HEAVY METALS IN CRAYFISH POPULATIONS OF BUFFALO CREEK, CARROLL COUNTY, GEORGIA

Mining activities are one of the most well known sources for heavy metal contamination of streambed sediments. Industrial effluent from industries whose waste includes high concentrations of these metals, however, can also introduce excess amounts of these contaminants to the sediment in a stream. Buffalo Creek, a tributary of the Little Tallapoosa River in west Georgia, was the site of our investigation of the presence and concentrations of heavy metals in the crayfish populations resulting from sediment contamination by the past industrial activities of a wire and cable manufacturer which has been in operation since 1950. Although the company has recently developed an aggressive environmental stewardship policy, the early years of operation resulted in the industry’s contribution to the release of heavy metals into the waters of Buffalo Creek. Copper, cadmium, lead, and zinc are among the contaminants that were released, and consequently adsorbed onto the sediments of Buffalo Creek. These contaminants have remained in the sediments, subject only to relatively slow transport downstream. In order to determine the incidence of heavy metal concentrations entering the food chain in the study area, crayfish were selected as a bio-indicator species due to their highly limited range (30 m), virtually constant contact and interaction with the affected sediments including burrowing and possible ingestion, and their well-researched tendency to bio-accumulate metal contaminants. Crayfish from sites upstream and downstream of the point source, as well as samples collected from Dowdell Creek, a member of an unrelated watershed in Harris County, Georgia, were collected, depurated, and analyzed by acid digestion, using both ICP technologies and spectrometry methods. Results revealed a typical point source pattern, with the highest levels of metals recovered from crayfish found just downstream of the point source, followed by a gradual decrease with progression downstream. Copper levels were as high as 819 ppb. Zinc was the most abundant of the detected heavy metal contaminants with values on the order of 5.55 parts per million. Lead values followed similarly with values as high as 2.19 ppm.