Hi Geo peeps/fans! Simon here.

          I just started working in the lab over this Winter Term, and I'll be continuing into the next semester. I'm a senior Geology and Environmental Studies double-major from Baltimore, MD, and I'm thrilled to be doing research in this lab.

          I've been learning the nuts and bolts of working in the lab: what we do, and how to do it. I've been learning how to leach samples, centrifuge them, dry them down, and then run them in the Germanium detector. There's only Monica and myself working in the lab right now, so there is plenty to do!

Sieving a soil sample

Pouring a dried sample into a leaching bottle

Pouring Hydrochloric Acid into a sample to leach it

Once the leachate is removed from the solid residue through centrifuging,
I add Sodium Hydroxide to neutralize it

          Amanda gave me a project to determine how much water the samples absorb as they sit in the sample containers after being dried down. The assumption is that they do absorb some water because they have a high salt content (from the HCl reacting with the NaOH) and salts tend to absorb water. Gaining a better understanding of the water content in each sample will allow for a more accurate analysis of the composition of each sample.

          To test how much water is absorbed, I took some prepared samples and dried them down by placing them on the hot plate for two days. Of the nine samples, I chose three each of various masses to be left open, closed, or closed and sealed with electrical tape. I just started the experiment this morning, but I'm already seeing results, particularly from the samples left open to the air.

Water absorption experiment

          This Winter Term is going well and I'm looking forward to a great semester working in the Geomorphology Lab!

Until next time,

Simon

Selfie with Harbin (the germanium detector)

We're not in (Ar)Kansas Anymore!

Hello everybody,

For the first part of my winter term project this year I was able to help take samples at a few sites within Northern Arkansas. The project began as way for Dr. Amanda Keen-Zebert and Dr. Stephanie Shepherd to return to home and do some investigating in their backyard and developed into a hugely collaborative endeavor. Professors, grad students and undergrads (hey, thats me!) from different institutions across the US have expressed interest and offered to help in whatever way possible. The goals of this trip in particular were to obtain OSL samples from several terraces within some federally recognized park sites and also to perform Terrestrial Lidar Scanning (TLS) on bluffs that were of interest.

While we flew in on Wednesday night, we didn't make it back to the cabin until around 1AM, so there wasn't anytime for introductions or anything like that. So the next morning after breakfast we had a more formal sit down chat where everyone had the chance to introduce themselves and learn about the project. After that was done we loaded up the cars with supplies and headed out to the first site, Steel Creek. This location was only a 15-20 minute drive from our cabin, which was really nice as the day became brutally cold very quickly. Dr. Keen-Zebert had intended to spend the day both digging and scanning but as it was such a easily accessible and popular location for campers, we didn't know if we had permission to dig. So onto scanning then. The scanner is a machine that looks like a larger than usual lunch box with a rotating camera embedded on the top, which has to be mounted and leveled on a tripod. This machine also costs upwards of $40,000, so you want to make sure that tripod is firmly planted into the ground. Scanning went well enough for most of the morning, but as snow and the temperature started falling, the batteries started failing. After running back and forth between charging stations and the scanner for nearly an hour we had to call it quits.

Here I was able to level the machine with the assistance of Malcolm Willamson (Red Hat) and Mike, an Auburn University graduate student

Friday and Saturday the weather was still cold but we were able to keep warm by digging! After making the two hour journey to the Margret White site, Dr. Shepherd and Keen-Zebert showed us the locations for the two trenches. There isn't a whole lot to say about these days, they just included a lot of physical labor. On Saturday, before we started digging we did get to do a small field trip and explore the surrounding region, learning about the different rock types that are present within the local environment. Not surprisingly in a region shaped by fluvial activity, there was a lot of sandstone. 

The open field before we started trenching

On Sunday we had a little bit of a repreive after digging for two days and were able to learn about and see how Optically Stimulated Luminescence (OSL) sampling works. Its a process which takes advantage of impurities in the structures of quartz rich samples. Specifically Amanda was looking for a sample which doesn't have a uniform composition and holes were allowed to develop at the molecular level. These holes allow electrons to get stored when the sample is not in the presence of light. The process is somewhat analogous to charging a battery. 

The team finding a location to sample from on a bank that is somewhat shielded from direct sunlight.

Monday we went back to the Margret-White trenching site, this time accompanied by Amanda and Stephanie's professor from grad school who specialized in soils. The weather had also made a complete 180 and turned out to be around 60-70 degrees.

Sam, a Grad Student from Auburn University, explaining soil horizons to Hannah, Kathleen and I

Tuesday we had the fun job of refilling and erasing all of our hardwork  the trenches.

