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Tools of the Trade

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:

Geology Photo of the Week #33

May 13, 2013

The photo of the week this week is of a very special place in Canada. Yes, predictably, it is the Yukon. However, this part of the Yukon is unique. It is a special region known as Beringia, which extends into Alaska and Siberia and it is the only part of Canada that was not covered by kilometers of ice during the last glaciation. Beringia is a special place because it is believed that that first human inhabitants of North America made their way across the exposed land bridge form Siberia into the Yukon and spread west and south. Geologically, Berinia is interesting as it is full of Pleistocene mammal fossils like mammoths, short faced bears, giant beavers and other giant mammals. It is also strange because of the degree of weathering and erosion that the rocks have undergone is like nowhere else in Canada. Piles of talus may not seem like a big deal to people from other parts of the world, but for a Canadian geologist this is a somewhat unusual sight as most of our mountains had a good scraping 20,000 years ago and we just don’t see this level of weathering anywhere else in the country.

Cheers,

Matt

Geology Photo of the Week #32 – Name that squid!

May 6, 2013

This edition of the photo of the week highlights another piece from my personal collection.

Cephalopod – Matt Herod Collection (Photo: Matt Herod)

This is a cephalopod. More specifically it is a member of the Order Endocerida and the Family Endoceratidae. This creature, which hopefully you can see was pretty large (golf tee for scale) was the largest of the Ordovician cephalopods found in Ontario and this is a particularly fine/large example mainly because it tapers all the way to the apex at the end, which is a very rare find, and because of its large size (~7ocm). Cepahlopods, such as Endoceras, were the top predators of the Ordovician ocean that once covered most of southern Ontario and they grew up to several metres long. The cephalopods of the past resembled modern squids of today. Indeed, they were the progenitors of the Cretaceous ammonites and the squid and octopi of today’s oceans. If you enjoy calamari, thank a cephalopod!

(Photo: Matt Herod)

This zoomed in look at the cephalopod shows the siphuncle and the suture lines, which divide the inner chambers. The siphuncle was an inner tube that ran the length of the cephalopod and allowed it to control its buoyancy. The fact that the siphucle and sutures are clearly preserved is a great feature of this cephalopod, however, there is more….

When I was extracting this fellow from the giant boulder he was in I was unfortunate enough to break him in several pieces, which I have now super-glued together. But why, you may ask, did I not super-glue him completely together? The answer is pictured below.

(Photo: Matt Herod)

One of the points at which he broke contained this tiny little trilobite, which I am pretty sure is a Bumastus, based on the shape of its pygidium (tail). I decided not to rejoin the parts together so that we could still see this little dude that made this find a 2 for 1 deal. The obvious question is what is this little guy doing in a cephalopod? Was he eaten? Was he seeking shelter? Was he eating the already dead cephalopod? I have no idea, and it is pretty hard to prove one way or the other now. Please weigh in and let me know how you think he got in there!

Also, the other great fossil in my collection, the two trilobites that were featured in the Photo of the Week #25 and are named “Bert and Ernie”. We have a similar pair here, but they lack the awesome name. Please suggest your favourite names for this odd couple.

Cheers,

Matt

Guest Post: Dr. Sam Illingworth – To Boldy Go

May 2, 2013

Satellites are now so ubiquitous in our lives that there is something of a precedent to take them for granted. A normal daily routine for may people across the world may include watching television (satellite) as you check your twitter account (satellite) and have a look at the weather (satellite), all before you’ve even eaten your breakfast (not a satellite); whilst for those of us in the remote sensing community, whose work consists of analysing data from a large plethora of Earth-observing satellites, it can often seem that our lives are intertwined with those majestic flying machines as they dance their cosmic waltz far above the confines of planet Earth. It is almost staggering to believe that just over 50 years ago there was not a single manmade satellite in space, especially when you take into the consideration the fact that since its conception in 1957 the United States Satellite Surveillance Network (SNN) has chartered some 8,000+ anthropogenic obiters.

