Rapid survey of anthropogenic contaminants in surficial sediments of the Ashley River, Charleston, South Carolina
Noakes, Scott Edward
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The Continuous Sediment Sampling System (CS3), a unique, rapid seafloor sediment sampling system developed at The University of Georgia’s Center for Applied Isotope Studies, has been routinely utilized in the offshore dredged material disposal sites, but recently has been applied in riverine and estuarine environments. The CS3 is capable of rapidly collecting surficial sediment samples over a large estuarine or riverine environment in a relatively short time period enabling a cost-effective method for completing large scale regional environmental surveys. The Ashley River, located in Charleston, South Carolina, served as an excellent test site for such a survey because of contamination problems resulting from extensive, long-term regional industrial and urban development. The sediment mapping results for the Ashley River clearly demonstrated the usefulness for the CS3 in the riverine or estuarine environment. The CS3 was effectively deployed without event and was able to collect numerous samples within a short period of time. Many of the contoured survey analytes showed trends of elevated concentrations that appeared to be directly associated with known industrial and urban contamination sources. The Ashley River has a high concentration of silt and clay, which due to their high surface area and ionic attraction tend to adsorb trace metals. This affiliation is commonly referred to the grain-size effect. One method for normalizing the data to offset the grain-size effect is to ratio the metals to aluminum, a common geochemical normalizing factor. However, after normalizing the data, many of the contoured trends still showed correlation to these potential contaminant sources. As a result of this study, it has been demonstrated that the technology now exists to rapidly survey large estuarine and riverine environments in a cost-effective manner. Large databases of elemental, organic, chemical, and physical data can be compiled to aid in the prediction and assessment of the environmental fate of contaminant chemicals in the aquatic environment.