1996-10-04_REVISION - M1977493 - Laserfiche WebLink

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7 ` September 1996 -6- 963-2128.002 2.3 Chemical Extraction Methods EPA - Method 3050 (USEPA 1986a) was employed by source-POTWs to determine whether or not total biosolid Cu concentrations met regulatory threshold values. Biosolid Cu concentrations (mg/kg on a dry weight basis) were determined by digesting biosolid samples in nitric acid. The extracted solutions were analyzed by inductively coupled argon plasma - flame emission spectroscopy (USEPA 1986b). In biosolids applications, it is important to realize that method 3050 is a reliable tool (USEPA 1989). EPA Method 3050 was analyzed to determine if elements are mobilized/dissolve in direct proportion to their concentration in the matrix. Cu was analyzed using Method 3050 and found to be linear over a range of 50 to 1,000,000 µg/g UUmbrough and Wakakuwa 1992). EPA Method 3050 is an accepted, reliable and reproducible method for determining total Cu concentrations in biosolids. Threshold concentrations of trace metals in biosolids to be applied to soils refer to total content of each trace metal. This approach is oversimplified, because the total content of trace metals is of little importance in determining the quantity of trace metal uptake by plants (Petruzzelli 1989). It is well recognized that some measure of the bioavailability and mobility of metals in soil is necessary to understand the chemical behavior and fate of trace metal contaminants in soil and to construct environmental guideline limits for potential toxic hazards (Sadusky, and Wentsel 1991). An ammonium acetate (1N NH4OAc) extraction method (ASA Mono. No 9 a) was employed to measure the bioavailability of Cu in the biosolids applied to the Robinson Tailings Impoundment. The extracted solutions were analyzed by inductively coupled argon plasma - flame emission spectroscopy (USEPA 1986b). The result from the ammonium acetate extraction analysis is found in Table 1. MENV=u=uau x.DW Golder Associates