Contamination of groundwater by nitrate is considered a global problem. Nitrates are introduced in the groundwater from a variety of sources like agricultural activities, poor sewer system, wastewaters, and industrial activities. In the present research, a survey of wells (n = 1,060) was undertaken in all 13 regions of the Kingdom of Saudi Arabia to assess the contained nitrate (NO(3)) levels. The results indicated variation in nitrate levels from 1.1 to 884.0 mg/L as NO(3) throughout the Kingdom. The average nitrate levels in milligrams per liter as NO(3) were as follows in descending order: 65.7 (Jizan), 60.3 (Asir), 60.0 (Qassim), 51.3 (Hail), 41.8 (Makkah Al Mukaramma), 41.3 (Madina Al Munnawara), 38.0 (Al Baha), 37.0 (Najran), 30.7, (Tabouk), 25.2 (Eastern Province), 18.8 (Riyadh), 15.8 (Al Jouf), and 9.1 (Hadwed Shamalyah). The results indicated that nitrate levels exceeded the maximum contaminant limits for drinking water (45 mg/L as NO(3)) in a number of wells (n = 213) in different regions of the Kingdom. The maximum and minimum wells exceeding the maximum contaminant limits for nitrate in drinking water were in Jizan (52.6%) and Hadwed Shamalyah (4.9%), respectively. Most of the wells which exceeded the maximum allowed limits for nitrate were in the areas which were used for agricultural and residential purposes.
A funded research project was conducted during the period July 1992 through November 1994. The project was designed to evaluate indoor and ambient air quality in and around buildings of different types and uses in Riyadh, the capital of Saudi Arabia. Thirty intercity buildings and two outercity (background) sites were carefully selected and monitored for air quality. Ten air pollutants, together with relevant meteorological parameters, were monitored indoor and outdoor at each site continuously and simultaneously for a period of two weeks covering summer and winter seasons. This article discusses the results obtained for sulfur dioxide (SO2), ammonia (NH3) and formaldehyde (HCHO). Results of this investigation revealed that most sites had on the average exceeded the recommended standards for SO2 and NH3 both indoor and outdoor, with indoor levels being worse than outdoor during winter time. Several sites also showed high levels of HCHO, with outdoor levels being consistently higher than indoor. Statistical and frequency analyses were performed on the collected data, showing seasonal and sector by sector variability, and outdoor-indoor correlations.
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