DISTRIBUTION OF TRACE ELEMENT CONCENTRATIONS ALONG THE MISSISSIPPI GULF COAST FOLLOWING HURRICANE KATRINA

Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, resulting in a storm surge that may have increased trace metal contamination in the coastal environment. We measured surface sediment trace metal concentrations monthly following the storm from 10 sites along the Mississippi Gulf Coast (Mobile, Grand Bay Heron and Cumbest (GBBC), Pascagoula, Ocean Springs (GCRL), Biloxi Gulf, Back Biloxi Bay (BBB), Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina (GPM)). Sediments were characterized for particle size and carbon and nitrogen contents. Samples were divided into two particle size fractions, <2 mm and <63 μm, and both sets were analyzed for 11 elements by collision reaction cell ICP-MS, including As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn. Most of the sites consisted of primarily medium- to fine- sand-size particles (93%), but a few, such as BBB, contained a notably higher amount of silt- and clay-size particles (44%). In general, sites that contained the most silt and clay content (GBBC, GCRL, and BBB) also had the highest percent total carbon (1.9%, 1.1%, and 1.5%, respectively; r = 0.540, p < 0.001). Overall, BBB had the highest concentrations of trace metals, followed by GBBC and GCRL. GPM contained the lowest concentrations of metals. For example, maximum Zn concentrations detected at BBB, GBBC, GCRL, and GPM were 666 ppm (February 2006), 299 ppm (June 2006), 237 ppm (July 2006), and 181 ppm (May 2006), respectively. In general, concentrations of the metals were greater in the <63 μm size fraction, compared to the <2 mm fraction. However, both size fractions were lossely correlated for all metals (r = 0.24 – 0.72, p < 0.03). No significant (p < 0.05) temporal variability in the metal concentrations at any site was detected. This data set will provide a baseline to compare with during storm recovery or future storm impacts. Supported by NOAA-NCDDC and NOAA-NIUST.