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Can Manganese Help Save the World from Climate Change? Let’s Find Out!

Friday, July 21, 2017, by Sarah Pardi
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[Working in the anaerobic chamber to weigh out soil samples as well as make the substrate, L-DOPA, for the enzyme assays. Photo by Alex Gamble]Each morning after I eat breakfast with my fellow researchers/friends, I make my daily commute to University of Massachusetts, Amherst. It’s a beautiful 45 minute drive along windy roads through dense forest and quaint rural towns. Upon arrival at Paige Lab, I get to work on the soil samples I’ve collected from our plot back at Harvard Forest.

My research this summer, under the mentorship of Marco Keiluweit and Morris Jones, focuses on the role of manganese on forest floor litter decomposition through a soil moisture gradient. What most people don’t realize is that soil releases three times more CO2 than cars, fossil fuels, and other anthropogenic factors. With today’s global concern on climate change and green house gas emissions, carbon dynamics is a hot topic for research. As leaf litter decomposes, CO2 gets released from soil into the atmosphere. Manganese is directly related to this process since it is what fungi use to breakdown leaf litter. The rate of litter decomposition is correlated to how much carbon is emitted by soils. [Marco overseeing Sarah as she’s hard at work coring soil for redox probe installation within the wet region of the soil moisture gradient. Photo by Rachelle LaCroix]So if decomposition rates increase, the amount of CO2 emitted by soils and thus released into the atmosphere, also increase. What my project hopes to find is the rate of activity of the enzyme responsible for litter decomposition, the rate of litter decomposition, and what forms of manganese are found in the different soil layers. Our hypothesis is that along the soil moisture gradient, the transition zone (between the dry and wet regions) is where the greatest amount of litter decomposition activity occurs since that’s where most of the fungi like to hang out.

[Redox probes (Sarah assisted in making) installed in the transition zone of the soil moisture gradient. Photo by Sarah Pardi]At the beginning of this summer, I went out into the field to collect soil samples from the litter, organic, and A horizons along a moisture gradient (dry, transition, and wet). Later on I helped install redox probes (which I assisted in making) and moisture probes along that soil moisture gradient, and take readings from them once a week. (My dad was very proud of the fact that I learned how to solder, since making these redox probes required soldering metal wires together.) After collecting soil samples I let them air dry and sifted through them to get rocks and twigs out so only fine particles of soil are left. In the lab I then run enzyme assays and perform mineral extractions on the soil samples. My work consists of a lot of pipetting, a lot of pipetting. The enzyme assays measure the rate of activity of the enzyme responsible for litter decomposition. And the mineral extractions tell us what minerals, especially what forms of manganese, are in the different soil layers.

Even though each day is a busy one, to say the least, it’s nice to come “home” to a group of fellow researchers I call my friends. All 18 of us in the program live in a large house on the Harvard Forest property. We are assigned weekly household chores and meal shifts. Each week we help Tim, our chef, either prepare or clean up meals. It’s pretty fun helping Tim in the kitchen. He spoils us with the amazing meals he prepares each day, and everyone looks forward to the decadent desserts he makes. What’s great is that he also makes delicious vegan options! Having meal shifts and household chores really helped us learn how to live together as a large group and taught us to be responsible for our shared living spaces.

[96-well plates used for the enzyme assays. Photo by Sarah Pardi]I’ve made some really good friends during my time here at Harvard Forest. Every weekend we go on fun trips. We’ve stayed the weekend in New York City, spent a couple weekends in Boston, gone camping, and some of us are even going sky diving in Canada! I love the people in my lab and my mentors, too. Working with other undergraduate and graduate students in the lab has enhanced my experience.

I’ve really enjoyed my time here and have learned a lot along the way. I’ve learned what it means to be an independent researcher and be in charge of your own research project. I also learned that I’m very much allergic to the bugs here and that no matter how much DEET bug repellent you put on, the mosquitos in Massachusetts are immune to it.

Sarah Pardi is a rising senior at Loyola Marymount University in Los Angeles, CA where she majors in Biology and minors in Psychology.