Hello! I’m Anna Kottkamp, a new MS student studying carbon dynamics in the soil-water interface at the Tully-Palmer Lab interface. Part of bridging this gap is introducing a new study system to the AgroEco Lab: the freshwater Delmarva Bays of the central Delmarva Peninsula.

Since this is a new study area for the AgroEco Lab, I wanted to give a brief background about these systems. Delmarva Bays are typically small, round/elliptical-shaped wetlands with a “sandy rim.” Delmarva Bays are also affectionately called “whale wallows,” and, while I like the imagery of whales once lounging around in places that are now exposed land, the origin of these bays is thought to be linked to wind patterns during the last ice age (read: sadly, not whales). Similar to the Prairie Potholes of the Midwest and Carolina Bays, Delmarva Bays belong to a class of wetlands referred to as “Geographically Isolated Wetlands.” Don’t let that title fool you- there is evidence that these wetlands often have temporary or slow connections to adjacent bodies of water and therefore influence landscape water quality and quantity (Cohen et al. 2015). According to recent estimates using LiDAR data, there are over 17,000 of these small wetlands throughout the Delmarva Peninsula (Fenstermacher et al. 2014). Many of these bays have been drained and/or converted to agricultural lands, and the differences between “natural,” “agricultural,” and “restored” bays makes for an interesting gradient to ask scientific questions about restoration, heterogeneity, and connectivity. In addition, many of these bays are in watersheds associated with the headwaters of rivers draining to the Chesapeake Bay, and thus could have implications for water quality in the Bay.

For my project with the Delmarva Bays, I hope to study the linkages between the soils surrounding these wetlands and the wetlands themselves to understand more about the role of soils in key carbon transformations to wetlands. At the beginning of September, my Palmer labmate Alec and I installed lysimeters at one by for some preliminary data collection –a critical component of the scientific process. During the install, I made sure to follow the Number One Rule of the Field: looking good.

We then collected soil solution samples to study Dissolved Organic Carbon (DOC) with a cool method called Fluorescence Excitation-Emissions Matrix Spectroscopy that I hope to describe in a future post. For now, I wanted to show some of the water samples we took from lysimeters as well as from the ponded water itself--- can you guess which one is the ponded water?

Pond water from the bay (appropriately named “Dark Bay”) is in the bottle furthest to the right.
The filters we used to filter samples also suggest differences between lysimeter/water samples--- check out that iron oxidation!

We are just at the beginning of exploring ways to differentiate DOC, look for more to come!
-​By Anna Kottkamp

Fellow student Jesse Wyner and I have spent this Spring semester in an ongoing scientific tease. We have our transitional soil samples, we have a good majority of the extractions completed, but the data we are aching for is still right over the horizon. Don’t get me wrong. Both of us have been very busy in the lab executing bicarbonate and DCB extractions which entail grinding soils, weighing soils, mixing up reagents, shaking test tubes, filtering samples, and freezing samples until we are ready to run them through their respective analysis. So far, my favorite extraction has been the bicarbonate extraction and digestion (testing for inorganic and organic P) because it is on the shaker table for 19 hours which means I get to sleep in a little bit more than with the DCB extraction! However, once we run the samples, I am most excited for the Oxalate extraction samples which we will run for aluminum and iron (and other cations) using the flame atomic absorption (AA) spectroscopy.
            Let me explain. The AA is a very precise, very expensive machine that demands respect. To begin, a small straw pulls up your ultra-filtered sample and then, before your very eyes, vaporizes it using a gas flame. The flame colors are magnificent- bright oranges, fuchsia, neon greens. These meaningful wild colors indicate various levels of each cation you are testing for. The atomic emissions are then measured when the AA reads the amount of light absorbed through the vaporized sample by shining a light beam into the flame [1] The concentration of the cation is directly translated through the computer system and the data is now ready to be compiled for analysis. Many studies have shown that P in soil is primarily bound to Fe; therefore, I am expecting to see a similar positive correlation between the bio-unavailable P released from the soils and the amount of Fe found in the soils because the P was previously bound up with Fe [2,3].
            For the remainder of the semester, Wyner and I will complete the final extractions and will begin focusing on the analysis of the samples. I am excited to use what I have learned about micronutrients, macronutrients, and nutrient chelation when I begin my next journey as a Plant Science Intern managing greenhouses in Orlando Florida for Walt Disney World.
 
References
1. Woodward, Simon. "How Does Atomic Spectroscopy Work?" Tecmec Ltd - Home. N.p., n.d. Web. 07 Apr. 2017. <http://www.atomicabsorption.co.uk/about.html>.
2.Jordan, Thomas; Cornwell, Jeffrey C.; Boynton, Walter R.; Anderson, Jon T., 2008. Changes in phosphorus biogeochemistry along an estuarine salinity gradient: The iron conveyor belt. Limnology and Oceanography 53:1. 172-184
3. Loeb, Roos; Lamers, Leon P.M.; Roelofs, Jan G.M., 2008. Prediction of phosphorus mobilisation in inundated floodplain soils. Environmental Pollution 156, 325-331

- By Natalie Agee