Status, Sources and Assessment of Potentially Toxic Element (PTE) Contamination in Roadside Orchard Soils of Gaziantep (Türkiye)

Abstract

To identify the sources of contamination with potentially toxic elements (PTEs) in roadside orchard soils and to evaluate the potential ecological and environmental impacts in Gaziantep, soil samples from 20 mixed pistachio and olive orchards on roadsides with different traffic densities and at different distances to the roads were analyzed. Concentrations were 23,407.36 ± 4183.76 mg·kg−1 for Fe, 421.78 ± 100.26 mg·kg−1 for Mn, 100.20 ± 41.92 mg·kg−1 for Ni, 73.30 ± 25.58 mg·kg−1 for Cr, 65.03 ± 12.19 mg·kg−1 for Zn, 60.38± 7.91 mg·kg−1 for Pb, 17.74 ± 3.35 mg·kg−1 for Cu, 14.93 ± 4.94 mg·kg−1 for Co, and 0.30 ± 0.12 mg·kg−1 for Cd. It was found that the Ni content in 51% and the Cr content in 18% of orchard soils were above the legal limits for agricultural soils (pH > 6) in Türkiye. Factor analysis (FA) showed that Co, Cr, Cu, Fe, Mn, Ni, and Pb loaded on the first factor (FC1), while Cd and Zn loaded mostly on the second factor (FC2). It was found that Cr, Ni, and Pb were primarily enriched through pedogenic processes, whereas Cd most likely originated from agricultural activities, while the impact of road traffic as source of PTE contamination was insignificant. It has been revealed that the soils are of low quality for agricultural production due to PTE contamination (PIave ≥ 1). The SOPI values from environmental and ecological individual indices showed that the soil pollution level was moderate for Cd, Ni, and Pb, and low for Cr. The soil pollution index (SOPI) proved to be suitable for evaluating and comparing PTE pollution in regions with different soil properties.