Acidification/neutralization effect of ions in wet deposition samples in Pamukkale, Denizli, Western Turkey

Abstract

Acidification/neutralization effect of some ions in wet deposition samples was investigated from December 2011 to November 2012 in Pamukkale, Denizli, Turkey. Ca+2, SO4-2, and K+ account for 31.1%, 17.3%, and 15.2% of the total ions, respectively. The daily total concentrations decreased exponentially as the daily precipitation rates increased. The high contributors to total flux rates were SO4-2 (winter and spring), Ca+2 (summer), and K+ (fall). The rainwater was alkaline with a volume weighted mean pH of 6.94 +/- 0.86. However, 10.0% about samples was found acidic due to dominance of acidic components. About 21.6% of acidity of precipitation was caused by NO3-, and 78.4% by SO4-2. The calculated fractional acidity was approximately 0.14, indicating 86.4% of acidity was neutralized by alkaline constituents. Ca+2, Mg+2, and NH4+ played an important role to neutralize the acidity of rainwater. Enrichment factors showed that Ca+2 and Mg+2 were non-enriched ions. K+, F-, and Na+ indicated moderate anthropogenic enrichment, while Cl- was highly enriched from a variety of anthropogenic sources. The principal component analysis indicated that ion-containing precipitation was a two-component system, consisting of a mixed component (crustal and anthropogenic), and a local pollution component, which explains 72.6% of the total variance. Backward trajectories indicated that long-range atmospheric transport of pollutants, from northern Europe Mediterranean route, and northern African countries in the Saharan region, may have affected the composition of precipitation.