Spatial Distribution and Ecological Risks of Potentially Toxic Elements along the Roadside of Ge-Mang Highway on the Qinghai-Tibet Plateau

<p indent="0mm">Traffic-derived potentially toxic elements (PTEs) are emerging as key ecological risks on the Qinghai–Tibet Plateau. To protect its fragile ecosystems a thorough understanding of PTE distribution and environmental risk assessments along highways is indispensable. Here, PTE (Cu, Cd, Pb, Zn) contamination in roadside soils along the Gemang Highway (Golmud–Mangya) in the northeastern plateau was invesgitaed. PTE concentrations were determined using ICP–MS, and their spatial patterns and risks were assessed through multivariate statistics, geo-accumulation index, potential ecological risk evaluation, and human health risk assessment. The major findings include: (1) Cd levels averaged 1.09 times the background value, with frequent exceedances in forested areas; (2) PTE concentrations peaked within <sc>25 m</sc> of the roadside and approached background levels beyond <sc>200 m.</sc> Vertically, PTEs decreased with soil depth, reflecting minimal migration; (3) Cd posed the highest environmental risk, particularly in forested areas and within <sc>50 m</sc> of the road. However, human health risks in general remained negligible. In conclusion, surface soils along the desert highway exhibited PTE accumulation, with Cd being most pronounced, while deep soils were less affected. Road traffic primarily influenced PTE levels and environmental risks within <sc>50 m</sc> of the highway, with variations across land-use types.