Acid deposition and ion leaching from a podzolic soil under hardwood forest

The extent of the contribution of acid precipitation to base cation leaching from an old-growth forest on an acid podzolic soil at the Turkey lakes catchment, Ont., was examined during 1983. In surface soil horizons, the movement of base cations was largely related to nitrate, sulphate, and organic acid anions, below the effective rooting zone to sulphate and nitrate, and in streamflow to sulphate and bicarbonate. The soil in situ showed no strong affinity for sulphate. Annual inputs of sulphate and nitrate in precipitation contributed significantly to cation leaching from the soil. However, the rate at which reserves of exchangeable base cations in the soil were being depleted was not known.