Natural background and pollution levels of some heavy metals in soils from the area of Dayton,Ohio

In a reconnaissance study, trace amounts of Cd, Cu, Pb, and Zn were determined in “A-zone” soil from 22 locations in the Dayton, Ohio, area. Soil samples were collected at high-volume air monitoring sites in urban, suburban, and rural areas. Measurable amounts of the elements were found in all of the samples. Positive correlations occur between each metal and particulate matter, with correlation coefficients of aboutr=0.70, at the 99% confidence level. Natural background values for the elements were measured in soil from rural areas. Theoretical background values, which are very close to those measured, were calculated from the individual regression equations. Natural background levels do not exceed 1.00 ppm Cd, 15 ppm Cu, 25 ppm Pb, and 55 ppm Zn. The heavy metal contents of most soils in the area exceed background by factors of up to 3.0 for Cd, up to 4.5 for Cu, up to 11 for Pb, and up to 4.5 for Zn. Significant positive correlations among the metals suggest a common source (or sources) for at least some, if not most, of the heavy metals. For the most part, the highest metal values are found in soils near coal-burning plants. Fly ash from a local plant contains substantial amounts of the elements. The high lead values are largely due to vehicular exhaust. However, there is evidence that the metals can also come from the normal deterioration of vehicles. It appears that airborne pollution is an important source of heavy metals in Dayton area soils.