EGU Blogs

Matt Herod

Matt Herod is a Ph.D Candidate in the Department of Earth Sciences at the University of Ottawa in Ontario, Canada. His research focuses on the geochemistry of iodine and the radioactive isotope iodine-129. His work involves characterizing the cycle and sources of 129I in the Canadian Arctic and applying this to long term radioactive waste disposal and the effect of Fukushima fallout. His project includes field work and lab work at the André E. Lalonde 3MV AMS Laboratory. Matt blogs about any topic in geology that interests him, and attempts to make these topics understandable to everyone. Tweets as @GeoHerod.

GeoPoll: What should we do with radioactive waste?

GeoPoll: What should we do with radioactive waste?

I don’t think it is any secret that the world is facing an imminent energy crisis. We are trying to generate more power than ever before, but at the same time, we now realize we have to do it in a sustainable way that does not harm the environment or exacerbate any existing issues such as climate change. The problem is these two goals are often mutually exclusive. Most of our power generation methods have environmental implications or are simply at the early technology stage and cannot be relied upon the produce the juice that we all need. Thus, we’re stuck between a rock and a hard place when it comes to generating power. Therefore, the question becomes: we need more power, but at what cost? What are we willing to compromise to generate the energy? The answer is generally something in the environment protection aspect. We now accept that in generating the power we need we will have to affect the environment either to obtain the natural resources required or use huge tracts of land. The trick is how do we best manage the risks and impact of power generation?

The Bruce Nuclear Generating Station in Ontario, Canada. The largest nuclear plant in the world. (Wikipedia Commons – User: Cszmurlo)

This post isn’t about energy policy though. Instead, I would like to write about how we manage the risks of nuclear power, specifically the waste? One of the big knocks against nuclear energy is what do we do with the potentially dangerous and long lived waste that it generates? Over the years a huge range of ideas have been proposed, some silly, and some practical.  In this post I intend to explore some of these proposals and see which ones make the most sense given that this is a problem the world is facing now and is going to face for the foreseeable future, especially, if nuclear energy generation expands. One important point is that most radioactive waste is classified as low/intermediate level. This is essentially everything that is not heat generating fuel. The high level waste is the left over fuel. For all intents and purposes the disposal options aren’t different it’s just that high level waste seems scarier and has the potential to cause more environmental or human health damage if it escapes. Either way the waste, no matter what variety, has got to stay isolated essentially forever.

What are the key features that every storage solution must have?

1. Must be immobile/isolated from the environment and people for at least 100,000 to 1,000,000 years.

The reason for this requirement is pretty obvious. Nuclear waste is dangerous and therefore, it must be isolated from the environment for long periods of time. The reason it must be completely isolated for so long is because the half lives of the isotopes within the waste vary greatly. Thus even though the most highly radioactive isotopes decay to almost nothing within the first 1,000 years there are others, like iodine-129, which have long half lives and remain radioactive for millions of years.


This shows the relative activity of each major isotope in high level radioactive waste and how it decays overs time. The top red line shows the total radiation over time. This way you can easily see which isotopes are contributing the most to the total radioactivity of the waste over long time scales.

2. Must be potentially recoverable.

The reason that the waste must be potentially recoverable is two-fold. Should there be a problem with the repository it must be possible to remove the waste and either fix the problem or relocate it. The second reason is that as nuclear technologies advance it may become feasible to re-use the waste for energy generation or some other purpose. Therefore, the waste must remain isolated yet accessible during the lifetime of the repository.

3. Must be able to withstand every possible circumstance for incursion.

This one is clearly a key characteristic of a repository. This waste can be used for potentially nefarious reasons and thus it cannot be simple to access. Furthermore, given that the lifetime of the repository is far greater than human civilization has already existed it must also be able to withstand unintentional incursions by future generations. For example, future generations may not use existing languages. Therefore, it must be communicated unmistakably that you should not dig here.