Sputnik 1 (souce: www.interestingfacts.org)

After the Second World War, the two global powerhouses of that era, the USA and the USSR, found themselves locked in a conflict of attrition that will come to be known as the Cold War. A war whose victors are judged not by the more conventional markers of land gain or battle tallies, but rather through the accumulation of weaponry and the rapid advancement of technology, of which the race to get into space plays a key and pivotal role. Most people, if asked who they considered to be the winners of the Space Race, would tell you that it was of course the USA, taking one small step for man and one giant leap for capitalism when Neil Alden Armstrong walked across the lunar landscape on July 21st 1969. Ask another group of people from a certain vintage or scientific persuasion, and they would probably tell you that the true winners of the Space Race were the Soviets, seeing as they were the first to actually get something up there with the launch of Sputnik 1 on October 4th 1957.  But for me there can only be one winner, and it is neither Apollo 11 nor Sputnik 1, but instead the much less lauded US satellite: Explorer 1.

The Sputnik satellite may have been the first into space, and the Apollo missions may have bee the first to demonstrate the capability of manned spaceflight, but as an Earth observational scientist it was the Explorer 1 satellite that I find to be the most intriguing, being as it was the first to carry a scientific payload; a set of instrumentation which would be used to make the first great scientific discovery from space.

The achievements of the Russian polymaths in ensuring that the Soviets were the first into space should of course never be overlooked, nor would it be strictly fair to say that the scientific significance of Sputnik 1 disappeared as soon as it had successfully reached the edge of the atmosphere – by measuring the drag on the satellite, scientists were able gain useful information about the density of the upper atmosphere – but I like to think of Sputnik 1 as that valiant guest at a wedding, who wishing to get the party started with suitable aplomb, makes a line straight for the empty dance floor only to find that once there they lack any of the necessary moves to do anything of particular note. Explorer 1 on the other hand can be thought of as the louder, more eccentric cousin of Sputnik 1, strutting up to the dance floor without a tie (incredibly there was no tape recorder installed on Explorer 1, meaning that data could only be analysed in near real time as it was transmitted back down the scientists on the ground) before starting to cut shapes that would make even a computerised lathe turn green with envy.

From left to right: William H. Pickering, director of the Jet Propulsion Laboratory, which designed and built Explorer 1. James A. Van Allen, University of Iowa physicist who directed the design and creation of Explorer’s instruments.
Wernher von Braun, head of the U.S. Army Ballistic Missile Agency team that designed and built the Jupiter-C rocket (Source: Smithsonian National Air and Space Museum).

Explorer 1 was launched on the 31st January 1958, becoming the first of the USA’s forays into the vast unknowns of the surrounding cosmos. The design and build of the scientific payload was Lead by Dr. James Van Allen of the University of Iowa, its purpose being to measure cosmic rays as they made their way from the Supernovae explosions of distant stars within our galaxy and towards the Earth. The instrumentation was effectively a Geiger-Müller counter, set up to count the number of high energy cosmic rays as they passed through the relatively fragile shell of the satellite’s metallic exterior, and it was expected that the instrument would return values of approximately 30 rays per second. However, the scientists noted that at certain points in its orbit the instrumentation was returning values of 0 rays per second. Upon closer inspection of the data (along with the measurements taken by Explorer 3, launched on 26th March 1958, and complete with requisite tape recorder) it turned out that these zero values all seemed to be concentrated around South America, and that they only seemed to be present when the satellite was flying at an altitude of greater than 2000 km; at altitudes less than this the instrument recorded the expected 30 counts per second. The team at Iowa soon deduced that these zero counts weren’t zero counts at all, rather they were errors in the data brought about by the instrumentation being bombarded by a powerful stream of highly energised particles that were beyond its measuring capabilities. Van Allen (and others at the University of Iowa) proposed that the reason for this localised concentration was a doughnut-shaped belt of highly energized particles, trapped in formation as a result of the Earth’s magnetic field. These belts have since been named after their discoverer (and not as I had assumed, much to the amusement of one of my undergraduate lecturers, after US rock-hero Eddie van Halen), becoming the first scientific discovery to be made from space.

The Van Allen belts (source: Wikipedia

It was this monumental achievement that formed a significant contribution towards the potential of satellites to inform on the many wonders of our home planet, and it is for this reason that I put forward the Explorer 1 (and by association the USA – sorry soviet fans) team as the true winners of the Space Race, a worthy recipient of a truly intergalactic (well ok, monogalactic) battle.

 

Sam is a postdoctoral research assistant at the University of Manchester, where he spends most of his time working on the development of an algorithm for the retrieval of trace and greenhouse gas measurements from aircraft measured spectra, an algorithm that he affectionately refers to as MARS (the Manchester Airborne Retrieval Scheme). In his spare time Sam enjoys convincing scientists that they can learn to communicate their research more effectively by embracing theatrical technique in all its many guises.

Thanks for reading!