Identification of the potential sources of nitrate in groundwater from shallow aquifer in Wadi Qudaid, Western part of Saudi Arabia

Abstract EN

An investigation to identify the potential contamination of groundwater from on-site domestic wastewater systems blasted in the alluvial deposits in Wadi Qudaid basin, west of Saudi Arabia, was conducted during April, 2010.

Groundwater samples were collected at a variety of depths and distances along the groundwater flow path from the cesspool.

Impacts of on-site systems on the shallow aquifer are evidenced by the elevated concentrations of NO3-and Cl.

The chemical analyses results of the groundwater samples collected from private domestic wells in a residential site, show that the NO3 concentration in the groundwater exceeded the maximum contaminant level (MCL) of 45 mg / l.

It ranges from 43 to 193 mg / l with an average of about 77.0 mg / l which is greater than the average background (19.0 mg / l) of the NO3 concentration in the undeveloped region within the wadi basin itself.

The high NO3 content is a widespread pollutant that possesses a serious threat to the public health.

Nitrate contamination is generally observed in close proximity to potential point waste sources.

The dominant groundwater movement in the area is the major factor enhancing the groundwater deterioration by nitrate that leached from on-site wastewater disposal systems.

Chloride-Nitrate and (Sodium Nitrate) Chloride and other relationships have been used to differentiate the potential sources of Cl–.

None of Faecal coliforms were detected in the groundwater samples even in samples with the highest NO3 concentrations, implying that the depth to the groundwater body was sufficient for bacterial die-off.