Objective This study aimed to investigate the spatial distribution characteristics, interactions, and ecological risks of selenium (Se) and heavy metal elements (Pb, Cd, Cr, As, Ni, Hg) in soils from typical agricultural areas of Xinjiang, in order to provide a scientific basis for the safe development of Se-rich land resources, the prevention and control of heavy metal pollution in the region.

Method The main agricultural zones in Urumqi, Shihezi, Aksu, Yili, Emin, Yanqi, and Bozhou in Xinjiang were selected as the study area. A total of 4,863 surface soil samples were collected from 195 planting areas, and the pH, Se content, and concentrations of six heavy metal elements were determined. The single pollution index method, Nemerow comprehensive pollution index method, and potential ecological risk index method were employed to evaluate the degree of heavy metal pollution and the associated ecological risk. Cluster analysis and correlation analysis were used to reveal the relationships between elements and their source characteristics.

Result The soil Se content in the area was generally at an adequate level, but significant spatial variation was observed. Se-rich areas (Se ≥ 0.300 mg kg⁻¹) were mainly distributed in Emin (46.8%) and Yili (37.4%), whereas noticeable Se deficiency was found in Yanqi and Aksu, with Se-deficient proportions of 23.7% and 19.8%. The soils were weakly alkaline, with pH ranging from 7.9 to 8.8. Cluster and correlation analyses indicated that Se, Cd, Cr, Ni, and Hg were likely derived primarily from soil parent materials and shared a common origin. A significant synergistic enrichment relationship was identified between Se and Cd and Cr (P < 0.05). In contrast, the source or geochemical behavior of Pb was relatively independent. Pollution assessment results showed that the single pollution index for each heavy metal was below 1, indicating that the soil was generally clean. However, potential ecological risk assessment revealed that Cd was the primary risk element, reaching moderate to nearly strong risk levels in Se-rich areas such as Bozhou and Yili. Moreover, its risk showed a synergistic increasing trend with Se content.

Conclusion The soils in typical agricultural areas of Xinjiang exhibit synergistic enrichment characteristics of Se with Cd and Cr. Cadmium is identified as the key factor restricting the safe utilization of Se-rich resources. It is recommended that the Se-rich agricultural products should be developed in low-risk areas, and a safe utilization model of "low-accumulation crops + passivation remediation" should be adopted in medium to high-risk areas.