Hydrogeochemical Cycling in a Watershed-Groundwater System: Fort River and Cadwell Creek, Massachusetts

摘要

This study has determined the principal hydrochemical processes in the headwaters of the Fort River near Amherst, Massachusetts and has initiated a detailed analysis of groundwater in Cadwell Creek, a tributary of the Quabbin Reservoir. Incoming precipitation has an average pH of 4.06 and total dissolved solids of approximately 3.5 ppm, although seasonal variations do occur. Over 99% of the incoming H+ ions are being neutralized in the watershed, primarily by cation exchange and silicate weathering reactions. This produces stream water with a pH between 5.2 and 6.0, and total dissolved solids of 25 to 30 ppm. Major cations are leaving the watershed at a rate six times greater than they are entering. Drainage basins underlain by till are more effective at neutralizing precipitation acidity than those with abundant stratified drift and/or shallow bedrock.