Metal Concentrations in Earthworms From Sewage Sludge‐Amended Soils at a Strip Mine Reclamation Site

Abstract

AbstractA 3‐yr study of earthworms was initiated in selected minesoil and nonmined fields at a Fulton County, IL land reclamation site. The purpose of this research was to determine the effect of the land application of anaerobically digested sewage sludge, used to reclaim the site, on heavy metal accumulations in earthworms.Two species of earthworms, Lumbricus terrestris and Aporrectodea tuberculata, were identified in the sludge‐amended and nonamended, nonmined fields sampled. Only A. tuberculata was found in the sludge‐amended and nonamended minesoil fields sampled.Earthworm metal concentrations generally increased with time in all the sampled fields. The decreasing order of metal accumulation by earthworms in all sludge‐amended fields sampled was Cu > Cd > Ni > Cr > Pb > Zn. Sewage sludge applications to fields on both land types resulted in significant accumulations of Cd, Cu, and Zn. Land type (minesoil vs. nonmined) significantly affected earthworm Zn concentrations, with levels being higher in all nonmined fields sampled. Earthworm Cd and Cu accumulations in all fields sampled were significantly related to the current amounts of sludge‐applied metals, the amount applied since the previous sampling. Concentrations of Ni, Cr, and Pb in earthworms were not significantly related to sewage sludge applications during the 1975 to 1977 sampling period. The higher Cd and Cu concentrations in earthworms from sludge‐amended fields may pose a potential hazard to predators.