Dissolved Uranium and Arsenic in Unregulated Groundwater Sources – Western Navajo Nation

Abstract

Concentrations of dissolved uranium (U) and arsenic (As) above drinking water standards in unregulated water sources pose various human health risks. Although high natural background concentrations may occur in some environments (Runnells et al. 1992), anthropogenic contamination concerns are especially troublesome on the Navajo Nation (NN), where past U mining activity may have contaminated water supplies. This research investigated U and As groundwater contamination issues in unregulated wells in the western portion of the NN. Objectives of this research were to provide insights to human health risks by assessing the spatial extent and seasonal variability of U and As concentrations while effectively communicating the potential contamination risks to the local Navajo people. Eighty‐two unregulated wells were sampled in 2018; nine of these sources exceeded the maximum contaminant level (MCL) for drinking water standards for U (30 µg/L), and 14 exceeded the MCL for drinking water standards for As (10 µg/L). U and As levels were highest in the southwest portion of the study area and seasonal variability was observed in a subset of wells, especially shallower hand dug wells and hand pumps. The results were compiled into a report that was presented to NN chapters included in the study as well as the Navajo Department of Water Resources and the NN Environmental Protection Agency. Implications for regional water quality patterns can help to direct policy recommendations for well monitoring, water use, and remediation targets.

Chemical Toxicants in Water: A GeoHealth Perspective in the Context of Climate Change

“…Similarly, Jones et al. ( 2020 ) demonstrated the negative environmental impacts and human health risks associated with mining activities on unregulated groundwater sources in the Western Navajo Nation. While these case studies were conducted across different regions, all of them identified that populations exposed to high concentrations of chronic chemical contaminants (e.g., arsenic, uranium etc.)…”

“…For instance, Ward et al (2018) did a meta-analysis of epidemiological studies and found linkages between an increased exposure to nitrates through drinking water and methemoglobinemia, adverse reproductive outcomes, cancer, and thyroid disease in women. Similarly, Jones et al (2020) demonstrated the negative environmental impacts and human health risks associated with mining activities on unregulated groundwater sources in the Western Navajo Nation. While these case studies were conducted across different regions, all of them identified that populations exposed to high concentrations of chronic chemical contaminants (e.g., arsenic, uranium etc.)…”

Hydrophobic core formation and secondary structure elements in uranyl(vi)-binding peptides

“…7 These values are well below the threshold recommended by the World Health Organization. Yet there are eventually large deviations in uranium concentrations in drinking water 8 and these values need to be carefully monitored.…”

Uranium in Waters of The Southern Colorado Plateau: Implications for the Navajo Nation

“…Surface water is scarce on the Colorado Plateau, and elevated uranium (U) in groundwater further complicates water access. Water scarcity is driven by a low annual rainfall that is below 20-30 cm per year (Credo et al, 2019;Jones et al, 2020;Ingram et al, 2020), and enrichments of U in these waters pose health concerns for people and animals (USDHHS 2013;Hund et al, 2015;Rock et al, 2019;Hoover et al, 2020;Ingram et al, 2020;Lister et al, 2021;Nozadi et al, 2022). The southern Colorado Plateau is the ancestral land of the Navajo (Diné) people and the current boundaries of the Navajo Nation are located entirely in the region (Figure 1A).…”