Radioecological studies of tritium movement in a tropical rain forest
Several experiments on the movement of tritium in a tropical ecosystem have been conducted in the montane rainforest of Eastern Puerto Rico by the Bio-Medical Division of the Lawrence Radiation Laboratory, Livermore, in cooperation with the Puerto Rico Nuclear Center. Tritiated whaler was used as a tracer for water movement in: a) mature evergreen trees of the climax rainforest; b) soil and substory vegetation and c) rapidly growling successional species. A feasibility study on the Atlantic Pacific Interoceanic Canal is currently being conducted. If thermonuclear explosives were used in constructing the canal, tritium would be deposited as tritiated water and distributed among the several biological compartments of the tropical ecosystem in that area. The main hydrogen compartments are water in the soil and in leaves, limbs and wood of forest trees. Organic tissue hydrogen comprises another compartment. In the tree experiment, tritiated water was injected directly into several species of mature, broad leaved evergreen tropical trees. Transpiration and residence time for tritium was determined from analyses of leaves sampled during a several month period. Transpiration ranged from 4 ml/day/gm dry leaf for an understory Dacryodes excelsa to 10.0 and 13.8 ml/day/gm dry leaf for a mature Sloanea berteriana and D. excelsa, respectively. Mean residence time for the S. berteriana was 3.9 {+-} 0.2 days and the understory and mature D. excelsa values were 9.5 {+-} 0.4 and 11.0 {+-} 0. 6 days, respectively. In another experiment, tritiated water was sprinkled over a 3.68 m{sup 2} plot and its movement down into the soil and up into the vegetation growing on the plot was traced. The pattern of water movement in the soil was clearly demonstrated. The mean residence time for tritium in the soil and in trees was found to be 42 {+-} 2 days and 67 {+-} 9 days, respectively. The residence time for tritium in the trees in this experiment was considerably longer than for the single injected input pulse due to the continuous root uptake of tritium as the diffuse peak moved down into the soil past the root zone. Tritium was removed from the plot by transpiration and by interflow. Using transpiration rates from the previous experiment, rainfall records, tree density data and other measurements, average transpiration for the Puerto Rico rainforest was computed to be 3.64 kg/m{sup 2}/day. The effective capacity of the soil compartment was calculated to be 280 {+-} 12 kg/m{sup 2}. In the final experiment, tritiated water was injected directly into several species of successional trees in a cleared plot. After several weeks, the trees were harvested and aliquots selected for bound tritium assay. The amount of tritium incorporated into the tissue was about 0.1 percent of the total amount applied to the tree. Based on all experimental data, the distribution of tritium from a simulated rainout following a one megaton thermonuclear detonation is presented for a climax tropical rainforest and for successional vegetation. The fraction of input tritium remaining in each compartment as a function of time is tabulated. The residence time for each of the compartments determines the persistence of tritium deposited in a tropical ecosystem. (author)
- Research Organization:
- California Univ., Livermore, CA (United States). Lawrence Radiation Lab.; Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- NSA Number:
- NSA-24-041491
- OSTI ID:
- 4106840
- Report Number(s):
- CONF-700101-(Vol.1)
- Resource Relation:
- Conference: Symposium on engineering with nuclear explosives, Las Vegas, NV (United States), 14-16 Jan 1970; Other Information: From Symposium on engineering with nuclear explosives, Las Vegas, Nevada, January 14--16, 1970. Proceedings. UNCL. Orig. Receipt Date: 31-DEC-70; Related Information: In: Symposium on engineering with nuclear explosives. Proceedings. Vol. 1, 871 pages
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION
CAVITIES
EARTH
EXCAVATION
FALLOUT
FORESTS
GROUND WATER
NUCLEAR EXPLOSIONS
OPENINGS
PLANTS
PRECIPITATION
SOILS
TRACER TECHNIQUES
TRANSPORT
TREES
TRITIUM
TROPICAL REGIONS
UNDERGROUND EXPLOSIONS
ZONES
ECOSYSTEMS/tritium movement in tropical
tracer studies of
TRITIUM/transport in tropical ecosystems
tracer studies of
NUCLEAR EXPLOSIONS
UNDERGROUND/tritium fallout from
movement through tropical ecosystems of