Geoscience Frontiers: The oldest water ever!!!

That's right! The oldest water ever found on Earth has been discovered and dated at 2 billion years. 
Up until now I have written about very well understood geologic concepts. I think it is now time to push the boundaries a little bit and attempt to review and simplify ongoing research. The article I have chosen is hot off the press and I only learned about its existence through seeing a breakdown of the article on CBC and then hearing about it on Quirks and Quarks.

The article is entitled: 

Neon identifies two billion year old fluid component in Kaapvaal Craton
Chemical Geology, In Press, Corrected Proof, Available online 6 February 2011
Johanna Lippmann-Pipke, Barbara Sherwood Lollar, Samuel Niedermann, Nicole A. Stroncik, Rudolf Naumann, Esta van Heerden, Tullis C. Onstott

Sounds pretty complicated eh? But it doesn't have to be...


First, lets describe the setting of this paper. The sample collection was performed at the bottom a large gold mine in the Witwatersrand Basin which is part of the Kaapvaal Craton located near Johannesburg, South Africa.

Cratons of Southern Africa

The Kaapvaal Craton was formed during the Archean period between about 3.07 and 2.71 billion years ago as a result of several large granite bodies emplacing themselves into the continental crust. The emplacement of the granite batholiths was then followed by several continental collisions by island arcs throughout the Archean. This led to mountain building and subsequent erosion of these mountains leading to the formation of thick sedimentary and volcanic sequences over the Kaapvaal Craton some of which now compose the Witwatersrand Basin. Many of these sedimentary were metamorphosed to a low degree over time giving rise to the hydrothermal gold deposits in the area. 


In this study, water samples were collected from nine gold mines in the Witwatersrand basin in order to try to establish the age and origins of waters deep beneath the surface of the Earth and look for evidence of life in this hitherto unexplored potential ecosystem. The water samples came from fractures in the rock deep underground, fluid inclusions within the rock itself and fluid inclusions from quartz veins. 

(J. Lippman-Pipke et al., 2011)

These waters were analysed for their neon isotope ratios (turns out it can be used for more than just colourful signs after all). Neon (Ne) is one of the noble gases and is very nonreactive under normal environmental conditions.  This inert nature of neon allows it to be used as a tracer. It can be used to trace fluids from their origins, fluid transport and the ages of the fluids that neon is dissolved in. I am calling the water in the fractures and fluid inclusions "fluids" because they are so saline that they don't fall under the same category as normal water. Neon has several natural isotopes that are produced in different ways and exist in constant ratios to one another. For example, the neon ratio of the atmosphere is different than that of the mantle as the neon in the atmosphere comes from different sources than neon in the mantle. Most of the ratios we find in water today are mixtures of many different neon sources making it difficult to distinguish one source. Much of the neon found in the subsurface comes from nucleogenic sources. What this means is that the neon we find in the subsurface is actually created there through the interaction of alpha radiation from uranium and thorium with oxygen and fluorine in the rocks. When the alpha radiation interacts with the the oxygen and fluorine it is changed into neon. This means that the amount of neon that is produced is proportional to the amount of uranium, thorium, oxygen and fluorine that is present. This process takes place in both the crust and the mantle, with each location having its own characteristic neon ratio, due to the differences in chemistry between the crust and the mantle. 


In this study the neon isotope ratios were analyzed in the fracture water to see if there was any contribution of neon from the mantle and to date the water.  The results of this paper show that there are some anomalous values for neon ratios present. Neon ratios traditionally plot along a straight line between the neon ratio found in air and that of crustal fluids and don't deviate from this line. This means that any neon ratio along this line is simply a mixture of these two end members. However, the neon ratios found in this study DO NOT fall on the neon mixing line and are unlike any neon ratios that have ever been reported! 

(J. Lippmann-Pipke et al., 2011)

These anomalous neon ratios are the highest ever recorded in groundwater or fluid inclusions. Now, given what we know about neon ratios this could be caused by any number of factors. For example, really high levels of uranium could produce a high neon ratio, or lots of oxygen and fluorine. However, this is not the case. To find the real answer for the anomalous values we have to examine the source of the water being analyzed.

The water that is being analyzed and contains the high neon ratios is not from a single source. It is, in fact, a combination of water from two isolated reservoirs. The reservoir that is the source of the high neon ratios is fluid inclusions. Fluid inclusions represent "time capsules" for geologists. They are like little bubbles of water that were trapped when the rock formed and have not been added to, subtracted from or changed in any way since the time of formation. This means that even if the water was trapped billions of years ago, as is the case in this setting, it has not changed since and represents the chemistry of water billions or millions of years ago.

