Spatial Distribution and Pollution Levels of Aluminum (Al) and Iron (Fe) in Road Dust in Da Nang City

Abstract

This study aimed to assess the concentrations, spatial distribution, and pollution levels of aluminum (Al) and iron (Fe) in road dust in Da Nang city, Viet Nam. A total of 60 road dust samples were collected in 2024, including 56 samples representing wards/communes (based on the former administrative boundaries) and 4 background samples from areas with minimal urban activity. The samples were analyzed for Al and Fe concentrations using the ICP-OES method, and the results were statistically processed in combination with spatial interpolation using the Inverse Distance Weighting (IDW) method. The findings showed that the average concentrations of Al and Fe ranged from 7.123-24.211 mg/kg and 6.408-17.385 mg/kg, respectively. Spatial analysis revealed that suburban areas, particularly those adjacent to hills or bare lands, tended to accumulate higher levels of Al and Fe compared to the city center. The geo-accumulation index (Igeo) was used to evaluate pollution levels, indicating that most areas fell within the “uncontaminated” to “moderately contaminated” categories, except for a few locations with Igeo > 1 for Al. The uneven distribution of Al and Fe suggests that natural geological factors predominantly influence their presence, while the impacts from traffic and industrial activities appear to be minimal. These results suggest that road dust monitoring should be conducted at higher spatial resolution, especially in suburban areas. Furthermore, establishing local geochemical background values for lithogenic elements such as Al and Fe is essential to accurately assess the pollution levels of more hazardous metals in urban environments.