Basically pH Testing...

Protecting Our Water

https://www.youtube.com/watch?v=xn_UmOwhPIE

It probably won't come as a shock to you that radionuclides can get into and then contaminate our water supply.As you have seen the worst case scenarios, of radionuclides entering almost every other medium, it may seem like common sense that our water should be under watch as well. You would be correct in assuming this after all I have written up to this point. Radionuclides can enter the water supply, and if they exhibit high activity and high in high concentration can pose very high risk upon consumption. That would be upon consumption by anyone: plants, animals, humans. But before you start reaching for the bottled water, over these next few posts, I hope to answer whether on not we are currently in such a situation that could warrant drastic action. Fukushima. Chernobyll. Nuclear Testing. Surely that is reason alone? Actually, the US has been monitoring the radiation levels in our air, precipitation, drinking water, and even our milk. To this point, they have found no cause for alarm as almost all radionuclide levels are undetectable or much lower than any level that would pose a health risk.

To start of this series, for this post I thought I'd ramble a little bit on the how the our water is actually tested. Radionuclides can exist dissolved in the water, bound to solids in the water, or in the rock surrounding the water. They can then contaminate out water, and when one goes to drink from this aquifer they also get a mouth-dose (my new unit) full of radionuclides. These pose the obvious health risks. The nuclides can be man-made or naturally occurring from the rock. So how do we figure out the levels that are present in the water? By sampling. There a few different types of sampling, but today we'll talk about Sampling by Evaporation and by Coprecipitation. 

Sampling by evaporation actually works how it sounds. A sample is taken from the water source and evaporated down to a solid film. These would be the solid nuclides that would have contributed to your high mouth-dose (it'll catch on). Coprecipitation works through the addition of a Barium Sulfate/Ferric Hydroxide Mixture. This mixture binds with the radionuclides and at high concentrations precipitates out of the solution. Remove the water and you are left with a rather similar film of nuclides. The end goal of this is to rate the water source's GAA or Gross Alpha Particle Activity. Alpha Particles are one of the more dangerous types of radiation when it comes to ingestion. A high GAA is thus very bad for a water supply. These films from the samples are held against a detector in order to serve as an average for the water supply as a whole. Chemical anlaysis can also be done in order to figure out actual chemical concentration as opposed to just radioactivity analysis. However, some assumptions must be made and inaccuracies tracked as to why the GAA can vary greatly from the actual GAA of your water source. The source usually exist in equilibrium. New nuclides enter the water at a rate, leave the water at a rate, and change into new elements at a rate. These rates eventually combat against each other and concentrations equilibrate.  Removing a sample from this balance and you subject to disorder again. It may eventually reach another equilibrium but with just a water sample, that equilibrium will definitely be different from what it was originally. The more time  that its removed from the source the further these concentrations will be and the further away your GAA will be from the truth. Another consideration to be made is the source itself can vary, as it could operate on its own yearly cycle. Seasons affect temperature, temperature affects the entry rate of nuclides into the water, the entry rate affects equilibrium and GAA.  The solution to  atleast this is to perform a quaterly sample. A sample is taken 4 times during 4 three month periods. These samples are averaged together and lead to a clearer picture of the average water source activity and its GAA. Using these methods one can diagnose and track the potential health threat that is water dispersion. 

Cited:

(1)http://www.waterrf.org/PublicReportLibrary/3028.pdf