Sulfate sorption of acidified forest soils in the Otter Creek Wilderness Area

Acid deposition has caused tremendous stress to forest ecosystems. Increased soil acidification due to acidic inputs from acid deposition may cause declines in forest productivity through the depletions of soil nutrients, increased mobility of aluminum and increases in acid anion concentrations, primarily nitrate and sulfate. The retention of sulfate in soil is a critical mechanism regulating soil acidification. Sulfate adsorption acts as a buffer delaying the elevation of solution sulfate concentrations. A soil will continue to adsorb sulfate until all the sites are filled and sulfate saturation is reached at which point leaching resumes. Therefore it is important to measure the sulfate adsorption potentials and saturation point in forest soil. The lack of method standardization makes it difficult to compare sulfate adsorption with other soils. Sulfate adsorption capacities of forest soils in the Otter Creek Wilderness Area of the Monongahela National Forest were determined using the adsorption isotherm method and the single point method. However a new two-point method was identified that measures the sulfate adsorption. This method was able to determine the maximum sulfate adsorption capacity while still accounting for oversaturation.