<b>Radiation and the Human Footprint</b>

There is an anthropogenic footprint that's much more visible than the theoretical behaviors of ocean dynamics and climate patterns. This reality lies within the composition of water, gas and the solid ground on which we walk. Unstable Isotopes can be used to date a field specimen. Stable Isotopes have been used to depict global ice volume. It wasn't until the birth of the hydrogen bomb, and the plethora of field testing that occurred before radioactive hydrogen isotopes were used to date water masses.

The amount of tritium that has been released into the atmosphere since the 1950s, when nuclear bomb test sites were first created, is astronomical. When we compare the isotopes' natural-occurring concentration versus the elevated concentration from radioactive power plants and weapons testing, we find a significant spike despite is rather short half-life of 12.32 years. The minute concentration of tritium naturally-occurring in our environment could be accumulated and weighed at a few kilograms. After releasing several hundred kilograms, which quickly spread across the northern hemisphere through atmospheric transportation, we marked the surface water in our oceans with a human footprint.

Although very harmful, as is the nature of all rapidly-decaying radioactive isotopes, scientists have used this tracer as means to study and better understand ocean dynamics. What is known as the thermohaline circulation (THC), or in general terms the path of ocean water across the globe, can now be studied with a visible vector depicting the age and path of ocean water. The presence of elevated tritium concentrations help us visualize deep water convection cycles as well as intermediate mixing of ocean water. The relative age of these rather young water masses was never before accurately measured since other dating methods (such as carbon dating) were inadequate.

Resources:

http://en.wikipedia.org/wiki/Tritium

http://www.waterencyclopedia.com/St-Ts/Tracers-of-Ocean-Water-Masses.html

http://www.whoi.edu/oceanus/viewImage.do?id=4614&aid=2330

*Image Courtesy of Woods Hole Oceanographic Institute