Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2007
Publication Date: 6/5/2007
Citation: Stuczynski, T., Siebielec, G., Daniels, W.L., Mccarty, G.W., Chaney, R.L. 2007. Biological Aspects of Metal Waste Reclamation With Sewage Sludge. Journal of Environmental Quality. 36:1154-1162. Interpretive Summary: Industrial contamination of soils by heavy metals has commonly occurred at mine and smelter sites for non-ferrous metals. We have developed and demonstrated the use of biosolids plus byproduct limestone and other by-products to alleviate metal toxicity to plants in order to achieve revegetation of such highly phytotoxic soils. Six grass species were grown on the remediated soil and control treatments; little or no plant growth was observed on the untreated smelter waste, while the treated smelter waste supported grown of ryegrasses, tall fescue and Calamagrosis. Besides revegetation, the soil ecological activites must be restored in such soils so that plant residues are degraded over time, and nutrients in plant residues are released for reuse by plants and other organisms. The remediation treatments also alleviated adverse effects of the metals on soil biological activities such as phosphatase, dehydrogenase, urease and soil respiration. Hay grown on the remediated soil and on an uncontaminated soil were fed to beef cattle to evaluate toxicity and metal residues in tissues of the cattle. Cadmium was the focus of concern so control hay plus Cd equal to the remediated hay and control hay plus Cd and Zn equal to the remediated hay were fed for comparison. These results indicated that Cd in the remediated hay caused little increase in tissue residues, while addition of Cd salt to the control hay caused a large increase in Cd in liver and kidney; addition of Zn with the Cd reduced the tissue Cd residues but not to the level in cattle which consumed the hay grown on remediated soil. Overall, the studies showed that remediation of such highly metal phytotoxic soils could be achieved inexpensively, and cover crops growing on the site could be safely consumed by wildlife and even used as livestock feed. The pronounced interaction between Cd and Zn in the cattle feeding test illustrates the large error in testing Cd risk if the simultaneous presence of Zn in the soil and plants are not taken into account.
Technical Abstract: Smelter waste deposits pose an environmental threat worldwide. Sewage sludges are potentialy useful in reclamation of such sites. Biological aspects of revegetation of Zn and Pb smelter wastelands are discussed in a paper. The goal of the studies was to asses to what extent sludge treatment would support ecosystem functioning as measured by biological indicators such as enzyme activities of revegetated metal waste or plant growth. Another crucial aspect was related to the assessment of metal transfer to the ecosystem which could affect the health of local fauna and also create a food chain risk. A field experiment was conducted on a smelter waste deposit in Piekary Slaskie with two separate fields – established on Welz and Doerschel wastes. The tested methods allowed revegetation of the fields - application of municipal sewage sludge at the rates 150-300 dry tons per hectare combined with the incorporation of lime in an oxide and carbonate form at the rate of 1.5 tons and 30 tons for Welz waste and use of a 30 cm by-product lime cap followed by incorporation of sewage sludge at a rate of 300 t ha-1 for more acidic Doerschel waste. Studies on biological activities indicate the reclamation methods used as an effective way to establish new, fully-functioning ecosystems that support plant growth. Forage crops grown on Zn, Cd and Pb contaminated sites reclaimed using lime and biosolids do not pose any particular risk for wildlife and food safety.