Deep Geologic Repositories (DGR’s) 

The most popular of all solutions for long term disposal of radioactive was these day has to be deep geologic repositories. The idea behind this solution is to bury the waste hundreds of metres underground in an engineered space in a geologically impermeable and stable location. Almost every nation around the world with a nuclear program is investigating this means of disposal. This solution, while certainly expensive, meets the above criteria on all counts. The waste will be isolated for geological time scales. The site evaluation will use a wide variety of methods to confirm this. The waste will be recoverable as it is not that deeply buried and is still on land. In fact, some proposals I have seen for these repositories include an underground lab as well so people will actually be working at the repository site. Finally, the hundreds of metres of solid rock and engineered barriers will withstand attempts to access the waste. Most of these site investigations are looking at igneous rock, however, there is a strong case to be made that sedimentary sites may even be better. The current Canadian site under evaluation for low and intermediate level waste is in sedimentary rock and shows excellent potential as an environment that has been isolated for the last 400 million years.

A conceptual diagram for the proposed DGR in southern Ontario

A conceptual diagram for the proposed DGR in southern Ontario – Source: NWMO (2011), Descriptive Geosphere Site Model

Dilution in the ocean/Sub seafloor burial

This option is likely not going to be the most popular in my poll below, but in order to give equal treatment to all of the proposals I feel that it should be mentioned. The basics behind this idea are best described by the old and oft-repeated quote “dilution is the solution to pollution”. In essence, the idea is simple: drop the waste into the deep ocean where it can slowly disperse, decay and dilute. Obviously for high level waste this is a bad idea and is certainly not popular among the international community. However, while it may seem that this idea is ludicrous there are numerous operating nuclear facilities that currently release radioactive isotopes into the ocean. In fact, the nuclear fuel reprocessing facilities of Sellafield and La Hague are allowed to release a certain amount every year. These radioisotopes are then dispersed in the ocean currents and diluted. They are released at extremely low levels to begin with. However, their presence has afforded oceanographers the opportunity to use these isotopes as tracers of ocean currents.

Burial of the waste beneath the ocean floor has also been proposed as an option. It bears a similarity to deep geologic disposal, however, in a more remote and isolated environment. This slant does have some merit as long as the waste could still be recovered, however, the cost would be extremely high build the repository and recover the waste. Furthermore, this solution still has the problem of potentially releasing radionuclides into the ocean only with the added difficulty that fixing a leak would involve working hundreds of metres underwater. That said a leak of a small amount of radionuclides would be diluted within the ocean and would be unlikely to result in significant contamination unless it was very large.

Deep sea trenches/Subduction zones

This option might seem kind of similar to the sub seafloor burial option since trenches and subduction zones are part of the seafloor. However, the idea with this option is that the waste would eventually get subducted into the mantle and return to whence it came. Basically this idea is kind of like composting the waste, which admittedly seems appealing. However, this idea has all of the drawbacks of sub seafloor disposal and would certainly make the waste unrecoverable…at least once it had started its journey through the crust.

Blast it into space

This solution certainly meets the permanently isolate criteria as well as withstanding accidental incursion. 2 out of 3 ain’t bad, right? However, it does fall down when it comes to waste recovery for obvious reasons. This is a solution, that while appealing on the surface never really gained significant traction. One of the biggest reasons for this is the extremely costly nature of shuttle launches. The other major issue is where do we aim the rocket? Towards another planet? Into the vastness of space? Into the sun? All of these options are fraught with difficulties. Finally, if the launch should fail there is a possibility that the waste could be released into the local environment as well.

Disposal in ice sheets

Disposal of radioactive waste in ice sheets has been considered as well, although never very seriously. Continental ice sheets, such as the Antarctic and Greenland ice sheets, have been stable for many thousands of years. Additionally, as high level wastes are heat generating storage in glaciers would provide in situ cooling. Win-Win right? At least that was the early logic on the proposal when it came out the 70’s. In practice, this is clearly a pretty bad idea, especially since as the climate warms the long term stability of continental ice sheets is not as certain as it was when this idea was proposed. Furthermore, the heat generating capability of high level waste does not go away quickly, as the figure above shows, meaning that the waste could potentially melt its way out of the ice sheet or mix with the meltwater that was produced spreading radioisotopes. Thus, ensuring the waste’s stability for millions of years into the future is uncertain at best with this storage solution.

