Metal contamination of Arizona soils in areas adjacent to a copper smelter

Certain metals, such as cadmium and lead, have been shown to be a health hazard in both humans and livestock when introduced into the food cycle. Since certain particulate metals in the atmosphere surrounding Douglas, Arizona have increased in the past few years and since Douglas is one of the few locations in the state where agricultural production is located near a smelter, the authors have investigated the relationships between these metals and the soils of the area. Forty soil samples collected monthly between June 72 and Jan. 74 were analyzed by atomic absorption spectrometry. Within 10 km of the Phelps-Dodge copper smelter, lead, zinc, cadmium, and copper were found to occur in higher concentrations than soils more distant from the smelter. Certain of these metals occur within 5 km of the smelter at a concentration reported by others to be toxic to plants. Sodium, potassium, and manganese appear not to be related to smelter activity. The metals were found to occur principally in the top 5 cm of the soil, with very little downward movement taking place. While some seasonal variations were observed, these did not affect any correlations between metal concentrations and distance from the pollution source.