Transformations of Organic and Inorganic Sulfur: Importance to Sulfate Flux in an Adirondack Forest Soil

Abstract

Sulfate flux from forest soils as a result of inputs from acidic deposition is thought to be a critical process in regulating acidification of surface waters. The purpose of this study was to evaluate biotic transformations of sulfur in an Adirondack Mountain forest soil by adding 35S-sulfate to the forest floor. In September 1983 to each of two 0.5 m2 plots, 2.22 × 1010 dpm of 35S-sulfate was added in 4 liters of solution. Analysis of soil horizons from the plot at the end of the six week incubation indicated that 70 and 99 percent of the added 35S was retained in the soil at plots 1 and 2, respectively. More than 70 percent of the 35S was found in Oa, Bh, and Bs1 horizons. In O horizons greater than 80 percent of the 3sS was found as organic sulfur, whereas in mineral horizons most was found as adsorbed sulfate. These findings indicated that a portion of the sulfate moving through the soil is both rapidly immobilized in the forest floor and adsorbed in the mineral horizons. On a net basis, however, the ...