Potential Toxic Elements in Urban Soils of Arica, Northern Chile: Evidence of Persistent Legacy Contamination

Urban pollution typically arises from a combination of traffic emissions, dust resuspension, and domestic activities. In some cases, historical events leave toxic legacies that persist in urban environments for decades after emissions have ceased. In Arica, an industrial region in northern Chile, abandoned mining waste from the 1980s containing arsenic (As), lead (Pb), and zinc (Zn) has become integrated into the urban environment and remains a concern despite remediation efforts by local authorities. In this study, we analyzed 17 surface soil samples collected across Arica to quantify acid-extractable potentially toxic elements (PTEs) using EPA Method 3051 and atomic absorption spectroscopy. Elevated concentrations of As (up to 47 mg kg-1), Pb (up to 487 mg kg-1), and Zn (up to 1740 mg kg-1) were observed. Spatial analysis and screening-level risk assessment identified contamination hotspots consistent with both historical waste deposition and contemporary urban influences, indicating a complex exposure scenario for local communities. Unlike previous studies that focused on immediate post-remediation assessments, this study suggests that contamination persists and undergoes spatial reconfiguration more than three decades after the incident. These findings emphasize the need for sustained environmental governance addressing both historical and ongoing sources of urban soil contamination.