Recently the University of Saskatchewan has decided that it needs to increase its graduate enrollment substantially.  It has asked the Department of Soil Science to have 50 graduate students enrolled in its graduate programs. On average the University has a ratio of 2 M.Sc. for every 1 Ph.D.  Currently in Soil Science, we have 38 graduate students, 19 M.Sc. and 19 Ph.D.  There are 12 tenured faculty in the department which means that the University expects the Department to supervise on average 4.1 students (Appendix D:  CGSR Strategic Plan).  This means that we need to teach an additional 12 students.

It has been suggested that we radically need to re-think our teaching strategies.  That is, we should offer a strong non-thesis based program which would be completely course based.  In my opinion, this is not a great option.  Graduate students are not trained but rather mentored.  When I consider my relationships with Brian, Alexis, Wai, Sam, Kyle, and Juliska, I am reminded of my martial arts training.  A black belt is merely an indication that you are a serious student.  Similarily, my Ph.D. merely indicates that I have learned how to learn.  Thus, I try to train my students how to learn.  In turn, they try to train me how to think.

This is why graduate students are so valuable to society, to companies and to the world.  Not because they are highly trained soil scientists and toxicologists.  But rather because they have learned how to grasp difficult concepts, apply original solutions and then evaluate these solutions through sophisticated and rigorous analyses.

It is difficult to imagine how one would do this in a course based approach. Each one of the students who works with me is different.  They are all very smart and creative.  But each in their own way.  This is not a trivial motherhood statement but rather a close observation of how my students achieve their Ph.D.  A graduate student typically faces a data storm. By this I mean a vast amount of conflicting data points that overlap and need to be organized into a coherent story.  Alone they face the unknown and somehow craft a conceptual masterpiece from disparate data.  I am always reminded of Mickey Mouse in Fantasia as the Sorcerer’s Apprentice.  Every one of my students is a Sorcerer’s Apprentice.  My job is to make sure the broom doesn’t run amok.

I know of no way to teach this in a course.  Instead, what is needed is a dedicated, very smart student and a dedicated, very smart professor.  Then, one has a good graduate experience and everyone learns something, society, student and professor.   I don’t think we should change this.  We have great students and professors in our department.  We are one of the best Departments of Soil Science in the country and internationally recognized.  Lets not mess up a good thing.

A recent article (doi:10.1016/j.chemosphere.2007.08.035) by Budinsky et al investigated how readily dioxins and furans that contaminate soil can enter into our bloodstream.  They used two different animals to test this, a rat and a swine model. They used a rat model because the carcinogenic risk factors associated with dioxins and furans have been derived from rat toxicological data.  They also used a swine model because juvenile swine are our best available animal model for human exposure to ingested contaminated soil.

Two key findings jump out of this study. The first is that for rats around 30% of the dioxins reached the bloodstream whereas for pigs it was around 23%.  In contrast, a common chemical test meant to assess exposure to humans predicted only a 17%.  Thus, it looks like certain in vitro digestors might be underestimating exposure by around 2 fold. This should not be too surprising as currently the use of in vitro digestors for organic chemicals is not well accepted and still require substantial research and development before we begin to accept their use to predict human exposure.

The second key finding was that EROD activity varied depending on if the rats were exposed to dioxins in soil compared to oil.  This finding is very troubling.  Often we assess exposure of organic chemicals on the induction of these EROD enzymes (a subset of the P450 enzyme group).   The work by Budinsky et al. indicates that this may not be appropriate.  The reason is that typically an animal is exposed to the organic chemical in some sort of carrier, like corn oil and then this is compared to the organic chemical in soil.  What Budinksy et al. findings show is that the soil itself influences EROD activity.  Thus, if we calculate relative bioavailability through EROD activity it will be confounded by the dosing vehicle.

At the end of the day, I think that the Budinsky et al. article highlights how little we understand about pollutants in soil.  It certainly demonstrated to me that when working with pollutants in soil we need to be extra vigilant that we don’t make any assumptions until they are rigourously checked.

