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Kyle Chambers - Biogeochemistry

Ohio State University, Columbus

Plant Effects on the Iron and Methanogenic Pathways of Carbon Metabolism in a Tidal Freshwater Marsh

Wetlands are the largest natural emitters of methane, a powerful greenhouse gas.  Methane production by wetland soil bacteria can be suppressed by competition with other soil microbes.  Experimental plots were constructed in a tidal freshwater marsh of eastern Maryland.  The purpose was to observe the competition for organic carbon between methane producing bacteria and iron reducing bacteria in the presence and absence of vegetation.  In order to explain the plant effect, vegetation was removed from half of all experimental sites.  Porewater concentration of methane and iron, and flux rates of methane and carbon dioxide were quantified from June through August. Methane concentration increased in the absence of plants.  Methane emission rates were not significantly different for vegetated and unvegetated sites. Discrepancy between methane presence in vegetated and unvegetated sites is likely due to the differing pathways that methane is released from the soil to the atmosphere. Results show that iron reduction is not a significant pathway for anaerobic carbon metabolism at the experimental site.