Soil-plant-animal relationships and geochemistry of selenium in the Western Phosphate Resource Area (United States): A review

• Published in: Chemosphere (Oxford) 2021-03, Vol.266, p.128959, Article 128959
• Main Authors: Favorito, Jessica E., Grossl, Paul R., Davis, Thomas Zane, Eick, Matthew J., Hankes, Nathan
• Format: Article
• Language: English
• Subjects: Animals; Bioavailability; Mine soils; Mining; Phosphates; Selenium; Selenium - analysis; Soil; Soil Pollutants - analysis; Soil Pollutants - toxicity; United States; Western aster; Western phosphate resource area
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.128959

While naturally found in trace quantities, several regions throughout the world have been designated as “seleniferous” or containing an overabundance of the trace element, selenium (Se), in soil. In particular, portions of the Western Phosphate Resource Area (WPRA) of the United States are considered seleniferous, notably due to past phosphate mining reclamation practices that have promoted Se release and accumulation in soil from weathering overburden waste rock. Concern over Se soil contamination in this region has been attributed to its high levels (ranging from 2.7 to 435 mg Se kg−1 soil), bioavailability, and subsequent hyperaccumulation in vegetation at toxic concentrations (exceeding 10,000 mg Se kg−1 plant tissue). The Se hyperaccumulator, western aster (Symphyotrichum ascendens (Lindl.)), is responsible for the vast majority of acute selenium livestock poisonings and fatalities throughout the region. This inherent bioavailability is largely controlled by soil redox chemistry and sorptive processes. The purpose of this review is to integrate information related to the unique site history of the WPRA from onset mining to current Se problems. This review will provide current details and connection of WPRA mining geology, soil Se geochemistry, plant hyperaccumulation, and related livestock fatalities. Soil remediation strategies will also be discussed along with their applicability and viability in this particular anthropogenically-influenced seleniferous region. •Mining of the Western Phosphate Resource Area lead to seleniferous soils.•Semi-arid, alkaline soil conditions are favorable for selenate predominance in soil.•Widespread Se hyperaccumulation in vegetation noted, particularly in western aster.•Western aster is responsible for regional acute selenium poisoning of livestock.•Plausible remediation strategies that reduce Se bioavailability are discussed.