Potentially toxic elements in urban soils: source apportionment and contamination assessment

Area of Science:

• Environmental Science
• Geochemistry
• Urban Ecology

Background:

• Urban soils are critical for environmental quality and public health.
• City soils and street dusts accumulate contaminants, including potentially toxic elements (PTEs), from human activities.
• Hamedan, a rapidly growing city in western Iran, requires assessment of its urban soil condition.

Purpose of the Study:

• To investigate elemental concentrations in Hamedan's urban soils.
• To identify sources of elemental contamination using statistical and geochemical methods.
• To map the spatial distribution of key PTEs.

Main Methods:

• Collection and analysis of 34 topsoil samples (0-10 cm) for 63 elements using ICP-MS.
• Application of multivariate statistical methods (PCA, cluster analysis) and geochemical indices.
• Geographic Information System (GIS) for spatial variability mapping of PTEs.

Main Results:

• Arsenic, cobalt, chromium, manganese, molybdenum, nickel, and vanadium concentrations were comparable to background levels, suggesting geogenic origins.
• Moderate to considerable enrichment/contamination of cadmium, zinc, lead, and antimony was observed.
• Anthropogenic factors, particularly vehicular traffic, were identified as major contributors to elevated levels of cadmium, copper, mercury, lead, antimony, and zinc.

Conclusions:

• Lead and antimony show significant enrichment, linked to general urban emissions and transport networks, irrespective of land use.
• Arsenic concentrations correlate with metamorphic rock influences in the southern part of the city.
• High spatial variability in elemental content highlights the diverse impacts of urban activities, with traffic being a key factor for Cd, Sb, and Pb enrichment.