The contamination of urban soils with heavy elements due to the rapid development of urbanization and urban services has become a major environmental and human health challenge. This study provides insight into the urbanization controls on combined pollution severity and health risk potential of heavy metals in corn-cultivated urban versus non-urban soils. A multifaceted assessment was conducted using enrichment factor (EF), ecological risk (ER), bioconcentration factor (BCF), transmission factor (TF), hazard index (HI), and carcinogenic risk (CR). The results indicate a significant increase in the concentration of all metals in urban farmlands. When compared to the non-urban soils, EF implies a significant increase of all metals in the urban soil, downgrading this index from minimal enrichment (EF < 2) in the control soils to moderate enrichment (2 ≤ EF < 5) in the urban soils. Likewise, the average ER value showed an increase in the urban soils than in the control soils in the order of Fluvisols (66.6%) > Regosols (66.1%) > Cambisols (59.8%) > Calcisols (47%). The BCF and TF values for different elements decreased in the order of Cd (0.41–0.92) > Cu (0.1–0.23) > Zn (0.1–0.18) > Ni (0.01–0.03) > Pb (0.005–0.011) and Zn (0.75–0.94) > Cu (0.72–0.85) > Pb (0.09–0.63) > Cd (0.17–0.22) > Ni (0.01–0.21), respectively, which indicates that certain metals were not mobilized to the extent that they had been accumulated in the plant roots. The total carcinogenic risk was ranged from 5.88E−05 to 1.17E−04 for children and from 1.17E−04 to 2.30E−04 for adults, which implies a greater associated health risk for children.

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Soil fertility and nutrient management are the main factors that directly affect the yield of the product. To evaluate the soil fertility at different elevations (including 1600-2000, 2000-2400, 2400-2800, and >2800 m), 350 surface soil samples (0-30 cm) were collected from the agricultural lands of northwestern Iran.Then, soil properties, including soil texture (%), CaCO 3 (%), pH, EC (dS.m -1 ), organic matter (OM) (%), and soil nutrients (macro and micro) (mg.kg -1 ), were measured. Finally, the interpretation and classi cation of the soil samples were made using the nutritional value index (NIV) based on the Gomez and Common methods. The comparison of the NIV index based on elevation changes showed that the Gomez method tends to classify the soil properties in the optimal class due to its tendency towards the center of the data. But the Common method is more consistent with reality. After classifying the NIV index using the Common method, it was determined that CaCO 3 (%) and soil salinity is not the main problem for soil fertility in different elevation classes. However, in all elevations, high pH, low OM (%) at elevations >2800 m, total nitrogen (TN) (mg.kg -1 ), available phosphorous (AP) (mg.kg -1 ), and micronutrients de ciencies (except Zn at the elevation of 1600-2000 m) are the main limiting factors for soil fertility of agricultural lands. Therefore, to improve the soil fertility in all the elevations of the agricultural lands in the northwest of Iran, there is a need to improve the condition of macro and micronutrients (mg.kg -1 ), especially TN (mg.kg -1 ). Highlights 1. The NIV is a suitable and practical index for evaluating soil fertility.2. At all elevations, TN and pH were the factors of limited soil fertility.3. The EC and CaCO 3 do not limit soil fertility at any elevation.

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