Geochemistry

The Mysteries of Maqarin

Matt Herod July 19, 2013

We all know that cement is a man-made substance and therefore cement is always synthetic right? Wrong!

In the unusual case of Maqarin, Jordan the stars aligned to produce natural cement and many of the “synthetic” minerals found therein. The Maqarin site has been the subject of an intense geological investigation by a consortium of over 100 researchers for years in an attempt to try and understand this system and its implications. A fairly good overview is available here. Maqarin is located in north-east Jordan, near the border with Syria, in the river valley of the Yarmouk River. The valley is deeply incised allowing a good view of the stratigraphy. There are also several springs coming out of the sides of the valley wall and it is these and their relationship to the unusual geology that make Maqarin so interesting.

A map of Jordan. The location of Maqarin is starred. (Source)

Geologic History

The geologic history of the Maqarin site is very interesting and in many ways unique. Indeed, it was a unique combination of geology and geological events that led to its formation.

1. During the Cretaceous bituminous marls are formed. Basically, rocks that are full of bitumen and calcium carbonate. This rock has up to 20% organic matter! Bitumen forms when organic matter is heated during lithification and is similar to oil. It will burn. The marl is a white, chalky mineral primarily made of CaCO3. There is also about 10% sulphate, which becomes important later on in the geologic history.

2. Overlying the bituminous marls are chalky limestones that were deposited in the Tertiary.

3. The upper unit is basalt, which was deposited during the Pleistocene.

4. The bituminous marl underwent “pyro-metamorphism”. Basically, the rocks were heated to a point where the carbonate rocks cooked and formed high temperature cement minerals such as portlandite, ettringite and thaumasite. The heating though was not due to burial but actually from spontaneous combustion of the bitumen (Khoury et. al., 1992). The presence of sulphate allowed these minerals to form and better simulated a modern cement environment. When the marl, which is CaCO3, is combusted CaO or lime is formed. Then the infiltrating groundwater allows portlandite to form, which then reacted with the suplhates and silicates present to form the other cement minerals.

5. The rocks in the area are all highly fractured allowing water to easily seep through the site. This has led to weathering of the cements. The water seeping through the sites discharges near by and has a pH of 13!!!! The water that seeps through the “cement zone” of the Maqarin site picks up all sorts of dissolved ions and minerals. Remember that heating carbonate + water gives Ca(OH)2. Therefore, there is a huge supply of hydroxide available to raise the pH.

These 5 steps created the Maqarin analogue site as we see it now. Everything had to be perfect for it’s formation to happen: the rocks had to have the right chemistry, pyro-metamorphism had to occur and, the hydrogeology had to allow water to infiltrate and react with the rocks to produce the hyperalkaline springs. See the references below for a more detailed description of the geology and mineralogy of Maqarin.

An image of the Yarmouk River Valley from the Jordan Times. Notice the bedded cliffs along the river. At Maqarin it is these cliffs that have the springs in them. In the distace you can also make out the sraker, overlying basalt. (Source)

Some Geochemistry

I mentioned the “hyper-alkaline springs” above. These springs are super interesting to geochemists, since there not very many places on Earth where we can find springs of highly elevated pH. Indeed, it is much more common to find acidic springs than alkaline ones. However, the springs of Maqarin have exceptionally high pH’s. Why?

The alkaline springs, which flow out of the hillsides at Maqarin, formed due to the unique combination of the hydrogeology, structural geology and mineralogy of the site. As the water infiltrates through fractures in the rock it intially dissolves NaOH and KOH followed by Ca(OH)2, which is the cement mineral portlandite. All of the OH ions that enter solution contribute to the raising of the pH to around 12.5. This now caustic water is then able to react with other minerals and pick up a lot of metals such as uranium, chromium, vanadium and other exotic elements that would usually be insoluble and hence difficult to transport (Khoury et. al, 1992).

The stable isotopes also tell and interesting story about the origins of the water and its pathways at Maqarin. In arid climates, such as Jordan, the groundwater often reflects evaporation that took place either before or during recharge. The waters of Maqarin plot below the local meteoric water line, which is indeed indicative of evaporation before or during recharge of the groundwater. However, there is more to these waters than just evaporation. In fact, the hydration of the cement minerals, such as portlandite, can cause an 18O enrichment, which can also be seen in the Maqarin groundwaters, although it is difficult to differentiate this effect from that of evaporation, which also produces the same trend (Khoury et. al. 1992).