A composite satellite image of Antarctica. Source: Wikimedia Commons

Long term above ground storage

The final choice is store the waste in an engineered facility on the surface of the Earth. Generally, this disposal option is considered temporary or only for low-level radioactive waste. However, it has been investigated as a long term solution as well. The idea is the the waste is placed together in a constructed facility that has been engineered to isolate it from the environment and withstand any attempts at incursion. At the same time the facility would still be easy to access and make waste recovery very simple.One issue with this option is that since the waste is on the Earth surface it is impossible to truly seal it. Thus, future generations would also have to be responsible for maintaining the facility and ensuring the waste remained isolated.


An example of a long term above ground storage facility and its engineered barriers. This facility is planned for low-level waste in Port Hope, Ontario. Source


Ultimately, the legacy of nuclear power generation has to be dealt with in a safe and responsible manner for thousands to millions of years into the future. As a society we recognize this and the ideas outlined above range from the practical to the fantastic. I would like your opinion this question. Which of these solutions do you prefer? If the answer is none of above please comment below and encourage discussion on this topic!

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Shades of L’Aquila: Italian Geochemists avoid Huge Miscarriage of Justice

Shades of L’Aquila: Italian Geochemists avoid Huge Miscarriage of Justice

On rare occasions I hear about a story that must be told. This story is one of those and I feel that it deserves attention from the broader geoscience community.

We have all heard of the L’Aquila verdict against the Italian seismologists concerning the devastating earthquake in 2009. If you haven’t, read these articles by Chris Rowan. At the time the guilty verdict was handed down the entire geoscience community felt stunned that such a thing could have happened. The prevailing attitude was that it should not be possible to accuse and convict scientists for practicing responsible science. However, the old adage goes: those who don’t learn from history are doomed to repeat it. This brings me to the topic of this post, which was a very near miss by the Italian justice system against four geochemists from the University of Siena.

I originally heard of the story at Goldschmidt 2013 in Florence during a presentation by Dr. Luigi Marini and I wrote a short note about it in my daily summary of the conference on this blog. After the conference I asked Dr. Marini for more information as I felt the details of this case needed to be heard. I recently heard back from Dr. Marini that the case has now been resolved in favour of the geochemists and I am now free to write about their story on this blog.

The story begins, in December 2002, with several geochemists from the University of Siena being asked by the Italian Ministry of Defense to perform a geochemical-environmental study in the Sardinian Poligono Interforze Salto di Quirra (PISQ), comprising the two firing ranges of Perdasdefogu and Capo San Lorenzo.

Numerous different military activities were carried out at the PISQ since July 1st, 1956, including: (i) launch of rockets (ii) release of bombs from airplanes and helicopters (iii) use of artillery, from land and ships (iv) tests of pressurized pipes.

According to media and some local associations, Depleted-Uranium (DU) ammunitions were used in the PISQ and caused the so-called “Quirra Syndrome”. The “Quirra Syndrome” refers to an apparently greater-than-normal incidence of illnesses in the local population and military personnel that served at the Quirra base. It occurs mainly as cancers and natal genetic malformations. However, the “Quirra Syndrome”  has not been confirmed by the Italian national health authority, the Istituto Superiore di Sanità (ISS).

So one of the goals of the Siena geochemists was to determine if DU had been used in tests.


Google screen capture of Sardinia. Quirra, which is the subject of the study, is the red pointed location.

On the face of it the task seems simple enough: analyze soil, plants and water for U and its isotopic ratio and other potential contaminants from the munitions range (of which are there many). However, the complicating factor in all of this is that fact that adjacent to the firing range is an abandoned mine site called Baccu Locci. The Baccu Locci mine contains significant quantities of arsenopyrite and galena, which are arsenic and lead bearing minerals. Both arsenic and lead are known to have detrimental effects on the environment and humans. So the real question then becomes which is it? Mine waste or DU or other military contaminants? Furthermore, historical records from PISQ say no DU was used in the region, however, lots of other munitions with their own suite of toxic components may have been. Therefore, isolating a single cause of the possible impacts on the environment and humans becomes very complex indeed.

