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  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
Soil samples waiting for the next phase.
Soil samples and matrix extraction being filtered.