Jailene Cerezo, Mount Saint Mary's University

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Abstract:

Changes in the biogeochemical processes found in the marine sediments of the Chesapeake Bay’s Patuxent River, have been currently influenced by sulfate intrusion due to sea-level rise. In our investigation of these biogeochemical processes we collected core samples along a salinity gradient in the river at 4 stations. Using one of the replicate core samples, characterization of the core was conducted by analyzing for trace metals iron (Fe) and manganese (Mn²⁺), porosity, methane in pore water, major ions, and sulfide (H₂S). The first 10 cm of the second core sample from each station was then used to create four slurry mixtures. From the homogenized sediment, triplicate sediment samples were taken for each treatment type for a total of 36 incubations; a potassium hydroxide (KOH) kill control, a sulfate enriched treatment and the native sediment at in situ sulfate concentrations. Station 1.5 showed the greatest concentrations of CH₄ (ppm) for all treatment types. The highest concentration of CH₄ was seen in the in situ overlying water treatment at 5270 ppm. High SO₄^2- treatment showed final CH₄ concentrations at 216 ppm and basified treatment showed average cumulative CH₄ at 52 ppm. Overall this study looks to further expand research needed to understand sulfate mediated anaerobic oxidation of methane (AOM), which is performed between methanotrophic archaea and sulfate-reducing bacteria, and how it affected by external factors such as sea-level rise due to sulfate intrusion (Segarra et al., 2013).