Lead in roadside soils of Merida City, Venezuela.

The lead content of soil along the roadside in Mérida City was investigated. Where motor vehicle traffic volume was less than 5000 motor vehicles per day, almost no lead accumulation was observed in the surface soil (0-2 cm), but where the motor vehicle traffic volume was greater than 10,000 motor vehicles per day, levels of lead increased by a factor of up to approximately 18. The soil lead content decreased with distance from the edge of the roadside and with depth of sampling.