Lead, Cadmium, and Zinc Contamination of Aspen Garden Soils and Vegetation

Abstract

AbstractSamples of old silver mine dump materials, garden soils contaminated with mine dump materials, noncontaminated garden soils, and vegetation grown in these gardens were collected to determine the extent of Pb, Cd, and Zn contamination in Aspen, CO. Total HNO3‐HCIO4‐HF‐soluble and NH4HCO3‐DTPA (AB‐DTPA)‐extractable metals in mine dump materials and soils, respectively, were determined by inductively coupled plasma atomic emission spectrometry (ICPS). Plant samples were diegested with HNO3 and analyzed by ICPS. Total metals ranged from 135 to 21 700 mg kg−1 Pb, from 13.3 to 223 mg kg−1 Cd, and from 144 to 20 000 mg kg−1 Zn in mine dump materials. The AB‐DTPA‐extractable metals ranged from 9.2 to 808 mg kg−1 Pb, from 0.2 to 14.2 mg kg−1 Cd, and from 8.4 to 484 mg kg−1 Zn in garden soils. Many of the mine dump materials and soils contained sufficient quantities of Pb and Cd to pose potential health risks if the contaminated materials were ingested. Plant tissues were sampled from the above gardens. In general, leafy tissue concentrations of Pb, Cd, and Zn were highest. Root and other tuber crops were intermediate, lower than leaves, but higher than fruits. The range of concentrations of metals in the leafy tissues were from <5.0 to 45 mg kg−1 for Pb, from 0.6 to 11.9 mg kg−1 Cd, and from 16 to 444 mg kg−1 for Zn. In the roots, metals ranged from <5.0 to 12 mg kg−1 Pb, from 0.5 to 3.6 mg kg−1 Cd, and from 19 to 150 mg kg−1 Zn. Vegetable fruits contained <5.0 mg kg−1 Pb, from <0.5 to 2.7 mg kg−1 Cd, and from 46 to 107 mg kg−1 Zn. Members of the species Brassica oleracea did not accumulate Pb in leaves, even when grown on highly contaminated soils, but accumated Cd and Zn. It was concluded that old mine dump materials have contaminated garden soils placed on them with Pb, Cd, and Zn. The contaminated material poses a health hazard, especially for children. These potential health risks caused the USEPA to list the site on the National Priority List (Superfund sites). The USEPAh as completed its REMEDIAL INVESTIGATION/FEASIBILITY STUDY of Aspen mine dumps and has scheduled implementation of remedial action (clean up) to begin in 1991.