Precipitation scavenging of polycyclic aromatic hydrocarbons in Mumbai, India.

The concurrent rain and air sampling was conducted for thirteen rain events between the last week of May and end of June 2001. Concentration of total PAHs varied from 84.25 to 777.49 ng/l whereas that in air was in the range of 4.05 to 34.42 ng/m(3). In rainwater the lower molecular weight PAHs (e.g. Phenanthrene, Fluoranthene and Pyrene) were found to be more prominent than the higher molecular weight compounds. The gas phase scavenging ratio (Wg) was found to increase with the molecular weight of the compound. The particle phase scavenging ratio (Wp) values for the more volatile PAHs were generally much higher than those for less volatile PAHs. The higher MW PAHs have Wg values equal to or larger than their Wp values.