Tritium Plume Dynamics in the Shallow Unsaturated Zone in an Arid Environment

摘要: Effective isolation of tritium (3H) and other contaminants at waste-burial facilities requires improved understanding transport processes pathways. Previous studies documented an anomalously widespread (i.e., theoretically unexpected) distribution 3H (>400 m from burial trenches) in a dry, sub-root-zone gravelly layer (1–2-m depth) adjacent to low-level radioactive waste (LLRW) facility the Amargosa Desert, Nevada, that closed 1992. The objectives this study were to: (i) characterize long-term, spatiotemporal variability plumes; (ii) quantify controlling behavior beneath native vegetation facility. Geostatistical methods, spatial moment analyses, mass flux calculations applied spatiotemporally comprehensive, 10-yr data set (2001–2011). Results showed minimal bulk-plume advancement during period limited Fickian spreading mass. Observed rates generally consistent with theoretical vapor-phase dispersion. plume diminished more rapidly than would be expected decay alone, indicating net efflux plume. Estimates upward via diffusive-vapor movement >10× greater by dispersive-vapor or total-liquid movement. Total vertical fluxes >20× lateral fluxes, highlighting importance migration toward land surface. Mass-balance contributed majority loss. indicate losses substantially exceeded any continuing contribution LLRW 2001 2011 suggest resulted before 2001.