Isotopic and chemical characterization of groundwater in the northern Tucson Basin, Arizona

Abstract

The chemical and isotopic characteristics of the groundwater in the Canada del Oro Valley were investigated, and existing hydrologic information compiled to determine processes affecting groundwater chemistry in this area. Evidence suggests that dissolution of calcite and cation exchange on clays are the dominant reactions occurring in the aquifer. Values of 8D and 8 180 lie within the range for winter precipitation in the Tucson Basin. Tritium data indicate that most recharge to the valley occurs along the edges of the Santa Catalina Mountains, in particular along the Canada del Oro Wash. Recharge along Big Wash appears to be minimal. Relatively high concentrations of sulfate and lower 834S values in groundwater along the Cariada del Oro Wash may be a result of historical smelting operations to the northeast of the study area.