Effects of Simulated Acid Rain on Glucose Mineralization and Some Physicochemical Properties of Forest Soils

Abstract

Abstract To study the effects of acid rain, samples of forest soils were exposed to a continuous application of 100 cm of simulated acid rain (pH 3.2–4.1) at 5 cm/hour, or to intermittent 1‐hour applications of 5 cm of simulated acid rain three times per week for 7 weeks. The major effects of the simulated acid rain were localized at the top of the soil and included lower pH values and glucose mineralization rates, and higher exchangeable Al and total and exchange acidity. The acidity penetrated further in the more acid soils. The mineralization of 14 C‐glucose was measured at concentrations of 1.5–54 µ g glucose/g of soil. Glucose mineralization in the test soils (pH values of 4.4–7.1) was inhibited by the continuous exposure to simulated acid rain at pH 3.2 but not at pH 4.1. The extent of inhibition depended on the soil and the initial glucose concentration. Exposure of one soil to 7 weeks of intermittent applications of simulated acid rain at pH 3.2 reduced the mineralization rate at the three glucose concentrations tested. These data suggest that acid rain may have a significant impact on microbial activity.