 

Its totally not a grave, I swear

We then closed off the week by going back to the Steel creek site and helping finish off the TLS work that we could not do because of the weather earlier. The process involved setting up the scanner with the right parameters and letting it do its thing for anywhere from 30-40minutes. In that time you could do anything you want, Malcolm and I skipped a lot of rocks, but you just had to make sure to not be in the field of view while the scanner was going. 

Malcolm being a brave, brave soul and carrying the scanner into the water and across very slippery rocks

Well, that was pretty much the extent of the trip, I had an absolute blast and if this at all interested you, there is a facebook page, Buffalo River Geoscience, set up which posts periodic updates about the project. 

Until next time,

Marcus

As our work intensifies, the winter does not

Hello Geo lovers! Monica here!

It's officially halfway through winter term and I can say for a fact that I do not believe snow on the ground has lasted without melting for more than a couple days since I arrived. It (almost) makes me nostalgic for the frigid and snowy Wisconsin winter days I chose to forgo to spend Winter Term here in Oberlin!

While the winter weather may disappoint, work in the lab is more exciting than ever. I spend my first week focusing on creating graphs and playing around with some variables to further refine the leaching process and better understand how specific we need to be to still be accurate with the programs/technology we use in the lab.

I finally (!!!) finished my project where I was testing out different ratios for the acid:sediment relationship during the leaching process. Even though the curve I created wasn't as smooth as we would have liked it to be (or frankly, smooth at all), it still showed that the original ratio we used is effective and the best choice. Which, perhaps, might be actually the best result. It's always reassuring to get confirmation you were doing something the best way all along.

Amanda also gave me a little side project of figuring out how light the elements we want to detect (to get the composition of a sediment) need to be to still get accurate activity levels. This is essentially because elements get harder and harder to detect the lighter (smaller on the periodic table) they get. I got to use my old friend ANGLE to run a bunch of calculations fiddling with different elements and it made me nostalgic for the days of STRONG this summer, although I am grateful for how time has dramatically improved my abilities to navigate excel.

I am also tracking down, compiling and preparing all of the data for the samples we need to our next paper on the leaching process. Unfortunately Amanda's multitude of projects create a lot to search through when a sample decides to go rogue, but it's good preparation for part of my work for the second half of winter term, which is to organize and catalog all the lab samples. Luckily I have the help of Simon, who just started in the lab and will post next week. I've also been busy teaching him the ways of the Dirt lab (aka leaching) and generating camaraderie between the current dirt lab members and alums (s/o to Joe).

Regardless, between writing/editing our paper, generating graphs, running samples, leaching, and organizing samples, things are busy and happy in the lab. I guess I'll use the time I wanted to spend sledding and skating leaching more samples and wishing for colder days.

-Monica

And Now for Something Completely Different: Archaeology Post

Hey all,
My name is Lucas Brown, and I was doing some research this last semester with Amanda advising me, so she asked that I do a short post about my findings.

Over the course of this last semester I was doing a hydrology study of an area in Italy that has been dug by archaeology professor Susan Kane since the mid 90's. This area has been inhabited for thousands of years by various cultures; first the Samnites, then the Romans, and now modern Italians. In ancient times the area was heavily terraced, so I was attempting to find out if the ancient terracing had affected the watersheds and general hydrology of the area. To do this I used a modern DEM of the area and also created another DEM using data that has been collect on the local terraces. I then created two sets of watersheds to see if they differed.

I found that several of the watersheds that had many of the terraces within them did have some changes, showing that the terraces did affect the local hydrology. Below are several figures that show the general area and also the watersheds that had changes.

The Monte Pallano area within the Abruzzo region

Base DEM watersheds

Terraced DEM watersheds

Hey everyone,

As the semester has come to an end, so has my time in the Geomorph lab until next Fall. Like Chloe, I'll be studying away in New Zealand next semester. As I wrote in my first blog post, research this semester has truly been a learning experience. I learned a lot not only about the subjects we are researching and how our methodology plays into it, but also about how research groups operate, particularly in a college setting.

After fall break, I quickly learned that there was a lot about the research that I didn't even touch on in this first semester, particularly the computational and qualitative aspects. After working with Chloe and Monica on leaching and running the CH-0xx samples, Chloe and I were tasked with running the numbers on as many of these samples as we could. Using a combination of several programs, we gathered and organized the data and eventually exported it to Excel. We then took the activity levels for lead-210 and cesium-137 and corrected these values taking into account radioactive decay, finally getting the numbers we were looking for. At the beginning of the semester, I had no idea how much number-crunching we would be doing, and it was really satisfying to have an actual number to point to and say "that's our data".

It has also been really cool to see that research is a work in progress for everyone. When I first joined the research group, I thought that the methodology was set in stone, but I quickly learned that this methodology was constantly being reviewed and refined through trial and error. I saw this process in action this semester with the introduction of neutralization into the leaching process, which has come with its own set of challenges, but has ultimately proven to be a successful idea.

