Chemical composition of wet precipitation in Irbid, Jordan

Rainwater samples were collected in Irbid city using 24 hour sampling perio ds from December 1996 to April 1998. All samples were analyzed for major ca tions (Na+, K+, Ca2+ and Mg2+), major anions (Cl-, NO3- and SO42-) and pH. High levels of Ca2+ and SO42- were observed. Together, Ca2+ and SO42- made up more than 52.4% of the total ion mass, while Ca2+ alone contributed over 39.0% of the total cation. The majority of the rain samples collected had pH values higher than 5.6. The average pH was 6.4 +/- 0.9. High values of p H are attributed to the neutralization by natural alkaline local dusts whic h contain large fractions of calcite. Correlation and mineralogical analyse s indicated that Ca2+, K+ and fractions of Na+, SO42- and Mg2+ are of crust al origin. Results of the present study suggested that the atmospheric comp osition in the city is strongly influenced by natural sources rather than a nthropogenic.