A Proxy Approximation

Collecting pore water. These samples will be tested for Germanium among other elements.

So we’ve talked a lot in previous blogs about the various ways Iron is being tested for, and used to test for other metals.  However, we really haven’t discussed Germanium’s role as a proxy, or what a proxy is for that matter.  Proxies are used in the case of research as an indicator of the levels of something else, something you are looking for.  For example, if you wanted to figure out just how hot of a day it was outside, without measuring the temperature or watching the people on board, you could measure the number of ice cream bar wrappers in the trash; knowing that the hotter the day, the more wrappers you would find.  You are measuring one thing, as a way of indirectly accounting for another.

The treasure chest of icy deliciousness that has been depleted daily throughout the trip.


Germanium is being used as a proxy for historic geological events, as well as other trace metals; mainly, it’s being looked at for events caused by continental weathering.  You can look at sediments in a “forensics” kind of way, where this chemical fingerprint leaves a lasting impression of something that happened tens of thousands of years ago.  You cannot use something like salinity or temperature as a proxy for those events, because they are constantly changing and not a good indicator.   


So if you think of the ocean as a box, we have some definite measurements showing Germanium coming in either from hydrothermal vent activity on the ocean floor, or from rivers and run-off from the continent and its shelf.  Once it enters the ocean’s system, it stays there with no known activity.  What Dr. Hammond is looking to find, is if the isotopes of the Germanium coming out of the sediments we have collected, are the same configuration as those that are known to enter the ocean.  In a base description: he wants to find if what went in is the same as what is coming out.

Going back to the Iron’s role in all this forensic frenzy, because other trace metals will attach to it, they also move through phases with it.  If Iron re-dissolves into the oceans, Germanium will re-dissolve along with it; if Iron precipitates to the sea floor, Germanium will go right along with it.  Iron has that sticky elemental property, where other metals will attach to it (think the “Swiffer,” or duster, again).  Due to its abundance in the ocean, you have a better chance of capturing it with other elements in tow; again why Iron puts the “Fer” in our FerrOCious Cruise.  Dr. Severmann, is hoping to find that Iron off the shelf is from continent, and that it has same isotope configuration; it would not be coming from atmosphere.  She is testing out her theories in the “smaller” Gulf of Mexico, before heading out into the great oceans of the world, with the same hypotheses to prove. Which is why we were in pursuit of the particles the other night; so far things have been looking good in the evidence of the samples.

The sediment and water interface, where many elemental questions reside.

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About Cris Wagner

Cris Wagner is currently working with the Navarre Beach Marine Science Station, in Navarre, Florida. Prior to moving to the Panhandle, she had the privilege of being the Director of Education and Exhibits at Florida Oceanographic in Stuart, FL.
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