Evaluation of hourly-based precipitation chemistry in suburban site of Bolu

Abstract

Precipitation chemistry is important for understanding atmospheric chemistry and transportation mechanism for a region. Therefore, 6-h rain samples were collected manually on the Black Sea Region of Turkey between March 2019 and May 2019. Totally, 21 wet deposition samples were collected in 12 rainy days. The collected rain samples were analyzed by ion chromatography for ions, including Cl−, NO2−, NO3−, SO42−, Na+, Ca2+, Mg2+, K+, NH4+. Volume weighted mean (VWM) concentrations of ions were calculated and were in the order of Na+ > Ca2+ > Cl− > SO42− > NO3− > Mg2+ > K+ > NH4+> NO2−. The pH values of individual precipitation varied from 4.70 to 8.07. Anion to cation ratio was 0.74 ± 0.34 thus it was an indication of anion deficiency. A strong correlation between NH4+ and SO42−, NH4+ and NO3−, Ca2+ and SO42−, Ca2+, and NO3− was found in the samples due to the neutralization process. The back trajectory model was used to find the long-range sources and the influence of air masses coming from Saharan, Europe, and the Black Sea. Calcium ion was found to be an effective ion in the neutralization processes by analysis of multiple linear regression and neutralization factor calculation. Approximately 79.5% of SO42− and 59.7% of NO3− were neutralized by Ca2+ and NH4+. The washout mechanism for Na+, Mg2+, Ca2+, and K+ was dominantly observed on the March 12, 2019. Rainout mechanism was seen on the April 13, 2019 rain event due to the long-range transportation from Saharan Dust.