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Free Content Helium, neon, and tritium in the Black Sea

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Abstract:

Measurements of the 3He/4He ratio, and concentrations of helium, neon, and tritium have been made in samples collected at station 1355 in the Black Sea during the 1975 cruise of R/V Chain. Helium concentrations increase rapidly from 400 m to about 1000 m and then less rapidly below 1000 m. The maximum He concentration excess is about 16% above solubility equilibrium. Neon concentrations are constant, within a few percent of solubility equilibrium, below 400 m. The He-Ne data thus clearly indicate a large component of radiogenic 4He in the deep water from decay of U and Th in the bottom sediments. Tritium concentrations decrease from 67.2 T.U. at the surface to near-zero values at 726 m, 968 m, and 1358 m. Two deeper samples at 1745 m and 1939 m contain some tritium—0.6 ± 0.3 T.U. and 0.7 ± 0.2 T.U. respectively, which shows that a small amount of high-tritium surface water has descended to the bottom during the past twenty years. A one-dimensional three-box model using our tritium concentrations and the geothermal heat flux values measured by Erickson and Simmons (1974) gives vertical exchange times of 440 ± 180 years between the deep water (1000 m-2000 m) and the middle water (400 m-1000 m), and 125 ± 75 years between the middle water and a layer above from 200 m to 400 m in the salinity interval 21.50‰-22.00‰. The fluxes of radiogenic 4He and primordial 3He into the deep water are found to be 1.3 ± 0.5 × 105 atoms cm—2 sec—1 and 1.1 ± 0.6 atoms cm—2 sec—1 respectively which may be compared with world-ocean estimates of Craig et al. (1975)—3 ± 1.5 x 105 atoms cm—2 sec—1 and 4 ± 1 atoms cm—2 sec—1.

Document Type: Research Article

DOI: https://doi.org/10.1357/002224083788223045

Publication date: 1983-02-01

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  • The Journal of Marine Research publishes peer-reviewed research articles covering a broad array of topics in physical, biological and chemical oceanography. Articles that deal with processes, as well as those that report significant observations, are welcome. In the area of biology, studies involving coupling between ecological and physical processes are preferred over those that report systematics. Authors benefit from thorough reviews of their manuscripts, where an attempt is made to maximize clarity. The time between submission and publication is kept to a minimum; there is no page charge.
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