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i 0 <br /> September 19% -2- 963-2128.002 <br /> 1.0 INTRODUCTION <br /> At the outset, some generalities regarding land application of biosolids must be stated. <br /> Biosolids are considered an excellent medium for plant growth which increases the soil <br /> moisture holding capacity; soil aeration; soil porosity and permeability; provides natural <br /> biological control of diseases caused by soil-borne plant pathogens; as well as providing a <br /> source of slow release organic nitrogen (EPA Workshop 1992). Based on long-term field <br /> biosolids studies investigators have shown that plant availability of biosolid-borne metals is <br /> highest during the first year after biosolids are applied (Hinesly and Hansen 1984; Bidwell <br /> and Dowdy 1987; and Chang et al. 1987). Studies of biosolids chemistry indicate that <br /> digested biosolids in addition to being 50 percent organic matter (on a dry weight basis) is 50 <br /> percent inert inorganic mineral forms (including Fe and Al oxides, silicates, phosphates, and <br /> carbonates) that are reactive with the metals and environmentally stable (McCalla et al. 1977; <br /> Essington and Mattigod 1991). No adverse effects from contaminants in municipal solid <br /> waste (MSW) have been reported other than B toxicity to plants (a temporary problem). <br /> Neither Zn, Cu, or Ni phytotoxicity has been observed, nor have Cd, Pb, or xenobiotic <br /> organic compounds been observed to cause injury to humans, livestock or wildlife (EPA <br /> Workshop 1992). The positive effects resulting from MSW application far outweigh the <br /> potential negative effects (Xin-Toa He, Taina, and Logan 1992). <br /> Although increases in metal concentrations in biosolids-amended soils have been shown <br /> (Barbarick, Ippolito, and Westfall 1995; Fresquez et al. 1991; and Corey et al. 1987), <br /> demonstrations of potential risk from the increases in soil metals have not been reported. <br /> Golder concludes that the principle criterion for regulating land application of biosolids <br /> should be the environmental risk associated with the potential for biosolids application to <br /> cause phytotoxicity. This implies that concentration alone is less important than potential for <br /> mobilization of environmental targets and exposure pathways. The literature review and data <br /> summary presented below has been arranged to elucidate the factors which effect Cu-induced <br /> phytotoxicity in biosolids-amended plant growth medium. Biosolids disposal regulations are <br /> LROM21=12eu x m Golder Associates <br />