Chile is an important producer of copper, and it has serious soil contamination problems, mainly related to mining activities. A typical example is the Aconcagua River basin, which has been the scene of large-scale mining operations throughout history, making it critical to analyze due to the high concentrations of heavy metals in its soils. The objectives of this study are (1) to assess the level of As, Cu, Pb, and Zn contamination in the surface soil ecosystem based on different environmental indexes and (2) to determine the health risks of adults and children located in watersheds of the Aconcagua and Casablanca Rivers. A database of the Aconcagua River and Casablanca River basins is used to achieve the objectives. From the Aconcagua River basin, 20 topsoil samples from agricultural sectors without mining activity and 127 topsoil samples from sectors with mining activity were selected. On the other hand, thirty-five topsoil samples of the Casablanca River basin, without mining activity, were analyzed. The evaluation of soil contamination was done using environmental indexes. Finally, carcinogenic and noncarcinogenic risks to humans were calculated using the USEPA model. The mean concentration of chemical elements in the Aconcagua River basin for samples without mining presence was As 10.55 mg kg⁻¹, Cu 85.75 mg kg⁻¹, Pb 26.65 mg kg⁻¹, and Zn 139.5 mg kg⁻¹. The correlations show that the elements As, Cu, Pb, and Zn come from anthropogenic sources, which are also enhanced by the geogenic origin of Cu and Zn. The spatial distribution of the analyzed elements shows a spatial pattern that extends across industrial areas and emission sources, with higher concentrations of As, Cu, Pb, and Zn identified near mining areas of the Aconcagua River basin. The upper limit of the geogenic values determined by the MAD (median absolute deviation) method for the Aconcagua River basin without mining presence was 14.5 mg kg⁻¹ for As, 94 mg kg⁻¹ for Cu, 37.5 mg kg⁻¹ for Pb, and 194 mg kg⁻¹ for Zn. Finally, the geoaccumulation index, contamination factor, integrated contamination index, and potential ecological risk registered exceptionally high contamination in some soil samples, especially in areas with mining influence. It is essential to highlight that there are non-carcinogenic risks related to As, Cu, and Pb, a hazard quotient (HQ) higher than 1, and acceptable carcinogenic risks between 1.0 × 10⁻⁶ and 1.0 × 10⁻⁴ to As and Pb in children and adults in the Aconcagua River basin.

Soil is a component of the environment. An environmental policy should identify the sources of trace metals in the soil and their effects on people and living beings. The concentrations of 29 surface soil samples (0–25 cm) were determined using the methods EPA 3050B. The data were analyzed using simple and robust statistical analysis that allowed for determining geochemical baseline values. Principal component and correlation analyses were performed, which, together with a spatial analysis, allowed us to distinguish between geogenic and anthropogenic sources. The degree of soil contamination was evaluated using different ecological indices, and the health risks to children and adults were calculated using formulas proposed by the United States Environmental Protection Agency (USEPA). The median concentrations of the analyzed elements correspond to Al 17,666 (mg/kg), As 8.7 (mg/kg), Ba 61.4 (mg/kg), Cd 0.17 (mg/kg), Cr 11.3 (mg/kg), Cu 20.5 (mg/kg), Fe 25,953 (mg/kg), Hg 0.06 (mg/kg), Mn 499 (mg/kg), Ni 20.8 (mg/kg), Pb 15.9 (mg/kg), and Zn 60.6 (mg/kg). In the principal component analysis, four factors were identified that explain 70.3% of the variability of the elements, which, together with the correlation analysis, suggest that the origin of the elements is mainly geogenic with some possible anthropic contributions. The elements analyzed in the soil with moderate contamination correspond to As, Cd, and Pb, in addition, As is the only element that indicated a value above the limit for carcinogenic risk in children. The estimated geochemical baseline values correspond to Al 34,734 (mg/kg), As 15.3 (mg/kg), Ba 113 (mg/kg), Cd 0.41 (mg/kg), Cr 33.8 (mg/kg), Cu 42.9 (mg/kg), Fe 46,181 (mg/kg), Hg 0.12 (mg/kg), Mn 1015 (mg/kg), Ni 42.2 (mg/kg), Pb 21.6 (mg/kg), and Zn 121 (mg/kg). 89.7% of the total samples are at a low level of contamination. The carcinogenic risk due to As in children represents 3.4% of the total samples, so it is considered insignificant.