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RESTORATION OF METAL CONTAMINATED SOILS USING BIOSOLIDS
Citation:
Brown, S. L., C. Henry, H. Compton, M. Sprenger, AND K G. Scheckel*. RESTORATION OF METAL CONTAMINATED SOILS USING BIOSOLIDS. Presented at Sustainable Land Application Conference, Lake Buena Vista, FL, January 04 - 08, 2004.
Impact/Purpose:
To inform the public.
Description:
Biosolids in combination with different types of limestone have been applied to metal mine tailings in Bunker Hill, ID, Leadville, Co, Joplin, MO and Tar Creek, OK. For each of these sites, tailings were unable to support a vegetative cover prior to amendment addition. Elevated concentrations of Pb, Zn and Cd , low nutrient status, and poor physical properties were contributing factors to the absence of vegetation. For each site, biosolids, applied at reclamation rates (>44 Mt ha-1) were able to restore a plant cover to the tailings. Concentrations of metals in folia tissue were generally within normal levels. Earthworm Toxicity Tests were conducted on the amended soils from two of the sites. Amendment addition was sufficient to alleviate toxicity and body weight of worms was similar to those in uncontaminated, control soils. Additional assessments of microbial activity in the soils indicated that both microbial activity and diversity were increased following amendment addition.
Additional studies of biosolids compost addition to Pb contaminated soils have shown that compost addition is sufficient to reduce the in vitro and in vivo bioavailability of Pb by 20-40% over control soils. Analysis of the soils using X-ray adsorption spectroscopy showed an increase in the adsorbed fraction of the Pb. These results indicate that the metal adsorption capacity of the biosolids that may account for the observed differences in behavior in biosolids versus salt amended soils can be used to alleviate metal toxicity in contaminated soils.