Plot of 18O vs 2H in the hyperalkaline springs of Maqarin, Jordan. The local meteoric water line (Irbid) and the eastern Mediterranean meteoric water line are both shown. Modified from Khoury et. al., 1992.

Why study Maqarin?

We need to understand how cement will behave over long time scales because in most nuclear waste storage or carbon sequestration designs one of the primary barriers between radionuclides/CO2 and the environment are the engineered barriers, many of which are made of cement. In fact, in a repository setting cement is everywhere. It will be used to contain the waste itself, plug up fractures, reinforce structures, and eventually to seal the whole place up. Sealing the place up water-tight (hopefully radio-nuclide tight also) is great, but what happens to the seals when they are subjected to a million years of groundwater flow? Well, the modelling suggests that…. Wait, did I just say modelling? You mean we rely on computer generated geochemical models to tell us what might happen in a number of scenarios? We don’t know exactly what will happen to all that cement that is plugging up a waste site?

An artists depiction of a deep geologic repository for low and intermediate level radioactive waste. (Source)

Enter Maqarin. Maqarin is such an interesting place because “cement” occurs naturally here and it provides a rare opportunity for researchers to actually see how cement and the minerals composing it behave over long time scales when subjected to weathering processes. Therefore, the site can be considered an analogue for the future behaviour of cement in the environment. Indeed, the hydration process that occurs in Maqarin when the groundwater reacts with NaOH, KOH and Ca(OH)2 is exactly what will happen when “man-made” cement is exposed to groundwater. Understanding the geochemistry and hydrogeology of a site like Maqarin gives real-world insights into the outcome of our modelling and we can take the data collected at places like Maqarin and compare them to our model results to verify its accuracy. Furthermore, using observations and empirical data to make conclusions about the future of waste repositories adds a whole new level of confidence in their design or identifies possible weaknesses.

In summary, since radioactive waste storage facilities, which are designed to have million year lifespans, are made of cement it is crucial that we know what will happen to them over long time periods. However, the problem is that modern cement is just that: modern. Therefore, we don’t really know how it will behave in certain environments or when conditions change, or during an ice age, etc, etc. In order to solve this problem we must turn to the next best thing, which is a natural site, such as Maqarin, that mimics the environmental conditions we are looking for and hopefully it can answer some of these questions. Hence, the beauty of the natural analogue.

Thanks for reading,

Matt

References

Khoury, H.N., Salameh, E., Abdul-Jaber, Q., 1985. Characteristics of an Unusual Highly Alkaline Water from the Maqarin Area, Northern Jordan. Journal of Hydrology 81, 79–91.

Khoury, H.N., Salameh, E., Clark, I.D., Fritz, P., Bajjali, W., Milodowski, a. E., Cave, M.R., Alexander, W.R., 1992. A natural analogue of high pH cement pore waters from the Maqarin area of northern Jordan. I: introduction to the site. Journal of Geochemical Exploration 46, 117–132.

Guest Post – Mike Power – Using surficial geochemistry to detect buried mineral deposits

Matt Herod June 27, 2013

Finding the next big mineral deposit is a dream of many geologists past, present and future. However, in the past hundred years or so, many of them close to surface have already been found and developed. This is because they can be found relatively inexpensively by traditional methods such as geochemical surveys, shallow geophysics, drilling, and a lot of luck. In the 21^st century, mineral exploration is focussing on methods to find deeply buried mineral deposits, ones that can lie almost 800m beneath the surface!

To develop new methods for finding such deposits, I travelled up to northern Saskatchewan, Canada, to the Athabasca Basin, which is home to the world’s highest grade uranium deposits. As part of my M.Sc. thesis at the University of Ottawa, I completed surficial geochemistry surveys above two different uranium (U) deposits – one (Phoenix) of which is “unconformity-related”, which means it lies between the Paleoproterozoic Basin and underlying Proterozoic basement rocks at 400 m depth below the surface. The other (Millennium) is a “basement-hosted” deposit, which means it lies entirely in these basement rocks at nearly 750 m depth. When I say surficial survey, I mean taking materials from the surface or near-surface environment – soils, tills, water, gas, and sandstone, and testing them with various geochemical methods to see if we can detect signatures possibly related to the U deposits beneath (fieldwork photo, Figure 1). For soils, sandstones & tills, we used total and partial digestion with various acids to leach out what is considered the “mobile” trace metal fraction that may have migrated from an ore deposit to the soil. For water, we looked at trace metals and also tritium, a known decay product of U. For gases, we looked for dissolved gas (helium) in water-filled drill holes, as this is also a known decay product of U and its daughter products.

