Processes Influencing the Ph of Geothermal Waters

Abstract

The present study is based on geochemical studies of about 400 samples of natural waters in Iceland. They include surface waters and groundwaters ranging in temperature from (ambient) to over The of these waters most often lies in the range of about 6 to 10. Surface waters most often have a between 6.5 and 8. Cold and warm waters have higher 9-10, but with increasing temperature the falls and is generally in the range at temperatures above 200?C. There are essentially three processes that affect the water They are: 1) The supply of acids to the water from various sources, 2) rock dissolution and 3) precipitation of various minerals. The second process causes water to increase whereas the two other processes cause it to decrease. ion activity ratios in waters appear to be controlled by close approach to chemical equilibrium between solution and hydrothermal silicate minerals. This equilibrium fixes water in these geothermal waters in conjunction with the aqueous cation activity.