Distinguishing Between Naturally and Anthropogenically Elevated Arsenic at an Abandoned Arctic Military Site

Soil arsenic exceedances of a project specific cleanup criterion at an abandoned military site in Nunavut, Canada, prompted a study to distinguish the arsenic source as natural or anthropogenic. Principal components analysis and X-ray absorption near edge spectroscopic analysis revealed that samples containing arsenic above and below the criterion value were indistinguishable with respect to their soil elemental “fingerprints,” and their exact chemical form of arsenic (arsenate). Bioaccessibility measurements, used to assess the potential risk from exposure, also demonstrated the similar release of low concentrations of arsenic from all soils tested. Therefore, elemental fingerprint, chemical speciation, and bioaccessibility were useful tools to demonstrate that elevated arsenic levels—up to 40 mg/kg—were likely natural in origin. Moreover, the natural arsenic likely does not pose an environmental or a human health concern at this Arctic site.