ABSTRACT

In 1993, approximately one year after passage of Hurricane Andrew, samples were taken from 97 locations in the Barataria estuary to determine the impact of the storm on bottom sediment texture and heavy metal content. Bottom sediments of the Barataria estuary are enriched in sand relative to other southeastern Lousiana estuaries (e.g., Lakes Pontchartrain and Maurepas). Sand content of bottom sediments is comparable to that of Perdido Bay, Alabama/Florida and other estuaries along the Mississippi-Alabama-Florida coast, but this has not always been the case. Comparison of ternary sediment diagrams for 1969 and 1993 indicates that bottom sediment sand content has increased over the past 24 years. In 1969, the bottom of Barataria estuary consisted predominantly of sandy and clayey silts; presently, sand-silt-clay is the most abundant sediment type. Passage of eight hurricanes near the estuary, including Hurricane Andrew in 1992, caused the relative increase in sand content of bottom sediments.

Bottom sediments of the Barataria estuary contain an average of approximately 5 moles/g acid volatile sulfide (AVS). Assuming sediment AVS is due to the presence of monosulfides, the average binding capacity of bottom sediments is approximately 5 moles divalent heavy metal/g. The Barataria estuary, therefore, has a limited capacity to absorb heavy metals via exchange reactions with sediment AVS. Heavy metal data for bottom sediments indicate that, with the exception of Ba, there has been no significant anthropogenic input of heavy metals into this estuary. Because bulk metal content is controlled largely by sediment texture, low metal concentrations are expected in a estuary containing relatively coarse-grained bottom sediments.