If you want to find this article and read about it yourself, simply open http://dx.doi.org and enter doi:10.1016/j.chemosphere.2007.08.035 in the text box provided, and then click Go

Last night I attended a talk given by Peter Prebble on climate change, oil sands and Saskatchewan.  It was a delightful talk and Peter’s discussion of climate change, oil sands and Saskatchewan was well researched, thoughtful, balanced and well delivered.  Peter made an interesting moral argument.  He argued that Saskatchewan has the highest per capita (tied with Qatar) greenhouse gas emissions at 72 tonnes per year in the World.  This is well above Canada’s average of around 20 and well above the world average of 5.  As a result, he argued that Saskatchewan should invest around 2% of its GDP (around a billion dollars) to help reduce these greenhouse gases.  He reasoned that we could not ask countries with a much larger greenhouse gas footprint but whose per capita emissions are lower, to reduce emissions if we did nothing to reduce our per capita emissions.  I asked him, if instead of focussing on reduction we should focus on mitigation.  He responded that he thought that mitigation should also be addressed but at a lower rate than reduction.

I disagree with Peter.  The future is bleak for Saskatchewan. We will be facing severe water shortages in our lifetimes.  These water shortages will endanger our ability to grow crops, mine potash and uranium and extract oil.  As a result,  our economic activity will become restricted as we move towards the middle of this century.  When I think about Saskatchewan and our moral obligation to the world.  I think about our ability to provide food, fuel and fertilizers to the world.  For example, potash is key to allowing China to be self sufficient in foodstuffs for example.   Our food exports prevent famine in many parts of the world.  It seems to me that our first obligation should be to insure that we can continue contributing to the worlds food, fuel and fertilizer needs in 2050.  In order to do that, we need to invest heavily in mitigation technologies.   We need to invest in technologies that reduce water use for all of our processes.    Think of it this way, yes our emission rate is high at 72 but there are only 1 million of us, so we only produce 72 million tonnes.  In contrast, emission rates of another country might be 5 tonnes per year but there are 500 million people in that country, so they produce 2.5 billion tonnes.  Would that second country really care that we reduced our emissions to 36 million tonnes but were unable to provide them with fertilizer or food and thus provoked a famine in their country.  I feel it would be much better to have the second country reduce their emission rate to 4.98 t (only a 1.4% reduction) and have Saskatchewan guarantee that we can continue to provide them with fuel, food and fertilizer.  Mother Nature wouldn’t care because global emissions would have been reduced by the same amount.

As a province, we need to begin having this discussion.  Can we afford to both mitigate and reduce or can we only do one?  If we only select one.  What would be best for the world and for us.  Climate change is upon us.  We need to come to a consensus and make our choices.

Arctic soils emit a greenhouse gas called nitrous oxide.  Nitrous oxide is 300 times more powerful than carbon dioxide in warming the planet.  In addition to its potential to warm the planet, nitrous oxide is one way that Arctic soils lose nitrogen.  This is important because nitrogen limits plant growth in the Arctic. Thus, the less nitrogen there is, fewer plants grow and then fewer caribou, muskox, rabbits, etc can live in the Arctic.

The release of nitrous oxide from soil typically increases as the soil temperature increases.  As the Arctic grows warmer, it will begin to contribute to greenhouse gas production.  This is one example of a positive feedback loop. Ecosystems that currently help control our temperature will begin to help increase our global temperature creating a runaway train that may destroy our civilization.  In addition, as these ecosystems grow warmer, they will begin to lose more and more nitrogen to the atmosphere and we do not know if they will then also increase their nitrogen fixation ability.  So, Arctic scientists are very interested in how Arctic soils will respond to temperature increases.

We’ve been investigating this issue at a place called Truelove Lowland which is a beautiful spot on Devon Island in Canada’s Arctic

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Stream on Truelove Lowland

.  We found that, yes, as soils warm, they do indeed emit more nitrous oxide.  However, surprisingly we found that this increase in emission dependended on the form of nitrogen available in the soil.  There are two major forms of inorganic nitrogen in soil, nitrate and ammonia.  Typically, nitrate is the form that is readily available to animals, plants and bacteria.  But in the Arctic, this is not always the case and normally when we do our analyses, we find that the amount of ammonia is the best predictor of how much nitrous oxide the soil is going produce.  In this experiment, when we fertilized with nitrate we saw large increases in nitrous oxide production with increasing temperature but when we fertilized with ammonia, we didn’t see this large increase.   This surprised us because in the field, we knew that the primary source of nitrous oxide was ammonia and not nitrate.  Using chemicals that inhibit certain groups of organisms, here is what we think is going on:

In the Arctic soil, fungi compete so strongly for nitrate that the only form of nitrogen available for release as nitrous oxide is ammonia.   So, this explains our field results, that is, ammonia dominates in the field settings because fungi suck up all the nitrate.