I look forward to returning next Fall and doing more research!

Gabe

End of Fall Semester Update

Hey ya’ll! Chloe here.

The end of the semester is almost upon us. I hope everybody is getting through reading period and final exams in one piece. Whew, this was a long, fulfilling semester.

The semester began with Gabe, Monica, and I partnered up. We began working through the CH-0XX samples and managed to put a good dent in them through leaching and running. GSA was a big adventure way back in September and I am so grateful that I had the opportunity to go to Denver along with a bunch of other Obie geology majors. Getting to see Obie graduates was also a plus and I know that Monica and I both learned a great deal about how to present a research poster at a conference!

Moving past that, I was able to become more comfortable with the whole leaching process, even while the lab had to deal with acid rain in the fume hoods and the switch to using sodium hydroxide as a base. Using the base in order to neutralize the sample is not difficult and does not add on much more time to the overall leaching process, which is a lucky fix for our acid rain problem. And there is a lovely ~COLOR CHANGE~ in the leachate when adding the base, which is always entertaining. Using pH paper strips, we can just dab a drop of the solution onto the paper to see how acidic or basic it is. We are shooting for a neutral pH, which tends to come out rather greenish on the pH strip and some sort of orange-brown-red color in the beaker full of leachate. When heating up the leachate in order to dry it down, there is a substantial amount of salt that forms on the sides of the beaker. This sneaky salt can simply be scraped off the sides of the beaker back into the leachate, but it is definitely a cool new addition to the whole leaching process!   

Gabe and I also learned how to calculate for decay corrected activity in a variety of CH-0XX samples. This involved learning more about the software on the lab computers and what it is capable of. It was a bit tricky, but with the help of Amanda and one or two of our lab group members, it was easily done. Gabe and I have uploaded our results, which include samples from the CH-0XX group, onto the shared lab group Google drive. J

Well, I’m off to study abroad in ~New Zealand~ next semester so I won’t be posting until next fall. I hope you all have a wonderful spring semester and the leaching process continues to progress smoothly!

Signing off,

Chloe

The Dirt Lab is getting salty

Its times again for another dirt lab update!

As the semester comes to an end I can definitely say this has been a more eventful experience than last year. As mentioned in previous posts our methodology for readying samples to be run was and is a multi-step process. The samples must first be sieved, then leached and centrifuged, separated into leachate and residue and then dried. A key component we've recently just added is neutralizing the sample using Sodium Hydroxide.

Neutralizing the sample means that we are now evaporating off just water rather than highly acidic HCl. Though, adding this step to the procedure turned out to be quite the undertaking. First, just getting the NaOH took longer than expected. In the down time Hannah, Monica and I (but really it was mostly Hannah and Monica) had the exciting task of locating and preparing samples which had yet to be run. Once the base came in we started to get to work on coming up with a way to get the pH of the solution to as close to 7 as possible. Initially we thought using an indicator would be the best route. We thought wrong. Trying to observe color change in an already colored solution which creates a black complexation as base is added is like trying to thread a needle from space. Its just not going work in a timely or efficient manner. Also considering that the base and acid are different concentrations and that the acid is reacting with carbonates within the sample means that its not the most straightforward process.

Still, we tried to create a method for this madness. Mae Kate, Monica and I started out by adding a fair amount of methyl red to our yellow solution, turning it a dirty orange. We then tried adding half the amount of acids worth of base and saw it turn immediately black and brown. Unsurprisingly, we over shot this delicate process and created a solution that was extremely basic. Which we then corrected by adding a healthy shot of dilute acid (turns out it was 10M instead of 12) which promptly brought it back down an overly acidic pH range of about 2.

After this event Amanda suggested a titration system so I went about setting one up. I found some clamps, a titration beaker and using the methyl red and a slightly expired pH meter kit, was able to correct the first sample to around 7.5 pH.  The end result was an beaker of very nicely separated H2O and sample.

As this way of checking the pH of the samples was extremely tedious, Amanda was able to get us pH papers to test with. The only problem with using those is the possibility of losing some sample to the paper. In order to minimize that we're using a stirring rod and then trying to remove all drops from the rod, so that it is as dry as possible while still being damp from the solution to check acidity levels. 

So thats primarily what we've been up to this semester in the lab. Perfecting this new method of leachate and residue separation. We're still working out the exact numbers to achieve neutrality, right now the easiest way to know when to stop adding base is by a significant color change. We also need to figure out the new composition of samples in regards to the metal content to salt ratio. Previously we were just accounting for Iron and Magnesium in our program calculations, but now that we're precipitating a salt there are new variables to be considered. 

Until next time,

Marcus