Sediment quality in near coastal waters of the Gulf of Mexico: Influence of Hurricane Katrina

Abstract

The results of the present study represent a synoptic analysis of sediment quality in coastal waters of Lake Pontchartrain and Mississippi Sound two months after the landfall of Hurricane Katrina. Posthurricane conditions were compared to prehurricane (2000-2004) conditions, for sediment quality data. There were no exceedances of effects range median (ERM) sediment quality guideline values for chemical contaminants in any of the sediment samples collected from the Lake Pontchartrain or the Mississippi Sound study areas following the hurricane. Lower threshold effects range low (ERL) values were exceeded for As, Cd, and Ni at several stations in both survey areas, similar to levels of contamination observed prior to the hurricane. The comparison of sediment quality indicators before and after the hurricane suggests considerable stability of these systems with respect to short-term ecological impacts. Although other studies have shown storm-related changes could be detected (e.g., effects on benthic communities associated with shifts in salinity), there were no indications of widespread sediment contamination.

Trace element concentrations in surface estuarine and marine sediments along the Mississippi Gulf Coast following Hurricane Katrina

“…Overall, some ecological changes were detected, but the evidence did not suggest widespread, permanent damage. In fact, some improvements to the coastal ecosystem may have occurred due to the "flushing" out of the area from the storm surge and rainfall (Macauley 2007;Macauley et al 2010).…”

The impact of a major hurricane on sediment geochemistry of a shallow subtropical estuary through strong resuspension

“…Goñi et al (2006) reported that a storm layer enriched with ne muds and higher organic content was formed one week after Hurricane Lili (2002) along the inner Louisiana shelf at ~ 20 m water depth, but not at depths < 10 m. They proposed that the elevated OC level in these relatively offshore sediments (0.3-0.9 wt% pre-hurricane, 0.7-1.7 wt% post-hurricane) was most likely contributed by the settling and deposition of the ner fraction of the resuspended seabed sediments. However, it was also reported that OC concentrations did not change in the sediments of Lake Pontchartrain and Mississippi Sound two months after Hurricane Katrina in 2005 (Macauley et al 2010), or those in the Neuse River Estuary one month following the passage of three hurricanes (Balthis et al 2006). Although the bulk OC content remained relatively constant in these examples, the source or composition of OC in the estuary sediment might have changed after the hurricanes.…”