SOURCE DELINEATION OF ARSENIC CONTAMINATION IN DRINKING WATER IN SOUTHEASTERN UTAH

The Navajo Sandstone Aquifer is an important source of drinking water for much of Southern Utah and Northern Arizona, with localized high arsenic concentrations. Our on-going research in the Navajo Sandstone, near Bluff, Utah, investigates the origin and emplacement of minerals, concretions and the associated facies which contain arsenic within the aquifer. Handheld XRF data are being used for field reconnaissance measurements of the presence/ absence of arsenic-bearing strata or concretions. Neutron activation analysis (INAA) is being used to quantify the abundance of arsenic and uranium, vanadium, nickel, iron oxides, zinc, and cobalt present in rock samples as they are associated with arsenic-bearing hematitic concretions within the Navajo Sandstone (Beitler, et al., 2005). Previous handheld XRF field data document that arsenic is concentrated in the interdune hematitic siltstones and shales of the Navajo Sandstone and the hematitic Kayenta Formation which underlies the Navajo Sandstone near Bluff (LaDuke and Gianniny, 2022). Our new data documenting arsenic occurrence and concentrations will be used to inform drinking water safety in this region and to evaluate the efficacy models of arsenic associated hematite concretion emplacement by Beitler et al. (2005) and Loope et al., (2010).