WEATHERING AND WATER QUALITY IN THE BLANCO RIVER, A SUBTROPICAL KARST STREAM

摘要

The Blanco River is a karst stream that traverses the Texas Hill Country and Balcones Fault Zone regions associated with the eastern Edwards Plateau. It is closely connected with the Trinity Aquifer, the Balcones Fault Zone Edwards Aquifer, and the San Marcos River, all being extremely valuable regional resources. This study characterizes water quality in the Blanco River from the headwaters to mouth, with particular attention given to the effects of spring and tributary inputs on concentrations of dominant ions calcium (Ca~(2+)), magnesium (Mg~(2+)), and bicarbonate (HCO_3~-). Historical correlations between discharge and concentrations of specific ions are considered as evidence of active diagenesis, specifically dedolomitization, in rock units of the Blanco River. A greater concentration of dolomitic weathering products in the headwaters region also supports this conclusion.