Ionic composition of precipitation at the Central Anatolia (Turkey)

Concentrations of major ions, SO42−, NO3−, Cl−, H+, Ca2+, K+, Mg2+, Ca2+ and conductivity were measured in approximately 300 daily, wet-only rain samples collected at a permanent rural station between 1993 and 1998. Concentrations of anthropogenic ions NH4+, SO42− and NO3− were among the highest values reported in whole EMEP network, suggesting that the Anatolian plateau is under strong influence of distant emission sources. Although transport of pollutants have significant influence on the chemical composition of precipitation, average pH of the rainwater is 6.2 due to extensive neutralization of acidity. Approximately 95% of the acidity in collected samples is neutralized, particularly in summer season. The neutralizing agents are primarily CaCO3 and NH3. Concentrations of crustal ions are higher in summer season due to enhanced resuspension of soil particles from dry surface soil. Concentrations of anthropogenic ions SO42− and NO3− do not change significantly between summer and winter due to higher intensity of rains in summer season. Although concentrations of ions measured in this study is among the highest reported in EMEP network, wet deposition fluxes are low compared to flux values reported for similar sites in Europe, due to low annual precipitation in the Anatolia. Wet deposition fluxes of all measured parameters are highly episodic. Source regions affecting chemical composition precipitation in the Central Anatolia is investigated using trajectory statistics.