Fig. 1: Here I am sampling above the Phoenix uranium deposit in September 2011, holding an auger with the various soil horizons we collected for sampling.

At the Phoenix survey site in 2011 & again in 2012, we discovered distinct metal anomalies in soil, till and sandstone (both humus, the organic-rich top fraction you might find in your local forest, and in B-horizon, the rich, brown soil a foot or so deeper) for U – but also Pb, Ni, Cu, Co, Mo, W, and Ag in these media (see Fig. 2a & 2b). Many of these elements are what are considered “pathfinder” metals for U, so will be enriched in the deposit itself or behave in a similar geochemical manner. Geochemical anomalies (high values) only exist when compared to background values that are low, whether a background station, or the mean + 2 σ (standard deviations) of each metal population, so any we considered had to meet this threshold. We found these anomalies directly above the deposit itself, and also above the location of a major ore-hosting fault, using a “transect” sampling method, or taking samples in a line across a targer. This allowed us to survey across the surface trace of the deposit perpendicular to the direction of the last major ice flow event, so this would not affect our results, or “smear” metals occurrences down-ice.

Fig. 2a: Contoured geochemical results for U in aqua regia digestion of humus soil samples from 2011-2012 and partial leach of the uppermost sandstones of the Manitou Falls Formation. The sandstone map showing interpolated U abundance from partial leach in were used as an independent base on which the soil transect results from aqua regia digestion were plotted. The surface traces of Zones A and B1 are also outlined for reference.

Fig 2b: Detailed 2012 humus soil sampling near the 2011 site (PHX028, furthest left on graph) that showed the highest U value. The results, (samples PHX231-237 & background measurement in 2012) confirm the reproducibility of anomalous U observed last year.

Based on the results we obtained at Phoenix, we decided to see if we could detect any anomalies in these materials that might be related to Millennium- the much deeper deposit. Using leaches on the humus and B-horizon soils, we were also able to see anomalies of U, Pb, Ni and Cu, which was encouraging, as these occurred over the deposit, and also over the surface projection of the ore-hosting fault, which was interpreted to come to surface based on a 3D seismic geophysics survey. Even more exciting, at this site, however, is that we obtained values of 4He (the main isotope of He) that were more than 700 times atmosphere in drill holes intersecting the deposit (Fig. 3)! (Ed Note: 4He is a product of uranium decay – the alpha particles that Uranium emits as it decays are, in fact, 4He nuclei. Therefore, an anomalously high 4He value is a good indicator of nearby Uranium decay.) It was important that in drill holes that weren’t near the deposit, we did observe atmosphere values, as to have a good measurement of background. Having anomalies in trace metals in the soils was one thing, but now we observed gas anomalies in water in the same locations. This led us to conclude that there was a high possible of redistribution and upward migration of U ore related metals and decay products from the deposit at depth.

Fig 3: Ratios of 4He/36Ar in the sample and 4He/36Ar in the calculated value for air-saturated water (ASW) vs. the inverse value of the abundance of 4He in each sample. Three samples (MLN G05-07) display extremely radiogenic values of 4He, while the typical atmosphere value is plotted (as a 4He/36Ar ratio of 1). The radiogenic 4He observed could possibly be sourced from the U deposit at depth

Now that we had our hypothesis of upward migration of metals (Phoenix) and both metals & gases (Millennium), could we guess if these processes are happening in modern times, or happened long ago? When we look at lead isotopes in humus at Phoenix, we observed that they show what is know as a common lead signature – which means lead not related to radiogenic, or radioactive, lead associated with active uranium decay. Therefore, we assume that this system is closed and metals have not migrated in many thousands (or millions) of years. At Millennium, however, we observe radiogenic He levels in modern-day groundwaters above the deposit, suggesting these products are actively migrating away from the deposit. So some deposits are closed at present day, and some are open. It just depends how you look at them!

That the geochemistry of surficial materials can be used to explore for deeply buried mineral deposits is a powerful idea, and much work still needs to be done depending on the deposit type and surficial environment being explored in. It is cheaper compared to geophysics and radiometrics, and can be completed with a relatively smaller crew of just a few people. And just like other techniques, it isn’t always going to find the next big deposit, but can be another useful instrument in the explorationist’s toolbox.

