Chemical characterization of rainwater at Singapore

A short term study of the chemical composition of rainwater was carried out from November 1999 to October 2000 in Singapore. The rainwater was typically acidic with a mean pH of 4.2. Sulfate was the most abundant ion and comparable to the results reported for other industrialized regions. The concentrations of major ions (NH4+, Ca2+, K+, Na+, Mg2+, SO42+, NO32−, Cl−, HCOO−, CH3COO−) varied monthly. Results show that local meteorological conditions influence the chemical compositions to a significant extent. The pollutants in rainwater were derived from long range and local (industry and traffic) sources.