Relationships between Dust and Transuranics in Aerosol Particles from the Carlsbad/WIPP Area

R. Arimoto, T. Kirchner, J. Webb, B. Stewart, D. Moir, and D. Schoep

Carlsbad Environmental Monitoring & Research Center, New Mexico State University, Carlsbad, NM 88220

Aerosol samples were collected and analyzed to characterize the spatial and temporal patterns in the activities and concentrations of selected radionuclides and inorganic substances in the atmosphere in southeastern New Mexico. High-volume total suspended particles (TSP) samples were collected from three sites located at increasing distances from the Waste Isolation Pilot Plant (WIPP): (1) On Site, (2) Near Field, and (3) Cactus Flats. ^239,240Pu and ²⁴¹Am were determined by alpha spectrometry following a series of chemical separations. Gravimetric determinations also were made to determine aerosol mass loadings on the high-volume radionuclide filters. A separate set of low-volume aerosol samples was analyzed for trace elements, using inductively-coupled mass spectrometry for the analyses.

The ^239,240Pu and ²⁴¹Am activity concentrations varied substantially with season, with the highest values generally observed in spring. There was no evidence for elevated activities of these nuclides due to WIPP operations. The ^239,240Pu and ²⁴¹Am activity concentrations also were correlated with each other and with aluminum (an indicator of mineral dust). A significant fraction of the observed variability in ^239,240Pu activity concentrations could be explained by wind travel; thus the resuspension of contaminated soils is implicated as an important determinant of ^239,240Pu and ²⁴¹Am concentrations in the aerosols from the WIPP environs.