Taking a quick step back let’s review some of the basic science in question here.

What is DU?

DU stands for depleted uranium and it was the central contaminant discussed in the case. Uranium comes in many isotopes but the two most common are 238U and 235U. Most uranium found in nature is ~99.2% 238U and ~0.7% 235U. However, most nuclear reactors use fuel that is enriched in the isotope 235U to around 20% as it is more easily fissionable than natural uranium. A by-product of the enrichment process is uranium that is missing its 235U and has a larger proportion of 238U than is normally found in nature. This uranium is said to be depleted as it has had the 235U removed. This DU can then be used for other applications outside of the nuclear industry as it has the rare property of being one of the most dense metals known. This property makes it used in a wide variety of industries but particularly in military applications as a tip for missiles, armour penetrating bullets and other types of scary munitions. DU munitions have been used in Desert Storm, Bosnia, Kosovo and recently in Iraq and Afghanistan and at numerous munitions test sites around the world.

Gunner's mates inspect linked belts of Mark 149 Mod 2 20mm ammunition before loading it into the magazine of a Mark 16 Phalanx close-in weapons system aboard the battleship USS MISSOURI

US Navy personnel inspect linked belts of DU tipped ammunition (Wikimedia Commons)

The problem is that when DU munitions are used the uranium is blown into millions of tiny particulates that can spread on the wind and introduce widespread contamination to the environment. DU contamination is a serious issue. The radiological risks of DU are low in comparison to many other radionuclides due the long half life of 238U and the low energy alpha particles that it emits although they cannot be ignored altogether if the concentration of DU is high. The far greater risk from DU, however, is the high toxicity of the uranium metal itself as it attacks the kidneys in people similar to metals such as lead and cadmium. DU exposure has been linked to cancer, birth defects and other diseases for people living in contaminated areas and diseases afflicting veterans of the Gulf War as it acts in concert with other contaminants from these former war zones.

Acid Mine Drainage

Acid mine drainage is a phenomenon that many geochemists work with every day. In brief it occurs when sulphide minerals like galena (PbS), pyrite (FeS2) or arsenopyrite (FeAsS) are left exposed to open atmosphere and precipitation. What happens is a chemical oxidation reaction in which the sulphide minerals such as galena (PbS), pyrite (FeS) or arsenopyrite (FeAsS) react with air and water to release sulphuric acid and free metal ions. In the case of galena you get lead or arsenic from arsenopyrite.


An extreme example of acid mine drainage from a mine in Spain. (Wikimedia Commons)

Indeed, Frau et. al. (2009), found significant evidence of contamination from Baccu Locci Mine wastes in streams leading from the region, which is a tributary of the larger Quirra River that flows through the village into the Tyrrhenian Sea. The paper found elevated concentrations of lead, cadmium, zinc and arsenic near mine wastes, however, concentrations decreased downstream due to dilution and precipitation of insoluble lead-arsenic minerals. These heavy metals could have detrimental effect on the health of local residents.

OK, so back to the case.

The researchers from the University of Siena did what was asked of them and analyzed over 1500 samples for a variety of contaminants, including the 235U/238U ratio (on selected samples), totalling 25,000 results. Their findings were that there was no contamination from DU in the region and that the 235U/238U was on par with the natural 235U/238U ratio. However, they did find elevated levels of arsenic and lead around the former mine site and in catchments draining it.

Distribution map of uranium concentrations in top-soils of the two firing ranges of Perdasdefogu and Capo San Lorenzo and nearby areas (from the Siena University report, 2004).

Distribution map of uranium concentrations in top-soils of the two firing ranges of Perdasdefogu and Capo San Lorenzo and nearby areas (from the Siena University report, 2004).

