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Section 779.21 (a) Continued. <br />• soils studie3 thus contain comparatively low quantities of this <br />element". Standards currently being utilized by tie Montana Depart- <br />ment of State Lands state that at pH's above 6.0 "suspect" levels <br />for lead are 15-20 ppm. Lead toxicity does not appear to present a <br />problem within the. permit area. <br />Mercury. Heil (1976) encountered mercury concentrations on the <br />proposed permit area ranging from 0.020 ppm to 0.042 ppm, with an <br />average of 0.028 ppm. Heil states thc't western soils commonly <br />range between 0.01 to 4.6 ppm. Gough and Sh~.c!:lette (1976) report <br />that the mean mercury level for soils in the conterminous U. S. was <br />0.071 ppm. They also state that most vascular plants absorb very <br />little mercury if grown in normal soils. <br />Guidelines published by the Montana Department of State Lands <br />(Dollhopf, et. al., 1977) state that "suspect" mercury levels are <br />• greater than 0.4 to 0.5 ppm. Data collected on the. permit areas <br />appears to fall well within the ranges for normal soils and hence <br />present no concern related to mercury toxicities. <br />Arsenic. Heil (1976) reported arsenic levels on the proposed <br />permit are ranging from 3.70 ppm to 8.40 ppm, with an average of <br />5.6 ppm. <br />Heil states that normal soils contain from 1 ppm to 50 ppm, with <br />most soils having less than 10 ppm. Gough and Shacklette (1976) <br />report that within the range ~f 1 to 40 ppm, "damage to plants is <br />not expected". The standards of the Montana Department of State <br />Lands (Dollhopf, et. al.., 1976) do not list a "suspect" level for <br />this element. <br /> Molybdenum. Heil (1976) found Molybdenum values on the permit area <br /> to range from lower or less than 0.01 ppm to a high of 0.80 ppm on <br />. an average of 0.29 ppm. The Montana Department of State Lands <br />779-300 <br />