Tritium, stable isotopes and nitrogen in flow from selected springs that discharge to the Snake River, Twin Falls-Hagerman area, Idaho, 1990-93
Open Access
- 1 December 1994
- report
- Published by Office of Scientific and Technical Information (OSTI)
Abstract
In 1990-93, tritium concentrations in water from 19 springs along the north side of the Snake River near Twin Falls and Hagerman ranged from 9.2{+-}0.6 to 78.4{+-}5.1 picocuries per liter (pCi/L). The springs were placed into three categories on the basis of their locations and tritium concentrations: Category I springs are the farthest upstream and contained from 52.8{+-}3.2 to 78.4{+-}5.1 pCi/L of tritium; Category It springs are downstream from those in Category I and contained from 9.2{+-}0.6 to 18.5{+-}1.2 pCi/L; and Category III springs are the farthest downstream and contained from 28.3{+-}1.9 to 47.7{+-}3.2 pCi/L. Tritium concentrations in precipitation and in the Snake River were relatively large in the 1950`s and 1960`s owing to atmospheric testing of nuclear weapons. Conversely, tritium concentrations in ground water with a residence time of several tens to a few hundred years, as occurs in the Snake River Plain aquifer hydraulically upgradient from the Category II springs, are comparatively small because of the 12.4-year half-life of tritium. The conclusion that recharge from excess applied-irrigation water from the Snake River has affected tritium in the Snake River Plain aquifer is supported by differences in the deuterium (2H) and oxygen-18 (180) ratios of water. These ratios indicatemore » that water discharged by the springs is recharged by waters of different origins. Irrigation recharge is more enriched in 2H and 180 than the regional ground water. Water from Category I springs is more enriched in 2H and 180 than is water from Category II or III springs because a large proportion of irrigation recharge mixes with the regional ground water in Category I springs. Nitrite plus nitrate as nitrogen concentrations also are greater in water from Category I springs than in water from Category II springs.« lessKeywords
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