Identification of major acidic and basic species in rain water at Semenyih Dam water resources area / Nor Azura Mat Desa

A comprehensive study on the composition of rainwater was carried out from July 2007 to September 2007 at Semenyih Dam Water Resources Area. This area is a semi urban with no agricultural activities within 15 km range, no industrial activities within 20 km and located 15 km heavy traffic. All samples were analyzed for pH, electrical conductivity and major ions (SO42- , NO3- , Cl- , Na+ , Ca2+ , K+ , NH4+ and Mg2+ ). The rainwater was not considered as acidic because highest pH value is 6.9 and the lowest 6.7 with the average 6.82. SO42- and NO3- were the main anions, while Na+ and Ca2+ were the main cations. As conclusion, rainfall in this water resources area is currently not exposed to large quantity of anthropogenic acidic emissions.