An assessment of lead pollution caused by vehicles emissions in a highly inhabited region of Sofia, Bulgaria

Abstract

Lead concentrations have been determined in air, soil and vegetation samples taken along a major boulevard in Sofia town. Concentrations of total suspended particles (tsp) were also measured. The following concentrations have been found: tsp ‐ 0.168÷5–1.242 mg/m³; Pb aerosols ‐ 0.00058÷0.00573 mg/m³; Pb in soil ‐ 16.2÷184.3 mg/kg; Pb in grass ‐ 2.6÷27.4 mg/kg. Tsp concentrations as well as Pb concentrations in air, soil and vegetation correlated negatively with distance to the road. Airborne particle Pb is the main source for soil and vegetation pollution. Sequential extraction showed that Pb was bound predominately to CO₃ ^2‐ and only in a small quantity to easily exchangeable phase, to iron and manganese oxides and to organic matter. The results showed that Pb concentrations in soìl meet the maximum permissible concentrations, except for the 5–10 meters adjacent to the road. However, a possibility exists for Pb accumulation in soil. Planting suitable vegetation and promoting use of unleaded fuel can be proposed as measures to be taken.

Key words:

• Urban traffic
• lead pollution
• air
• soil
• vegetation