ABSTRACT: A Rapid In Situ Survey of Metals in Sediments of Lake Pontchartrain, Lousiana

NOAKES, SCOTT E., DOUG K. DVORACEK*, and JOHN E. NOAKES

In September of 1996, the Center for Applied Isotope Studies of the University of Georgia (CAIS) worked in conjunction with the U.S. Geological Survey Office of Coastal Programs to conduct a regional bottom sediment survey of Lake Pontchartrain. Using a CAIS-developed rapid survey system for in situ collection of data and samples, over 750 surficial sediment samples were collected in a ten-day period, providing coverage on a three-quarter mile grid spacing over the entire lake region.

The Continuous Sediment Sampling and Analysis System, or CS³, samples the plume of surficial sediments generated by the movement of a towed sled along the seafloor. The CS³ is designed specifically for sampling of the fine sediments, which are the ultimate sink for most aquatic contaminants and the primary site of the sorption reactions which govern their fate and persistence. A sled-mounted submersible pump delivers an uninterrupted stream of sediment slurry to a shipboard processor, where the fine sediment fraction (<200 micrometers) is separated, dewatered, and deposited on a quartz fiber filter wafer.

The samples are presently undergoing analysis for elemental content using non-destructive energy-dispersive x-ray fluorescence spectroscopy (XRF). The analytical results will provide a baseline of elemental distribution values for the lakebed, delineating areas of greatest present concern and providing a basis for comparison for future environmental monitoring efforts.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana