Long-term natural recovery of heavy metal contamination and biogeochemical regimes of Mississippi Sound sediments post-Katrina

DSTR 21

S. Erin O'Reilly, eoreilly@nrlssc.navy.mil, Yoko Furukawa, yoko.furukawa@nrlssc.navy.mil, and Jody Bruton, jbruton@nrlssc.navy.mil. Marine Geosciences Division, Seafloor Sciences Branch, Naval Research Laboratory, 1005 Balch Blvd., Code 7431, Bldg. 1005, Stennis Space Center, MS 39529
Hurricane Katrina mobilized land-based contaminants as well as a significant quantity of bottom sediments. Consequently, previously buried, reduced sediments and microorganisms were exposed to the oxygenated water column, abruptly altering the fate of redox active sediment-bound heavy metal contaminants and the microbial community structure. This study examines the effect of hurricane Katrina on sediment biogeochemical regimes and natural attenuation of heavy metal contaminants. Mississsippi Sound sediment heavy metal distribution, porewater chemical data, and microbial community data are being monitored over time post-Katrina, and when possible, compared to pre-Katrina data. Depth profiles of box cores were analyzed for pH, conductivity, pore water components including SO42-, NH4+, and total TCO2, microbial community structure using fluorescent in-situ hybridization (FISH), and heavy metal concentration and association with solid sediment phases after sequential extraction using ICP. This monitors the natural recovery of environmentally significant variables in sediments after a catastrophic event.