Characterization of water-insoluble particulate matters in sequential rain samples collected by a novel automatic sampler in Antalya, Turkey

Three rainfall events were sampled sequentially in Antalya, Turkey on November 19 and December 04,13, 2020 by using an automatic rain sample collection device that was developed and validated by our group. Water-insoluble particulate matters (PMs) were characterized by using a scanning electron microscopy-energy dispersive X-ray fluorescence (SEM-EDS) and the particle size distributions in the rain sequences were determined by using particle size analyzer directly, without any sample pretreatment In order to determine the transport regions of the sampled rain events, back trajectory calculations were made using the HYSPLIT modeling program. In studies on the detection of air pollution in aerosol samples, the particles (PMs) are collected on the filter and examined. This method can cause many particles to accumulate on the filter and make it difficult to characterize them by using semi-quantitative methods. The use of particle size analyzer and SEM device to characterize and detect particles in rainwater provides more successful results. This method can provide direct evidence for single particle analyses, and the determination of compositions and morphologies of atmospheric PMs. In this study, the water-soluble ionic compositions were determined by using ion chromatography. Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) was used for water soluble and insoluble element concentrations. The pHs of all sequences changed from 6.88 to 7.84 The measured particle size distribution ranged from 0.073 to 1503.2 μm, 0.266–680.2 μm, and 0.406–530.7 μm, respectively for the 1st, 2nd, and 3rd series samples. Arithmetic mean and the standard deviation of the neutralization factors corresponding to calcium, potassium, ammonium, magnesium, and sodium ions were determined as 4.88 ± 7.03, 0.07 ± 0.11, 0.55 ± 0.29, 0.14 ± 0.09, 0.01 ± 0.04, respectively. The main aim of the study was to demonstrate the applicability of chemical compositions of water-insoluble PMs (from EDS) in source identification and the advantage of sequential sampling.