Analysis of lead in soils adjacent to an interstate highway in Tampa, Florida

In order to assess the amount and distribution of lead pollution in soils adjacent to a major interstate highway serving the city of Tampa, Florida, a total of 224 samples were collected from 32 transects perpendicular to the roadway. The lead content was measured using atomic absorption spectrophotometry. The highest levels of lead were found at distances of 81, 243, and 729 cm from the road. The results show that there is a weak negative correlation between soil lead and the distance from the roadside, as well as with traffic density. The weakness of the relationship is a result of confounding variables such as turbulence and other microclimatic factors, downslope movement of soils over time, and human action such as construction and highway landscaping. Nevertheless, over one-third of the samples collected in the study area contain more than 500 mu g g(-1) lead, levels considered to be hazardous by the United States Centers for Disease Control and the Environmental Protection Agency.