USING XRD TO DETERMINE SILICATE SOURCES OF SEDIMENTS FOLLOWING THE DHW SPILL

Following the Deep Water Horizon Spill of 2010, a large sedimentation pulse known as MOSSFA (Marine Oil Snow Sedimentation & Flocculent Accumulation) occurred. The event resulted in increased levels of sediments, siliceous organisms, and foraminifera accumulating on the sea floor. In the years 2010-2012, a significant increase in biogenic silica content in sediment was identified in areas surrounding the spill. The goal of this project was to use XRF (X-Ray Fluorescence) and XRD (X-Ray Diffraction) techniques to create a new way of identifying this biogenic silica pulse, as well as find baseline measurements of silicate levels before the spill. Using archived sediments from 3 well documented sites in the Gulf, XRF was used to find the amount of silica in parts per million. The sediments were then analyzed using XRD to determine the mineral composition of the sediment. A high amount of silica (from XRF analysis) corresponding with a low amount of quartz (from XRD analysis) indicates the missing percentage of silica is contained in biogenic silicates. Our baseline measurements provide new quantifications of sedimentation following the spill, as well as lay the unprecedented foundation for XRD in determining deep sea sediment composition.