Comparison of Ionic Concentrations (Na+, Ca2+, Mg2+, NH4+, Cl-, SO42-, NO3-) and Water Quality Parameters of Bulk Depositions Among Three Sites in Kandy Area, Sri Lanka

Abstract

The chemical composition of atmospheric deposition changes over time due to a variety of physical, chemical, and biological conditions. The objectives of this study were to use statistical methods to compare the composition of cations, anions, and water quality parameters of bulk deposition. Three sampling sites of 7 km apart in Kandy District in Sri Lanka were selected for the study: The Kandy City Center (KCC) site represented an urban environment located in a valley, the University of Peradeniya (UoP) site and the Polgolla sites represented a suburban environment. Bulk depositions were collected weekly over eight months (from 03.08.2018 to 27.03. 2019). The chemical analyses of anions (Cl-, NO3-, SO42-) and cations (Na+, K+, Ca2+, Mg2+, NH4+) in bulk depositions carried out using ion chromatography indicated that the volume-weighted mean (VWM) concentrations of cationic species in KCC, UoP, and Polgolla sites followed as, Na+> Ca2+> Cl-> K+> Mg2+> NH4+> SO42-> NO3-, Ca2+> Na+> Cl-> Mg2+> NH4+> SO42-> NO3-> K+, and Na+> Cl-> Ca2+> NH4+> K+> NO3-> SO42-> Mg2+ respectively. The VWA pH in KCC, UoP, and Polgolla sites were 6.93, 6.82, and 6.85, respectively, which are nearly neutral due to the neutralization effect. The VWA conductivity values of KCC, UoP, and Polgolla sites were 64.22 µS cm-1, 49.40 µS cm-1, and 42.66 µS cm-1, respectively. Average values of other water quality parameters (salinity, total dissolved solids, and hardness) were higher in the KCC site than those in the other two sites.