Michael Power is an MSc student in exploration geochemistry at the University of Ottawa in Ottawa, Canada. He did his undergraduate degree at Memorial University in Newfoundland, Canada. Michael has worked in a range of mineral and petroleum exploration related positions during and after his undergrad, from the oil sands of Alberta to the gold districts and offshore oil fields in Newfoundland. His MSc research is trying to better understand how geochemistry of surface materials can detect deeply buried U deposits. Tweets as @mikeyp22

Tools of the Trade

Matt Herod May 14, 2013

It is already May!! Crazy. Everyone in the department is incredibly busy right now trying to get all of those things on their winter to-do list checked off before it is time to head out to the field once again and re-fill the to-do list for next winter with sample prep, analysis and some interpretation. It is also time to start thinking of preparing for the field. Some of you hard rock folk might think it is a bit early to start prepping since all you need is a hammer, some canvas bags, and….what else do you need? However, for the geochemist it is time to start organizing our MESS aka. Mobile Experimental Sampling Supplies. Yes, I did just make that up, but I think you get my drift.

For real though, there are numerous essential items that every aqueous geochemist/hydrogeologist needs to bring or at least consider bringing into the field and since these type of items often get back ordered around this time of year it pays to start thinking about it early. Otherwise, one could find oneself lacking anything from their new pH meter to bottle caps the day before one leaves. Not that either of these things has ever happened to me…..mistakes are part of learning, right?

Uh-oh! Notice the chipped edges and the crack. These are not good things and this guy ended up in the garbage. (Photo: Ian Clark)

Key parameters that must be measured in the field are pH, Eh/ORP, temperature, alkalinity and conductivity. There are many other parameters that may be measured in the field, but those five are the most essential as they are subject to change once the sample is collected and therefore any long delay in measuring these can compromise the integrity of the data.

The most essential piece of field equipment is probably the pH meter. It is the one completely indispensable measurement that must be taken sitting beside the sampling site. The other four, are essential as well, but if I could only do one, I’d do pH. The reason I am touting pH measurements so highly is simply because in geochemistry so much depends on pH: speciation/redox, dissolved gases, dissolved aqueous complexes, mineral mobility, alkalinity, etc. The list goes on and on. The reason it is so essential to measure pH in the field is because it can often change once the sample is collected due to temperature changes or CO2 degassing. One key thing that must be done before any pH measurements are taken is calibration. It is very important to calibrate the probe at least once each day in order to make sure of getting the most accurate performance.

Our current pH meter and probe: the YSI Pro Plus meter and combination pH/ORP electrode. So far so good, although it has yet to face the rigours of the field. Note the geochemical nature of the background. (Photo: Matt Herod)

The other measurement that goes hand in hand with pH is Eh/ORP (oxidation reduction potential). ORP is a measurement of the oxidation/reduction potential of the water. It measures the electron activity of the water which has a major influence on the specification and solubility of elements and minerals in the water. Eh/ORP measurements are given in volts and often go hand in hand with pH. In fact, many pH probes also measure ORP at the same time so both of these crucial parameters are recorded simultaneously.

Conductivity is another measurement that uses its own probe. Conductivity of a water sample is a measurement of salinity of the water. It is basically a measurement of the ions in solution. Conductivity is not a particularly quantitative measurement in that the numbers that it gives are not super accurate, however, it does provide a very good idea of the relative salinity of different waters. For example a cold freshwater spring might have a very low conductivity whereas a lake after a rainstorm might be very high, due to increased sediment influx from runoff.

A nicer pic of our conductivity meter than I could take. (Source)

Alkalinity is another key field parameter that measures the acid buffering potential of the water sample, which directly corresponds to the concentration of HCO3 in the water, except in rare circumstances, where other species provide the acid buffering capabilities. Alkalinity titrations are a bit of a process, and do take a bit of time, but it is essential to do them ASAP as the loss of CO2 from the water can change the alkalinity. Alkalinity is measured by taking the initial pH and then slowly adding acid using a digital titrator and taking the pH along the way. The keys to this are to know the volume of water being titrated, the volume of acid added and the pH after each acid addition. With those basic numbers the amount of HCO3 can be calculated. The key equipment needed for alkalinity titrations are the pH meter, filtering apparatus, the digital titrator and a flask. By the way, helpful tip: don’t store the acid with the titrator, or make sure the acid is well sealed or else this can happen….and those babies aren’t cheap.

