ELEMENTAL ANALYSIS OF FLOODPLAIN SEDIMENTS FROM THE LOWER MISSISSIPPI RIVER AT SHIPLAND WMA AND ST. CATHERINE CREEK NWR

The Mississippi River is the fourth largest watershed on Earth discharging an average of 16-17k m³/s of water into the Gulf of Mexico. The Mississippi River is also one of the most heavily engineered waterways due to its commercial and agricultural importance. Human modifications along the river system have altered depositional patterns and rates in the floodplain, in some areas causing rapid sediment accretion between flood-control levees that consumes available flood storage.

This research focuses on the elemental characteristics of floodplain sediments sampled from 19 ~6m cores collected in the Lower Mississippi River batture at Shipland WMA and St. Catherine Creek NWR in Mississippi. Elemental analyses were done using (p)XRF, coupled with destructive lab techniques, LOI and magnetic susceptibility measurements, to derive semi-quantitative data that could support determinations for the best possible uses of the sediment if excavation is deemed necessary to help mitigate flooding. Further, these elemental data provide insight to the past several hundred years of floodplain deposition.

Preliminary data determined and expressed as percentages illustrates the following average elemental concentrations between two sites of study within Shipland WMA and one site of study within St. Catherine Creek NWR and are as follows: Shipland WMA (3.870% Al, .00056% As, 1.016% Ca, 1.281% Fe, 1.594% K, .062% P, .001863% Pb, 35.839% Si); St. Catherine Creek NWR (5.057% Al, .000842% As, 1.257% Ca, 2.372% Fe, 1.782% K, .177% P, .001863% Pb, 28.610% Si). Light elements (LE), elements lighter than Mg, make up most of the remaining percentage of each sample, with values typically ranging between 50-60%. Furthermore, the average LOI value exhibited for Shipland WMA is 1.34%, whereas St. Catherine Creek NWR is 2.85%. These initial findings lay the groundwork for further investigations into the soil composition and environmental characteristics of these important sites.