Recurrent sampling in soils inundated by Hurricane Katrina, St. Bernard Parish, Louisiana: Analytical results

Abstract

Recent flooding in New Orleans as a result of Hurricane Katrina caused surface waters to mingle with a variety of hazardous chemicals. The prolonged inundation of low-lying neighborhoods caused the potentially contaminated surface waters to saturate the underlying soils, possibly leaving behind contaminants once the floodwater receded. An area of Chalmette, St. Bernard Parish, was sampled on three occasions for the presence of Resource Conservation and Recovery Act (RCRA) metals and volatile organic carbons. Seven sample sites were established and sampled to a depth of 2 m (6.6 ft) on two or three site visits separated by approximately 30 days each. Additionally, surface bag sediments from each site were collected for toxicity testing. A total of 78 soil core, 12 surface soil bag, and several field reference samples were acquired. Key research questions were as follows. (1) Are detectable flood-related contaminants present in soil samples? (2) Are contaminants present at varying depths? (3) Do the concentrations of analytes change over time and by depth? (4) Are there possible toxicity and bioaccumulation effects? Flood-deposited sediments contained detectable contaminants. Sediment analysis revealed detectable levels of metals and organics in the soil at each location at each depth sampled. With deeper depths sampled, metal concentrations generally remained consistent, whereas the volatile organic concentrations generally decreased. Trending change in concentrations between events indicates a depth effect for metals. Results for volatile organics were mixed. Potential toxicity and bioaccumulation results will be discussed in the future.