8 mg/l. With the exception of few local anomalies, concentrations of iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), copper (Cu), cobalt (Co) and chromium (Cr) shows a general increase from east to west. Based on the above results, there is no reason to believe that the chemical fertilizers used on farm lands at AI Oha area has adversely affected groundwater in the Quaternary aquifer