This is what happens when the acid is put away with the titrator. (Photo: Matt Herod)

Other field parameters that can be measured depending on the type of work being done are dissolved oxygen (DO), which is a common parameter in groundwater sampling and ion selective electrode measurements (ISE). ISE’s can provide a guide to the concentrations of certain ions in the field such as Cl, NH4, F, etc. Ion selective electrodes are great, but they often have a higher limit of detection that the mass spec back in the lab. They are very useful for groundwater sampling or contaminated water sites, where the concentration of dissolved ions is high.

So that is the basics on the different things we have to measure in the field, but there is a lot more stuff that has to come out in order to make these measurements possible and take the samples…and it is really, really easy to overlook something. For example, you can have a great pH meter and probes and be ready to go, but it won’t be much use if you forget one of the calibration standards back in the lab a few thousand kilometers away.

The key pieces of this list (if it were mine) include a lot of random, but very necessary, items such as: filter papers, syringes, filter cartridges, DIC/DOC septa, pH standards, AA and AAA batteries, digital titrator tips, acid, de-ionized water for rinsing, instruction manuals, rock hammer, ziploc bags, GPS and many other little things.

The list of stuff that must be brought to the field is dependent on the type of sampling that you are trying to do. The most important part of planning to the go the field is to pick the parameters that you would like to sample for and tailor your gear list, sample collection methods and field measurements to make sure the samples are of the highest quality. Follow these words of wisdom: “Determine what you are analyzing for in advance and collect your samples according to the proper protocols for each analyte! An analysis can be only as good as the sample that goes into the ICP-MS” – Nimal De Silva (ICP-MS legend). Basically, what this means is that in order to ensure good results the samples must be collected properly, in the proper containers and stored the right way until they are analyzed. Failing to do so could compromise the quality of the results.

Thanks for reading and I would love to hear if I missed anything or if anyone else has field methods/gear that they use for other types of sampling. Please comment!

Wishing everyone a productive field season.

Matt

p.s. I forgot to mention the most important piece of field equipment in the geologists arsenal:

The Great Fracking Debate

Matt Herod April 12, 2013

Yesterday the “Great Fracking Debate” took place at EGU2013 and I tuned in via webstream for the royal rumble of good vs. evil that was sure to take place. I have to say I was a little disappointed (not really) because the tone of the debate was very respectful and sophisticated. I guess if I want to see a good verbal sparring match I’ll have to head over to Parliament and take in a question period. The panellists speaking were: Tom Leveridge from the Energy and Climate Change Select Committee at House of Commons, UK; Brian Horsfield from the Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Germany; Jesús Carrera from the Department of Geosciences, Institute of Environmental Assessment and Water Research, Spain and Jurrien Westerhof from Greenpeace, Austria.

The discussion ranged from talking about how much the world needs fossil fuels and the hydrogeological implications of contamination all the way to the environmental and energy policy and the political will needed for fracking to become practicable in Europe. Overall the debate was a little light on the science and a bit heavy on the policy for my taste. However, it is obviously critical to discuss the politics of fracking since the science is merely a tool to inform the ultimate political decision and is not itself able to determine what is right or wrong. To that end there was a good bit of discussion on the future energy needs of the UK and Europe and if fracking was a necessary tool in order to provide for the energy needs of future generations. Furthermore, the panelists made some excellent points about the need for basic science in this issue and how by continuing to study the impacts and develop more effective ways to extract shale gas we can open the door to a whole new resource for the world and not just Europe or the US. If you would like to watch the entire debate it is archived here.

Since the science wasn’t really discussed I thought I’d throw out this primer to fracking and how it works. Enjoy!

Why are we fracking?

