Study of the role of airborne lead in food chain of crops grown around a main highway in Egypt

ABSTRACT

The present study was conducted to clarify the fate of airborne lead derived from petrol and its role in the food chain of tomato cultivated in lead - contaminated -soil. Settled dust was sampled at 4 stations at 7, 75, 150 and 500 meters from Alexandria/Cairo highway, and analysed for lead, sulfate and nitrate. Tomato fruits -and plants - were harvested at the sampling sites and analysed for lead. Settled dust and lead content steadily decreased by distance from the highway, indicating that traffic derived lead aggregates with other pollutants in particles and settle at distance of a few hundred meters. The lead tends to be evenly distributed in aggregates of different particle sizes, while the sulfate and nitrate tend to concentrate in medium-sized aggregates. The lead in plants of different stages of growth correlated with that in the dust, and was the highest in fruit and roots. Lead contamination of the plant had an impact on tomato crop reduction. The levels of lead in tomato fruits were 17.7 ppm in the samples collected at 7 - 500 meters from the highway, while the legal limit for lead in food is 1 ppm