[Assessment and Traceability of Heavy Metal Pollution in Melon Cultivation Soil of Desert Oases in Northwest China Using Multi-index and Multi-model Coupling].

， respectively. Except for Cd， the average concentrations of As， Cr， Cu， Hg， Ni， Pb， and Zn were below the soil background levels for Gansu Province. Moreover， except for 3.4% of samples in which Cd levels exceeded the screening value set by the "soil environmental quality risk control standard for agricultural land （Trial）" （GB 15618-2018） for soils with pH > 7.5， the concentrations of As， Cr， Cu， Hg， Ni， Pb， and Zn in all other samples were below the screening threshold. ② Cd and Hg were the most severely polluted heavy metals in the melon cultivation soil， with highly contaminated samples located near transportation， industrial， and mining areas. ③ The accumulation of soil heavy metals in the melon cultivation area was influenced by combined sources： agricultural-traffic， industrial， and atmospheric deposition. The APCS-MLR model identified contributions of 43.56% from agricultural-traffic sources， 31.77% from industrial sources， and 19.33% from atmospheric deposition， while the RF model identified contributions of 46.55%， 26.03%， and 27.42% from these sources， respectively. The findings provide a scientific basis for managing soil heavy metal pollution risks and ensuring the safe and high-quality development of the melon industry in the region.