Geochemical interpretation of groundwater flow in the southern Great Basin

The study of geochemical processes and integrated water flow can help identify groundwater sources and improve predictions of contaminant fate and transport in groundwater systems. Understanding groundwater flow paths in and around the Nevada Test Site (NTS) is important due to the possible migration of contaminated groundwater to the neighboring communities. A total of 118 groundwater samples from the NTS and surrounding area (e.g., Oasis Valley, Ash Meadows, Death Valley, the Spring Mountains, and Pahranagat Valley) were collected and analyzed for trace elements and major solutes. Cluster analysis and principal component analysis (PCA), along with geographical information systems (GIS), were used to interpret the resulting hydrogeochemical data. Cluster analysis was used to group the ground-water samples into four major clusters. PCA was used to reduce the data into three components that describe differences in ionic strength, groundwater compositions, reflecting interaction with volcanic and/or carbonate rock aquifers, and redox characteristics. Twelve potential flow paths, characteristic of those reported in earlier studies, were identified.