| Abstrakt: |
Annual weighted average tritium concentration and total tritium rainout for United States precipitation continued to decline during 1966, 1967, and 1968. Arithmetic mean weighted average tritium concentration for 12 network stations decreased about 38% in 1966 compared to 1965; about 35% in 1967 compared to 1966; and about 30% in 1968 compared to 1967. The 1966, 1967, and 1968 values were only 20%, 13%, and 9% respectively, as great as they were in 1963. Tritium data for special samples collected following the Chinese nuclear bomb test on May 9, 1966, and June 17, 1967, indicate that no measureable tritium was added to United States precipitation as a result of these nuclear explosions. Tritium data are presented in both tabular form and on contoured United States maps in order that estimates of the tritium input function from precipitation to hydrologic systems can easily be made. [ABSTRACT FROM AUTHOR] |
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