Influence of Acid Deposition on Inland Water Chemistry - A Case Study from Hyogo Prefecture, Japan -

Abstract

The Influence of acid deposition on stream and lake water chemistry was studied in a forested watershed of Hyogo prefecture, Japan. Monthly sampling of four streams, one artificial lake, and precipitation was carried out from 1995 to 2000. The pH of the monthly bulk precipitation and rainwater were ranged from 4.06 to 7.10. No trends were evident during the monitoring periods. The pH and alkalinity in the four streams, which flow into the artificial lake, ranged from 6.37 to 8.72 and 0.077 meqL⁻¹ to 0.485 meqL⁻¹, respectively. The differences in the water quality of the four streams were related to the geology of each watershed. Lower pH and alkalinity were observed during high- discharge periods. On the other hand, the pH and alkalinity of the outflow from the lake ranged from 6.47 to 7.36 and 0.195 meqL⁻¹ to 0.339 meqL⁻¹, respectively. No acidification of the aquatic environment was observed during the investigated periods. The results suggest that this forested ecosystem has the capacity to neutralize incoming acid deposition.