Abstract
Flue gas desulfurization (FGD) by-product is created when a dolomitic lime [CaMg(CO 3) 2] is used to remove SO 2 during the burning of high sulfur coal in electricity generating power plants. This study evaluated growth of Northern red oak ( Quercus rubra L.) in an acid forest soil (Rayne silt loam—a fine loamy, mixed, mesic, Typic Hapludult) and water leachate quality when FGD by-product was applied topically or mixed within the A horizon at rates equivalent to 0.25, 0.50, 1.0, 1.5, 2.0 and 2.5 times the soil’s lime requirement. Soils were leached with deionized water on a monthly basis and the leachate samples were analyzed for pH, conductivity, P, S, B and metals (Al, Ca, Cr, Cu, Fe, Mn, K, Mg, Pb, Ti and Zn). Tree growth significantly increased ( p⩽0.05) when soil was treated with FGD and the greatest growth (75% increase over the untreated control) occurred when FGD was applied at 1.5 times the lime requirement rate. Boron toxicity symptoms were observed in plant tissue when FGD by-product was applied at two times (or higher) the lime requirement rate. Sulfur concentration increased from less than 10 mg l −1 (control soil) to 234 mg l −1 (soil treated with FGD at 2.5 times the lime requirement) in the leachate four months after treatment. Boron also approached toxicity concentrations (≈l mg l −1) in the leachate from soil treated at the highest rate during the initial leachings, but concentrations tended to decline with time. Applying FGD by-product onto acid forest soils has the potential to provide growth benefit to a commercially important tree species (red oak) but care will need to be taken to avoid using FGD materials that may release toxic levels of B.
Published Version
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