The first question that we should ask, before discussing what fracking is, is why are are we using hydraulic fracturing and what are its benefits. It’s an undeniable fact that the world is highly dependent on fossil fuels for energy, particularly natural gas and oil. However, our thirst for fossil fuels has led to the depletion of most of the easily accessible reserves around the world. This means that oil and gas companies, in their quest to meet demand, are developing new technologies and exploring new regions that were previously overlooked. One new source of natural gas is in shale. Most oil and natural gas is produced in shales due to their high organic content and subsequent heating during lithification (turn to rock). This heating produces oil and natural gas that slowly migrates from the shale into other rocks where it is trapped in what, until recently, were conventional reserves. Oil and gas recovery in the past focused on looking for places where oil and gas was trapped. However, the depletion of these reserves has forced us to look elsewhere, such as in the source rocks like shale, primarily for natural gas and coalbed methane. In theory this sounds great, similar to the old adage: why get an apple from the basket when you can get one from the tree, but in practice things are a little more difficult. The reason for this is that shale is made of very, very fine mineral grains. The natural gas that we would like to recover is trapped in the tiny pore spaces between these grains making it almost impossible to extract. In order to overcome this, the oil and gas industry has been forced to develop new technologies to enhance recovery. One of the most successful, but controversial, is fracking.

What is Hydraulic Fracturing (Fracking)??

The simplest answer to “what is fracking” is that it is a process in which fluids (more on that later) are injected into a borehole to increase pressure. This results in the rock at the bottom of the borehole fracturing. This allows us to recover resources that are hard to get more efficiently.

What is fracking? (Source: EPA Hydraulic Fracturing Study Plan,November 2011 – used with permission)

A good analogy is to think of a common scenario you likely tried as a kid. Imagine you have a juice box and instead of sucking on the straw (which represents the borehole) you blow into it instead. Most often this increase in pressure results in juice spraying out to top of the straw. However, one day you blow particularly hard, so hard that the sides of your juice box spit open and you experience catastrophic juice spillage on your favourite pants (not that this actually happened to me or anything…) However, the point is that this increase in pressure inside your juice box resulted in the sides splitting. Fracking works on the exact same principle. When the fracking liquid is injected into a drill hole the pressure on the surrounding rock goes up substantially If the pressure continues to rise we can cause the rock to fracture. As I mentioned above the permeability of shale is very low and therefore just drilling the well is not enough to recover the gas efficiently. In order to increase recovery we have to increase the permeability. Artificially creating fractures is the way we do so.

What gets injected?

Unfortunately, only the oil companies know the exact answer to this question. However, we do know that the mixture is mainly water with numerous chemical additives.

EPA Hydraulic Fracturing Study Plan, November 2011 – used with permission

Obviously there is a laundry list of chemicals that may be incorporated. It is worth noting that it would certainly not be beneficial to ingest any of these substances or to find them in groundwater. In fact, some of these chemicals can be toxic at ppb levels meaning that even the most minor contamination can have huge consequences. Furthermore, this is by no means a full list. The above chart is merely and example of some the chemicals you might expect to find in a fracking fluid. The fracking fluid that is used for each well is tailored specifically for that rock formation being targeted in order to maximize recovery.

What are the environmental effects?

One of the most controversial issues with fracking is the potential for environmental harm that may result from the practice. Some of these include surficial spills of the fracking fluid at the well site, contaminating groundwater either through subsurface migration of the fluid, infiltration from a spill, leaking around a bad well casing, or even earthquakes from the injection of the fluids. Furthermore, fracking requires large amounts of water and also produces large amounts of waste water. The problem created by getting this much clean water and then disposing of the resulting waste water also has potential for large environmental impacts on water sources such as local groundwater reserves in terms of both depleting and contaminating them.

EPA Hydraulic Fracturing Study Plan, November 2011 – used with permission

As of now, the impact of fracking is still being studied and moratoriums on drilling and fracking exist in many states and provinces in the U.S. and Canada. To date there have been numerous studies on the environmental impact of fracking and it is essential that these studies be performed in order to truly gauge the impact fracking could have at a particular site.

That is all for now. I realize that I have not addressed some of the more complex issues surrounding fracking. My intention was not to omit any piece of information, but to provide a basic primer about what fracking is and the issues surrounding it. For more detailed information or information about a particular site I encourage you to do more research. Thanks for reading.

Finally, what are your opinions on fracking? Is it a necessary evil? Or is it evil at all? Do you think we can be trusted to frack responsibly? I would love to hear other peoples thoughts on fracking.

Matt

References:

US Environmental Protection Agency: http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/index.cfm

US Environmental Protection Agency Hydraulic Fracturing Study Plan: http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/upload/hf_study_plan_110211_final_508.pdf

Note: This post was originally published at my pre-EGU blog on November 5, 2011. However, after recently watching the Great Fracking Debate at EGU2013 I thought I might do a re-post.