EFFECTS OF SULFATE ADDITIONS ON THE STATUS OF EXCHANGEABLE ALUMINUM IN A CECIL SOIL

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Abstract
We conducted a column experiment, using individual and combined soil horizons from a Cecil series soil, to study the influence of ambient and near-ambient levels of SO42− in acid precipitation on exchangeable Al. The columns were leached with two pore volumes of solution containing either 0, 5, 10, or 20 mg L−1 SO42+. We analyzed the leachates for Al, SO42−, and dissolved organic carbon (DOC) and the columns for exchangeable Al and SO42− with depth. Exchangeable Al increased inversely with SO42− in the Bt1 horizon Were attributed to formation of AlOHSO4 and basaluminite. Solution ionic strength values greater than 2.68 × 10−4 were found to reduce leachate DOC levels. We postulated that dissolved organic carbon reduced the rate of Al precipitation from solution, resulting in complex ion formation and increased exchangeable Al in the soil.