Chemical composition of precipitation near an industrial area at Izmir, Turkey

Wet and dry deposition samples were collected near an industrial area on the Aegean coast of Turkey. Concentrations of major ions (Cl−, SO42−, NO3, H+, Na+, K+, Cat2+ Mg2+ and NH4+ were determined. The pH of the precipitation, calculated from the volume weighted H+ concentration, was found to be 5.6, indicating extensive neutralization of the acidity in the rain. Neutralization was found to be a local process. The main base responsible for the neutralization of acidity was NH3 from fertilizer used in the region. The CaCO3 from resuspended soil accounts for 16% of the neutralized acidity. The annual wet deposition of ions was determined by two parameters, namely the precipitation amount and concentrations of ions in the precipitation. Precipitation amount accounted for approximately 70% of the annual wet deposition of ions in the Menemen region, whereas concentrations of ions in precipitation had only a minor influence. Although concentrations decrease with precipitation amount due to dilution in heavy rain, precipitation amount is not the only factor affecting concentrations of ions in precipitation. The main source of ions in wet deposition is the emissions from nearby industries. However, airborne NH4NO3 and (NH4)2SO4 fertilizer particles may also contribute to observed concentrations of SO22− and NO3− in rainwater. Dry deposition of most of the ions was higher than their annual wet deposition.