Application of Ultrasound in Isolating Microparticles from Soils and Road Dust to Determine Their Elemental Composition

Microparticles with diameters <1 and 1–10 μm (PM1 and PM1–10) are the most important components of road and city dust and atmospheric aerosols, soils, and other accumulators of toxic substances. The research examines sample preparation techniques and evaluates their influence on the results of the analysis of chemical composition of PM1 and PM1–10. The analyzed samples were taken from the sandy loamy umbric horizon of background southern taiga Glossiс Retisol and the clayey loamy chernic horizon of steppe Calcaric Chernic Phaeozem, as well as the contaminated upper horizon of Moscow Urbic Technosol and Sevastopol road dust. Microparticles were isolated using centrifugation without ultrasonic dispersion and with single and multiple dispersion. The trace element composition was analyzed by mass spectrometry and optical emission spectrometry with inductively coupled plasma. A single ultrasonic dispersion destroyed microaggregates, which led to an increase in the concentration of elements in PM1 and PM1–10 from Retisols and Urbic Technosols A horizon. In the Calcaric Chernic Phaeozem and Sevastopol road dust PM1 fraction, a single ultrasonic dispersion did not affect the concentration of elements in the PM1 and PM1–10, while repeated exposure destroyed the crystal structure of mixed-layer minerals of the kaolinite-chlorite group with low absorption capacity depleted in microelements, leading to a decrease in the concentration of elements. The obtained results showed feasibility of a single ultrasonic dispersion of samples to isolate PM1 and PM1–10 in sandy and loamy soils of the Moscow region; the use of ultrasonic dispersion to obtain PM1 and PM1–10 from clayey loamy soils and road dust in Crimea turned out to be ineffective.