Some samples of soils, water, air, and vegetation collected along paths of two tritium releases from a tritium production facility at the Savannah River Plant, Aiken, South Carolina, showed measurable elevation in the levels of tritiated water. The highest concentrations of tritiated water were found in the soil, where molecular tritium had been converted to tritiated water. Patterns of tritiated water movement, after the initial exposure period, agreed with other investigators' observations of tritiated water transport in terrestrial ecosystems. Dispersion and uptake were measured for puffs released under different meteorological conditions.

The uptake and rctcntion patterns of the blue-green alga, Plectonema purpureum,were determined by exposing laboratory cultures to various concentrations of C$" in both continuous flow and batch tests. A simplified laboratory apparatus was devised to provide a continuous flow of radioactive culture media through multiple flasks containing the filamentous algae, which were set up in parallel.In each type of test, the maximum uptakes of CS~' by the algae were proportional to the concentrations of CL? in the media. However, algal uptakes were higher by a factor of 7 in the continuous flow tests than in batch tests. Only 10% of the Csl"' was rctaincd by the algae three days after the algae were transferred into cesium-free media.

On 2 May 1974,479,000 Ci of tritium gas escaped from a Savannah River Plant exhaust stack. The tritium first reached the ground in a pine forested area and was partially assimilated into the ecosystem. Samples of vegetation collected and measured for a period of 70 days showed an increase in the levels of tritiated water. Cycling of the tritium retained in the forest ecosystem resulted in a higher concentration of tritiated water vapor in the air at breathing height near the forest floor than that calculated by the usual models used for predicting air concentration. In addition, the model for tritium cycling in the forest predicts a diurnal cycle of tritiated water vapor concentration with higher concentrations at night when air movement under the canopy is slower.The potential dose to the maximum individual because of inhalation and skin absorption of tritium as HTO after the release was calculated in three ways: ( I ) by using the body water model from the ICRP Publication 2 and assimilation during the passage of the puff, (2) by using the body water model from ICRP Publication 2 and assimilation during an extended exposure period to tritium determined by the experimental measurements and (3) by using a three-compartment dosimetry model with retention half-times of 9, 30 and 450 days with the extended exposure period used in (2). The potential doses were 0.14, 0.80 and 0.89 mrem, respectively. These potential doses show the necessity of considering the interaction of radioactive material with the ecosystem for dose calculation.

Tobacco, an important crop in the southeastern United States, can potentially contribute via the inhalation pathway to the dose-to-man from radionuclides. To evaluate this potential dose-to-man from the interception and retention of Pu aerosols, a tobacco crop was grown near a chemical separations facility at the Savannah River Plant (SRP) which releases Pu to the atmosphere. Average leaf 238Pu and 239, 240Pu concentrations were 9.8 and 5.1 fCi /g X dry wt, respectively. These concentrations indicate that 2.5% of the deposition occurring during the tobacco growth period was on merchantable leaves. Leaf Pu concentrations were slightly greater than Pu concentration of stem tissue. Tobacco grown near the facility had 10 times higher Pu concentrations than that grown off the SRP. Pu concentrations of tobacco were similar to other broadleaf crops. Dose commitment would be 1000 times greater for tobacco usage than wheat or soybean consumption when these crops were all grown under identical Pu deposition situations.