Histogram (left) and statistical parameters of uranium concentrations in the top-soils of the two firing ranges of Perdasdefogu and Capo San Lorenzo and nearby areas (from the Siena University report, 2004).

Histogram (left) and statistical parameters of uranium concentrations in the top-soils of the two firing ranges of Perdasdefogu and Capo San Lorenzo and nearby areas (from the Siena University report, 2004).

Furthermore, one of the supporters of the Quirra syndrome conducted health related modelling using a code called HOTSPOT and found that in order to cause the anomalous number of cancers observed in Quirra between 80-140 tons of DU had to have been used, which is an absolutely huge amount (Zucchetti 2005).

These results met with extreme opposition from the local prosecutor who acted on the advice of a nuclear physicist from the University of Brescia who felt that geochemistry was not the proper way to investigate this problem and that the University of Siena scientists were hiding something. Indeed, the physicist felt that thorium was the true culprit and that geochemists were not qualified to analyze for radioactive contamination. (I obviously take great exception to this notion as a radioisotope geochemist and user of an accelerator mass spectrometer). Anyway, the geochemists were charged with two crimes in connection with their results:

  1. Not stating the danger of anomalous concentrations of thorium present at the firing ranges.
  2. Using knowledge the geochemists had gained from their previous work on DU in Kosovo to select methods that prevented them from detecting depleted uranium at PISQ.

In answer to the first charge the geochemists provided results of Th analyses for soils in the Quirra region. These show that there are no Th anomalies present in the soil. Therefore, the notion that Th is somehow the hidden, skulking culprit in all of this is simply not the case.

In answer to the second charge that the geochemists knowingly sampled in such a way as to conceal the detection of DU one simply has to look at the aims of the two investigations. In Kosovo the Siena scientists were sampling a small area with known DU contamination and a documented history of DU use. This makes it much simpler to find DU and sample for it. On the other hand, in Quirra, the use of DU has not been confirmed and the study area was far larger. This means that instead of a small scale, targeted sampling campaign the appropriate investigation tactic was a broad, large scale sampling effort that attempted to give an overview of contamination in the region. If DU was found a more detailed look could then be performed in that specific site. However, since no DU was found no more sampling was necessary.

Ultimately, the court appointed an independent expert to examine the results of the University of Siena geochemists in the light of these two charges before proceeding to trial. The expert found that the methods used by the University of Siena researchers were completely reasonable and that there was no evidence of a Th or DU anomaly. Thus on July 11, 2014 the case against the geochemists was dismissed and they were completely exonerated as the victims of unjustified persecution.

This entire episode was certainly very hard for the scientists from the University of Siena. In addition, it should also serve as a cautionary tale for the larger scientific community. This story can only breed hesitation and reticence on the part of scientists to participate in such efforts to help the public. Such aggression on the part of the local prosecutor is a warning to other scientists to stay away from the Quirra region and avoid the potential liability that comes with it. On a larger scale, this trial warns scientists outside of Italy that participating in issues involving human health, or ones that are emotionally charged, can be a bad thing. This lesson is not one that helps people. By telling scientists that if we don’t like your results we’ll attack you personally only turns us away and ultimately enhances ignorance and short sighted decision making. It will be a sad day indeed when I or others turn down a project because of the liability risk involved when we could actually be helping the public interest by practicing responsible science. I hope that this is not what Italy or other nations are coming to.

Thanks for reading! I would also like to acknowledge Dr. Luigi Marini for keeping me updated over the past several months as the trial progressed and his permission to blog about such an important issue.


Cristaldi M, Foschi C, Szpunar G, Brini C, Marinelli F, Triolo L. Toxic emissions from a military test site in the territory of Sardinia, Italy. Int J Environ Res Public Health. 2013;10(4):1631–46.

Frau F, Ardau C, Fanfani L. Environmental geochemistry and mineralogy of lead at the old mine area of Baccu Locci (south-east Sardinia, Italy). J Geochemical Explor. 2009;100(2-3):105–15.

