Chemical composition of wet precipitation in Irbid, Jordan

Rainwater samples were collected in Irbid city using 24 hour sampling periods from December 1996 to April 1998. All samples were analyzed for major cations (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 pH are attributed to the neutralization by natural alkaline local dusts which contain large fractions of calcite. Correlation and mineralogical analyses indicated that Ca2+, K+ and fractions of Na+, SO42- and Mg2+ are of crustal origin. Results of the present study suggested that the atmospheric composition in the city is strongly influenced by natural sources rather than anthropogenic.