Lucinda Attakumah - Biogeochemistry
University of Maryland, College Park
The Influence of Plant Rhizosphere Activity on Anaerobic
Iron Cycling in Wetland Ecosystems
In saturated wetland environments, the plant rhizosphere (or rooting zone) introduces oxygen into otherwise oxygen-free soil environments. This plant-derived oxygen can have important implications for ecosystem processes. The goal of my project was to understand how iron cycling varied in areas dominated by vegetation and areas where vegetation had been excluded due to the construction of boardwalks. I also investigated differences in other anaerobic processes such as methanogenesis and sulfate reduction in these sites. Contrary to our initial hypothesis the presence of vegetation did not increase the concentration of poorly crystalline iron (an oxygenated form of iron used by iron-reducing bacteria). In one of our study sites, concentrations of poorly crystalline iron were actually double in the unvegetated soil under the boardwalk. There was also a general pattern of higher porewater methane concentrations in unvegetated sediments. Additional studies are required to determine if this pattern is explained by lower rates of methane production in the presence of plants or an increased venting of methane through plant biomass. Overall, this research suggests that the removal of plants during boardwalk construction has influenced microbial activities at these sites; however, the impacts could be through fundamental changes in soil dynamics rather than simply through the removal of the plant rhizosphere influence. Importantly, my work also served to develop analytical methods for a larger iron project that will begin in the spring of 2007. I learned a lot from this project and planned on using some of the skills I acquired on future research. I plan on applying to graduate school next year and hopefully after that apply to medical school as well.
Quote: It was fabulous. I learned a lot and it was the most fun I ever had while doing research.
Funding provided by the National Science Foundation – Research Experience for Undergraduates (REU)