A MIXED METHOD APPROACH TO EXPLORING AND CHARACTERIZING IONIC CHEMISTRY IN THE SURFACE WATERS OF THE GLACIERIZED UPPER SANTA RIVER WATERSHED, ANCASH, PERU

Dramatic glacier loss in the upper Santa River watershed in Ancash, Peru has significant impact on proglacial hydrologic systems, with implications for downstream impact on human water use activities. Glacial resources serve as freshwater reservoirs, mitigating the rain shadow effect that deprives the western slopes of the Andes of regular annual water resources via precipitation. The reduction of glacial resources is coincidental with economic and population growth, and concern for the quality and quantity of water resources drives research that contributes to understanding regional hydrologic systems. This research integrates hydrochemical analyses of proglacial surface waters and spatial exploration to assess inorganic water quality characteristics and determinant processes within the region. The chemistry of proglacial surface waters is primarily determined by weathering processes in rock-water contact areas, and pristine glacial meltwater inherits the chemical properties of the surficial lithology along a flow path. Using hydrochemical analysis methods, we identify elemental characteristics that are unique to the study region. Dominant hydrochemical processes include silicate weathering, coupled pyrite oxidation with silicate weathering, and to a lesser extent, carbonate weathering. We find that sulfate constituent is unusually high for portions of the upper Santa River watershed, and we attribute this to highly acidified waters immediately downstream from glacial point sources. Geovisualization and exploratory data analysis extend the results of the hydrochemical analysis by showing temporal change and suggesting connections between lithology, areas of high erosion and weathering rates, rapid deglaciation, and elevated sulfate concentrations.