Identification and characterization of the source water-insoluble single particulate matter in rain events in the province of Isparta

Abstract

Analyzing atmospheric pollutants in rainwater is crucial for evaluating the environmental impacts of both natural and anthropogenic pollution sources. Literature review indicates that air pollution studies commonly employ the collection of particulate matter (PM) on filters for subsequent analysis. However, this approach may result in significant particle accumulation on the filters, thereby complicating their characterization through semi-quantitative analytical techniques. This study characterized insoluble particulate matter from sequentially collected rainwater samples based on particle size, morphology, and chemical composition. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X‒Ray Spectrometry (EDS) and a particle size analyzer were utilized. Integrating SEM‒EDS data with particle size distribution analyses, chemical composition results, and upper atmospheric back-trajectory modeling made it possible to identify specific sources of insoluble particles in the rainwater samples. The rainwater samples were also analyzed for pH, electrical conductivity, and major anions and cations. The pH values ranged from 5.92 to 7.43, and electrical conductivity values varied between 6.19 and 102.4 μS/cm. Among the major ions, relatively high concentrations of Ca²⁺, SO₄²⁻, and NO₃⁻ were detected, while lower concentrations of F⁻, Mg²⁺, Na⁺, and Cl⁻ were observed. Elevated Ca²⁺, Mg²⁺, K⁺, and F⁻ levels were linked to local anthropogenic activities, including agricultural practices, biomass burning, and vehicular emissions. Conversely, NH₄⁺, SO₄²⁻, and NO₃⁻ presence was attributed to long-range atmospheric transport. Contributions from sea salt were evidenced by the levels of Cl⁻ and Na⁺ ions.