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acid soils, aluminum is released from thre crystal lattice of clay minerals to cation exchange sites and into <br />the soil solution (Sutton, et al., 19811. Aluminum toxicity is corrected by raising the soil pH or by <br />applying phosphorus. <br />Fluorine. Fluorine is an essential element for animals, but is not a required plant nutrient IAdriano and <br />Doner, 19821. Plants normally contain 2 to 20 ppm fluorine and total soil fluorine contents average 100 <br />to 300 ppm. Toxic levels of fluorine have been identified in planting mixtures, greenhouse cultures, and <br />water (Traynor, 19801. Agricultural lands receive substantial fluorine inputs from repeated applications of <br />superphosphates. Fluorine toxicity is limited to industrial situations where ores are processed or <br />agricultural environments where fluorine-containing insecticides are used IAdriano end Doner, 19821. <br />Toxicity can be corrected by liming materials and soluble phosphates which immobilize 'the soluble <br />fluorides and tend to produce the highl~~ insoluble, fluorine-containing mineral apatite. Plant uptake of <br />fluorine from soil is not related to the fluorine content of the soil, but rather is dependent on the soil <br />type, calcium and phosphate contents, and soil pH IAdriano and Doner, 19821. <br />Chloride. Chlorine is an essential element for plants and animals (Traynor, 19801. The chloride ion is <br />itself toxic if too greatly concentrated; also if too concentrated, the common natural chlorine compound, <br />sodium chloride, is toxic through its effect on osmotic pressure within the plant (Gough et.al., 1979). <br />Conditions favoring toxicity include areas inundated by sea water, closed geographic basins, over <br />fertilizing, or irrigation using slightly salty water with insufficient flushing of the soil. There have been no <br />reports of human or animal toxicity attributed to excessive chloride in the natural environment. <br />Total Combustible Solids. The total combustible solids analysis is often used to predict the potential for <br />coat fires in the spoil backfill. The total combustible solids level is highest for coal and carbonaceous <br />shale strata, typically ranging from 75 to 90 percent. The total combustible solids level for sandstone <br />strata ranges from five to ten percent. <br />Chromium. Chromium, an essential element for animals but nonessential for plants, is one of the least <br />toxic trace metals (Gough et al., 19791. Chromium toxicity can occur on soils derived from serpentine <br />parent material; however, there have been no reports of toxicity to people or animals from the <br />consumption of chromium in plants (Traynor, 19801. <br /> <br />16 Revised 9/96 <br />