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

Geology Can Be Confusing Sometimes: A Memoir

Hey Everyone,

I'm Gabe, a 4th year (ish), and I just started working in the lab this semester. And it sure has been a heck of a time. I'll start by saying that I came into geology relatively late. Since coming to Oberlin as a transfer last year, I've been taking as many geo classes as possible, and finally worked up the courage to declare last semester. It's been an eventful and exciting year, and I've learned so much over the past three semesters.

With that said, though, I'd be lying if I said I didn't find myself scratching my head sometimes, especially when it comes to research this semester. I took Earth Surface Processes last semester, and while I remember learning about isotopes and geochemistry... things have a way of slipping away during summer vacation. At the beginning of this semester, I figured that since I'm now a member of a team that's largely dedicated to working with these concepts, it's probably a good idea for me to understand them. During one of our first lab meetings this year, Amanda drew a few pictures and explained to me how the different fallout radionuclides (most importantly: ⁷ Be ²¹⁰Pb and ¹³⁷Cs) reach the soil, how they are differentially adsorbed and stored, and how they are useful to geologists for understanding erosion. On a broad level, I understood the purpose of the research and the driving observations but... there were still a lot of questions, many of which I couldn't even figure out how to put into words.

Over fall break, Amanda gave me three papers which are all directly relevant to the research we do in the lab. Reading science writing, an art in itself, is still something I'm getting used to, but I made my way through all three papers unscathed. What I found really cool about these three papers was how differently they used the same relatively specific tools to investigate fairly different things. One paper, from 1992, was largely theoretical. The paper investigates how radionuclides, or "radiometric fingerprints," can be used to gather information on suspended sediment sources (another topic I should maybe read up on) because they are independent of many otherwise limiting factors like lithology and soil type. Another paper focused on how radionuclides can be used to distinguish different types of erosion, specifically different types of sub-surface erosion. This paper had a slightly more practical approach, and talked about how this distinction between erosion types can help guide erosion mitigation attempts. The third paper did not discuss radionuclides, but instead focused on the calculation of sediment yields in order to understand anthropogenic effects. This paper also had some fun historical context which even attracted my parents into talking about geochemistry with me. 

Reading these three papers, especially combined with the experience of leaching and running samples, was incredibly helpful. Although I still don't understand a lot of the the nitty gritty geochemistry, and may have skipped or skimmed a few paragraphs here or there, I definitely feel a lot more confident with my role in the research group as we enter the second half of the semester. And I'm certain that my understanding will only become more refined as the semester continues.

Let the leaching begin!

Hey everybody!

I hope you all are having a wonderful semester and enjoying the refreshing autumn weather. October break will soon be upon us!

I’ve had a very exciting first few weeks back at Oberlin. A large portion of the semester consisted of prepping for GSA back in September. That involved finalizing the leaching data that Adrian and I collected last semester and any new data collected over the summer by Marcus and Monica. Monica, Marcus, Adrian and I also spent time putting together a poster worthy of a presentation at GSA. And before I knew it, I was on a plane to Denver, Colorado to present at the conference!

It was a fantastic experience overall. I had the opportunity to see Oberlin alums, meet professionals from all different fields of geology, and even explore the city of Denver a bit with my fellow geo-nerds. The presentation of the poster with Adrian and Monica went smoothly and we spent the rest of our time at GSA going to geology talks and meetings. It was a very informative trip and even gave me a few new ideas about which fields of geology I may wish to pursue in the future.

And now on to…LEACHING! Our lab group has split up into smaller teams and everybody is embarking on the wonderful adventure that is leaching in the Carnegie geochem lab. Each lab member is getting to learn how to do the entire process and many samples are being leached every week. Monica, Gabe, and I are working on the CH-0XX samples (samples from the China trip a year or two ago).

As of right now, that is all that’s been happening. I’ll upload another blog post later in the year and hopefully have more to say. Monica and Gabe are both on my mini-team for the leaching project, so feel free to check out any blog posts that they upload and keep up-to-date on our progress!

Hope you all are enjoying the amazing ~fall~ weather!

Bye-bye!

-Chloe

P.S. Check out Marcus’ post if you want a quick refresher on the leaching process! J

Mid Semester Update

Hello everyone,

The colors haven't started changing outside just yet, but inside Oberlin's geochemistry lab there's certainly a lot going on. This semester has been focused on leaching!A former student in the lab came up with a plan to obtain data without having to use all sorts of proxy methods and avoid getting unrealistic values. To do this we remove grain coatings from samples, increasing the accuracy of our measurements. This involves using a fair amount of HCl to completely soak the sample; after some trial runs we've concluded that a 4:1 ratio of acid to sample is the sweet spot. Our process involves soaking the sample for at least 24 hours in acid in nalgene containers which are mostly submerged in a sonic bath. This procedure is perfect for Halloween as the contents of the bottles turn a spooky orange-ish brown when they are done. After that we have to decant off the leached grain coatings from the rest of the sample, a meticulous process involving the centrifuge, De-Ionized water and lots of patience. This part is the most time-consuming overall, but once the two components are separated out its smooth sailing. Throw the container holding acid on a hot plate and let all the HCl sizzle off and put the other container holding the residue in the oven. When thats all over we should have to containers of one sample that are ready to be run through our gamma spectrometer. This is the process i've been working through alongside most of the others working in Amandas lab this semester and its been a good time so far. This half of field work isn't as glamorous as spending nearly three weeks in China but its still rewarding nonetheless. We've  faced a few hurdles this semester already but overall its looking to be very data rich end of 2016.

Once the semester is over we should have a computer full of meaningful data points which will make for a much more interesting post, full of analysis and maybe even some pretty graphs

But until then this is all I've got to offer,
Marcus