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ECOSYSTEM RESTORATION ON METAL-TOXIC SOILS USING BIOSOLIDS AND ALKALINE BYPRODUCTS
Citation:
Chaney, R. L., J A. Ryan*, S. L. Brown, C. L. Henry, T. I. Stuczynski, AND et al. ECOSYSTEM RESTORATION ON METAL-TOXIC SOILS USING BIOSOLIDS AND ALKALINE BYPRODUCTS. Presented at Society of Environmental Toxicology and Chemistry (SETAC), North America 23rd Annual Meeting, Salt Lake City, UT, 11/16-20, 2002.
Description:
Soils in many locations are mineralized or were contaminated by industry (e.g. mine wastes; smelter emissions). Zn-Pb-Ag-Cu ores often caused severe Zn phytotoxicity which killed vegetation and prevented normal colonization; severe N and P infertility also contributed to difficulty of remediation. Although metal tolerant grass ecotypes plus fertilizers can provide grass cover, this approach is not sustainable. A new approach has been demonstrated at a number of barren, highly Zn phytotoxic sites in which mixtures of high quality biosolids, alkaline byproducts (e.g., wood ash) and other materials which can add to soil fertility or help reduce soil metal bioavailability (precipitation or adsorption), and make the soil calcareous. The mixture also allows leaching of alkalinity down the soil profile. In more highly Zn phytotoxic sites, the remediated soil should be made calcareous to prevent pH decline. At such sites, Zn is usually 100-fold higher than Cd, which prevents Cd risks to plant consumers. High phosphate in biosolids/manures promote formation of chloropyromorphite, reducing soil Pb bioavailability to organisms which consume soil. The inclusion of high levels of amorphous Fe and Mn can increase metal adsorption capacity of the remediated soil. Diverse plants and earthworms thrive in such remediated soils. We believe that this approach offers inexpensive, but highly effective and persistent remediation of environmental risks of such metal contaminated soils thereby allowing ecosystem restoration.