The authors of this paper suggest that the water in the fluid inclusions contain a nucleogenic neon signature that is two billion years old and was produced by natural nuclear reactions and radioactive decay that took place in Earth's mantle!!! Pretty damn cool if you ask me.

So that is all for now. If you have any questions don't hesitate to ask. I'll do my best to answer. I leave for an international conference on Accelerator Mass Spectrometry in a few days so I'll post any cool things I see at the conference.

Matt

The Media Portrayal of Geologists

I have been wanting to write a somewhat humorous post for a while, so we will take a break from the science...for now.

As a geologist I find I am often stereotyped by people I meet and, by the media portrayal of my profession as a hard drinking, hiking boot wearing, bearded, bush man/woman who wears only plaid and carries a knife on my left hip and a hand lens on my right. Now, if you have met me, you know that most of this is actually true....but maybe me and others are all just conforming to the media portrayal of geologists. Perhaps, deep down I am a geologist who wants to dress like a hipster who wants to dress like a punk, but I am afraid of bucking the stereotype and being cast out of my profession by not appearing to be ready to hike through the apocalypse on any given day. In my case unlikely, but you never know.

Yukon Cornelius

Above you see a photo of Yukon Cornelius, in my opinion, the most baddest assedest geologist to ever lace up boots from the stop-motion Rudolph the Red Nosed Reindeer (epic Christmas tradition) that was made in 1964. He is so far the earliest mass media portrayal of a geologist I have been able to find. Note his gun, hammer, pack, knife, hiking boots and beard...this guy is clearly ready for everything the North can throw his way. In fact, he defeats the abominable snow man (bumble) also shows how awesome he really is and sets the bar high for future geologists to follow.

Check out the awesome video where Yukon Cornelius introduces himself and his noblest of professions.

Sorry for the poor quality. The original video was taken off YouTube. You only need to watch the first 28 seconds to meet Yukon Cornelius.

The next great portrayal of a geologist is from American Dad. Their take on geologists is somewhat non-stereotypical, however, it is quite effective at showing how wonderful we all are. 

I know, there are no hammers, knives, etc....none of the quintessential geologist tools. However, I think that the James Bond approach really works and shows what it really means to be a geologist...in short, everyone thinks you're awesome. This leads nicely into our next geologist portrayal by a former Bond.

For our next video we look at the Hollywood take on what a typical geologist is. To do so we go to a classic geology movie: Dante's Peak,  in which we see the power of nature vs. the power of a kick-ass geoscientist played by Pierce Brosnan. Guess who wins?!? 

Pierce wins!! He showed that volcano that geologists are the stereotypical survivors. As you can see there is not a whole lot of actual geology in Dante's Peak, but despite that Pierce delivers an excellent performance as the "whistle-blowing geologist that no-one wants to listen to until it is too late." Classic. It is also another great media stereotype of geologists as nerdy, but rugged, people who care more about rocks, water and gases than people. This one is also partially true (we also care about beer). This leads to our final video, which leaves the realm of fiction and brings us back to reality where we see the stereotype in the flesh. 

What can I say? It's true. We all love beer. While the other sciences are held together by "findings", "labs" and wearing white coats, the glue that binds the geology profession together is: beer. It also helps to ensure the continued survival of geologists into the future by providing just enough social lubricant help us shake off our woodsy hermit side and start shacking up together.   

Ok, so that is is for now. I really have only just scratched the surface of geology stereotypes (pun intended). Please comment on any geologist stereotypes that I have missed or any that you have observed. 

Red Green would say "keep your stick on the ice"...I say "keep your hiking boots laced"

Matt

The Truth about Radon

Every few months the media reports on a toxic and mysterious radioactive gas: Radon. I have personally done quite a bit of research on radon and think I might be able to offer an unbiased and scientific perspective...at least I'll try.

Chemical Description of Radon

As with most things radioactive the first questions asked are: what is it and where did it come from? How does it behave in the environment and what does this mean for me and others (aka: is it dangerous)? These are the questions I will answer for radon and in a following post will look specifically at Port Hope, Ontario, a town where radon is a major concern.

What is it and where does it come from?


Radon, chemical symbol Rn, is an odourless, colourless radioactive gas. In order to understand where radon comes from we have to discuss radioactive decay and uranium. The source of radon is the radioactive decay of uranium. Uranium is a radioactive metal that occurs naturally in almost all places on Earth. The major isotope of uranium is 238U. 238U comprises 99% of all uranium isotopes and has a half life of 4.47 billion years. One of the daughter products produced by the decay of uranium is radon.

