A SEDIMENTOLOGICAL AND GEOCHEMICAL STUDY OF LAKE ALLATOONA AND THE BERRY COLLEGE RESERVOIR, GEORGIA

Lake Allatoona (12,010 acres; located 30 miles NW of Atlanta) and Berry College Reservoir (20 acres, near Rome, GA) are man-made reservoirs. Lake Allatoona is heavily used, crossed by multiple roadways, including I-75, and a large percentage of its shores are heavily developed; receiving runoff from railways, residential and commercial areas, and treated sewage. The Berry College reservoir is a relatively pristine water body surrounded by undisturbed and undeveloped woodlands where no motorboats are allowed. Both are used as sources of drinking water, Allatoona for the cities of Atlanta and the surrounding communities, and Berry College for the campus. Another difference is the sediment composition. Lake Allatoona is underlain primarily by metamorphic rocks (mainly schist), while the Berry College Reservoir is underlain by sedimentary rocks (mainly shale and sandstone). The aim of this study is to obtain and analyze lake sediments from these two disparate reservoirs in northwest Georgia. Test sites were established around the lakes and representative samples, with some duplicates, from each site were taken. A total of 10 samples from Allatoona and 5 samples from different depths of the Berry Reservoir were obtained. The Allatoona samples were acquired from 1) close to the highway (I-75); 2) near a railroad trestle; 3) from a moderate and a heavily developed residential area; 4) near a marina and 5) in a cove surrounded by the Chattahoochee National Forest. Samples were washed through a 63µm sieve. The fine fraction was further analyzed using the standard pipette method and the coarse fraction was dried and Ro-Tap through a series of sieves. Metamorphic lithic fragments, micas and quartz dominate the sediments from Allatoona, with an average phi size skewed towards the coarse fraction (>63µm). The sediments from Berry are primarily silts and clays with an average phi size skewed towards the fine fraction (<63µm). Sediments for the geochemical analysis are wet-sieved through a stainless steel 63µm sieve. The sediment is also centrifuged to obtain a < 4µm fraction. Partial digestions using trace-metal grade reagents and Teflon vessels are performed using EPA SW-846 Method 3050B for both the <63µm and <4µm fractions. Heavy metals (Zn, Pb, As, Cd, Cu, Cr, Fe) will be analyzed using flame AA and the results will be presented as well.