Dine Citizen Science: Phytoremediation Of Uranium And Arsenic In The Navajo Nation

Mid-20th century mining in Naabeeho Binahasdzo (Navajo Nation) polluted soil and groundwater with uranium and arsenic. The Dine and other indigenous residents of this region use groundwater for drinking, livestock, and irrigation, creating a serious environmental health risk. Currently, many individuals and communities on the Na-vajo Nation must purchase and transport treated water from hours away. Sunflowers (Helianthus annuus) pref-erentially take up uranium and arsenic, potentially representing a tool to remove these contaminants through on-site, low-cost phytoremediation. This study reports the results of a collaboration among researchers, high school students, teachers, and tribal leaders to analyze water chemistry and perform a phytoremediation exper-iment. In 2018 and 2019, we compiled existing data from the Navajo Nation Environmental Protection Agency (NNEPA) and collected samples from surface and groundwater. We then used sunflower seedlings grown in local soil to assess whether phytoremediation could be effective at removing arsenic and uranium. For the NNEPA-sampled wells, 9.5% exceeded the maximum contaminant level for uranium (30 mu g per liter) and 16% for arsenic (10 mu g per liter). For the new samples, uranium was highest in surface pools, suggesting leaching from local soil. Unlike studies from humid regions, sunflowers did not decrease uranium and arsenic in soil water. Instead, there was no change in arsenic concentration and an increase in uranium concentration in both planted and control treatments, attributable to weathering of uranium-bearing minerals in the desert soil. Because much of global uranium mining occurs in arid and semiarid regions, the ineffectiveness of phytoremediation on the Navajo Nation emphasizes the importance of prevention and conventional remediation. More generally, the participatory science approach created meaningful relationships and an important collaboration between a tribal chapter and a university, providing both cultural and scientific experiential learning opportunities for Dine high school students, undergraduate researchers, and senior personnel. (c) 2018 Published by Elsevier B.V.