The Mississippi River (MR) stretches 2,320 miles across 10 states, and is fed by a range of organic matter inputs as it flows to the Gulf of Mexico. The United States Geological Survey (USGS) retrieves data, including gage height, dissolved oxygen, and dissolved nitrogen, from the Mississippi River in Baton Rouge, about 100 miles upstream from the mouth of the river. Although highly useful, these data do not provide insights into the chemical makeup of the dissolved organic matter (DOM) or the seasonal changes in this pool’s chemical makeup. In order to address this void in our understanding of the DOM chemical dynamics in the MR, a long-term sampling of the MR at its Southern end is being undertaken. This presentation reports on the initial six months of the project, which started in August 2017, and included 1) sampling before and after Hurricane Harvey to monitor how a major weather event impacts the MR carbon pool carbon and 2) daily sampling from September 27th to November 3rd, 2017 to closely monitor carbon level and composition fluctuations in the river over an extended period of time. Sample collection consisted of sampling the MR at three depths from the Baton Rouge public pier, on-site filtering of the water samples to 45 mM. The samples were then stored at 4 oC until the analysis, which included total carbon determination and UV/Vis and fluorescence (including parallel factor analysis) characterization. Using these data, the MR DOM pool dynamics will be discussed in terms of the amount and their nature (including terrestrial versus aquatic, freshness, and degree of humification).

Time-lapse view of carbon fluctuations in of the Mississippi River

255th National Meeting (2018)

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