Decay Chain of 238U (CNSC)

As the diagram above shows, the decay of 238U occurs over many years.  There are several steps to be taken before radon can be produced. There are two modes of decay shown in the diagram above: alpha and beta. Alpha decay is the radioactive decay process that occurs when a nucleus of a radioactive element ejects two neutrons and two protons (a helium nucleus). Alpha particles have a low penetration ability, but are very ionizing. This means that they cannot travel very far or through objects, but they have a high enough energy to be dangerous to living things very near them. Ingesting or inhaling alpha emitters is dangerous to people however, merely being in their presence is not very dangerous as alpha particles cannot penetrate skin. The other type of radiation emitted during the decay of uranium is beta. Beta decay involves the emission of an electron from around the atom and is more penetrating than alpha radiation. Gamma radiation is also emitted at several steps in the uranium decay process.

As these alpha particles and electrons are emitted, the decay progresses and eventually radon is produced.

How does radon behave?

The meaning of the question how does radon behave encompasses several other questions such as how it travels and interacts in the environment and where in the environment is it produced?

Radon is a noble gas. This means it is very un-reactive in the environment and does not interact readily with other compounds or elements that are present around it. This means that in the environment radon travels all on its own and does not attach itself to other elements as a way to get around. This does not hinder the ability of radon to transfer from air to water and back again, in fact, radon transfers very readily. As a gas radon is present in the atmosphere, in the gas trapped between soil grains, it can even be found dissolved in water. In fact, the transport of radon in water is a relatively new field in radiochemistry studies and it has been applied to tracing the movement of groundwater as well as the transport of radioactive waste over short distances and time spans. Up until now I have been taking it for granted that radon is in the environment, but I have not explained how it gets there in the first place. Sure, we have gone into the radiochemistry and basic physics side of how radon is produced from uranium, but this doesn't really explain how radon ends up in our water or air.

Uranium is present ubiquitously throughout the environment. It is in soil, it is in rocks, it is in the oceans, it is even in lakes, rivers, streams and groundwater. Of course, as we know, the decay of uranium produces radon and since there is uranium in pretty much everything radon can be produced from all of these places. The amount of radon produced is proportional to the amount of uranium present.

Is radon dangerous?


The short answer to this question is: yes, radon is indeed dangerous. The why, how are we exposed and what can we do about it are a bit longer. As I mentioned above radon is an alpha emitter, meaning that it is only dangerous when we are in very close proximity to it or it has been ingested or inhaled. Furthermore, once in our body the radon will continue to decay and produce other daughter products such as 214Pb and 214Bi, which are highly radioactive and very dangerous. The unfortunate thing is that as a gas it is very easy for us to inhale radon making it extremely dangerous. In fact, it is estimated that 10% of lung cancer is caused by radon inhalation, making it an extremely serious threat to human health.

Radon accumulates in confined spaces such as in our houses or other buildings, particularly in basements as radon is heavier than air. In the open air there is no threat from radon, however, Canadians and many other cultures spend a great deal of their time inside, especially during winter (it is  -20 with wind chill as I write this). This is a major concern as all of this time spent indoors can greatly increase radon exposure.

So how does radon get indoors in the first place and why does it accumulate there? Firstly, radon can enter our homes through two main pathways. It can come in as a gas through holes in our basements, sump pumps, windows... essentially any place where our homes are connected to soil or rock. It can also enter in our water, especially if we use groundwater. Once radon is dissolved in water it needs to interact with air in order to leave the water so a perfect place is our taps, and showers which cause air-water interaction and force any radon dissolved in the water to de-gas.  The source of radon for our homes has to do with the type of soil and bedrock where we live. If there is lots of uranium in the soil or bedrock our homes are built on then there will be lots of radon produced as well.

How radon enters our homes

In Canada the Health Canada limit for radon in air is 200Bq/m^3. Here is a map showing where radon exceeds this level in Canada. 

Radon in Canada

OK, well that is it for now. I hope this article, which turned out not as brief as I originally intended, has been a bit informative. Here are some links for more info on radon. Feel free to ask me any questions you might have about radon though, especially if you live in Ontario. There will be future posts relating to radioactivity as it is kind of an interest of mine...weird, I know.

Links:

Health Canada:
http://www.hc-sc.gc.ca/ewh-semt/radiation/radon/index-eng.php
Canadian Nuclear Safety Commission:
http://www.nuclearsafety.gc.ca/pubs_catalogue/uploads/February-2011-Radon-and-Health-INFO-0813_e.pdf

Matt