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analyses were performed on the overburden and interburden material <br /> sampled from Mine Areas 2 and 3. <br /> Cadmium. Plant toxicities due to elevated levels of cadmium under <br /> natural conditions or in reclamation are unlikely (Barth et al . , 1981 <br /> and Munshower, 19$3) . Overburden and interburden cadmium concentrations <br /> at Nucla Mine for Phase I samples were generally below the detection <br /> level and were also two orders of magnitude below the excessive level of <br /> 5 ppm (Tables 6-6 and 6-7) . No additional cadmium analyses are <br /> justifiable at Nucla Mine. <br /> Iron. Documented cases of iron toxicity are rare and appear to be <br /> limited to flooded soils (Barth et al . , 1981) . Iron deficiencies are of <br /> more concern in some reclamation situations where soils are alkaline. <br /> Extremely high levels of iron often are not toxic but cause imbalances <br /> or interfere with the uptake of other essential nutrients. <br /> Mean overburden and interburden iron concentrations at Nucla Mine for <br /> Phase I samples generally ranged between 200 to 300 ppm (Tables 6-6 and <br /> 6-7) . These levels are not toxic and should not cause nutrient <br /> imbalances if the regraded spoil is covered with adequate amounts of <br /> topsoil (personnel communication with Rick Barth , March 14, 1986) . Iron <br /> analyses were highly recommended for site 873E during Peabody's April <br /> 10, 1986 meeting with CMLRD. Consequently, iron analyses were completed <br /> on all samples collected from site 873E. <br /> Selenium. The concentration of water soluble selenium in soil commonly <br /> averages from 0.05 to 0. 1 ppm. Literature indicates that once the level <br /> of water soluble selenium in soil exceeds 2 ppm, vegetation is likely to <br /> accumulate sufficient selenium to poison livestock (Barth et al . , 1981) . <br /> Selenium levels in Phase I overburden and interburden samples at Nucla <br /> Mine were always less than 0. 1 ppm, more than 10 times less than being <br /> excessive (Tables 6-6 and 6-7) . No additional selenium analyses are <br /> warranted at Nucla Mine. <br /> Nitrate - Nitrite - Ammonium. Nitrate and ammonium analyses are <br /> generally determined on overburden and interburden material which will <br /> serve as a growth or aquifer medium. <br /> 6-36 Revised 3/6/87 <br />