Pollution of a Black Sea coastal city: potentially toxic elements in urban soils, road dust, and their PM10 fractions

Purpose

The study aimed to assess the accumulation levels, spatial distribution, and sources of the potentially toxic elements (PTEs), such as Zn, As, Cd, Pb, Cr, Co, Ni, Cu, Sb, Mo, V, W, Sr, Mn, Bi, Sn, Fe, Cs, Be, and Ba, in urban soils, road dust and their PM₁₀ fractions in Yalta, a seaside resort town of the Crimean Peninsula.

Materials and methods

The concentrations of the PTEs were measured in the urban topsoil (0–10 cm), road dust, and their fine particles, < 10 μm in diameter (PM₁₀), using ICP-MS and ICP-AES methods. The soil and road dust samples were collected in 2018 in various functional zones of Yalta and on different types of roads. In total, 69 soil samples and 57 road-dust samples were taken. The PM₁₀ fraction was isolated by sedimentation method according to Stokes' law.

Results and discussion

The urban soils and the road dust were contaminated by Pb, Sb, Zn, Sn, Cd, Cu, Bi, Mo, and Mn. The finer particles (PM₁₀) separated from the urban soils and the road dust showed higher accumulation of the PTEs than the bulk samples. The contribution of the PM₁₀ fraction to the total amount of the pollutants in the bulk soil and road-dust samples accounted for 50–80%. The strongest contamination of the urban soils was found in the residential areas, while the road dust was mostly contaminated on the major highways.

Conclusion

According to the results of the principal component analysis, most of the pollutants can be attributed to anthropogenic sources − non-exhaust and exhaust vehicle emissions. The other important sources of the PTEs are soil parent materials and the resuspension of soil particles. The contents of PTEs in the bulk soil and road-dust samples correspond to low and medium pollution levels. The elevated levels of the PTEs in the PM₁₀ fraction pose the greatest environmental hazard.