The distribution of bomb tritium in the ocean

Abstract

A global picture of the water column inventories of bomb‐produced tritium is constructed from the GEOSECS data set. this picture is compared with that obtained by combining the bomb tritium input function of Weiss and Roether [1980] with the bomb radiocarbon calibrated lateral redistribution model of Broecker et al. [1985]. While differences between the calculated and observed distribution exist, they are surprisingly small. Tritium distributions calculated using the lateral redistribution model provide predictions of the changes to be expected in the next few decades. Such predictions are essential to the design of sound strategies for continued monitoring of the tritium transient.

Use of the bomb radiocarbon chronometer to determine age of southern bluefin tuna Thunnus maccoyii

“…A second order polynomial function that describes the bomb-related increase in aI4C in the eastern Indian Ocean was established from a combination of the GEOSECS data, the Cocos-Keeling coral data, and the 2 small southern bluefin of known age (birth dates 1984 and 1992). Pre-bomb aI4C measured from sea- Broecker et al (1985). The resulting function was used to estimate the birth dates (Fig.…”

Temporally integrated estimate of the Indonesian throughflow using tritium

“…Van Scoy and her colleagues [Van Scoy et al, 1991] have shown that between the GEOSECS survey (1973 -1974) and their 1985 study, the 20% loss of decay-corrected tritium (TU81) in the Pacific subpolar gyre was indeed essentially balanced by a similar gain in the tropics. Figure 3 displays our best-estimate of the temporal change in the decay-corrected water column tritium inventory at the entrance of the Indonesian Seas from the start of the tritium fallout to 1989, based on the extrapolation of 1973 -74 GEOSECS Pacific tritium inventory distribution [Broecker et al, 1986]. This leads to a mean transit time t of 17.7 years, which corresponds to an intensity of the throughflow of 5.1 ± 0.8 Sv.…”

A study of North Atlantic ventilation using transient tracers

“…This hypothesis , however, is dependent on the assumed concentration oftritium in water vapor over the ocean for which little actual field data exists (Koster et al , 1989). Later work on oceanic tritium inventories has generally supported the vapor exchange hypothesis-observed inventories are significantly larger than the predicted value from precipitation and runoff alone (Michel, 1976;Weiss et al , 1979;Broecker et al, 1986), but some doubt still exists (Simpson, 1970;Koster et al 1989). Model estimates for the tritium deposition to the world ocean developed by Weiss et al (1979) and have gained wide acceptance as a method for specifying the tritium flux boundary condition in numerical ocean models ( cf.…”

“…The vapor flux term shown in Figure 3-4 has been corrected for HTO re-evaporation, computed with the surface water 1H concentration curves from Doney and Jenkins (1988). The continental vapor 3 H flux and river 3 H runoff shown in Figure 3-4 have been evaluated following the approaches outlined by ; the continental water vapor and rainfall 3 H concentrations are set equal to three and four times the marine Cp(t) levels, and the continental water vapor flux, runoff volume estimates, and river tritium concentration values are taken from Peixoto and Oort (1983), Baumgartner and Reichel (1983), and Weiss and Roether's (1975) (Weiss et al, 1979;Broecker et al, 1986); the predicted latitudinal pattern of the 3 H deposition is also in good agreement with that found from the GEOSECS 1955 1960 1965 1970 1975 1980 1985 1990 Year Figure A key prediction of the WR model, that vapor exchange, not precipitation, is the major delivery pathway for tritium to the ocean surface Broecker et al , 1986), has recently been called into question by Koster et al (1989). Based on modeling studies of 3 H transport in an atmospheric general circulation model, they conclude that the ratio of vapor to precipitation deposition Dv / Dp for the ocean should be 1.1, significantly smaller than the value of 2.8 calculated for the North Atlantic by .…”