Marini L. – Goldschmidt Abstracts 2013. Mineral Mag. 2013;77(5):1661–817. Available from:

Zucchetti M. Environmental Pollution and Health Effects in the Quirra Area, Sardinia Island (Italy) and the Depleted Uranium Case. J Environ Prot Ecol. 2006; 7(1): 82-92



I’m on TV!!

I’m on TV!!

About a year ago I was asked to appear as a guest on a kids television show about rocks and minerals called Finding Stuff Out. I was asked to come an talk about rocks, minerals, geology in general and how I got interested in geology. The show is for 8-10 year olds and it is truly fantastic! It has a really interesting format where kids actually ask questions and the host, Harrison, answers them with the help of experts (me), goes to places to find the answers or does experiments. In the end the show concludes with an answer to the question that started it all. In the case of my episode it was about diamonds.

I was fortunate enough to be involved in a significant amount of the show including the “gold” panning challenge and the final wrap up at the end of the show, which has a bit of a humorous slant to it!

This was my first experience filming anything let alone a full out TV show so I was not sure what to expect when I arrived at the studio in Montreal. The first thing I was given was a terrific lunch, so that was a nice way to start the afternoon off.

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Next I was shown to the set, which is incredible. See the pics below. It is truly amazing what the set designers and prop people can accomplish and I was pretty impressed. I was then given a script that had a few talking points. The actual dialog and what I say in the video is me speaking in my own words and basically making it up on the spot. This was pretty difficult so we would usually do a couple of takes as I polished my delivery a bit. All in all the 10 minutes of video that you see below took about 5-6 hours to shoot. The challenge section was by far the longest as we had to keep re-doing sections of the panning.

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There is also a lot of people watching as we would shoot each scene including sound people, script editors, prop people, cameramen…..and more. This was kind of a weird feeling since it felt like I was performing some sort of live show but I was supposed to be speaking directly to Harrison. I had to keep reminding myself not to worry about everyone else. Harrison, who looks younger than he actually is, was also fantastic. The guy is crazy talented and is a big part of making the show so interesting and popular. I had a great day shooting the episode and hopefully it won’t be my last experience with this sort of thing! Maybe I’ll do a video blog here or two when I finally finish my PhD!??

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Click here to display content from

I’ve edited the video above so it only includes parts of the show that I was in. There is lots more.

Hope you enjoy it!!

GeoPoll #3 – What got you interested in geology?

After a bit of an opinion hiatus I am back with the third geopoll. Every day I go to work at a university department filled with geologists. All of us are tackling different questions, but in the beginning we all started at the same place. Namely, not knowing anything about geoscience. In my conversations with colleagues over the years it appears that there is no single way to get into geology. We all entered the field from different avenues. For example, some people found it through a first year course, others, like me, started out as mineral and fossil collectors when they were kids or teenagers and still others only started in geology for graduate school and have a degree in chemistry or physics. Furthermore, geoscientists and professional geologists do not have a monopoly on enjoying and studying the Earth. In fact, geology is one of the few sciences that it is easy for anyone to practice at home and there are many amateur geologists out there that this poll also applies to as well. As I say, there is no single access point, but the passion unites us all. So, I have to ask: what got you interested in geology?

A gratuitous photo of the mineral Stibnite (SbS) from China. It is currently for sale here…if you happen to have a spare $23,500.

The serious side of this poll is perhaps it will hopefully inform how we can be better at geoscience outreach. If we have a better idea of how the current group of geologists got hooked perhaps we can target our outreach to a particular audience in the hopes of attracting a new generation of geoscientists. Or, as I suspect is the case, many people got hooked in university. Is this too late? Should we be trying to get geology courses into high school and elementary school curricula like chemistry and physics in order to get young people interested or at least educated about the earth? Perhaps us geoscience communicators need to work on attracting a younger audience?

Finally it is tough to think of good poll questions so if you have a good idea for a question(s) please post in the comments! As usual, click the view results button on the bottom of the poll to see how things are shaking out.

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