Editing Tritium (section)

=== North Atlantic Ocean ===
While in the stratosphere (post-test period), the tritium interacted with and oxidized to water molecules and was present in much of the rapidly produced rainfall, making tritium a prognostic tool for studying the evolution and structure of the [[water cycle]] as well as the ventilation and formation of water masses in the North Atlantic.<ref name="Oceanus"/>

Bomb-tritium data were used from the Transient Tracers in the Ocean (TTO) program in order to quantify the replenishment and overturning rates for deep water located in the North Atlantic.<ref name="Bomb Tritium">
{{cite journal
 |last=Doney |first=Scott C.
 |year=1992
 |title=Bomb tritium in the deep north Atlantic
 |journal=Oceanography
 |volume=5 |issue=3 |pages=169–170
 |doi=10.5670/oceanog.1992.11 |doi-access=free
}}
</ref>

Bomb-tritium also enters the deep ocean around the Antarctic.<ref name="Bomb Tritium Antarctic">
{{cite journal
 |last1=Michel    |first1=Robert
 |first2=Peter M. |last2=Williams
 |date=1973
 |title=Bomb-produced tritium in the Antarctic Ocean
 |journal=Earth and Planetary Science Letters
 |volume=20  |issue=3  |pages=381–384
 |doi=10.1016/0012-821X(73)90013-7  |bibcode=1973E&PSL..20..381M
}}
</ref> Most of the bomb tritiated water (H{{sup|3}}HO) throughout the atmosphere can enter the ocean through the following processes:
* precipitation
* vapor exchange
* river runoff
These processes make H{{sup|3}}HO a great tracer for time scales of up to a few decades.<ref name="Bomb Tritium"/>

Using the data from these processes for 1981, the 1-TU isosurface lies between 500 and 1,000&nbsp;meters deep in the [[subtropical]] regions and then extends to 1,500–2,000&nbsp;meters south of the [[Gulf Stream]] due to recirculation and ventilation in the upper portion of the Atlantic Ocean.<ref name="Oceanus"/> To the north, the isosurface deepens and reaches the floor of the [[abyssal plain]] which is directly related to the ventilation of the ocean floor over 10–20&nbsp;year time-scales.<ref name="Oceanus"/>

Also evident in the Atlantic Ocean is the tritium profile near [[Bermuda]] between the late 1960s and late 1980s. There is a downward propagation of the tritium maximum from the surface (1960s) to 400&nbsp;meters (1980s), which corresponds to a deepening rate of about 18&nbsp;meters per year.<ref name="Oceanus" /> There are also tritium increases at 1,500&nbsp;m depth in the late 1970s and 2,500&nbsp;m in the middle of the 1980s, both of which correspond to cooling events in the deep water and associated deep water ventilation.<ref name="Oceanus"/>

From a study in 1991, the tritium profile was used as a tool for studying the mixing and spreading of newly formed [[North Atlantic Deep Water]] (NADW), corresponding to tritium increases to 4&nbsp;TU.<ref name="Bomb Tritium" /> This NADW tends to spill over sills that divide the [[Norwegian Sea]] from the North Atlantic Ocean and then flows to the west and equatorward in deep boundary currents. This process was explained via the large-scale tritium distribution in the deep North Atlantic between 1981 and 1983.<ref name="Bomb Tritium" /> The sub-polar gyre tends to be freshened (ventilated) by the NADW and is directly related to the high tritium values (>1.5&nbsp;TU). Also evident was the decrease in tritium in the deep western boundary current by a factor of 10 from the [[Labrador Sea]] to the [[Tropics]], which is indicative of loss to ocean interior due to turbulent mixing and recirculation.<ref name="Bomb Tritium" />