Global cycling of tritium and iodine-129

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:7190579

Kocher, D C; Killough, G G

Dynamic linear compartmnt models are used widely to describe global cycling of environmental tritium and /sup 129/I. Important tests of these models by comparison of predictions with environmental data from anthropogenic sources are discussed. A tritium model, based on the global hydrologic cycle that reproduces time-series data from atmospheric nuclear weapons testing on concentrations in precipitation, ocean surface waters, and surface fresh waters in the northern hemisphere, concentrations of atmospheric tritium in the southern hemisphere, and the latitude-dependence of atmosperic tritium in both hemispheres is presented. The model includes: hemispheric stratosphere compartments; disaggregation of the troposphere and ocean surface waters into eight latitude zones; consideration of the different concentrations of water in air over land and the ocean in calculating the specific activity of atmospheric tritium; and use of a box-diffusion model for transport in the ocean. An important prediction of a global model for /sup 129/I, which we developed previously from data on cycling of naturally occurring stable iodine, is that the mean residence time in the first 1 m of surface soil is about 4000 y. However, a recent analysis of measured soil profiles of /sup 129/I near the Savannah River Plant, based on a linear compartment model for downward transport through soil, suggested that the mean residence time in the first 0.3 m is only about 40 y. A diffusion model is used to describe the measured soil profiles, and the resulting diffusion coefficient is shown to correspond to mean residence times in the first 0.3 m and 1 m of soil of about 80 and 900 y, respectively. The value for the first 1 m can be reconciled with the prediction of the global model.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7190579
• Report Number(s): CONF-8609191-3; ON: DE87001678
• Country of Publication: United States
• Language: English

Related Subjects

500300 -- Environment
Atmospheric-- Radioactive Materials Monitoring & Transport-- (-1989)
510300* -- Environment
Terrestrial-- Radioactive Materials Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
GLOBAL ASPECTS
HYDROGEN ISOTOPES
HYDROLOGY
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 129
IODINE ISOTOPES
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
MATHEMATICAL MODELS
NUCLEI
ODD-EVEN NUCLEI
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIONUCLIDE MIGRATION
SOILS
TRITIUM
YEARS LIVING RADIOISOTOPES