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Dominant Water Soluble Anions (Carbonate, Bicarbonate, and Sulfatel. Sulfate is use+d in the <br />formation of many proteins and is therefore essential for both plants and animals. Sulfur is <br />needed by plants in about the e,ame quantities as phosphorous. Spoils within the Northern <br />Great Plains Coal province ere typically high in sulfate. (Barth et al., 19771. The sedimentary <br />rocks in association with coal seams will often yield substantial amounts of sulfate ions <br />through the oxidation of pyrite and/or marcasite. Sulfuric acid produced in the oxidation of <br />pyrite and marcasite is commonly dissociated and buffered by the bicarbonate and c~,lrbonate <br />ions dissolved from the associated carbonate rocks, thus liberating sulfate ions into solution. <br />The major portion of sulfate found in spoils may be derived from the dissolution of gypsum. <br />The bicarbonate and carbonate ion content or alkalinity is generally a measure of buffering <br />capacity. Common sources of these anions are the solution of carbonate rocks, diagenesis of <br />CO2 from organic compounds, and CO2 from the atmosphere and soil. The presence of <br />bicarbonate verses carbonate is usually determined by the pH. Above a pH of 8.2, bicarbonate <br />ions dissociate to carbonate ions. Below a pH oT 4.5, most of the bicarbonate ions are <br />converted to carbonic acid (H2COg1. Between these two values, carbonate ions will normally <br />add H+ ions to become bicarbonate ions (Dollhopf et al., 19811. <br />Carbonates and bicarbonates also increase the sodium buildup hazard in soils by precipitating <br />calcium and magnesium as carbonates which have an extremely low solubility. Elevated levels <br />of bicarbonate in soils li.e., 10 meg/II can also adversely affect sensitive crops (Traynor, <br />19801. <br />Nitrate Ammonium-Nitrogen. Three major forms of soil nitrogen are typically found in the soil <br />environment: 11 organic nitrogen associated with soil humus, 2) ammonium nitrogen <br />associated with clay minerals and organic matter, and 31 soluble nitrate compounds. INost of <br />the soil nitrogen is in the organic form and is slowly released, through microbial action, as <br />ammonium and nitrate. This nitrification process requires nitrifying bacteria, a carbon source, <br />oxygen, water, and favorable soil temperatures. Nitrate and ammonium analyses are generally <br />determined on overburden material which will serve as a growth or aquifer medium. Nitrogen <br />levels influence soil productivity as well as ground water quality. <br />r1 <br />U <br />12 Revised 9/98 <br />