However, in some parts of the Arctic, in the bits that are soggy and wet, a group of organisms called denitrifiers will rapidly respond to climate change, if they have nitrate. They normally can’t get nitrate so this isn’t a problem, unless…

Many other Arctic scientists have found that nitrate levels can rapidly increase if snow depth increases.  It sounds counter-intuitive, but if the Arctic warms, then snow depth will likely increase.  So, people have been investigating what happens when snow depth increases as well as when the ecosystem warms.  Our results, suggest that Arctic soils that are currently unresponsive to increases in temperature, will suddenly become very responsive.

Is this a problem?  We don’t know yet.  How important is nitrous oxide contribution from Arctic soils to the world’s nitrous oxide budget?  Not really that important.  What will happen to nitrogen levels in these soils as they warm?  No one really knows.  We care about this because 50% of Canada’s carbon is safely stored in the Arctic soils.  If climate change was to suddenly release this carbon, very, very bad things would happen to our planet.

Approximately 50 soil scientists were brought together by Greg Henry to participate in the International Polar Year Project, Climate Change Effects on Canadian Arctic Tundra Ecosystems; Interdisciplinary and Multi-Scale Assessments.  Our goal in this project was to provide an assessment of Canadian Arctic soils.

About half Canada has permafrost, permanently frozen soil, and this permafrost dramatically changes how soils, plants and animals respond and contribute to climate change. We are investigating how these soils differ from one another in their responses and why they differ.  A key response is the storage of carbon because these permafrost soils hold 25% of the carbon sequestered in the terrestrial biosphere.  As a group, we have explored how these soils store, release and process carbon.  We knew that these carbon storage processes were controlled by nitrogen and thus, we also explored how nitrogen processing differed.  Our work in 2008, highlighted the ultimate importance of water for these soils.  Water affected how plants provided nitrogen to the soil; water affected how large organisms in the soil freed up this nitrogen and carbon for further storage and water affected how these soils released greenhouse gas back to the atmosphere.  Most surprisingly, we found that soils that had little water were most susceptible to climate change.  Our work highlighted that the vast desert that sits on the top of Canada, the Polar Desert, may be rapidly changing in response to climate change.  The sustainability of this change is not yet known and we worry that many fragile Arctic soils, such as the dunes and deserts, may be under threat.

The nitrogen cycle, controls carbon sequestration.  A key component of the nitrogen cycle in the Arctic is bryophytes which provide ammonia, which in turn is transformed to nitrate and used by plants.  As expected, bryophytes were controlled by moisture and needed phosphorus for maximum efficiency.  However, the normal organisms convert the nitrogen provided by bryophytes to a form available to the rest of the ecosystem, were absent.  The organisms, autotrophic ammonia oxidizers, were found at very low levels across the Arctic.  Instead, it appears that heterotrophic or archael ammonia oxidizers are the critical organisms in Canada’s Arctic.  This is important because heterotrophic and archael oxidizers respond very rapidly to increases in temperature whereas autotrophic oxidizers do not.  Thus, work in 2009 will focus on identifying what is the key group as this will be essential for predictions on how Arctic systems respond to climate change.

Most of Canada’s carbon is locked in the Arctic soils.  A key activity in 2008 was the collection of samples we need to estimate the Arctic soil carbon storage and if it was declining or increasing over the last 20 years.  This was a two step process, first we estimated soil carbon losses and/or gains over a long time period and then we estimated the variability associated with carbon storage in these soils.  These results are currently being linked to the Canadian Soil Carbon project.

All of our research teams report the same dependency in Arctic systems.  Response and contribution to climate change is highly dependent on plant species present in that soil. In other words, while moisture and temperature are important and have over the long term altered plant communities and soil types.  Current responses are linked intimately to the plant present at the sampling location.  As a group, we wish to highlight this observation as it suggests that invasive species in Arctic climes may have a significant influence on carbon cycling in Canada’s Arctic.