Vol.:(0123456789) 1 3 Air Quality, Atmosphere & Health https://doi.org/10.1007/s11869-023-01431-z Atmospheric quality through analysis of dry and wet deposition at selected locations in Kandy and Gampaha districts of Sri Lanka B. D. P. Dharaka 1  · N. Priyantha 2 Received: 7 January 2023 / Accepted: 3 September 2023 © The Author(s), under exclusive licence to Springer Nature B.V. 2023 Abstract The chemical composition of the atmospheric bulk deposition is a good indicator of atmospheric pollution and air qual- ity. Bulk deposition is a collective term for wet deposition in the forms of rain, snowfall, fog, hail, or ice crystals and dry deposition of atmospheric chemical components mainly under the gravitational settling. The objective of the study was to quantitatively determine rainwater quality parameters, using standard procedures, in selected areas of Sri Lanka. Analysis of weekly sampling of bulk deposition in three sampling sites in Divulapitiya, Kandy, and University of Peradeniya (UOP) of Sri Lanka performed for a period of 24 weeks from 08th of February 2022 to 19th of July 2022 indicated that the three sites had 16.7%, 8.7%, and 8.3% dry-only depositions, respectively; with rainfall levels of 30.2 ± 37.4 mm, 30.6 ± 32.6 mm, and 33.7 ± 39.8 mm; and volume-weighted mean (VWM) pH values of 6.23, 6.29, and 6.47, respectively. Acidic deposition events below pH 5.60 level were not recorded from any site. Chloride (Cl − ) was determined to be the predominant anion, and the VWM of anions varied in the order of NO 3 − < SO 4 2− < Cl − in all three sites. Among trace metals investigated, Fe, Zn, and Al were predominant. Moreover, a very strong positive correlation for conductivity, total dissolved solids, and salinity among each parameter, was observed in the Pearson correlation analysis for all sites. Divulapitiya area showed low air pollu- tion levels with respect to chemical and physical parameters determined in the study as compared to Kandy and UOP areas. Possible causes for the results would be vehicular, constructional, and industrial emissions, and natural geographical factors. Keywords Bulk deposition · Rainwater · Pearson correlation · Kandy · Trace metals Introduction Air pollution, a global environmental issue, is caused by the release of air pollutants into the atmosphere by natural and anthropogenic sources (Kampa and Castanas 2008; Le Roux et al. 2016; Chathuranga et al. 2020). Anthropogenic activi- ties are the major source of air pollutants which adversely affect the biosphere, and cause risks to human health (Kampa and Castanas 2008). Despite its source, chemi- cal components present in the atmosphere are scavenged back to the earth’s surface by vertical transportation meth- ods, namely, wet deposition, dry deposition, surface sink absorption, and cloud water deposition (Lovett and Kinsman 1990; Weiner and Matthews 2003; Kajino and Aikawa 2015; Araujo et al. 2015). Wet deposition and dry deposition are collectively termed as atmospheric bulk deposition (Cha- thuranga et al. 2020). Wet deposition is the main scavenging mode of atmospheric chemical components to the earth’s surface (Wang and Han 2011; Kajino and Aikawa 2015), and it can occur in the forms of rain, snowfall, fog drops, hail, or ice crystals. These forms are collectively known as hydro- meteors (Seinfeld and Pandis 2016; Holopainen et al. 2020). Rain or precipitation is the most efective scavenging pathway of atmospheric chemical components and pollut- ants (Migliavacca et al. 2005). Cloud type, precipitation type, solubility of gaseous species in rain, and air mass tra- jectory are some important factors that afect scavenging efciency. Furthermore, the nature, size, and shape of pre- cipitation media, and hydrometeors involved are important in the process of wet deposition (Gonçalves et al. 2007). The composition of wet deposition depends on pollutant transport, emission levels, elevation, sizes of raindrops, and the method of scavenging process (Migliavacca et al. * N. Priyantha namal.priyantha@yahoo.com 1 Department of Environmental and Industrial Sciences, University of Peradeniya, Peradeniya, Sri Lanka 2 Department of Chemistry, University of Peradeniya, Peradeniya, Sri Lanka